The feasibility to improve the response of quantum type (photonic) infrared (IR) detectors by applying surface plasmons is investigated. The HgCdTe material system is used as the detector platform of interest for which selected plasmonic structures and materials are applied and the influence studied by full-fielded electromagnetic simulations. It is shown that even for the several-micrometers-thick detector structures, similar to the commercial ones, broadband absorption enhancements of 30–40% can be achieved. The results suggest that improved, or new, pixel-level functionalities can be created for commercial IR detectors by relatively simple means. Additionally, high potential for cost reduction in high-performance IR imaging systems with multicolour capabilities is foreseen. Full article

We present a two-stage energy extraction circuit for a piezoelectric energy harvester, powering an asset-tracking system. Exploiting non-sinusoidal accelerations generated by many logistic transport devices, e.g., pushcarts, forklifts, assembly belts or cars, we are able to harvest sufficient electrical energy to transmit radio signals, which will allow to track the object when it is moving. By using the proposed energy extraction circuit, the energy extraction efficiency could be improved by at least 30% compared to a single-stage solution for sinusoidal excitations. In the practical use-case, the two-stage energy extraction network performs more than four times better compared to the single staged on. Full article

Integration of metal oxide nanowires in metal oxide gas sensors enables a new generation of gas sensor devices, with increased sensitivity and selectivity. For reproducible and stable performance of next generation sensors, the electric properties of integrated nanowires have to be well understood, since the detection principle of metal oxide gas sensors is based on the change in electrical conductivity during gas exposure. We study two different types of nanowires that show promising properties for gas sensor applications with a Scanning Probe Microscope—Scanning Electron Microscope combination. Electron Beam Induced Current and Kelvin Probe Force Microscopy measurements with a lateral resolution in the nanometer regime are performed. Our work offers new insights into the dependence of the nanowire work function on its composition and size, and into the local interaction between electron beam and semiconductor nanowires. Full article

According to LaMer diagram, a clearly separate of nucleation and grows step is required to synthesis of monodisperse nanoparticles. However, a critical mixing time T_c until the growth process is started, is not clear experimentally. In this paper, we prepared gold nanoparticles (GNPs) by liquid-phase reduction using citric acid on microfluidics with different flow rates. From relationship of the diameter of the prepared nanoparticle and the mixing time, T_c for the preparation of monodisperse GNPs was found for the first time. Full article

The implementation of additive manufacturing technology (e.g., digital printing) to the electronic packaging segment has recently received increasing attention. In almost all types of Fan-out wafer level packaging (FOWLP), redistribution layers (RDLs) are formed by a combination of photolithography, sputtering and plating process. Alternatively, in this study, inkjet-printed RDLs were introduced for FOWLP. In contrast to a subtractive method (e.g., photolithography), additive manufacturing techniques allow depositing the material only where it is desired. In the current study, RDL structures for different embedded modules were realized by inkjet printing and further characterized by electrical examinations. It was proposed that a digital printing process can be a more efficient and lower-cost solution especially for rapid prototyping of RDLs, since several production steps will be skipped, less material will be wasted and the supply chain will be shortened. Full article

We have been developing a sheet type shear force sensor. It has a unique structure consisting of two flexible electrode films, a rubber ring, and a liquid electrolyte. One of the electrode films has a central electrode and the other film had four symmetrically arranged electrodes. The diameter of the sensor head was 10 mm and the thickness was about 0.7 mm. We also developed mobile measurement circuit and software for the computer. This system can handle up to four sensors simultaneously. Furthermore, we obtained experimental data by attaching the sensor to a human body using a double‐sided adhering tape. Full article

The introduction and evaluation of a novel sensor design for a soil moisture sensor that can be manufactured on a PCB. The PCB acts as a capacitor, which uses the fringe effect to allow changes in permittivity of its surrounding medium to be identified, and this capacitance is measured via relatively simple charge and discharge times between two voltages through a series resistor. The system is implemented in a low-cost microcontroller, and coupled with being printable on a PCB, has the potential to make a highly cost-effective sensor. A custom Android Bluetooth application was produced to provide communication with and configuration of the sensor. Full article

Silver (Ag+) doped phosphate glass after exposure to ionizing radiation has an intense luminescence by stimulating with ultra-violet light. This phenomenon is called radiophotoluminescence (RPL). The RPL intensity was increased linearly with increasing X-ray irradiation dose up to about 1000 Gy. Small amount of bead-type RPL glass as large as about 0.05mm was well prepared with a jet flame system. It was confirmed that the RPL glass beads could be used as passive-type radiation dosimeters. Visualization and monitoring system of radiation dose distribution utilizing RPL phenomenon in the Ag+-doped phosphate glass are developed in this study. In the presentation, the basic luminescence properties are reported as well as the application of Ag+-doped phosphate glass beads to radiation dose distribution monitoring. Full article

Micro-milling is one of the commonly used methods of fabrication of microfluidic devices necessary for cell biological research and application. Commercial micro-milling machines are expensive, and researchers in developing countries can’t afford them. Here, we report the design and the development of a low-cost (<130 USD) micro milling machine and asses the prototyping capabilities of microfeatures in plastic materials. We demonstrate that the developed machine can be used in fabricating the plastic based microfluidic device. Full article

A ruthenium oxide (RuOx) electrode is being developed as potentiometric pH sensor for organs-on-chip applications. Open-circuit potential (OCP) of the RuOx electrode showed a response of −58.05 mV/pH, with no cross-sensitivity to potentially interfering/complexing ions (tested were lithium, sulfate, chloride, and calcium ions). Similar response was observed in complex biological medium. The electrode stored in liquid had a long-term drift of −0.8 mV/hour (corresponding to ΔpH of 0.013/hour) and response time in complex biological medium was 3.7 s. Minimum cross-sensitivity to oxygen was observed as the OCP shifted ~3 mV going from deoxygenated to oxygenated solution. This response is one magnitude lower than previously reported for metal- oxide pH sensors. Overall, the RuOx pH sensor has proven to be a suitable pH sensor for organs- on-chip applications. Full article

A novel coupling of a pair of identical two-contact (2C) magnetoresistors transformed into an in-plane sensitive Hall device is presented. The ohmic contacts are cross-linked, also adding a load resistor bridge, providing for constant current mode of operation and eliminating the inevitable parasitic offset. This silicon configuration, apart from its simplified layout, has linear and odd output voltage as a function of the magnetic field and current. The quadratic and even magnetoresistance in the two parts of this innovative device is completely compensated, which ensures high measurement accuracy alongside with identification of the magnetic field polarity. The experimental prototypes feature sensitivity of 110 V/AT. The mean lowest detected magnetic induction B at supply current of 3 mA over frequency range f ≤ 100 Hz at a signal-to-noise ratio equal to unity is Bmin ≈ 10 μT. Тhe high performance and the complete electrical, temperature and technological matching of the parts of this unusual Hall device make it very promising for many practical applications. Full article

A new 2D (two-dimensional) in-plane sensitive Hall-effect sensor comprising two identical n-Si Greek-crosses is presented. Each of the crosses contains one central square contact and, symmetrically to each of their four sides, an outer contact is available. Outer electrode from one configuration is connected with the respective opposite contact from the other configuration, thus forming four parallel three-contact (3C) Hall elements. These original connections provide pairs of opposite supply currents in each of the cross-Hall structure. Also the obligatory load resistors in the outer contacts of 3С Hall elements are replaced by internal resistances of crosses themselves. The samples have been implemented by IC technology, using four masks. The magnetic field is parallel to the structures’ plane. The couples of opposite contacts of each Greek-cross are the outputs for the two orthogonal components of the magnetic vector at sensitivities S ≈ 115 V/AT whereas the cross-talk is very promising, reaching no more than 2.4%. The mean lowest detected magnetic induction B at a supply current I_s = 3 mA over the frequency range f ≤ 500 Hz at a signal to noise ratio equal to unity, is B_min ≈ 14 μT. Full article

We present a simple equivalent circuit model for the transfer function of an optomechanical MEMS transducer capable of distortion-free electric field strength measurements. This model allows not only to qualitatively understand the characteristics of the transducer but also takes into account parasitic effects and material properties. Such parasitic effects have been observed while evaluating the first results of electric field measurements performed with the sensor. The model helped to identify and diminish these parasitic effects. Full article

We present a displacement-sensitive sensor comprising a microelectromechanical (MEMS) chip and organic optoelectronic components capable of measuring the heart and respiration rate on humans. The MEMS sensor relies on the inertial deflection of a small silicon oscillator. The readout of the deflection is optical and works via modulation of the light flux passing through the MEMS. Organic optoelectronics are used as light source and detector, since these offer a homogeneous light distribution and a more compact package in a future integration. Two types of MEMS, differing in their resonance frequency, were designed and characterised in combination with both organic and inorganic optoelectronics prior to measuring heart and respiration rate. Subsequently, by measurements on the neck, pulse and respiration rate were successfully measured. Full article

In this paper, the out-gassing from PolyEthylene (PE) film is studied under nuclear irradiation for the design and fabrication of passive MEMS dosimeters. The fabrication of sensor needs high temperature process that leads to specific constraints on the PE film. Radiation chemical yield of hydrogen production (G_H2) from PE under gamma irradiation is verified by mass spectroscopy after temperature annealing in vacuum up to 400 °C. Prototypes are fabricated to validate the fabrication of the sensor and then irradiated with high energy gamma radiation (with dose of 20 kGy). Measurements of membrane deflections after irradiation validate the G_H2 factor, showing low pollution level of PE during sensor fabrication. Full article

This work presents the investigation on a MEMS based optomechanical transducer for displacements or vibration regarding its cross-sensitivities to multidirectional input excitations. The principle of the optomechanical transducer is based on the modulation of the light flux passing through one static and one movable micromechanical aperture. This kind of transducer is of increasing interest for MEMS sensors since it has inherent benefits and can compete with state-ofthe- art readout concepts regarding its resolution. We have experimentally proven that the sensitivities of the device is 3.3 × 10⁷ V/m in x-direction, 8.23 × 10⁶ V/m in y-direction, while it is negligible in z-direction. Full article

We present our investigation on the gasochromic reaction of E141 (ii) towards the toxic gas nitrogen dioxide (NO2). E141 (ii) is a chlorophyllin-based food additive, typically used as green coloring for nearly all kinds of sweets. In this presentation we show an alternative approach for using E141 (ii) as optical gas indicator. All solid samples are prepared by multi-layer screen printing on different substrates like paper and PE-foil. Gas measurements are performed using an UV/Vis spectrometer. The influence of the substrate and according layer thickness is shown. Full article

Preparation and characterization of a WO₃-based thin film gas sensor are reported. The WO₃ film was prepared on a polished alumina substrate by a sol-gel method using an aqueous mixture solution of ammonium metatungstate hydrate and poly-vinyl alcohol, and fabricated into the gas sensor by forming interdigital electrodes on the surface. The characterization was conducted by measuring the electrical resistance change in NO, H₂, and NH₃ ambient as a function of gas concentration. It is revealed that the sensor has a specific sensitivity to NO, NO is detected as oxidizing gas although it is expected to be reducing gas, and the resistance changes with gas concentration in accordance with the Langmuir isotherm plot. Full article

Equivalent circuit-based analytical open-circuit sensitivity modelling of a capacitive-type MEMS acoustic sensor for Internet of things (IoT) application is presented. It can not only evaluate simply the characteristic of the sensitivity on wafer level, but also improve the accuracy of the sensitivity due to including the fringing field between the diaphragm and each etching hole in the back-plate. The effective capacitor model is obtained by applying the approximately linearized electric-field method (ALEM), resulting in the equivalent circuit-based dynamic model. From the sensor with a 325 µm-radius diaphragm, the effective radius and the effective residual stress of the diaphragm were extracted to be 299 µm and +23.0 MPa, respectively. With the pull-in voltage of. 12.0 V and the pad capacitance of 0.23 pF; the open-circuit sensitivity was modelled to 11.3 mV/Pa at 1 kHz in the bias of 10 V. Full article

We investigate the properties of highly confined Love modes in a phononic crystal based on an array of holes made in SiO₂ deposited on ST-cut Quartz substrate. An optimal choice of the geometrical parameters of the holes enables us to obtain wide stop-bands frequency for shear wave’s modes. The introduction of defect by removing lines of holes leads to nearly flat modes within the band gap and consequently paves the way to implement advanced design of electroacoustic filters and high-performance cavity resonators based on shear wave modes. The calculations are performed using finite element method based on the commercial software (COMSOL-Multiphysics). For transmission spectra, piezoelectric excitations are applied by considering the interdigital transducers, with results corroborating well the band structure predictions and the position of defects modes within the band gap. Full article

Passive and wireless SAW sensors can operate in extreme environment. However, there is no mass-market application for this technology yet, due notably to the lack of an adequate sensor housing solution. Package-less SAW sensors are therefore promising. Here, guided waves that propagate in a protective multilayer structure are used, instead of SAWs. However, issues will arise from the use of a multilayer structure. In particular, thermo-mechanical effects will impact the behavior of the devices. A solution must also be found to embed the antenna in the stack. We present here the results of a numerical study of the thermo-mechanical effects, in two package-less structures. One possible antenna design is proposed and evaluated. Full article

We present, for the first time, the design, development and testing of a portable ultra-low
velocity flow sensor with a disposable architecture for use in medical applications. 3Dmicroprinting
technique was used to fabricate high aspect ratio microscopic hair-like structures
from conducting polymers, in particular, poly(3,4-ethylenedioxythiophene):polystyrene-sulfonate
(PEDOT:PSS). These high aspect ratio micro-hairs are flexible and conductive that can respond to
air flowing over them. A disposable and portable flow sensor with a modular design that allows
tuning of measurement range was developed, for integration with an automated neonatal
resuscitator to provide closed-loop feedback. The developed portable sensor architecture is capable
of real-time indication of the air flow velocity range down to few millimeters/second. Full article

Demand for highly stretchable mechanical sensors for use in the fields of soft robotics and wearable sensors has been constantly rising. Carbon based materials as piezo-resistive material are low-cost and have been widely used. In this paper instead of using the controversial carbon-nanotubes, carbon black nano-particles mixed with Ecoflex^® as piezo-resistive nanocomposite are used and measure strain up to 100%. Two fabrication techniques incorporating the printing (namely-“layer-upon-layer” and “embedded”) of the carbon black nanocomposite will be explored and the performances of the sensors made from these techniques will be evaluated. Full article

Detection of dissolved methane and volatile hydrocarbons in water is a problem met in
leakage localization during exploitation of underwater pipelines, oil and oil product spill over water
surface, geological exploration work for the localization of oil and gas fields under water, etc. This
problem can be solved by the application of detection system based on tubular selective membrane
permeable for volatile organics and impenetrable for liquid water. Carrier gas (air) flowing through
this tube is saturated with dissolved gas and then gas concentration is measured using
semiconductor or other gas sensor. The system prototype was tested under laboratory conditions
and demonstrated low limit of gas detection (~20 ppb by mass of dissolved methane in water) and
short response time (~10 s). Full article

We have fabricated a custom quartz tuning fork (QTF) with a reduced fundamental frequency, a larger gap between the prongs and the best quality factor in air at atmospheric conditions ever reported. Acoustic microresonators have been added to the QTF, these were optimized through experiments. We demonstrate a normalized noise equivalent absorption of 3.7 × 10⁻⁹ W·cm⁻¹·Hz^−1/2 for CO₂ detection at atmospheric pressure. Influence of the inner diameter and length of the microresonators has been studied as well as the penetration depth between the QTF prongs. Full article

We present a detailed study of Si-based optical waveguides, which can be used as evanescent field sensors for the quantitative analysis of various gases and liquids. Direct quantitative comparison of simulation with experimental results of directional coupling structures allows fine-tuning the material parameters and provides important input for future sensor design. Full article

We report on the growth of ZnO thin films by plasma-enhanced atomic layer deposition as a function of substrate temperature. The method to ensure self-limiting growth with precise thickness control is discussed and the effect of temperature on the texture of the thin films is presented. Switching the texture from (100) to (002) by increasing the substrate temperature is a key property for functional devices. The ZnO thin films with tailored properties could find applications in a wide range of sensors and actuators. Full article

Here we report the first PCB-implemented electrochemical glucose biosensor using
covalently immobilized glucose oxidase (GOx) on the commercially fabricated PCB electrode
surface, taking particular care on the electrode surface characteristics and their effect on sensor
performance. Based on the results, this assay exhibits a highly linear response from 500 μM to 20
mM (R = 0.9961) and a lower limit of detection of 500 μM. Full article

We present a reference-electrode free sensor able to measure both pH and conductivity
based on impedance spectroscopy. The electrode is made of a layer of indium-tin-oxide (ITO). The
impedance of this electrode at low frequencies depends on its double layer capacity, which varies
with pH due to modification of oxide groups at the ITO surface. At high frequencies, the impedance
is determined by the resistance in the system, which corresponds to the inverse conductivity of the
solution. Because no reference electrode is needed for this technique, miniaturization of the pH
sensor is simple. We demonstrate a proof-of-principle experiment of the sensor for human plasma
pH measurements. Full article

This paper presents an optimized way of lead zirconate titanate (PZT) deposition in order
to selectively grow three different (100/001), (110), and (111) crystal orientation in two different
thickness ranges, thinner and thicker than 400 nm. The thickness of the PZT layer is also optimized
to not diminish the generated bending moment more than 10%. A 1μm PZT layer with (100/001)
dominant crystal orientation and highly columnar crystal structure is deposited and used in the
fabrication of a circular PMUT. The PMUT has a 410 μm diameter and resonates at 462 kHz with
the displacement of 1200 nm/V. Full article

We developed and optimized a new fiber optic sensor using palladium foils attached to optical fiber Bragg gratings (FBG) for hydrogen measurements. Fifteen in parallel processed sensors were characterized and qualified in two custom tailored experimental set ups and their response to a 5% hydrogen/nitrogen gas mixture and the same gas bubbled trough transformer oil was measured. The hydrogen response is similar for both medium and close to the theoretical maximum sensitivity, but the response time was found to be very different, much slower in oil than in gas. A theoretical comparison of hydrogen diffusion trough palladium and hydrogen absorption on the palladium surface as well as a measurement of the hydrogen uptake and diffusion trough the oil to the sensor have been done to investigate the origin of the different response time. They indicate that the response time determining step is the absorption of hydrogen on the palladium surface and that this process is slowed down in oil compared to a pure gas environment. Full article

The integration of strand-based pressure sensors directly into woven textiles is a promising strategy to maintain textile properties, such as the flexibility, and to functionalize fabrics. The development of capacitive sensing elements is often based on the construction of laminates, which adversely affect the flexibility and thickness of textiles. In this paper, we present two alternative approaches by manufacturing cylindrical, pressure-sensitive, variable capacitors and twisted strand-based capacitive sensors. They lead to an easy integration method, where sensors can either be embedded or used to construct the body of textiles. In the cause of these studies, SBR/gelatin has been found to be a very useful pressure sensitive insulation system for the production of low cost capacitive sensors. Full article

Droplet dosing devices for liquid medicine are widely spread in self-medication for prevention or in the event of illness. This paper presents investigations on the often unnoticed process of bubble formation in droplet dosing devices for liquid medicine which is decisive for the whole functionality of these systems. To obtain information about this process and how it affects the dosage, drip operations with an exemplary device have been evaluated. Based on these evaluations the bubble formation is explained qualitatively. Finally a mathematical approach to predict critical changes in the bubble formation process is presented. Full article

Hybrid System-in-Foil exploits the complementary benefits of integrating embedded silicon chips with on-foil passive and active electronic components. In this work, the design, fabrication and characterization of three on-foil components, namely a humidity sensor, near field communication antenna and organic thin-film transistors, are investigated. Full article

We present a SPAD-based LiDAR sensor fabricated in an automotive certified 0.35 µm CMOS process. Since reliable sensor operation in high ambient light environment is a crucial factor in automotive applications, four SPADs are implemented in each pixel to suppress ambient light by the detection of photon coincidences. By pixel individual adjustment of the coincidence parameters to the present ambient light condition, an almost constant measurement performance is achieved for a wide range of different target reflectance and ambient illumination levels. This technique allows the acquisition of high dynamic range scenes in a single laser shot. For measurement and demonstration purpose a LiDAR camera with the developed sensor has been built. Full article

Colloidal photonic crystals have attracted much attention of the scientific world due to their unique optical properties and potential applications in sensing, displays, optoelectronics, controlled superwetting and other fields. Here we report the fabrication of spherical colloidal photonic crystals featured with well-ordered nanopatterns from silica nanoparticles (SiO₂NPs) and gold nanoparticles (AuNPs) through a droplet-based microfluidic approach. The colloidal crystals show both the photonic band gaps (PBG) and surface plasmonic resonance (SPR) properties. These proposed hierarchically composite ‘superballs’ will have an excellent performance in sensing applications, due to the fast response (the scattering color change) to the dielectric properties of the surrounding medium. A robust and efficient strategy is proposed and demonstrated to fabricate the composite superballs with multifunctional properties, broadening the perspective of their applications by the advantages of precise control over the size of the particles and flexible change of the fluid composition. Full article

Mid-infrared (MIR) on-chip sensing on Si has been a progressive topic of research in the recent years due to excitation of vibrational and rotational bands specific to materials in this range and their immunity against visible light and electromagnetic interferences. For on-chip applications, integration of all the optical components including the MIR source is crucial. In this work, we introduce a slab photonic crystal (PhC) thermal source where the birthplace and the filtering of the photons occur in the same region. Due to the forbidden frequency bands and high density of states in the band edge, it provides electric efficiency and filtering performance. Full article

The effect of Rh loading on CO sensing was studied for the case of In₂O₃. This was done by performing measurements with sensors based on loaded and unloaded materials that were performed at an operation temperature of 300 °C in the presence of low background oxygen concentration according to an experimental procedure that was demonstrated to help clarify the reception/transduction functions of loaded Semiconducting Metal Oxides (SMOX). The experimental investigation methods were DC resistance and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). The results indicate that in the case of Rh₂O₃ loaded In₂O₃ the reaction primary takes place on the Rh2O3 cluster and the electrical properties of the In₂O₃ are controlled by the pinning of the SMOX Fermi-level to the one of the Rh₂O₃ cluster. Full article

A mathematical model is developed to describe the 2? in-plane flexural response of supported ring-based Coriolis Vibrating Gyroscopes (CVGs) as the ring is driven into large amplitude vibration. Whilst the 2? degenerate modes have same resonance frequency in the linear regime, mechanical non-linearity within the support structure induces a frequency split as the vibration amplitude increases. The origins and effects of geometrical non-linearity are investigated using the proposed analytical model. Full article

Within this work we developed a universal integrated photodetector platform for the detection, amplification and digitalization of various optical data signals. The concept features two internal plus two external photodiodes, signal amplification and output stages each. For each application a combination of the optimal input detector, the suitable amplifier plus gain setting and the appropriate output stage can be combined individually. Full article

Hydrogel thin films containing temperature sensitive chemical functionalities (such as N-isopropylacrylamide, NIPAAm) are particularly interesting for sensor and actuator setups. Complex 3D structures can be conformally coated by the solvent free technique initiated Chemical Vapor Deposition, with precise control over chemical composition and film thickness. In this study, NIPAAm-based thin films with film thicknesses ranging from tens to several hundreds of nanometers and with different amounts of cross-linking were deposited. Above the lower critical solution temperature (LCST), these films repel out water and hence shrink. The amount of cross-linking and the deposited film thickness were successfully identified to both affect shape and position of the LCST transition of these systems: a promising basis for tuning response properties. Full article

V₂O₅ thin films were deposited onto insulating support (either fused silica or alumina) by means of rf reactive sputtering from a metallic vanadium target. Argon-oxygen gas mixtures of different compositions controlled by the flow rates were used for sputtering. X-ray diffraction at glancing incidence (GIXD) and Scanning Electronic Microscopy (SEM) were used for structural and phase characterization. Optical transmittance and reflectance spectra were recorded with a Lambda 19 Perkin-Elmer double spectrophotometer. Thickness of the films was determined from the profilometry. It has been confirmed by GIXD that the deposited films are composed of V₂O₅ phase. The estimated optical band gap was ca. 2.5 eV. The gas sensing properties of V₂O₅ thin films were investigated at RT-690 K towards NO₂ gas of 0–20 ppm. The results indicated that material exhibited good response and reversibility towards nitrogen dioxide. Full article

Growing evidence suggests that endocannabinoid levels are modulated during pathological conditions affecting both central and peripheral nervous system. In the present study, a novel approach (patent pending) based on an innovative liquid biosensor has been used to analyze two relevant endocannabinoid molecules with calibration purposes: N-arachidonoylethanolamine and 2-arachidonoylglycerol. The system was able to predict both compound concentrations with a Root Mean Square Error in Cross Validation (RMSECV) of 6.61 nM and 23.50 nM, respectively. Full article

Irritable bowel syndrome is one of the most common gastrointestinal disorder. Despite its high prevalence, the factors responsible for the onset of the clinical symptoms are not clear yet. Recently, there was growing evidence the origin of IBS resides in a number of fermentable short-chain carbohydrates called FODMAPs. The present study assessed the possibility of using a multisensory system to detect the presence of FODMAPs in foods. Full article

Phthalocyanines and their analogs have practical interest at development devices with low consumption because these materials are known to considerably modify their electrophysical properties on adsorption of the active gases at low temperatures. The conductivity, resistance-temperature relationship, sensor properties relative to NO, O₂ and H₂S of films based on oligo-(OPc) and polyphthalocyanines (PPc) containing Co, Cu, Fe and Mn were investigated in the present work. Polymeric films were deposited on the test structures with a pair of interdigital metal electrodes. The sensor’s active area was 4.0 × 4.0 mm, and electrode gap was egual 0.08 mm. The sensitive layers were formed by two methods. The soluble OPcs were deposited from their saturated dimethylformamide solutions and insoluble PPcs were deposited by the thermal sputtering in vacuum. The investigations were carried out under the sensor thermal stabilization conditions in the range 50–250 °C with the constant values of the heater resistance. Full article

This paper experimentally demonstrates the stray-field robustness capability of a novel Hall-based rotary position sensor concept (Huber, S., et al, 2018). The sensor targets safety-related automotive applications, for example powertrain and power steering. In these applications, the safety requirement specifies a maximum stray-field induced error of 0.4°. Therefore, the robustness in corner cases needs to be assessed. We demonstrate the stray-field immunity in multiple corner cases for temperature from −40 °C up to 160 °C and over lifetime. The impact of a uniform 5 mT stray field over all conditions (3σ) is shown to be less than 0.25°. The fully-integrated automotive-qualified sensor is implemented in a 0.18-μm CMOS technology, and achieves 0.7° of angular accuracy. Full article

Among sensors using magnetic fluids, inclinometers are seriously addressed by the scientific community. This paper deals with an optical inclinometer exploiting a ferrofluid (FF) mass, a magnetic shaping system and an InfraRed (IR) readout strategy. A dedicated paradigm is also proposed, with the aim of defining a calibration model relating the inclinometer output quantity to the imposed tilt. The working range of the inclinometer is [−15°–15°]; the sensor accuracy and resolution are 0.61° and 0.005°, respectively. Moreover, the device shows a span-to-resolution ratio of 6 × 10³. Full article

The technological development of the last few years in the field of integrated electronic components has encouraged the use of wearable electronic devices. In the biomedical field, this improvement allows the registration and analysis of numerous values, starting from environmental parameters up to the vital parameters of a subject, without interfering with the normal daily activities of the individual. In this context, the present work is focused on the design, development and evaluation of a low power wearable and wireless electronic interface able to acquire and transmit signals generated by a gas sensor, based on electrochemical technology, to monitor air quality through the measurement of O2 and CO2 concentration. Among the existing wireless technologies, it was decided to use Bluetooth Low Energy (BLE) as it allows data transmission to multiple types of external devices, such as PCs and smartphones with low power consumption. Full article

The authors have developed a wireless fluorescence imaging capsule endoscope, potentially capable of detecting early signs of disease in the human intestine which can be missed by white-light imaging (WLI) capsule endoscopy (Figure 1). Intestinal fluorescence imaging exploits variations in tissue autofluorescence between healthy and diseased areas in response to illumination, or application of fluorescent labels which preferentially bind to diseased sites. To validate the capsule’s capability to image fluorescently-labelled tissue, a small area of a sample of ex vivo porcine small intestine was sonicated with 6 nm CdZnMg fluorescent quantum dots, and the labelled area clearly differentiated from surrounding tissue by the fluorescence imaging capsule. Full article

We present an always-on acoustic wake-up sensor interface, designed for prolonging the autonomy of energy-hungry hardware for underwater acoustic surveillance. Proposed design enables the detection of a passing ship by simultaneous listening up to three arbitrarily defined frequency-bands within the 2.5 kHz range, and generates a wake-up signal upon finding a match with a digitally preset template describing signal’s discriminatory time-frequency features. In this paper, we propose the architecture of such fully programmable, multichannel, mixed-signal wake- up circuit. We show the implementation of a PCB prototype, characterize its sensitivity, analyze its current consumption, and verify its response on real-world hydrophone recordings. It is demonstrated that the design consumes only 6.4 µA per channel (in total <20 µA) with ultra-low- power COTS components, while listening. Full article

Mixed potential ammonia gas sensors were fabricated by using two sensing materials of Ni₃V₂O₈ and Au-V₂O₅ as working electrodes, YSZ as electrolyte and platinum as reference electrode. The results have shown that the Ni₃V₂O₈ sensors show cross-sensitivity toward NO gas. However, Au-V₂O₅ working electrodes displayed a high sensitivity to NH₃ as well as fast response and recovery times at high temperatures. Furthermore, the results indicate that the selectivity of Au-V₂O₅ sensors increases by increasing temperature. Full article

A new microsystem, designed to detect and measure in real time the enthalpy of mixing of two fluid-constituents is presented. A preliminary approach to arrange miniaturized batch-cells allowing detecting enthalpy of dilution or mixing is first discussed. Then, a coherent rationale leading to structure devices operating in real time is formulated, considering the straightforward assessment of heat flux transducers (HFTs) capability. Basic thermodynamic observations regarding analogy between thermal and electrical systems are highlighted prior consideration of practical examples involving mixing of water and alcohols. Fundamentals about HFTs design are highlighted before presenting an adequate way to integrate both functions of mixing and measuring the entailed heat exchange as two continuously flowing fluids interact with each other. Then, a prototype of such a dedicated device is discussed with its relevant expected performance. Full article

This document deals with a new approach to the system level modeling of open photo-acoustic gas sensors (PAS) for CO₂ sensing applications. The complex nature of the sensor calls for a flexible co-simulation environment which combines diverse domains and physical quantities such as pressure, temperature, voltage and electrical power. After validation against laboratory measurements, the system model can be used to investigate different package or hardware options, to evaluate the impact of different types of coupling (e.g., electrical or acoustic) and explore new algorithms and signal processing methods for more accurate gas concentration estimates. Full article

CMOS-based devices and the control of the materials properties by nanotechnology enabled significant progresses in the field of metal chemiresistors for gas sensing applications both in terms of miniaturization and performances (e.g., gas sensitivity). In this regard, ink-jet printing is a powerful technique to achieve high-volume production and meet the emerging consumer market demands. The paste formulation is an obvious aspect to consider for achieving a viscosity range suitable for ink-jet printing. More importantly, it is often an underestimated task which impacts the gas response of the resulting chemiresistors in terms of sensitivity, cross-sensitivity and baseline drift. In this manuscript, the effects on the film morphology and gas response upon removing ethyl-cellulose from the paste formulation is reported. Improvements in terms of sensitivity and baseline drift were observed. Full article

Nondispersive infrared (NDIR) CO₂ gas sensor was developed by using White-cell structure and tried to compensate the temperature effects in order to monitor CO₂ concentrations without hindering the temperature variations. However, the absorptions of infrared light depend on not only the temperatures but also CO₂ concentrations. Thus, a single Beer-Lambert law couldn’t properly describe the tendency of voltage decrements within full scale input (FSI, 0 to 5000 ppm) because it was affected by both parameters. In this article, the absorbance of infrared light is defined according to the concentrations of CO₂ gas. Then, a new temperature compensation algorithm has been implemented into micro-controller unit (MCU), the measurement errors were within ±3.6% as the temperature-dependent absorbance was chosen at 1450 ppm CO₂ concentrations. Full article

This study focuses on the thermal characterization of porous gallium nitride (GaN) using
an extended 3ω method. Porous semiconductor materials provide a solution to the need for on-chip
thermal insulation, a fundamental requirement for low-power, high-speed and high-accuracy
thermal sensors. Thermal insulation is especially important in GaN devices, due to the intrinsically
high thermal conductivity of the material. The results show one order of magnitude reduction in
thermal conductivity, from 130 W/mK to 10 W/mK, in line with theoretical predictions for porous
materials. This achievement is encouraging in the quest for integrating sensors with opto-, powerand
RF-electronics on a single GaN chip. Full article

There are presented the generalized results of studies of performance degradation of hydrogen sensors based on MISFET with structure Pd-Ta₂O₅-SiO₂-Si. It was shown how responses’ parameters change during long-term tests of sensors under repeated hydrogen impacts. There were found two stages of time-dependence response’ instability, the degradation degree of which depends on operating conditions, hydrogen concentrations and time. To interpret results there were proposed the models, parameters of which were calculated using experimental data. These models can be used to predict performances of MISFET-based devices for long-time operation. Full article

Carbon dots (CDs) derived from chitosan via a solvothermal method were covalently
linked to an indium tin oxide (ITO) surface and showed a direct photoelectrochemical response.
We attribute the photocurrent of the ITO-silane-CD surface to a photogenerated electron-transfer
process by CDs under illumination. The ITO-silane-CD surface was successfully used for
ac-photocurrent imaging. This opens up new applications for CDs as biocompatible and
light-addressable electrochemical sensors in bioimaging applications. Full article

A thin-film thermoelectric generator (TEG) applying a novel folded design where both the heat flux and current flow are in the plane of the thin-film is presented. The performance of the first fabricated devices is demonstrated and the results compared with the computational ones. The produced power is analyzed against the power requirements of a wireless sensor node and it is shown that a thermoelectric module of the area of <1 m² consisting of the novel TEG units is able to power a wireless sensor node of various sensors applicable e.g., to environmental monitoring of a building. The integration of energy-autonomous sensors for multifunctional smart windows providing the required temperature gradient is anticipated. Full article

flat circular transmission-line based 300 MHz resonator is implemented for the noncontact
assessment of burn depths in biological tissue. Used as a transmit-and-receive sensor, it is
placed here at a 2 mm distance from organic material test samples (pork fillet samples) which have
been previously heated on one face in various heating conditions involving various temperatures,
durations and procedures. Data extracted from the sensor by means of a distant monitoring coil
were found to clearly correlate with the depth of burn observed on the tissue samples (up to 40%
sensor output changes for a 7 mm burn depth) and with the heating conditions (around 5% sensor
output changes for 5.5 mm burn depth obtained at 75 °C or 150 °C). These results open the way to
the development of easy to implement burn assessment and monitoring techniques, which could be
integrated in wearable medical dressing-like monitoring devices. Full article

We demonstrated the possibility of selective detection of hydrogen, ethanol, hydrogen sulfide, carbon monoxide, methane and ammonia gas using metal oxide gas sensor operating in non-stationary thermal regime. This non-stationary regime consists in fast heating of the sensing layer to high temperature followed by temperature stabilization at lower temperature. The analysis of the shape of the curve describing the sensor resistance as a function of time during this measurement cycle enables the quantitative analysis of gas mixture. The investigation of kinetics of the process in non-stationary regime permits to understand the mechanism of the processes on the surface of sensing material. Full article

This paper reports a novel 3D printed MEMS magnetometer with optical readout, which demonstrates the advantages of 3D printing technology in terms of rapid prototyping. Low-cost and fast product development cycles favour 3D printing as an effective tool. Sensitivity measurement with such devices indicate high accuracy and good structural performance, considering material and technological uncertainties. This paper is focusing on the novelty of the rapid, 3D-printing prototyping approach and verification of the working principle for printed MEMS magnetometers. Full article

This paper reports a novel 3D-printed MEMS resonant magnetometer with optical readout which features a mechanical conversion of a vertical oscillation into a horizontal one. This demonstrates the advantages of 3D-printing technology in terms of rapid prototyping, low costs and fast product development cycles. In addition, 3D-printing enables ‘true’ three-dimensional MEMS structures in contrast to the traditional MEMS technology which allows only two dimensional structures. The measurement approach comprises a hybrid implementation of an optical modulator, an LED and a photodetector. Full article

Love-wave (LW) sensors based on gas sensitive polypyrrole (PPy) nanoparticles (NPs) and their modification with different gold (Au) loads are developed in this work. The research is focused on the fabrication process of the gas sensor devices and their sensing properties to ammonia (NH₃). Full article

Nitric oxide (NO₂) is one of the air pollutants that pose serious environmental concerns over the years. In this study, SnO₂ nanowires were synthesized by evaporation-condensation method and graphene oxide were synthesized using modified Hummers method for low temperature NO₂ detection. Drop cast method was used to transfer graphene oxide (GO), to form composite GO-metal oxide p-n junctions. With integration of reduce graphene oxide (rGO), the UV light absorption was enhanced. This metal oxide composite has shown a reversible response in detecting low concentrations of NO₂ under UV irradiation, with a working temperature range of 50–150 °C. Pure SnO₂ shows 20% response to NO₂ (4 ppm) in dark conditions, while the response increasesupto60%usingUVirradiationat50°C.Furthermore, SnO₂/rGOshowsa40%ofresponse in dark, while the response increases to 160% under UV light illumination. This composite exhibits excellent recovery and maintains the baseline under UV light at low temperatures, which effectively overcome the drawbacks of low recovery typically shown by metal oxide gas sensors at low temperature. Full article

This paper reports on a novel, miniaturized magnetomechanical transducer/sensor made of borosilicate glass with wide dynamic range. The prototype is manufactured with laser micromachining and ablation techniques. Compared to state of the art, borosilicate glass substrate offers the highest thermal shock resistance and is best suited for MEMS magnetometers, for aerospace and space applications or magnetic monitoring systems for diagnostics and plasma stability control of nuclear fusion experiments, where thermal shock resistance is a critical requirement. Full article

A hydrogel coated fibre grating-based pH sensor for biomedical applications has been realised, where Graphene Oxide (GO) had been used to enhance the bonding between the coating and the fibre. Two methods of deposition of GO were analysed i.e., evaporation and co-electroplating. The paper concludes that the system of GO evaporated on the fibre + the hydrogel has a sensitivity much higher, (6.1 ± 0.5) pm/pH, than the system of Cu and GO co-electroplated + the hydrogel, (1.9 ± 0.1) pm/pH, for a pH range between 2 to 10. The other conclusion is that the first system has a less coating bonding energy with the optical fibre whereas the second system has a stronger bonding energy, with better durability. Full article

Gas microsensors based on tungsten oxide (WO_3-x) nanowires (NWs) silanized with APTES (3-aminopropyltriethoxysilane) are developed in this work. These surface modified microsensors are highly sensitive to ethanol at room temperature (RT) via photoactivation and show enhanced selectivity towards other volatile organic compounds (VOCs) including acetone and toluene. Full article

We have fabricated a new type of LSPR sensor featuring immobilized liposome or phospholipid single layer. LSPR principally shows an ultrahigh sensitivity on surface dielectric environmental change due to interaction with target, but little has been reported so far on applying phospholipid membranes and/or liposomes as model cell membrane. We newly tried to investigate biosensing capabilities using the membranes of the both structures on Au nanostructures of LSPR sensor chip. As a result, it was confirmed that the phospholipid single layer is more effective to improve the sensitivity than the liposome. Finally, we have clearly detected 100 nM target protein of CAB and estimated a possible detection of 10 nM range from wavelength resolution by interaction with the phospholipid single layer. Full article

This paper reports a calorimetric micro-sensor designed for aerodynamic applications. Measuring both the amplitude and the sign of the wall shear stress at small length-scale and high frequencies, the micro-sensor is particularly suited for flow separation detection and flow control. The micro-sensor was calibrated in static and dynamic in a turbulent boundary layer wind tunnel. Several micro-sensors were embedded in various configurations for measuring the shear stress and detecting flow separation. Specially, one was embedded inside an actuator slot for in situ measurements and twelve, associated with miniaturized electronics, were implemented on a flap model for active flow control experiments. Full article

A silicon microring-resonator (MRR) hydrogen sensor which utilizes platinum-loaded tungsten oxide (Pt/WO₃) thin film was fabricated and evaluated. The uniform film was deposited on MRR portion by using sol-gel technique. By the exposure to pure hydrogen gas, the sensor devise showed the large resonant wavelength shift at room temperature. It is suggested that the change in the optical properties of hydrogen sensitive layer results in this response. Full article

Integrated silicon photonics in the mid-infrared is a promising platform for cheap and miniaturized chemical sensors, including gas and/or liquid sensors for environmental monitoring and the consumer electronics market. One major challenge in integrated photonics is the design of an integrated detector sensitive enough to detect minimal changes in light intensity resulting from, for example, the absorption by the analyte. Further complexity arises from the need to fabricate such detectors at a high throughput with high requirements on fabrication tolerances. Here we analyze and compare the sensitivity of three different chip-integrated detectors at a wavelength of 4.17 µm, namely a resistance temperature detector (RTD), a diode and a vertical-cavity enhanced resonant detector (VERD). Full article

Conductivity is a routinely measured parameter to assess impurities in water. Changing the geometry from parallel plate electrodes to planar microfabricated dual-band or interdigitated electrodes, these sensors could be miniaturized. Based on this approach, we designed 2-electrode conductivity sensors and compared their performance with a commercially available device. Adding another electrode pair (either as dual-band or meandering between interdigitated electrodes), a 4-electrode sensor was formed for which the measuring range could be enhanced to 3 × 10⁻⁶–12 × 10⁻³ S/cm. Full article

A back-illuminated time-of-flight (ToF) image sensor based on a 0.2 µm silicon-on-insulator (SOI) CMOS detector technology using fully-depleted substrate is developed for the light detection and ranging (LiDAR) applications. A fully-depleted 200 µm-thick bulk silicon is used for the higher quantum efficiency (QE) in a near-infrared (NIR) region. The developed SOI pixel structure has a 4-tapped charge modulator with a draining function to achieve a higher range resolution and to cancel background light signal. A distance is measured up to 27 m with a range resolution of 12 cm at the outdoor and average light power density is 150 mW/m²@30 m. Full article

Sensing of gases is a promising area for applications of photonic sensor devices that operate in the mid-infrared spectral range. We present a numerical investigation of slot waveguides for evanescent field sensing of CO₂. The sensor platform is a poly-silicon slot waveguide on silicon dioxide, where both layers are deposited on a standard silicon substrate. The evanescent field ratio, which is a crucial parameter for the sensing performance of the waveguides, was determined and values as high as 42% were obtained. Full article

In this contribution, we demonstrate the realization and application of a low-cost, flexible, small and fast hyperspectral imaging approach operating in the midinfrared fingerprint region where most molecules exhibit their fundamental vibrations. Following this approach, the recording of chemical images of macroscopic-sized samples at standoff distances in reflection geometry is possible. The optical setup is based on spectral identification by means of a MEMS-based Fabry-Pérot interferometer combined with 2D-snapshot spatial resolution using a bolometer camera. Results show the successful spatially resolved (resolution below 500 µm) chemical identification of different samples deposited on a metal surface (FOV = 6 × 5 cm) at a working distance of 35 cm. Full article

In this work, we have succeeded in synthesizing monoclinic and hexagonal La₂O₂CO₃ using two different routes and revealed that both of them are sensitive to CO₂ to the same degree. Moreover, we observed that the resistance of the sensor based on hexagonal phase is much higher and more stable than the one of the sensors based on the monoclinic phase. Using Operando and time resolved XRD measurements, we have also demonstrated that the resistivity of the sensor based on monoclinic La₂O₂CO₃ increases because of the material transformation into the hexagonal phase during an exemplarily aging process. Full article

This work presents a thermocouple that is fully screen printed and consists exclusively of carbon black conductors. Two different carbon black inks were printed to form a thermocouple, which has been characterized regarding its output voltage. For reference, each of the carbon black inks was used in combination with gold to form two further thermocouples. These have also been characterized and the output voltage used to predict the output of the associated thermocouple consisting of pure carbon black conductors. The results have been compared with the measurement results and show that the output of the pure carbon black thermocouple is roughly 10% lower than expected. Full article

This work deals with the realization of a fully printed thermocouple-array on a flexible substrate for condition monitoring applications. The thermocouple-array consisting of carbon black and silver was fabricated on PET-foil in a screen printing process and characterized up to a junction temperature of 150 °C. To ensure that no spurious voltages of the thermocouple occur due to deformations of the flexible substrate, the cross-sensitivity to deformation of the foil was investigated as well. Finally, as a test case, the temperature gradient of a plastic bar heated on a single end was measured with the thermocouple-array. Full article

We present a fast method to monitor hydrogen sulfide (H₂S) in ambient air based on a visible color change. Therefore, an immobilized copper(II) complex of the azo dye 1-(2-pyridylazo)-2-naphtol (H-PAN) was synthesized and prepared in a matrix for screen printing. Different materials, reaching from opaque paper to transparent foils served as substrate. The reaction of the copper(II) complex (Cu-PAN) to the target gas H₂S was measured in reflection via UV/VIS spectroscopy. Full article

A novel strategy to design piezoelectric sensor clusters suited for direction of arrival (DoA) estimation of Lamb waves is presented in this work. The designed clusters are composed by three piezoelectric patches (P1, P2 e P3) to be bonded on the structure to be inspected. In particular, by exploiting the Radon Transform, the proposed sensor design procedure computes the shape of P2 given the shape of P1 so that the difference in time of arrival (DToA) of the Lamb waves at the two patches is linearly related to the DoA. Such properties allow to minimize the DoA uncertainty. The sensor P3 is designed to perform the estimation of DoA without knowing the actual wave velocity. Numerical results show that DoA is extremely robust. Full article

Autonomous sensors are of interest in all cases where a continuous power source is not available or difficult to realize. Besides harvesting of electrical energy for a complex storage system, it is of interest to directly store an event in a non-electrical storage, but in a way that allows a later electrical read-out. Therefore, a miniaturized micromechanical binary counter is presented, which enables counting of threshold events, such as exceeding temperature limits or high mechanical shocks. An electro-mechanical digital-to-analog converter integrated in the binary counter is demonstrated as an option for monolithic electrical read-out of the mechanically stored information. Full article

Assistant robots need a tactile sensing system. We propose a tactile sensor head with a nerve-net sensing system which measures force, temperature and heat flow with a heater simultaneously on a robot finger. For accurate heat flow measurements, it is necessary to stabilize the contact conditions between the sensor head and an object. A sensor stick which consists of the sensor head and an actuator was fabricated to control applied force. Heat flow measurements in three materials of different thermal conductivities such as polyethylene, glass and Aluminum were made with the sensor stick. As a result, three materials were discriminated clearly by heat flow peak values, saturations values and time constants. The tactile sensor stick with temperature measurement and force control is useful to discriminate materials of objects. Full article

Contactless magnetic position sensors are used in countless industrial and automotive applications. However, as a consequence of the electrification trend the sensors can be exposed to parasitic magnetic stray fields, and their desired robustness may be compromised. In this paper we publish for the first time how this challenge is addressed and constructively solved using a complete paradigm change leaving conventional magnetic field measurement behind and entering into the realm of magnetic field gradient measurement. Our novel sensor system consists of an integrated Hall sensor realized in 0.18 μm CMOS technology with magnetic concentrators and a four-pole permanent magnet. The intrinsic angular accuracy was assessed comparing the rotary position of the permanent magnet with the sensor output showing angle errors below 0.3°. Additional end-of-line calibration can be applied using built-in memory and processing capability to further increase the accuracy. Finally, we demonstrate the immunity against stray fields of 4000 A/m which led to errors below 0.1°, corresponding to 0.06% of the sensors fullscale angular range. In conclusion, this novel sensor system offers a compact and flexible solution for stray-field immune rotary position measurement in harsh environment. Full article

This contribution outlines the design and manufacturing of a biosensor for retrieval and detection of bacteria RNA. The device is fully made of Cyclo-Olefin Copolymer (COC), which features low auto-fluorescence, biocompatibility and manufacturability by hot-embossing. The RNA retrieval is carried on after bacteria heat-lysis by an on-chip micro-heater. Two additional carbon resistive temperature sensors printed on the biochip sealing film monitor the heating process. RNA is hybridized with capture probes on the reaction chamber surface and identification is achieved by detection of fluorescence tags. The application of the mentioned techniques and materials facilitates the development of low-cost, disposable albeit multi-functional microfluidic system, performing heating, temperature sensing and chemical reaction processes in the same device. By proving its effectiveness, this device contributes a reference to show the potential of fully thermoplastic devices as biosensors. Full article

We designed and realized a low cost relative humidity (RH) capacitive sensor having an interdigitated transducer coated with a cheap sensing material working at room temperature (polyimide). Thermally perturbed diffusion of water molecules into the polyimide layer is studied by heating the sensor locally and measuring the sensor capacitance change. The swelling and deswelling model is applied to determine the time constant of involved processes. This simple method, using an evaluation kit developed by our group, to measure the sensor capacitance and to study the diffusion process of water molecules into polyimide could be generalized to analyze the gas diffusion processes into polymer based sensing layer generally used in the field of gas chemical sensors. Full article

Neural probes can be equipped with light for optogenetics applications. Different approaches are used for delivering light to the tissue: an optical fiber coupled to the probe, a µLED or a waveguide integrated on the probe. Small probe dimensions, adequate optical power for photostimulation and good tissue penetration for in-vivo experiments are critical requirements. Thus, integrating a waveguide is a promising solution. This work shows the design and simulation of a SU-8 based waveguide for integration in a neural probe. The waveguide contains 3 apertures, spaced by 0.5 mm, which will allow the photostimulation of different brain regions simultaneously. Full article

The influence of substrate type in boosting thermoelectric properties of co-evaporated Bi2Te3 and Sb2Te3 films (with 400 nm-thick) is here reported. Optimized power factor values are 2.7 × 10⁻³ W K⁻² m⁻¹ and 1.4 × 10⁻³ W K⁻² m⁻¹ for flexible Bi2Te3 and Sb2Te3 films, respectively. This is an important result as it is at least 2 times higher than the power factor found in the literature for flexible Bi2Te3 and Sb2Te3 films. A flexible infrared thermopile sensor was developed with high detectivity (2.50 × 10⁷ cm √HzW⁻¹). Full article

In the past decade the significant progress in the cellular stress response was witnessed. Nevertheless, the development of the minimally-invasive and accurate sensing tools for the identification of the increasing number of potentially relevant species in clinical diagnostics, using smaller sample volumes is a major challenge. Herein, the potential of the electroplated nanomaterials towards biomedical sensing and diagnostics is summarized. The key factors affecting the surface functionality, dimensionality, S/N ratio and analytical response of the prepared chips are highlighted. Furthermore, the application of electroplated chips as a fast “read out” platform for profiling of clinical samples was demonstrated. Full article

Amorphous carbon in ultra-thin thicknesses shows amazing mechanical properties that make it particularly interesting for MEMS, especially as a vibrating membrane. We present the experimental results obtained on devices comprising composite membranes of a few nanometers thick suspended above cavities of 1 to 2 μm in width. The behaviors in quasi-static mode—at low frequency—and also in resonant mode were observed and measured. Resonances frequencies of 20 MHz to 110MHz depending on the geometry were measured. Full article

Azelaic Acid (AzA) is a signaling molecule that plays a role in plant immune response when these are infected with pathogens, such as Botryitis cinerea, making its early detection in the field critical in the monitoring and prevention of large spread infection in crops. In this work, a microfluidic platform for the rapid detection of AzA in grapes is presented. AzA detection is achieved via an enzyme-enabled colorimetric reaction performed in a microfluidic chip coupled to a thin-film silicon photodiode. The detection of nM concentrations of AzA in buffer was achieved and initial results for AzA measurements in artificially spiked grape juice show potential for detection in realistic sample conditions. Full article

In this paper, we report the significant role played by the testing chamber for measuring the true gas sensor responses. Two different designs were studied and compared. The first one has a cross-shape in which the direction of gas flow is perpendicular to the sensor surface. The second one has a boat-shape in which the gas flow is tangential to the sensor surface. The results demonstrated that contrarily to the cross-shape chamber, the gas concentration is highly homogenous and equal to the set point in the boat-shape chamber. Additionally, the sensor responses are much stable, faster and higher. Besides, all the mathematical modeling and simulation results are in a good agreement with the experimental studies, which allow the validation of the proposed boat-shape chamber model. Full article

Miniaturization of devices for analysis of chemical composition is being still developed. In this article we present a portable device with a microplasma excitation source. The microdischarge is ignited inside a ceramic structure between a solid anode and a liquid cathode. As a result of cathode sputtering of the solution, it is possible to determine its chemical specimens by analysis of emission spectra of the microdischarge. We fabricated cathodes with a microfluidic compartment and two types of anodes. Devices were tested experimentally. Spectroscopic properties of the microdischarge and its analytical performance depended on the used ceramic structure, the surface area of the cathode aperture and the flow rate of the solution. Full article

Chemoresitive gas sensors based on multiple nanowires (M-NWs) randomly grown and electrically inter-connected on the top of interdigitated electrodes (IDEs) and arrays of single nanowires connected between faced nanoelectrodes (A-S-NWs) are developed in this work. These systems, consisting of gas sensitive tungsten oxide nanowires (NWs), are tested to NO₂, and their performance regarding the response magnitude, sensitivity and response rate are evaluated here. Full article

It is demonstrated for the first time that the registration of the optode signal under non-equilibrium conditions reduces analysis time and shifts the sensor working range. The fabrication of optode-like color standards for digital color analysis (DCA) is described, and a multi-parameter color scale for calibration-free sensor arrays is proposed. Advantages and limitations of monochrome and color camera for DCA with colorimetric optodes are discussed. Full article

Pollutants affect water worldwide and consequently present a risk to both the environment and to human health. Cu is an essential element for many organisms, but becomes toxic at relatively high concentrations. Current laboratory-based methods are not able to monitor water quality continuously, as they require laborious sampling and offline monitoring. A potential method that is capable to addressing this problem, guaranteeing the continuous monitoring of water resources, is the integration of microwave spectroscopy with functionalised electromagnetic (f-EM) sensors. The feasibility of using this combined method for achieving a more specific response toward low concentrations of Cu has been demonstrated. Full article

Self-heating operation, or the use of the resistance-probing signal to warm up and control the temperature of nanowire devices, has been the subject of research for more than a decade. The state-of-the-art shows that this approach is serving to lower the power demand in temperature-activated devices, especially in conductometric gas sensors, but the simplicity of eliminating the heating element comes with the complexity of integrating 1-dimensional nanomaterials in electronic devices. The advantages of the efficient self-heating effect in nanowires have already been probed in a broad range of systems and materials. But when it comes to transfer this operating principle to new systems and materials natural doubts arise: how to do it?, how much savings in power will be achieved? We will address these questions in this review contribution. Full article

Planar fluxgate structures have been the focus of multiple experimental studies. However, theoretical treatises are still limited to the classical models that describe 3D structures. In this paper we derive an effective fluxgate equation for planar systems, dealing with strong stray fields and direct coupling, and show the stability and applicability of the Vacquier implementation. To support the theoretical model, FEM simulations are performed that also provide means of layouting planar fluxgates by pure magnetostatic simulation. Full article

The planar fluxgate is an emerging technology feasible for system integration contrary to it’s bulky 3D counterpart. Recently, a novel structure based on an asymmetric double core layout for improved sensitivity and energy efficiency was proposed. The aim of this paper is, for the first time, to conduct a direct experimental comparison between single- and asymmetric double-core structures. The results confirm the original conjecture and show that asymmetric double core structures can easily boost the sensitivity by a factor of two for similar power supply. Full article

We present finite element method (FEM) simulations of a thermal flow sensor as well as a comparison to measurement results. The thermal sensor is purely based on printed circuit board (PCB) technology, designed for heating, ventilation, and air conditioning (HVAC) systems. Design and readout method of the sensor enables the possibility to measure the flow velocity in various fluids. 2D-FEM simulations were carried out in order to predict the sensor characteristic of envisaged setups. The simulations enable a fast and easy way to evaluate the sensor’s behaviour in different fluids. The results of the FEM simulations are compared to measurements in a real environment, proving the credibility of the model. Full article

Gas sensors based on CaFe₂O₄ nanopowders, which are p–type metal oxide semiconductor (MOX), have been fabricated and assessed for ethanol gas monitoring under visible light activation at room temperature. Regardless of their inferior sensitivity compared to thermally activated counterparts, the developed sensors have shown responsive sensing behavior towards ethanol vapors confirming the ability of using visible light for sensor activation. LEDs with different wavelengths (i.e., 465–590 nm) were employed. The highest sensitivity (3.7%) was reached using green LED activation that corresponds to the band gap of CaFe₂O₄. Full article

Thick films of zinc oxide (ZnO) in form of nanospheres or hexagonal prisms and of tungsten-tin (W-Sn) mixed oxides at nominal Sn molar fraction (0.1, 0.3 and 0.5) were prepared. The functional materials were synthesized and characterized by SEM and TEM, X-ray diffraction, specific surface area measurements, UV-Vis-NIR and IR spectroscopies. The gas sensing measurements highlighted that ZnO is more performant in form of nanoprisms, while W-Sn sensors offer a better response towards NOx and ozone with respect to pure WO₃. Full article

We report the design and implementation of a unique, wafer sized stretchable and bendable monolithic silicon matrix structure. The achieved stretchability allows for simultaneous omnidirectional folding, required to conform the structure to complex curved 3D surfaces. Moreover, it also enables dynamic mechanical deformation of the structure to cope with a moving environment, like e.g., the wall of the heart muscle. Due to the nature of the fabrication process, normal silicon wafer processing can be performed prior to rendering it stretchable. This is first demonstrated by the fabrication of two metal layers on top of silicon, which act as the electrical interconnects of a final flexible and stretchable LED-matrix. Currently, the possibility to postprocess an existing commercial CMOS process is investigated. This would lead to a revolutionary potential of new applications, especially in the medical field, by enabling complex silicon monitoring systems to be linked to organs without hindering them. Full article

Magnetic multimedia control elements have many advantages in comparison with other systems based on mechanical, electrical, or optical readout. For system layouting, the practicality of analytical models over extensive numerical simulation was demonstrated in the past. In this work, we apply the analytical approach to design magnetic multimedia control elements. Particularly, we focus on a joystick that includes only a single 3D magnetic sensor and can be used in continuous operating mode. Presented results relate to a system based on a single permanent magnet and a single 3D sensor. The scheme was used to build a prototype to perform prove of principle experiments. A semi-analytic method to determine positions of the joystick from the observed magnetic field is discussed. Full article

The perspective catalysts usable for the fabrication of thermocatalytic gas sensors were studied. The analysis of CO oxidation kinetics by Pd decorated Al₂O₃, ZSM-5, SnO₂, CeO₂/ZrO₂ and some other carriers of catalysts showed that the application of these catalysts leads to the ambiguity of sensor response (light-off effect). It was demonstrated that a catalyst based on CeO₂/ZrO₂ carrier could be used for the fabrication of sensors characterized by the univocal correspondence between CO concentration and sensor response. The developed model of the CO oxidation on all Pd catalysts with inert carrier enabled the description of the CO oxidation using a single value of activation energy. Full article

Contactless readout of passive LC sensors composed of a capacitance sensor connected to a coil can be performed through an electromagnetically coupled readout coil set at distance d. Resonant frequency f_s and Q-factor Q_S of the LC sensor can be extracted from the measurement of the impedance at the readout coil by using a technique theoretically independent of d. This work investigates the effects on the measurement accuracy due to the unavoidable parasitic capacitance C_P in parallel to the readout coil, which makes the measured values of f_s and Q_S dependent on d. Numerical analysis and experimental tests confirm such dependence. To overcome this limitation, a novel electronic circuit topology for the compensation of C_P is proposed. The experimental results on assembled prototypes show that for a LC sensor with f_s ≈ 5.48 MHz a variation of less than 200 ppm across an interrogation distance between 2 and 18 mm is achieved with the proposed compensation circuit. Full article

This paper reports a MEMS gradiometer consisting of two independent, laterally oscillating masses on a single chip with integrated optical readout featuring a responsitivity of 35V/T at resonant operation. The symmetrical design of the two masses offers high accuracy and low cost by using conventional MEMS batch fabrication technology. The sensing principle is based on lateral displacement of the masses actuated by Lorentz forces which modulates a light flux passing through a stationary mask and the moving mask integrated in the masses. Phase and intensity detected by photodiodes reveal information about the uniformity of an external applied magnetic field, hence, enables the measurement of gradient-, homogeneous- and offset gradient magnetic fields. Full article

Miniaturized and integrated analytical devices, including chemical sensors, are at the forefront of modern analytical chemistry. The construction of novel analytical tools takes advantage of contemporary micro- and nanotechnologies, as well as materials science and technology. The goal of this study was investigate electron transfer resistance in model solution and protein adsorption using integrated electrochemical cell with different geometry. Full article

Arrays of 1D-vertically arranged gallium nitride (GaN) nanorods (NRs) are fabricated on sapphire and connected to both bottom and freestanding top contacts. This shows a fully validated top-down method to obtain ordered arrays of high-surface-to-volume elements that can be electrically interrogated and used, e.g., for sensing applications. Specifically, these will be used as highly integrated heating elements for conductometric gas sensors in self-heating operation. Detailed fabrication and processing steps involving inductively coupled plasma reactive ion etching (ICP-RIE), KOH-etching, interspace filling, and electron-beam physical vapor deposition technologies are discussed, in which they can be well adjusted and combined to obtain vertical GaN NRs as thin as 300 nm in arbitrarily large and regular arrays (e.g., 1 × 1, 3 × 3, 9 × 10 elements). These developed devices are proposed as a novel sensor platform for temperature-activated measurements that can be produced at a large scale offering low-power, and very stable temperature control. Full article

In this work the application of a self-sensing and self-actuating cantilever for gas-flow measurement is investigated. The cantilever placed in the flow is excited permanently at its first resonance mode. Simultaneously the resonance amplitude, the resonance frequency and the static bending of the cantilever are detected. All three sizes are related to the velocity of the gas-flow. Full article

Surface bio-functionalization plays a critical role in the performance of a biosensor and numerous techniques for the enhancement of a biosensor’s surface coverage with oriented capture biomolecules have been developed with the ultimate goal of optimizing a sensor’s performance in terms of its sensitivity and linear response over a wide dynamic range. Herein, highlights of a comparative assessment into the most promising approaches to achieve this goal are being presented. For aptamer-modified surfaces, polyamidoamine (PAMAM) dendrimers and polysaccharide networks were employed with the obtained results clearly indicating that a much denser surface coverage with aptamers can be achieved with the use of the latter. For the functionalization of surfaces with antibodies, the orientation and density of immobilized antibodies onto recombinant protein A/G- or boronic acid-modified substrates were compared, with the former leading not only to increased antibody loading but also with such an orientation that permits enhanced antigen binding. The conclusions reached can be used as a starting point for the customization of sensor functionalization in a plethora of clinical, environmental and even food-industry-related biosensing platforms. Full article

This work reports the clamping effects on the performance of a carbon nanotube based
nanoresonator. A direct comparison of two different nanotube-clamping geometries on the same
nanotube device is presented. The nanotube was mechanically dry transferred and clamped through
van-der-Waals forces onto palladium electrodes resulting in a bottom clamped configuration. A 20
nm platinum layer was then selectively deposited on the electrodes through atomic layer
deposition resulting in top-bottom clamped configuration. With top clamping, a Q-factor increase
of 1.5~2× has been observed accompanied by a decrease in the resonance frequency. Full article

This paper focuses on the use of microporous PDMS foams as a highly deformable film to improve the sensitivity of flexible capacitive pressure sensor dedicated to wearable use. A fabrication process allowing the mechanical properties of foams to be adjusted is proposed together with a non-linear behavioral model used to objectively estimate the sensor performances in terms of sensitivity and measurement range. Sensors fabricated and characterized in this study show that the sensitivity and the measurement range can be adjusted from 0.14%/kPa up to 13.07%/kPa, and from 594 kPa to 183 kPa, respectively, while the PDMS film porosity ranges from 0% up to 85%. Full article

An increasing need for portable personal time- and size-resolved monitoring of the fine airborne particulate matter drives the development towards miniaturization and cost reduction of the optical particle counters. In an integrated design of the optical particle counters, the confinement of the air is becoming more critical, since variations in particle positions are getting bigger relative to the dimensions of the sensor. Variations in particle position directly affect the light collection angle and hence induce the particle sizing error. We have developed a 3D simulation framework based on a Lorentz-Mie theory and analyzed the effect of particle position on the particle sizing error. We show that the relative sizing error induced by particle position is detrimental and seriously limits the sizing performance of downscaled PM2.5 sensors. Full article

Due to specific dynamics of the operating environment and required safety regulations, the amount of acquired data of an automotive LiDAR sensor that has to be processed is reaching several Gbit/s. Therefore, data compression is much-needed to enable future multi-sensor automated vehicles. Numerous techniques have been developed to compress LiDAR raw data; however, these techniques are primarily targeting a compression of 3D point cloud, while the way data is captured and transferred from a sensor to an electronic computing unit (ECU) was left out. The purpose of this paper is to discuss and evaluate how various low-level compression algorithms could be used in the automotive LiDAR sensor in order to optimize on-chip storage capacity and link bandwidth. We also discuss relevant parameters that affect amount of collected data per second and what are the associated issues. After analyzing compressing approaches and identifying their limitations, we conclude several promising directions for future research. Full article

One of the most widely known biogenic amines is histamine, which plays an important role in the human immune system. Some people suffer from allergic reactions after a histamine-rich diet; this is called histamine intolerance. The aim of this work is to develop a quick and reliable method for the detection and quantification of histamine in food, based on an electrochemical approach. In presence of biogenic amines, a reduction cascade induces a current at the working electrode. Prior to chronoamperometric measurements, Finite Elemente simulations were performed. The results are presented in this work. Full article

Exceptionally sensitive and selective graphene-based chemiresistive gas sensors were produced as a result of graphene functionalisation with a sub-nanometer V₂O₅ layer by using the method of pulsed laser deposition. Two different types of graphene were used—epitaxial graphene on SiC and CVD graphene on Si/SiO₂—and both showed remarkable enhancement of sensing properties in terms of response and recovery speed, response magnitude and selectiveness towards NH₃ gas. The epitaxial graphene-based sensor was demonstrating the highest relative response towards ammonia amounting to 80% for 0.1 ppm NH₃. Full article

We report on a new optical sensing principle for measuring the electric field strength based on MEMS technology. This method allows for distortion-free and point-like measurements with high stability regarding temperature. The main focus of this paper rests on an enhanced measurement set-up and the thereby obtained measurement results. These results reveal an improved resolution limit and point to the limitations of the current characterization approach. A resolution limit of 222 V/m was achieved while a further improvement of roughly one order of magnitude is feasible. Full article

We propose to use an integration process based on Transducer Electronic Data Sheets applied to a magnetic sensor system for the realization of artificial landmarks. Magnetic sensors provide an advantageous alternative in surroundings where GPS and optical sensors do not work. These landmarks can be used by passing autonomous vehicles, e.g., drones, for re-orientation and re-calibration. To facilitate the usage of these landmarks also by any vehicle, known or unknown, a standardized process for automatic connection and identification of the landmarks is suggested. During this process, all necessary information such as protocols, calibration data etc. is made known to the vehicle passing by. Based on the provided information, the vehicle itself can decide whether and how to use the provided sensory information. Full article

This work reports the process optimization of various electrospinning parameters to fabricate polyvinylidene fluoride based piezoelectric flexible nanofiber webs for passive sensing and energy harvesting applications. Process parameters like electrospinning voltage and drum speed have been taken into consideration while optimizing the electrospun nanofiber webs for maximizing their piezoelectric property. Finally, the optimized recipe is used to fabricate a flexible PVDF nanofiber energy harvester to demonstrate the energy harvesting capability of such nanofiber webs. Full article

A new signal processing technique has been developed for resistive metal oxide (MOX) gas sensors to enable high-bandwidth measurements and enhanced selectivity at PPM levels (<50 PPM VOCs). An embedded micro-heater is thermally pulsed from 225 to 350 °C, which enables the chemical reactions in the sensor film (e.g., SnO₂, WO₃, NiO) to be extracted using a fast Fourier transform. Signal processing is performed in real-time using a low-cost microcontroller integrated into a sensor module. The approach enables the remove of baseline drift and is resilient to environmental temperature changes. Bench-top experimental results are presented for 50 to 200 ppm of ethanol and CO, which demonstrate our sensor system can be used within a mobile robot. Full article

Time-of-Flight (ToF) sensors are a key technology for autonomous vehicles and autonomous mobile robotics. Quantifying the extent of perturbation induced by atmospheric phenomena on ToF imaging is critical to identify effective correction strategies. Here we present an approach that uses optical ray-tracing to simulate the ToF image, while the distance information is recovered by analyzing the optical path of each ray. Such an approach allows, for example, understanding the effects of different ray paths on the ToF image, or testing various retrieval/correction algorithms upon running a single ray-tracing simulation. By modelling several scattering scenarios, we show that ranging errors arise mostly from light backscattered to the sensor prior reaching the scene. Scattering events close to the sensors (<1 m) have the largest influence, therefore strategies capable of filtering out signals from distances shorter than the range of interest can significantly improve the accuracy of ToF sensors. Full article

Several wearable technologies for the prevention of diabetic foot ulcers have been developed by the scientific community. However, they are often very invasive and normally just one parameter between pressure loads or temperature is acquired. Moreover the amount of thermal reading points is lower than 5 and the accuracy of thermal sensors is greater than 0.5 °C. This work presents a low invasive and accurate smart insole in which both temperature and pressure data are acquired in 8 reading points and then transmitted to a gateway, through a wireless protocol, in order to communicate the foot health status to the caregiver. Full article

A three dimensional, additively manufactured interdigital capacitive sensor for fluid level measurement applications is introduced. The device was fabricated using the fused filament fabrication (FFF) additive manufacturing (AM) process and an off the shelf conductive filament with a volume resistivity ρ = 0.6 Ω cm. The 3D fabrication process allows great flexibility in terms of sensor ̇ design and an increase of the surface area between the electrodes, compensating the relatively large plate separation and yielding a high sensitivity to increasing fluid levels. The measurements presented in this abstract show the average increase of capacitance in response to an incrementally increasing volume of de-ionized water (DI-water) filled between the separate digits. Full article

A flexible simulation platform to design new piezoelectric MEMS (micro-electro-mechanical systems) microphones with signal-to-noise ratio (SNR) evaluation is presented. The platform is made of two blocks: a multiphysical FEM model, in order to study the acoustic, mechanical and electrical behavior of the MEMS structure, and an equivalent electro-mechanical-acoustic lumped-element model, which allows studying the microphone system, i.e. the MEMS-package-ASIC interaction. The platform gives precise estimation of sensitivity and SNR, key parameters of a microphone. Full article

In this paper, a hybrid optical guiding system based on low group velocity offered by photonic crystal (PhC) waveguides and vertical confinement as well as high field enhancement of. Surface lasmon polaritons (SPP) is proposed. We show that for efficient sensing, conventional two-dimensional PhC waveguides with finite height require a high aspect ratio in the order of 30 in order to efficiently confine the guiding mode. The fabrication of devices with such a high aspect ratio is considered too challenging and inefficient for mass production. By combining a PhC waveguide and SPPs, the proposed system efficiently confines the optical mode vertically while benefiting from the lateral confinement enabled by PhC structures. As a result, the required aspect ratio drops to about 4 making the fabrication in large scale feasible. This design provides strong light-matter interaction within small dimensions, which is beneficial for miniaturizing on-chip photonic sensors. Full article

A sensor for biomedical markers based on a split ring microwave resonator (SRR) was developed. The surface of the microwave resonator is covered with receptors that specifically bind to the target proteins where the local permittivity is changed. The resonator is part of a microwave oscillator circuit. Changes in the local permittivity caused by coupling of the target proteins result in a change of oscillator frequency which can be easily and accurate measured with high sensitivity. Full article

Pinhole‐shaped light‐emitting diode (LED) arrays with dimension ranging from 100 μm down to 5 μm have been developed as point illumination sources. The proposed microLED arrays, which are based on gallium nitride (GaN) technology and emitting in the blue spectral region (λ = 465 nm), are integrated into a compact lensless holographic microscope for a non‐invasive, label‐free cell sensing and imaging. From the experimental results using single pinhole LEDs having a diameter of 90 μm, the reconstructed images display better resolution and enhanced image quality compared to those captured using a commercial surface‐mount device (SMD)‐based LED. Full article

In the energy transition from fossil to renewable resources, gas is foreseen to play an important role. However, the composition of the gas is expected to change due to a wider variation of sources. In order to mitigate potential challenges for distributors and end-users, a new low-cost gas composition sensor was developed that will be able to monitor the composition and energy content of these gas sources, ranging from biogas to liquid natural gas (LNG). Together with industrial and academic partners a gas sensor was realized that can be inserted in an existing gas grid. A first demonstrator was realized that was small enough to be used in low and medium pressure gas pipes (100 mbarg—8 barg). Adding the pressure and temperature data to the chip readings enables to determine the concentrations of methane, ethane, propane, butane, nitrogen and carbon dioxide, including small fluctuations in water vapor pressure and subsequently calculate the Calorific Value, Wobbe Index and Methane Number. Full article

We present a novel MEMS sensor for the detection of magnetic particles in liquids, which consists of a microcantilever excited piezoelectrically in resonance and having an integrated planar coil on its free end. Due to the latter component, magnetic particles are attracted and accumulate on the sensor surface. The additional mass introduced by the particles changes the resonance frequency of the microcantilever serving as measured quantity. To evaluate our design, we dispersed 250 nm iron-oxide particles in de-ionized water and monitored the resonance frequency during particle accumulation. 100 min after measurement start, a total resonance frequency shift of 6 kHz was found, which can easily be measured and shows the high potential of the proposed sensor design. Full article

A novel transparent and nanostructured ion-sensitive electrode based on indium tin oxide (ITO) coated with cobaltbis(dicarbollide)-doped poly(pyrrole) (PPy) is presented in this work. This metallacarborane-doped PPy was used as conducting polymer due to its high stability and chemical resistance. The ion-sensitive electrode was coupled to a miniaturized and low-cost potentiostat, in a final autonomous kit for potentiometric determination of pH. Qualitative calibration of the system revealed Nernstian behavior, resulting promising for novel point-of-care biomedical applications. Full article

This work reports for the first-time integration of continuous microfluidic channels to the paper-based electro-osmotic pumps (EOPs) with liquid bridges. In addition, 0.2 μm pore sized cellulose acetate (CA) membrane filter is used to eliminate pressure-driven flow instead of filter paper which is common in paper microfluidics and has an average pore size of 10 μm. A factor of 57 increase in hydraulic resistance is achieved with the new paper. Fabrication of the pumps and microfluidic channels using paper, wax, adhesive film and PMMA plates is explained. Volumetric flow rate of 19 nL/min is achieved in the microfluidic system with 61 V/cm electrical field magnitude applied to DI water. The capability of the integrated system is shown with precise liquid motion in a Y-shaped microfluidic channel integrated with two EOPs. Full article

This study concerns the design of surface acoustic wave sensors functionalized with bisphenol S based molecules for lead ions detection. (4-hydroxyphenyl, 4′-benzyloxyphenyl) sulfone (M1), (4-hydroxyphenyl,4′-anthrylmethyloxyphenyl) sulfone (M2) and (4,4′-bis (anthrylmethyloxyphenyl)) sulfone (M3) were synthesized and then drop-coated on the SAWs sensing areas. Gravimetric results indicate that the limit of detection of the three sensors is in the picomolar range and that the M3/SAW sensor has the highest affinity towards lead ions compared to M1/SAW and M2/SAW. Density functional theory (DFT) calculations were investigated to support experimental results and to understand the nature of interactions involved between lead ions and the three synthetized molecules. Full article

We present a reproducible process to directly pattern 3-Dimensional (3D) polydimethylsiloxane (PDMS) structures for Organ-on-Chips (OOC) via automated molding. The presented process employs a commercially available system from IC packaging improving the fabrication process for microfluidic channels and thin membranes, which are components frequently used in OOCs. The process removes the manual steps used previously in the fabrication of microfluidic channels and improves the control over the thickness of the PDMS layers. The process was also employed to fabricate and pattern thin PDMS membranes on silicon wafers, without the use of lithography and etching steps and in combination with 3D structures. The use of foil assisted molding techniques presented in this work is an important step toward the large-scale manufacturing of OOCs. Full article

The properties of Iridium oxide (IrO₂) decorated Multi-Wall Carbon Nanotubes (IrO₂-MWCNTs) are studied for detecting nitrogen dioxide and ammonia vapors. IrO₂ nanoparticles were synthetized using a hydrolysis and acid condensation growth mechanism, and subsequently employed for decorating the sidewalls of carbon nanotubes. Decorated MWCNTs films were deposited onto SiO₂/Si substrates for achieving chemoresistive gas sensors. NO₂ and NH₃ gases were detected under different experimental conditions. Higher and more stable responses towards NH₃ and NO₂ were observed for iridium-oxide nanoparticle decorated MWCNT material, compared to bare MWCNT material. Raman Spectroscopy was employed to study the nanomaterials and the optimal operating temperatures were determined. Full article

This study proposes a microfabricated resonant pressure sensor based on electrostatic excitation and low-impedance piezoresistive detection in which a pair of double-ended tuning forks were utilized as resonators for differential outputs. In operations, targeted pressures deforms the pressure-sensitive membrane, resulting in stress variations of two resonators, leading to shifts of the intrinsic resonant frequencies, which were then measured piezoresistively. The developed microfabricated resonant pressure sensor was fabricated using simple SOI-MEMS processes and quantified in both open-loop and closed-loop manners, where the quality factor, differential sensitivity and linear correlation coefficient were quantified as higher than 10,000, 79.4 Hz/kPa and 0.99999, respectively. Compared to previous resonant piezoresistive sensors, the developed device leveraged single-crystal silicon as the piezoresistor, with advantages in simple sensing structures and fabrication steps. Furthermore, the differential setup was adopted in this study which can further improve the performances of the developed sensors. Full article

In situ optical measurement systems for gas detection with high temporal resolution enable new possibilities of detection opportunities for continuous pipe gas streams. A tomographic absorption-based measurement system has been developed to detect the ammonia (NH₃) concentration distribution within an exhaust pipe on a hot gas test bench. Multiple ammonia line concentrations are measured in situ by applying nondispersive absorption spectroscopy in the deep ultraviolet (DUV) region. The detectors consist of photodiodes in combination with optimized transimpedance amplifiers (TIV) allowing high sampling rates up to 3 kHz while providing a high signal-to-noise ratio (SNR). Despite the short path length of only eight centimeters a detection limit of 1 ppm has been achieved. Full article

A compact lensless microscope comprising a custom-made LED engine and a CMOS imaging sensor has been developed for live-cell culture imaging inside a cell incubator environment. The imaging technique is based on digital inline-holographic microscopy, while the image reconstruction is carried out by angular spectrum approach with a custom written software. The system was tested with various biological samples including immortalized mouse astrocyte cells inside a petri dish. Besides the imaging possibility, the capability of automated cell counting and tracking could be demonstrated. By using image sensors capable of video frame rate, time series of cell movement can be captured. Full article

We present a novel thermopile-based infrared (IR) sensor array fabricated on a single CMOS dielectric membrane, comprising of poly-silicon p⁺ and n⁺ elements. Processing of the chip is simplified by fabricating the entire array on a single membrane and by using standard CMOS Al metal layers for thermopile cold junction heatsinking. On a chip area of 1.76 mm × 1.76 mm, with a membrane size of 1.2 mm × 1.2 mm, we fabricated IR sensor arrays with 8 × 8 to 100 × 100 pixels. The 8 × 8 pixel device has <2% thermal crosstalk, a responsivity of 36 V/W and enhanced optical absorption in the 8–14 µm waveband, making it particularly suitable for people presence sensing. Full article

In this paper, a self-out-readable, miniaturized cantilever resonator for highly sensitive
airborne nanoparticle (NP) detection is presented. The cantilever, which is operated in the
fundamental in-plane resonance mode, is used as a microbalance with femtogram resolution. To
achieve a maximum measurement signal of the piezo resistive Wheatstone half-bridge, the
geometric parameters of the sensor design were optimized by finite element modelling (FEM).
Struts at the sides of the cantilever resonator act as piezo resistors and enable an electrical read-out
of the phase information of the cantilever movement whereby they do not contribute to the
resonators rest mass. For the optimized design, a resonator mass of 0.93 ng, a resonance frequency
of ~440 kHz, and thus a theoretical sensitivity of 4.23 fg/Hz can be achieved. A μ-channel guiding a
particle-laden air flow towards the cantilever is integrated into the sensor chip. Electrically charged
NPs will be collected by an electrostatic field between the cantilever and a counter-electrode at the
edges of the μ-channel. Such μ-channels will also be used to accomplish particle separation for sizeselective
NP detection. Throughout, the presented airborne NP sensor is expected to demonstrate
significant improvements in the field of handheld, MEMS-based NP monitoring devices. Full article

In this work, a novel multispectral sensing system consisting of nanostructured filter matrix and a charge-coupled device (CCD)-based image sensor has been developed to overcome the limitation of the conventional pigment filtered sensors, which are difficult to be fabricated at a microscale and usually showing a pronounced degradation. By designing the filters in guided-mode resonance (GMR) architecture, light transmission efficiencies of ~90% with low sidebands and sharp peaks can be obtained, which are critical characteristics for realizing precise optical measurement systems. To optimize the transmission functions, various materials and structural parameters have been simulated. Electron beam nanolithography is employed in the device fabrication to fabricate pixel-wise independent filter functions. After being characterized in terms of their wavelength filtering capability, the developed GMR filters are then combined with image sensors, particularly for addressing biological applications. Full article

Moisture content and water activity are important parameters for quality characterization
of products like bulk materials, powders, granules. Thus, an exact determination is necessarily
required in a wide range of industrial applications. Moisture of materials is the content of
non-chemically bound water in a solid or liquid. Water activity (aw) is a characteristic/parameter of
the non-chemically bound (“free”) water in materials and is measured as humidity over a
solid/liquid surface at constant temperature (equilibrium moisture content). It is an important
parameter to characterize the quality of e.g., pharmaceutical and food products. In our
contribution, we present the developed MOISHUM device for staged determination of water
activity and moisture content of liquid and solid materials. Full article

Microchips have been designed and fabricated for the fast thermal characterization of samples by extension of the 3-omega method. Both solid and liquid samples can be measured by applying a small amount of material under investigation on the chip containing a micro heater/sensor. Two types of chips have been fabricated and tested: silicon chips with porous silicon (PS) layer as thermal isolator and glass chips with through glass vias (TGVs) for the back side contacting of the top side heater/sensor. Full article

In this work we present a complex, wireless, ambient energy powered and easy-to-use solution for vibration analysis. It is designed to incorporate the latest commercial technologies and achievements in the field of energy harvesting and wireless sensor networks with an emphasis on energy efficient spectrum estimation algorithms for embedded systems. This solution is realized on a small printed circuit board and contains all the necessary circuit components for hybrid energy harvesting; acceleration sensing; data acquisition, storing and analysis; and wireless communication. The on-board microcontroller was programmed to choose the most energy-efficient data handling algorithm (direct transfer or embedded analysis) based on the weighed combination of user settings and ambient energy. We tested and calibrated our system in laboratory environment with reference sensors, as well as in an engine room, simulating practical applications. Full article

Accurate measurement of fluid flow velocities is challenging but essential in many disciplines. Inspiration of possible measurement methods can come from nature, for example from the lateral line organ of fish, which is comprised of hair cells embedded in a gelatinous cupula. When the cupula is deflected by water movement, the hair cells initiate neural signals that generate an accurate image of the fish’s surroundings. We built a flow sensor mimicking a hair cell, yet coupled it with an optical detection method. Fluid flow bends the waveguide; this leads to a measurable light loss that depends linearly on the waveguide deflection. Full article

In this work, we present a durable and miniaturized photonic lab on a chip (PhLOC) integrating functionalized silk fibroin pads for optical glucose quantification in whole blood samples. The PhLOC consists of a poly(methyl methacrylate) (PMMA) disposable structure for the pad holding and a coupling system for commercial optic fibers connection. The silk matrix, together with the PMMA design, has the capability to separate the plasma from the cell fraction of whole blood by plasma diffusion into the silk, minimizing the absorbance interferences from the hemoglobin of the erythrocytes. Then, the enzymes present in the matrix react with the glucose in the sample and produce a color change in an amplified process where the analyte—mediator—matrix interacts sequentially, increasing the common signal from the oxidized mediator (2 fold). The sensor works in the adequate linear range to distinguish between healthy and unhealthy glucose levels (0 to 12 mM), with a sensitivity of 0.084 a.u. mM⁻¹, a limit of detection of 0.18 mM and a limit of quantification of 1.44 mM. Furthermore, durability of the sensor is remarkable, maintaining its response unchangeable during the first 7 months of tests. Full article

ZnO nanorods (NRs) arrays with good vertical alignment were selectively grown on microscale patterned surfaces by a MEMS-compatible, low-temperature chemical-bath deposition method (CBD). The direct-current (DC) sputtered and subsequently annealed ZnO seed-layer was found to have a crucial effect on the ZnO NRs growth. Depending on the pre-annealing temperature between 200 °C and 700 °C, which is compatible with our microcantilever fabrication process, diameters and area densities of the NRs of 60–99 nm and 17–27 µm⁻² were observed, respectively, with the best alignment at 600 °C. A surface-area enlargement factor of 48 was achieved with respect to a ZnO layer indicating the potential of ZnO NRs arrays for MEMS applications, such as gas sensing. Full article

An existing phase-locked-loop (PLL) based contact-resonance measurement system is studied and optimized. Improvements to the electronics’ circuit to reduce both nonlinear behavior and noise are realized and experimentally tested. The improvements enable to analyze signals even at highly damped vibrations of the cantilever. Full article

This work presents a first approach to the utilization of Lossy Mode Resonance (LMR) based optical fiber sensors for gas detection. The optical sensor is based on a SnO₂ thin-film fabricated onto the core of cladding removed multimode fibers (MMF). The time response of the device to four different gases (NH₃, NO, CO₂ and O₂) was monitored obtaining the best sensitivity for NO whereas the response to NH₃ revealed the best repeatability. Full article

Transferable substrate-less InGaN/GaN light-emitting diode (LED) chips have successfully been fabricated in a laser lift-off (LLO) process employing high power ultrashort laser pulses with a wavelength of 520 nm. The irradiation of the sample was conducted in two sequential steps involving high and low pulse energies from the backside of the sapphire substrate, which led to self-detachment of the GaN stack layer without any additional tape release procedure. To guarantee their optoelectrical function and surface quality, the lifted LED chips were assessed in scanning electron microscopy (SEM) and electroluminescence (EL) measurements. Moreover, surface characterizations were done using atomic force microscopy (AFM) and Auger Electron Spectroscopy (AES). Full article

Guidelines for the fabrication of nanoscale light-emitting diode arrays (i.e., nanoLED arrays) based on patterned gallium nitride (GaN) with very small dimensions and pitches have been derived in this work. Several challenges during top-down LED array processing have been tackled involving hybrid etching and polymer-based planarization to yield completely insulated highaspect-ratio LED fin structures and support the creation of p-GaN crossing line contacts, respectively. Furthermore, simulations of the light emission patterns were also performed providing hints for enhancing the device designs. As a result, regardless of the required device processing optimization, the developed nanoLED arrays are expected to offer high potential as novel illumination sources in biomedical imaging and sensing applications (e.g., mini compact microscopes and wearable biological/chemical nanoparticle counters) Full article

In this work we present the study of copper(II) oxide thin films for the fabrication of lossy mode resonance-based (LMR) optical fiber sensors. This material has proven to be capable of generating such resonances with a promising result. Their optimal optical properties have allowed the achievement of a sensitivity of 7234 nm/RIU, higher than that obtained with other metal oxides such a SnO₂, indium tin oxide (ITO), aluminum doped zinc oxide (AZO) or indium-gallium-zinc oxide (IGZO). The use of this new film may facilitate the use of LMR based sensors for applications that require maximum sensitivity and stability. Full article

The state-of-the-art infrared (IR) detection uses quantum photodetectors and bolometers. Quantum IR photodetectors are expensive and require cooling, and exotic and toxic materials. Whereas, bolometers are cost-efficient and uncooled, but they are much slower and less sensitive. Recently we have demonstrated that ultra-thin, highly-doped silicon membranes can be used to build fast and highly-sensitive thermoelectric bolometers. We present the fabrication of these devices, electro-thermal characterization results, and estimate the full potential of this technology. Full article

Amino acids containing thiol-groups such as Cysteine (Cys), Homocysteine (Hcy), and Glutathione play an important role in a great variety of biological processes. However, too low, but also too high concentrations can have negative effects on human health. Therefore, it is of great importance to sensitively detect these risk factors for cardiovascular and neuronal diseases. Furthermore, Cys is an essential amino acid for the growth of pathogenic water-borne bacteria, like Legionella sp. Hence, a reliable, sensitive and selective Cys-detection method that is incorporated into automated biosensors would represent a great tool for a broad range of biological and medical applications. We describe the simple synthesis of fluorescein aldehyde probes for the detection of biologically important thiols, focusing on Cys. The probes displayed highly sensitive responses to L-Cysteine hydrochloride monohydrate in the range of their physiologically relevant levels in the visible and UV spectral region. Full article

Resonant micro- and nanoelectromechanical systems (MEMS/NEMS) are typically subject to interaction with a liquid or gaseous environment. Recently, it has been demonstrated that non-conventional eigenmodes exhibit remarkably high quality factors (Q factors) in liquids. However, the physical origin of this phenomenon remains elusive. Here we introduce a definition of non-conventional eigenmodes for cantilever structures and develop a boundary integral method for describing the interaction of an incompressible viscous fluid and a non-conventional eigenmode of a MEMS/NEMS resonator. With this framework we are able to study the influence of the mode shape on the fluid-structure interaction. Full article

A laser lift-off (LLO) process has been developed for detaching thin InGaN/GaN lightemitting diodes (LED) from their original sapphire substrates by applying an ultrafast laser. LLO is usually based on intense UV irradiation, which is transmitted through the sapphire substrate and subsequently absorbed at the interface to the epitaxially grown GaN stack. Here, we present a successful implementation of a two-step LLO process with 350 fs short pulses in the green spectral range (520 nm) based on a two-photon absorption mechanism. Cathodo- and electroluminescence experiments have proven the functionality of the LLO-based chips. The impact of radiation on the material quality was analysed with scanning (SEM) and transmission electron microscopy (TEM), revealing structural modifications inside the GaN layer in some cases. Full article

A sensors network based on 8 stationary nodes distributed in Bari (Southern Italy) has
been deployed for urban air quality monitoring during advection events of Saharan dust in the
period 2015–2017. The low-cost sensor-systems have been installed in specific sites (buildings,
offices, schools, streets, airport) to assess the PM10 concentration at high spatial and temporal
resolution in order to supplement the expensive official air monitoring stations for citizen science
purposes. Continuous measurements were performed by a cost-effective optical particle counter
(PM10), including temperature and relative humidity sensors. They are operated to assess the
performance during a long-term campaign (July 2015–December 2017) of 30 months for smart cities
applications. The sensor data quality has been evaluated by comparison to the reference data of the
9 Air Quality Monitoring Stations (AQMS), managed by local environmental agency (ARPA-Puglia)
in the Bari city. Full article

We present recent results of the electrochemical impedance spectroscopy (EIS) measurements for interdigitated electrode arrays (IDAs) ranging from several micrometers down to hundreds of nanometers. Simulations have shown that the electric field strength between the electrodes scales with the gap size. Therefore, electrodes of varying gap sizes were fabricated and functionalized with ssDNA to empirically validate these findings. The results have shown that the impedimetric response strongly correlates with the width of the electrode fingers: the smaller the electrode gap, the larger the impedance increase. Full article

Over the last decades, the use of Surface Acoustic Waves (SAW) has emerged as a promising technology in many applications such as filters, signal processing but also sensors. We report the fabrication and the characterization of a SAW delay line magnetic field sensor using uniaxial multi-layered 14×[TbCo_2(3.7nm)/FeCo_(4nm)] nanostructured thin film deposited on Y36° Lithium Niobate (Figure 1a). The sensor shows an interesting dependency to a tunable bias magnetic field with different orientations relative to the easy axis. The obtained results are well explained using an equivalent piezo-magnetic model described in a previous work. Full article

The electrode processes governing response behavior of a solid electrolyte CO₂ sensor have been studied using electrochemical impedance spectroscopy on symmetric cells exposed to various temperatures and gas compositions. It was shown that the electrochemical processes leading to potential formation at the Au/Na₂CO₃ electrode can be described by adapting models commonly used in the field of molten carbonate fuel cells. Full article

Recently, organic electromechanical transducers have attracted intense scientific and technological interest due to their unique mechanical flexibility and their piezoelectric properties. However, the fabrication of organic MEMS devices is challenging. For example, a lift-off process cannot be used on polymers, because of the solvent in photoresists. Here, we present a straightforward and low-cost batch process for organic MEMS devices using standard micromachining techniques. As organic material we used the ferroelectric (co-)polymer poly(vinylidene fluoride-trifluorethylene) (P(VDF-TrFE)). The integration of the polymer in a CMOS-compatible process was optimized in terms of deposition and patterning of the polymer and the corresponding metal layers. Micromachined devices, such as capacitors and cantilevers, were fabricated and analysed. The ferroelectric perfomance was evaluated by electrical and electromechanical measurements. Our first results indicate that the proposed fabrication process is reliable resulting in well-functioning organic MEMS devices. We measured as piezoelectric constant a d33 of −32 pm/V with our organic P(VDF-TrFE) capacitors. Full article

We present a systematic methodology to generate machine-readable patterns embodying all the elements needed to carry out colorimetric measurements with conventional color cameras in an automated, robust and accurate manner. Our approach relies on the well-stablished machine-readable features of the QR Codes, to detect the pattern, identify the color reference elements and the colorimetric spots, to calibrate the color of the image and to conclude a quantitative measurement. We illustrate our approach with a NH3 colorimetric indicator operating at distinct color temperature ambient lights, demonstrating that with our design, consistent measurements can be achieved, with independence on the illumination conditions. Full article

In this work, a flexible tin oxide (SnO₂) gas sensor was successfully fabricated by inkjet printing technology. This thin film deposition technique requires the formulation of stable suspensions with specific fluidic properties. Aqueous Sol-gel method was applied to synthesize a stable sol based on tin oxide, then transformed into ink with the appropriate viscosity and surface tension to be printed using a drop-on-demand piezoelectric inkjet printer. Thermal analyses of synthetized sol show that a crystallized structure of SnO₂ could be obtained at 350 °C, which is lower than crystallization temperatures of SnO₂ previously reported in the literature, and entirely consistent with our plastic substrate. The printed thin-film was then sintered at 350 °C on polyimide foil (Upilex-50S) and characterized as sensor. Full article

In this paper, we present a concept, simulation and characterization results of a dual-frequency piezoelectric energy harvester with magnetic frequency tuning capabilities. We demonstrate that the frequency-agile multi-mode capability enables the device to harvest on a wider range of operating frequencies than classical vibration harvesters. Full article

This paper constitutes the analysis of the impact of low doped intrinsic p-type EPI thickness (20 µm and 30 µm) and bottom anti-reflective coating on the electrical and optical performance of various PIN photodiodes designs. The intrinsic p-type layer with a target resistivity of 400 Ω cm is an epitaxial layer (iEPI) grown on a low resistive substrate of 20 mΩ cm. Optimization of the photodiode’s spectral responsivity (for a specific wavelength) includes a Bottom Anti-Reflective Coating (BARC) layer deposited over the silicon surface. BARC thickness is optimized for λ = 425 nm, λ = 750 nm and λ = 900 nm wavelengths. With respective BARC in place, the photodiode’s quantum efficiency (QE) approaches 100% for λ = 750 nm with 20 µm and 30 µm iEPI thickness and for λ = 900 nm with 30 µm iEPI reaching also a maximum spectral response of 0.63 A/W at 800 nm. QE of 72% could be achieved at 425 nm. The leakage current varies from 3.5 pA for 20 µm iEPI thickness to 10 pA for 30 µm at 1 V reverse biasing for 365 µm circular PIN photodiode. Full article

Glyphosate is the most frequently used herbicide worldwide, its hazard potential is unclear and nowadays a threshold limit value has not yet been determined. We used eight chemoresistive gas sensors based on semiconducting nanopowders for the identification of N-(phosphonomethyl) glycine in air. The sensors were tested at their proper working temperature in presence of volatile glyphosate at concentrations within the range of 6 ppb–1 ppm, i.e., a plausible interval of interest for its monitoring. The sensing material that best performed was a solid solution of Tungsten oxide and Tin oxide (WS30). This study opens up to design portable devices suitable for monitoring glyphosate concentrations at which workers and people are exposed. Full article

Gas distribution modelling can provide potentially life-saving information when assessing the hazards of gaseous emissions and for localization of explosives, toxic or flammable chemicals. In this work, we deployed a three-dimensional (3D) grid of metal oxide semiconductor (MOX) gas sensors deployed in an office room, which allows for novel insights about the complex patterns of indoor gas dispersal. 12 independent experiments were carried out to better understand dispersion patters of a single gas source placed at different locations of the room, including variations in height, release rate and air flow profiles. This dataset is denser and richer than what is currently available, i.e., 2D datasets in wind tunnels. We make it publicly available to enable the community to develop, validate, and compare new approaches related to gas sensing in complex environments. Full article

We present aluminum nitride (AlN) on silicon (Si) CMOS-compatible piezoelectric micromachined ultrasonic transducers (pMUTs) with an extended detection range of up to 140 cm for touchless sensing applications. The reported performance surpasses the current state-of-art for AlN-based pMUTs in terms of the maximum range of detection using just a pair of pMUTs (as opposed to an array of pMUTs). The extended range of detection has been realized by using a larger diaphragm allowed by fabricating a thicker diaphragm than most other pMUTs reported to date. Using a pair of pMUTs, we experimentally demonstrate the capability of range-finding by correlating the time-of-flight (TOF) between the transmit (TX) and receive (RX) pulse. The results were obtained using an experimental setup where the MEMS chip was interconnected with a customized printed circuit board (PCB) using Al wire bonds. Full article

A biodegradable inductively coupled pressure sensor is presented. Three sensors were fabricated using melt processed biodegradable polymers and electron-beam evaporated magnesium. All the sensors showed similar pressure responses from 0 to 0.2 bar. In addition, the responses of the sensors to temperature changes and static pressure are reported. Due to the limited quality factor of the resonance sensors, single measurements were noisy. For this reason, averaging of multiple measurements was needed to achieve consistent results. Full article

In this work we propose a method for on-cantilever force control for application in force distance (F-z) spectroscopy for intermolecular interaction sensing. In this method we perform the F-z measurements with cantilevers integrating functionalized spheres attached to them. The F-z curve is obtained by controlling the Lorentz force acting at the cantilever free end. The intermolecular interaction forces are measured by measuring the force necessary to retract the cantilever from the surface. The required force is generated by the current passing through the cantilever. In this scenario we monitor the bending of cantilevers using optical beam deflection (OBD) method. Moreover, as deflection of the cantilever was electromagnetically controlled it was possible to calibrate the OBD response as well. Full article

A smart textile for live bacteria detection of antimicrobial hospital tissues is here proposed. The capacity to detect viable bacteria is based on the use of Prussian Blue (PB) as electrochromic compound, with a clear reversible change of colour from PB to Prussian White (PW) after reduction from a bacterial metabolism process. PB nanoparticles are incorporated to polyester cotton fabrics by ultrasonic deposition. After performing different tests with bacterial samples of E. coli and S. aureus, a full colour change of the textiles was observed. These smart textiles will allow to determine the self-life of the antibacterial compounds as well to improve the control of hospital infections. Full article

Light-addressable potentiometric sensors (LAPS) measure ac photocurrent at electrolyte-insulator-semiconductor (EIS) and, more recently, electrolyte-semiconductor structures to produce spatiotemporal images of chemical or biological analytes, electrical potentials and impedance. One of the most important properties for LAPS is spatial resolution, which determines the smallest features that can be resolved in LAPS images. In this work, the use of nanostructured ZnO for LAPS was explored. The effect of ZnO morphology on the spatial resolution was studied with a LAPS setup. The best resolution of 2 µm was achieved in ZnO films produced by aerosol-assisted chemical vapour deposition (AACVD). Full article

Artificial lipid bilayers are an essential tool to investigate channel forming proteins. A particular challenge is to study antibiotic uptake through bacterial porins requiring low volume and parallelization. Here, we present a lipid bilayer silicon chip having a Parylene-C coated silicon nitride membrane with different aperture sizes. The Parylene-C allows very fast lipid bilayer membrane fabrication, 30 to 130 s. The realization-success is very high and an average lifetime of at least 9 h was established. Furthermore, a 3D-printed holder is realized where parallel assembly of the chips, including fluid inlets for the pipetting robot, is demonstrated. Full article

In this work we present how to describe mechanical impedance of a photon force (PF) MEMS sensor dedicated to structures’ optomechanical studies. An actuating force (photon force) is caused by the reflection and absorption of the electromagnetic radiation beam due to the radiation pressure effect. Specially designed very soft (low k-constant, ca 10–150 mN/m) cantilevers are presented. The structures integrate a Lorentz loop, which enables electromagnetic actuation. The construction with two mirrors is proposed so that parasitic thermal actuation can be neglected. The MEMS displacement is measured with the use of a laser vibrometer. The mechanical impedance model is presented using which the stiffness is calculated. As validation measurements: thermal noise and known mass adding methods are used. Full article

The readout methods for inductively coupled resonance sensors were simulated using a lumped element model. The purpose of the study was to analyze the readout methods at high frequencies where the self-resonance of the reader coil is likely to interfere with the measurements. Furthermore, the changes in the reading distance cause measurement errors. This phenomenon was studied using simulation. In addition, an algorithm that compensates these errors was tested. The simulation results were in agreement with the test measurements. In addition, the tested error compensation improved the resonance frequency estimates calculated using the simulated and measured data. Full article

This study presents a squared AlN piezoelectric micromachined ultrasonic transducer (PMUT). Using this PMUT greater level of output pressure and higher reception sensitivity has been achieved, compared with the state-of-the-art. Another outstanding characteristic for this PMUT is that it can be monolithically integrated on CMOS substrate, being remarkably advantageous in relation to the bonding method implemented until now. Full article

This paper presents, for the first time, a displacement sensor with inherent read-out circuit using an inverter built with WG-FET that has 16-nm-thick single crystalline silicon film. In WG-FET, electrical double layer (EDL) capacitances are formed at water/silicon and water/top gate interfaces. These two capacitances and the resistance of the de-ionized (DI) water droplet build a first order RC network. Propagation delay of an inverter built with WG-FET depends on this RC constant. When the distance between top gate and silicon film changes, EDL capacitances remain the same, but resistance of the DI-water droplet changes. Accordingly, propagation delay of the inverter changes linearly with this distance. Increasing the distance from 400 µm to 1200 µm changes low-to-high propagation delay tplh of the inverter from 1.08 ms to 1.36 ms and high-to-low propagation delay tphl from 0.48 ms to 0.56 ms, which yields sensitivities of 0.35 µs/µm and 0.1 µs/µm, respectively. Full article

This paper presents a long-term stable thermoelectric micro gas sensor with ligand linked Pt nanoparticles as catalyst. The sensor design gives an excellent homogeneous temperature distribution over the catalytic layer, an important factor for long-term stability. The sensor consumes very low power, 18 mW at 100 °C heater temperature. Another thermoresistive sensor is also fabricated with same material for comparative analysis. The thermoelectric sensor gives better temperature homogeneity and consumes 23% less power than thermoresistive sensor for same average temperature on the membrane. The sensor shows linear characteristics with temperature change and has significantly high Seebeck coefficient of 6.5 mV/K. The output of the sensor remains completely constant under 15,000 ppm continuous H₂ gas flow for 24 h. No degradation of sensor signal for 24 h indicates no deactivation of catalytic layer over the time. The sensor is tested with 3 different amount of catalyst at 2 different operating temperatures under 6000 ppm and 15,000 ppm continuous H₂ gas flow for 4 h. Sensor output is completely stable for 3 different amount of catalyst. Full article

Employing a tri-electrode topology for electrostatic actuators can significantly reduce needed control voltages. The tri-electrode topology employs a perforated intermediate electrode between the MEMS structure and pull-down electrode, and provides a low voltage control for the MEMS structure. Simulations of a spring supported MEMS in a conventional electrostatic actuator offering ~4.5 µm displacement with 20 V on the pull-down electrode, were compared to the tri-electrode actuator. This study showed that the intermediate electrode can act to provide similar controlled displacement with only 1/3 and 1/4 the voltage for the cases with the pull-down electrode held fixed at 20 V and 40 V respectively. A fabricated prototype experimentally showed that the intermediate electrode can provide similar displacement control with only 1/6 the normal control voltage of an electrostatic actuator. Full article

Ultrasonic sonar sensors are commonly used for contactless distance measurements in application areas such as automotive and mobile robotics. They can also be used to identify and classify sound reflecting objects. In the presented work, we classify simple sonar targets of different geometric shape and size. For this purpose, we built a test stand for echo measurements that facilitates defined arbitrary translation and rotation of the targets. Artificial neural networks (ANNs) with multiple hidden layers were used as classifiers and different features were evaluated. The focus was on two features that were derived from the echoes’ cross-correlation functions with their excitation chirp signals. We could distinguish different target geometries with our features and also evaluated the ANNs’ capabilities for size discrimination of targets with the same geometric shape. Full article

In this study we propose a piezoelectric MEMS vibration energy harvester with the capability of oscillating at low (i.e., less than 200 Hz) resonant frequency. The mechanical structure of the proposed harvester is comprised of a doubly clamped cantilever with a serpentine pattern associated with several discrete masses. In order to obtain the optimal physical aspects of the harvester and speed up the design process, we have utilized a deep neural network, as an artificial intelligence (AI) method. Firstly, the deep neural network was trained with 108 data samples gained from finite element modeling (FEM). Then this trained network was integrated with the genetic algorithm (GA) to optimize geometry of the harvester to enhance its performance in terms of resonant frequency and generated voltage. Our numerical results confirm that the accuracy of the network in prediction is above 90%. Consequently, by taking advantage of this efficient AI-based performance estimator, the GA is able to reduce the device operational frequency from 169 Hz to 110.5 Hz and increase its efficiency on harvested voltage from 2.5 V to 3.4 V under 0.25 g excitation. Full article

A gold-silver alloy film based spectral surface plasmon resonance imaging (SPRi) sensor has been prepared for in-situ quantitative detection of biochemical analytes at the sensor surface. This novel sensor has lower detection cost yet higher sensitivity relative to the conventional counterpart with a gold film. Using the laboratory-made multifunctional SPR sensing platform, both the resonant color images and the resonant spectra for the Au-Ag alloy film were measured at different incident angles. The quantitative relationship between the resonant wavelength and the average hue of corresponding resonant color image was established. With this relationship the most hue-sensitive spectral range was determined. After setting the initial resonant wavelength in the hue-sensitive spectral range, the refractive-index sensitivity of the Au-Ag alloy film based SPRi sensor was measured as Δhue/Δn_c = 29,879/RIU, being 8 times higher than that obtained with the gold-film SPRi sensor. The immunodetection of benzo(a)pyrene (BaP) in water was fulfilled using the Au-Ag alloy film based SPRi sensor. The average hue of the SPR color image linearly increases with increasing the BaP concentration up to C = 0.5 μg/L and the slope is Δhue/ΔC = 132.2/(μg/L). The sensor is responsive to a change of BaP concentration as low as ΔC = 0.01 μg/L. Full article

This work report the preliminary results of crowdfunding/crowdsensing campaign run in Italy aimed to functional test of a smart air quality monitoring infrastructure. Design and implementation of the cooperative monitoring infrastructure are described along with details of crowdfunding campaign. Participating users received, for a whole month, a field validated electrochemical sensors based air quality monitoring node and a companion APP capable of reporting sophisticated concentration estimations. Calibration functions are actually based on machine learning components correcting for environmental and non target gas interferences. Data gathered in the cloud allowed for evaluation of acceptability and reliability of the node as well as for mapping concentrations measurements inside city landscape through an ad-hoc GUI. Full article

The assembly, structure, composition and sensing properties of novel bisdithiocarbamate based gold nanoparticle networks have been investigated. The sensing properties have been studied with vapors of toluene, 1-propanol, water, and 4-methyl-2-pentanone. We demonstrated that bisdithiocarbamates based chemiresistive sensors show sensing properties versus volatile organic compounds (VOC) comparable to thiol based composites but that they are superior in their long term stability. Full article

The perspective combination of laser micromilling technology and jet (aerosol) printing technologies for ceramic MEMS producing of microhotplate in the surface mounted device (SMD) package for the metal oxide (MOX) sensor is describing. There are discusses technological and economic aspects of small-scale production of gas MOX sensors. Experiments with laser micromilling of Al₂O₃ ceramics confirmed possibility to produce MEMS microhotplate for MOX gas sensor in SMD package with form-factor SOT-23. Developed technology process is close to 3D prototype philosophy—rapid, simple and cheap. Full article

In this work gas sensing properties of Langmuir-Schaefer monolayer organic field-effect transistors (LS OFETs) prepared from organosilicon derivative of [1]benzothieno[3,2-b][1]-benzothiophene (BTBT) have been investigated. The monolayer has been deposited using Langmuir-Schaefer method, which results in a uniform low-defect monolayer with excellent electrical performance, hole mobility up to 7 × 10⁻² cm² V⁻¹ s⁻¹, the threshold voltage around 0 V and on-off ratio of 10⁴. Developed sensors demonstrate a long-term stability of a half-year storage under ambient conditions. Preliminary investigations demonstrated that the LS OFETs give instantaneous response on ammonia and hydrogen sulfide at low concentrations. The results reported open new perspectives for the OFET-based gas-sensing technology. Full article

A miniature sensor and control system is developed to facilitate human eye ciliary muscle movement detection and to drive the corresponding liquid crystal based lens to create an autofocusing lens for cataract patients. The movement of the ciliary muscle is detected by a marker that detunes a Colpitts oscillator. The change in oscillation frequency is measured by the implantable circuit and sent to an external control unit. This external unit calculates the corresponding focal length and returns corresponding commands to the implantable system to change differential signal driving the lens. The system is built with state-of-the-art Commercial-Off-The-Shelf (C.O.T.S.) components around a miniature ultra-low power Filed Programmable Gate Array (F.P.G.A) and a hand full analog components. The system fits on a 10 mm outer diameter Printed Circuit Board (PCB), consumes less than 2.5 mW and is able to measure up to 1 mm ciliary muscle displacements. Full article

The contribution focuses on the development of microresonant sensor solution integrated in microfluidic platform for the haemostasis assessment at realistic rheological flow conditions similar to the one in blood vessels. A multi-parameter sensor performs real time analysis of interactions between immobilized collagen and platelets. The detection and characterization of such interactions at controlled flow rates provide information to evaluate the dynamic of each step of primary haemostasis. The microresonant sensor concept was developed and is described in the contribution. Full article

We present a novel, wafer-based fabrication process that enables integration and assembly of electronic components, such as ASICs and decoupling capacitors, with flexible interconnects. The electronic components are fabricated in, or placed on precisely defined and closely-spaced silicon islands that are connected by interconnects embedded in parylene-based flexible thin film. This fully CMOS compatible approach uses optimized DRIE processes and an SiO₂ mesh-shaped mask, allowing for the simultaneous definition of micrometer- to millimeter-sized structures without compromising the flexibility of the device. In a single fabrication flow a unique freedom in dimensions of both the flexible film and the silicon islands can be achieved making this new technique ideal for the realization of semi-flexible/foldable implantable devices, where structures of different sizes have to be combined together for the ultimate miniaturization. Full article

The high-throughput generation of polymeric nanoparticles (PNPs) with tailored size and narrow size distribution is key for applications as relevant as sensing and nanomedicine. Here we show how cavitation bubbles in a microfluidic channel can induce rapid nanoprecipitation of PNPs with user-selectable control. Specifically, we used two tip-electrodes perpendicular to the flow to induce electrical breakdown of a polymer solution and a miscible non-solvent. As a result, a plasma is formed causing cavitation and rapid mixing of the fluids, yielding nanoprecipitates of polymer. We demonstrated mL/min generation of PNPs with a diameter as low as 150 nm and polydispersity below 0.15. Full article

Reliable bonding of microstructured polymer parts is one of the major challenges in industrial fabrication of microfluidic devices. In the present work, the effects of a UV/ozone surface activation on the bonding process were investigated for the combination of a commonly used thermoplastic cyclic olefin copolymer (COC) with an elastomeric COC (eCOC) as a new thermoplastic elastomer material. Bonding was studied using two-component injection molded parts of COC and eCOC, together with microfluidic COC chips. Surface activation and bonding process parameters were optimized and bond strengths were characterized by the wedge test method. The results showed that strong bonding of this polymer materials combination can be achieved at temperatures significantly below the bulk glass transition temperature of COC. Full article

A new methodology for the real time monitoring of hydraulic oil aging based on the vapor analysis using metal oxide semiconductor (MOX) gas sensors has been successfully developed. A dedicated hydraulic test bench was designed and realized to age the oil under controlled condition. Gas chromatographic analyses were performed to detect oil volatile compounds (VOCs) and their concentrations at increasing oil working time. Moreover, a laboratory sensor system have been realized to test the headspace of the same samples. Both measurements highlighted a decrease of the VOCs concentrations. Full article

Here we present a novel, compact 3D-printed diffusion cell as an in vitro tool for skin permeation investigation. As proof-of-concept, a diffusion cell for studying the permeation of a model molecule (FITC-dextran, 4 kDa) through explanted mice skin is fabricated and characterized. Good viability of the tissue up to 24 h incubation in the cell is demonstrated via MTT assays. The real-time diffusion of the molecule by means of fluorescence microscopy allowed the determination of its diffusivity through the skin (~2·10⁻¹⁰ m²/s). Our results open the door for the real-time, high-throughput and cost-effective investigation of skin in any labs. Full article

Gas sensors produced and working at low temperatures are particularly interesting for their compatibility with temperature sensitive substrates such as flexible ones or for their use in specific environments. In this work, we present the chemical synthesis of silver nano-islands grown on ultrathin tungsten oxide nanowires (Ag/WO₃ NWs) in order to obtain sensing materials for nitrogen dioxide (NO₂) detection at temperatures below 150 °C. We compare the efficiencies of NO₂ gas sensing, for WO₃ NWs both before and after the silver growth, by drop-casting the nanomaterials from colloidal solutions onto substrates. Interestingly, the working temperature is reduced down to 130 °C even for NO₂ concentrations as low as 0.2 ppm, with a clear improvement in sensitivity in the case of the Ag/WO₃ NWs. Additionally, continuous UV irradiation reduced greatly the recovery time. Full article

Lung cancer, especially lung adenocarcinoma, is one of the main causes of death worldwide. This paper reports on the real-time detection methods of human lung adenocarcinoma A549 cells. The proposed approach is based on using optical, impedance and microwave spectroscopy in an attempt to develop an online tool that can be easily used for early cancer diagnostics and treatment monitoring not only in the hospital labs, but at point of care. Low power athermal electromagnetic waves as a sensing mechanism for early cancer detection showed a particular promise. The techniques were also applied to other cells, such as PC3, LL24, HLF, HACAT and DU145, to ensure selectivity of the sensors. Providing real-time information at point of care will be a significant leap on its own as it will dramatically increase screening capabilities. Full article

In this study, a microplasma discharge device (MDD) was modelled and simulated for sterilization applications. The MDD was modelled with copper and dielectric based electrodes on flexible polyethylene terephthalate substrate. COMSOL Multiphysics^® simulation performed on the MDD model demonstrated varying electron density and electric field distribution for AC terminal voltages ranging from 500 V to 8000 V. A variation of 14% and 54% was also observed for electron density and mobility, respectively when the temperature was increased from 240 K to 360 K, at constant pressure of 1 atm. In addition, a variation of 90% and 78% was observed for electron density and mobility, respectively when the pressure was increased from 0.3 atm to 1.3 atm, at constant room temperature of 295 K. The response of the MDD is analysed and presented in this paper. Full article

An electrochemical sensor was fabricated on a flexible polyethylene terephthalate (PET) substrate for the detection of cadmium sulfide (CdS), a heavy metal compound. The sensor consists of a working and reference electrode that were gravure printed using silver (Ag) ink on the PET substrate. The performance of the sensor was investigated by measuring electrical impedance spectroscopy (EIS) for varying concentrations of the CdS. From the EIS based response, an impedance change of 11 ± 1%, 23 ± 1%, 34 ± 2% and 50 ± 3% was observed for the 1 pM, 1 nM, 1 µM and 1 mM concentrations of CdS, respectively when compared to de-ionized (DI) water, thus demonstrating the potential of employing gravure printed electrochemical sensors for heavy metal detection applications. Full article

A novel pulsometer was successfully developed using microelectromechanical systems (MEMS) based silicon-on-glass (SOG) technology for biomedical applications. The sensor was modelled and simulated in COMSOL Multiphysics^® for pressures ranging from 0 to 40 mmHg. The capability of the fabricated pulsometer to detect movements in x and z-axis directions was investigated. The simulation results demonstrated displacement changes as high as of 98% and 36% in the x and z-axis directions, respectively for 40 mmHg, which correspond to typical radial blood pressure (rBP) on the wrist. In addition, an average capacitance change of 1 nF was experimentally obtained in the x-axis direction, from −5 V to 5 V. The response of the pulsometer is analyzed and presented in this paper. Full article

Nanoporous microbead-based microfluidic systems for biosensing applications allow enhanced sensitivities, while being low cost and amenable for miniaturization. The regeneration of the microfluidic biosensing system results in a further decrease in costs while the integration of on-chip signal transduction enhances portability. Here, we present a regenerable bead-based microfluidic device, with integrated thin-film photodiodes, for real-time monitoring of molecular recognition between a target DNA and complementary DNA (cDNA). High-sensitivity assay cycles could be performed without significant loss of probe DNA density and activity, demonstrating the potential for reusability, portability and reproducibility of the system. Full article

The temperature and electrical modes influences on radiation sensitivity of n-channel MISFETs sensors of the total ionizing dose were investigated. There were measured the MISFET-based dosimeter output voltages V as function of the radiation doses D at const values of the drain current I_D and the drain–source voltage V_D, as well as the (I_D–V_G) characteristics before, during and after irradiations at different temperatures T (V_G is the gate voltage). It was shown how the conversion function V(D) and the radiation sensitivity S_D are depending on the temperature T for different electrical modes. To interpret experimental data there were proposed the models taking into account the separate contributions of charges in the dielectric Q_t and in SiO₂–Si interface Q_s. The model’s parameters ΔV_t(D,T) and ΔV_s(D,T) were calculated using the experimental I_D–V_G characteristics. These models can be used to predict performances of MISFET-based devices. Full article

Smart sensors are sensing devices that include computational and communication functionalities. In this work we present a reference model aimed at simplifying the implementation of smart sensors and their integration in IoT applications. The proposed model is micro-controller agnostic and it is viable in different scenarios ranging from the management of a single analog sensor to the orchestration of a heterogeneous array of sensors. The model is open-source and the implementation is available online as reference for the development of custom smart sensors. The evaluation of our framework shows that it can be implemented with limited overhead. Full article

Herein, copper oxide nanorods were hydrothermally synthesized on SiO₂ substrates with inter digital gold electrodes fabricated by photolithography method. This method offers the advantage of practical usage as a sensor device. Hydrothermal synthesis were carried out at 85 °C for 4 h. Fabricated nanorods were decorated with Pt for 30 s via magnetron sputtering system. SEM, XRD and EDX studies were performed to characterize the samples. Sensing properties of nanorods were tested with H₂, NO₂ and CO at 200 °C. Results showed that Pt decoration enhanced sensor response to H₂ while decreasing sensor response to NO₂ and CO. Full article

Fungi are widespread throughout the environment and can cause health as well as indoor problems. One of the most common fungi involved in building damage are Aspergillus sp. This study describes a rapid method for the detection of fungal spores. It is based on the ability of fungi to produce the enzyme cellulase, which can cleave the substrate Aminophenyl-β-d-cellobioside (APC) resulting into 4-Aminophenyl (AP). This cleavage product can then be oxidized leading to an increased output current signal. In the experimental setup several growth media and different parameters were tested over time, for instance growth conditions like pH or incubation temperature. Furthermore, various spore concentrations, which are related to the cellulase activities, were examined. This method presents a technique that makes it possible to specifically detect low concentrations of fungi spores in short time. Full article

This paper presents a new way of dealing with drinkable water shortness all over the world. The developed devices’ functionality is based on the well-known and established SODIS (SOlar DISinfection) method. The whole device, Scipio—Scientific Purification Indicator, is designed in a way, that it is self-powered by solar cells and can be placed inside a bottle in order to provide best measurements. The device is capable of communicate via Bluetooth with other devices. Thus, an observation or control of the correct application of the SODIS method can be established. The paradigm shift we offer in terms of development aid not to simply help the people but to empower them to care for themselves. It is a very important that everyone can purify their own drinking water without the need of subsequent supplies. Full article

Peptide cross-linked poly(ethylene glycol) hydrogel is a promising biomaterial that has been used widely for drug delivery and tissue engineering. However, the use of this material as a biosensor material for the detection of collagenase has not been explored. Collagenase play a key role in rheumatoid arthritis and osteoarthritis. Detection of this class of enzyme using the degradable hydrogel film format is promising as a point-of-care device for disease monitoring. In this study, a biosensor was developed based on the degradation of a peptide cross-linked poly(ethylene glycol) hydrogel film for the detection of collagenase. The hydrogel was deposited on gold-coated quartz crystals and their degradation in the presence of collagenase was monitored using a Quartz Crystal Microbalance (QCM). The biosensor was shown to respond to concentrations between 2 nM to 2000 nM with a lower detection limit of 2 nM. Full article

Since the entrance into the industrial era and the increasing demand for energy due to global economic growth and development, the amount of energy-related emissions have continuously grown every year to significantly high levels. Greenhouse gases like carbon dioxide, nitrous oxide or methane cause an increase in the earth’s temperature. Toxic gases like nitrous oxides, Sulphur dioxide and carbon monoxide are extremely detrimental to the health of all living beings. Over the past few years, global organizations are imposing tighter limits by international laws for flue-gas emissions from fossil-fuel combustion. Emission-limiting techniques like filter and scrubber systems have to be installed for waste gas treatment in the exhaust gas streams. In addition, exhaust gas measuring technologies detect the actual emission values of the respective target gases. We present the development of a low-cost and highly sensitive photoacoustic gas detector for the monitoring of emitted combustion gases. First tests were carried out with the toxic Sulphur dioxide (SO₂) in secure lab conditions, where a sensitivity below 1 part per million (ppm) was achieved during continuous flow of the gas. Full article

Numerous non-ideal effects can distort the functionality of sensor interfaces and have to be considered during the design phase. In order to relax the requirements for the analog circuit components, adaptive filtering and digital calibration are used in this work to detect and correct different gain- and offset-errors. The error detection is performed by transmitting a test signal through the sensor interface continuously and in parallel to the sensor signal. In the digital domain, variations of the test signal are evaluated and present errors can be determined and eliminated. In this way, an on-line error correction is realized, which makes the sensor interface more robust against static and dynamic non-idealities. The proposed concept is demonstrated by correcting different gain- and offset-errors in a 65nm CMOS sensor interface. Full article

Tungsten trioxide (WO₃) nanowires decorated with iridium oxide nanoparticles (WO₃-IrO₂) have been studied as candidate towards low NO₂ concentrations gas detection. Furthermore, reducing gases such ammonia vapors and hydrogen have been also studied. WO₃ nanowires were grown following an aerosol assisted chemical vapor deposition (AACVD) methodology; and decorated in two steps. As first step, nanowires were grown and subsequently annealed at 500 °C for two hours in order to remove impurities and enhance the oxidation ratio. In a second step, employing an iridium oxide nanoparticles suspension they were decorated through AACVD. Iridium oxide nanoparticles were synthetized from an inorganic precursor through an acidic hydrolysis synthesis route. The sensors were also characterized through environmental scanning electron microscopy (ESEM) and X-ray photoelectron spectroscopy (XPS). All iridium oxide based sensors shows a higher response towards all the gases tested in comparison towards pristine sensors, despite showing the best performance towards NO₂. Full article