Electrodes for non-enzymatic glucose sensing based on gold nanostructures onto graphene paper (GP-AuNPs) have been obtained inducing dewetting, by laser annealing, of 8 nm-thick Au layer deposited by sputtering. Molten-phase dewetting of gold layer, which produces the formation of spherical nanoparticles (AuNPs), was achieved by nanosecond laser annealing using a pulsed (12 ns) Nd: yttrium aluminum garnet YAG laser operating at 532 nm. The Surface of the electrode presents gold rich regions consisting of graphene nanoplatelets covered by spherical AuNPs. The sizes of AuNPs are in the range of 10–150 nm. Glucose was detected at a potential of 0.17 V vs SCE, which corresponds to the intense peak of two electrons oxidation. Highest sensitivity of 600 µA mM⁻¹ cm⁻² of glucose detection was obtained. The resulting sensitivity, detection limit and linear range of glucose detection are very promising since comparable to the actual state of art results for nanostructured gold electrodes which are, however, produced by complex multi-steps processes. Full article

This approach presents a localization technique within mobile robotics sustained by visual sensory data fusion. A regression inference framework is designed with the aid of informative data models of the system, together with support of probabilistic techniques such as Gaussian Processes. As a result, the visual data acquired with a catadioptric sensor is fused between poses of the robot in order to produce a probability distribution of visual information in the 3D global reference of the robot. In addition, a prediction technique based on filter gain is defined to improve the matching of visual information extracted from the probability distribution. This work reveals an enhanced matching technique for visual information in both, the image reference frame, and the 3D global reference. Real data results are presented to confirm the validity of the approach when working in a mobile robotic application for visual localization. Besides, a comparison against standard visual matching techniques is also presented. The suitability and robustness of the contributions are tested in the presented experiments. Full article

In this work, we present and discuss on the deflection estimation of a bi-dimensional panel by using Fiber Bragg Gratings (FBGs) as strain sensors embedded in the structure and a method based on the classical beam theory. The existing difficulties in the direct measure of the deflection are overcome thanks to the proposed technique and a real-time indirect structural monitoring is possible both on small and large structure. In many tests the estimated deflection with the proposed method has been compared with direct deflection measurements obtained with a mechanical comparator showing good agreement. A resolution of few tens of microns over a surface of the order of 1 m² has been reached. Full article

A femtosecond laser direct writing system was developed to explore the fabrication of long-period fiber gratings (LPFGs) in SMF28 fibers. The LPFGs, showing the mode LP_1,6 at 1500 nm, were exposed to high-temperature annealing up to 950 °C. Modifications in the refractive index (RI) modulation are observed through a blue-shift in the LPFG attenuation bands and above 850 °C, the mode LP_1,7 appear at 1600 nm. The wavelength sensitivity to external RI from 1.300 to 1.452 was estimated for both modes before and after annealing. Greater sensitivity was found for the higher order mode in the entire range reaching 2400 nm/RIU around 1.440. Full article

Dissolved carbon dioxide (dCO₂) evaluation is very important in many different fields. In this work, a new, integrated, colorimetric-optical fiber-based system for dCO₂ monitoring in aquaculture industry was developed. The sensing chemistry is based on colorimetric changes of the used indicator—poly p-nitrophenol (pNPh)—in contact with CO₂. Preliminary tests were done in a laboratory environment (calibration) and in a laboratory Recirculating Aquaculture System (RAS) with controlled CO₂ injection. The results have shown the suitability of the new sensor for assessing dCO₂ dynamics in RAS and its fast detection of low dCO₂ concentrations in an appropriate operation range. Full article

Optical fiber sensors (OFS) based on long-period fiber gratings (LPFG) or on surface plasmon resonance (SPR) represent attractive solutions for detection systems in remote areas. An interrogation system consisting on wavelength modulation of fiber coupled distributed feedback (DFB) lasers was implemented and tested. The system uses a single photodetector to individually acquire the intensity of each DFB laser modulated by the OFS and the real transmission spectrum is reconstructed through curve fitting. Testing was accomplished by measuring the spectral features of an LPFG when changing the surrounding refractive index and errors lower than 1.8 nm in the 1530 to 1570 nm wavelength region were obtained. Full article

High concentration of biogenic amines (BA) is an indicator of deterioration of food and the determination of their concentration is an important method of food control. The hydrogen peroxide (H₂O₂) is a side product of the degradation of BAs by certain enzymes. It is presented an experimental technique grounded on chemiluminescence to measure small quantities of H₂O₂ with concentrations as low as 0.01%w/w up to 0.08%w/w. Luminol and cobalt hydroxide are added to hydroxyethyl cellulose to obtain an active membrane which will react with the sampling solution and the amount of total light emission is directly related to the H₂O₂ concentration. Full article

Two sensors for the detection of the metal ion Cu(II), based on the same sensing layer, are compared. They rely on different transduction methods, i.e., electrochemistry and surface plasmon resonance (SPR). D,L-penicillamine was used as the specific receptor since it is a strong ligand for copper(II). Moreover it is easily immobilized on a gold layer by a self assembling procedure by contacting the gold layer overnight with water/EtOH (80/20) containing D,L-penicillamine, taking advantage of the spontaneous interaction of thiols with gold surfaces. Both the electrochemical and SPR platforms were derivatized in the same way. In the first case a gold disc was used as working electrode, and in the second one a thin gold layer (60 nm thick) was deposited by sputtering over the exposed core of a plastic optical fiber (POF), after removing the cladding along half circumference. Full article

Our contribution focuses on humidity gas-sensing device formation of metal oxide materials such as BaTiO₃ nanorods and TiO₂-BaTiO₃ nanotubes. Processing of humidity sensors based on BaTiO₃ nanostructured materials, that can operate under severe environmental conditions is of great relevance due to their small size and small weight. As a result, these sensors possess high stability, fast response times and reproducibility. Furthermore, gas sensor properties are not only interesting in terms of device applications, but also pave the way to study in deep ionic and electronic conduction mechanisms in individual nano-based devices. Full article

This work presents a novel design of a bidirectional Inductive Power Transfer (IPT) system capable of continuous monitoring of cardiac pressure. The proposed system results from a robust electromagnetic coupling between an external reading coil and an implanted two-level (3D approach) inductor array. In this design, each coupling module follows a 13.56 MHz operating frequency, where both passive RCL networks are near field tuned. Among our main results, we obtained a Power Transfer Efficiency (PTE) of 94.1% across the 3.5 cm-thick composed biological tissue whereas the implanted coil array is about 50% of its conventional size. Since the resulting PTE efficiency is 40% higher, based on the optimized L and Q parameters, this novel approach could be used in other medical applications. This IPT system design is based on a low-cost thin film fabrication technology. Full article

Underwater acoustic technology is a major method in current ocean research and exploration, which support the detection of seabed environment and marine life. However, the detection accuracy is directly affected by the quality of underwater acoustic signals collected by hydrophones. Hydrophones are efficient and important tools for collecting underwater acoustic signals. The collected signals of hydrophone often contain lots kinds of noise as the work environment is unknown and complex. Traditional signal denoising methods, such as wavelet analysis and empirical mode decomposition, product unsatisfied results of denoising. In this paper, a denoising method combining wavelet threshold processing and empirical mode decomposition is proposed, and correlation analysis is added in the signal reconstruction process. Finally, the experiment proves that the proposed denoising method has a better denoising performance. With the employment of the proposed method, the underwater acoustic signals turn smoothly and the signal drift of the collected hydroacoustic signal is improved. Comparing the signal spectrums of other methods, the spectral energy of the proposed denoising method is more concentrated, and almost no energy attenuation occurred. Full article

This manuscript presents low-cost sensing systems for the monitoring of liquids, namely water and beverages quality assessment, with remote and in-site monitoring capabilities. The collaboration with several research groups allowed the development of smart optical platforms and low-cost sensors based on plastic optical fibers for the measurement of turbidity, color, refractive index and water contaminants. Full article

Methylated DNA is a covalent post-translational modification, which plays a crucial role in pathological and physiological processes including several diseases, such as cardiovascular disease, diabetes or cancer. Despite that, methylated DNA presents a new generation of biomarkers, which brings a promising alternative for using in point-care diagnostic. Regarding this fact, DNA based electrochemical sensors enable fast, reliable, low-cost, time-consuming and efficient detection. The application of these biosensors as possible alternatives for the determination of methylated DNA is recently growing. Therefore, a biosensor for the determination of methylated DNA was fabricated. This study was aimed to develop an efficient biosensor, with an amplified electrochemical signal which is suited for the detection of the low-level concentration of methylated DNA. The bare gold electrode was first covered with the graphene oxide modified with gold, silver and copper nanoparticles. These composites have a strong affinity to DNA probe and their effect on the sensitivity and selectivity of the biosensor was investigated. The developed biosensor shows promising analytical characteristics with a wide detection linear range. The electrochemical impedance spectroscopy (EIS) was used to detect the hybridization of the DNA probe with methylated DNA target. Full article

The field of biochemical sensing is evolving from the use of bulky apparatuses to the development of miniaturized systems allowing personal sensing and point of care analysis. We report a wearable platform capable of measuring the concentration of multiple electrolytes in sweat (Na⁺, K⁺, Cl⁻). The platform accesses sweat emerging through the skin, drawing it across solid-state ion-selective electrodes by capillary action. The electrolyte composition is monitored in real time by potentiometry. The sensor data is digitised and transmitted via Bluetooth to a mobile phone or laptop. The platform has been employed in on-body trials during controlled exercise. Full article

In this work a multiparameter plastic optical fiber (POF) sensor is presented. A three lobes POF consisting of polymethylmethacrylate (PMMA) core and a fluorinated polymer (FP) for the cladding was fabricated. The aim is to use a plastic fiber with non-circular shape to implement a bending direction and rotation sensor. The mode confinement in the plastic filament obtained with the extrusion process was simulated, and the effect of bending evaluated. The POF sensor is interrogated in transmission using an LED as light source and a charge-coupled device (CCD) to capture the light intensity distribution inside the core, and then analyze the changes when a bending or a rotation is applied. Full article

An Optical Voltage Sensor prototype has been developed suitable for operating as embedded sensor in capacitive dividers for monitoring Medium Voltage in distribution networks. It is based on a retracing scheme, which consists of Lithium Tantalate crystals used as voltage transducers, and on telecom standard single mode fibre components. In this work a optimization of the optical layout via a numerical and an experimental investigation is reported for guaranteeing the OVS sensor survival under fast over-voltages. Tests carried out under different configurations of the electric circuit did not evidenced critical electric field gradients within the transduction path which could damage or deteriorate over time the performance of the OVS sensor. Full article

Methyl nicotinate (MN) is an important tuberculosis biomarker, and can be effectively measured using electrochemical methods. In this study, we have developed a novel N-doped phenolic polymer nanocomposite in situ dispersed with reduced graphene oxide and cobalt (Co)-nanoparticles as a sensor electrode (Co-rGO/PC). Co-nanoparticles were used for the MN recognition. Carbonization was performed for the reduction of GO and the synthesis of Co-nanoparticles. The prepared electrode materials were characterized using SEM, EDS, EIS, and CV. Tested using differential pulse voltammetry, Co-rGO/PC showed its pplicability (RSD < 6%) over 0.05–20.0 mg L⁻¹ MN concentration with high sensitivity (S/N ratio = 3). The present method and materials can also be used for the development of sensors for the other biomarkers. Full article

In a recent article, we have reported that a fabric-sheet unified sensing electrode (FUSE) can detect electrocardiogram (ECG), body proximity at the chest and abdomen (BPx_chest, BPx_abd) and respiratory movement at the abdomen (RM_abd) via worn clothes and bedsheet simultaneously from recumbent human subject. We conducted feasibility study involving 21 subjects to assess the influence of individual difference on this FUSE system. Results revealed that individual difference of physical constitution had little impact on both accuracies of ECG R wave and RM_abd under the current FUSE configuration, but had some influence on the voltage changes in BPx_chest and BPx_abd caused by postural change. We deemed to revise some dimensions of the FUSE to avoid individual threshold setting for sitting up detection. Full article

Electrochemical immunoassays were developed for the analysis of HER2-ECD, a cancer biomarker. A sandwich assay was performed using SPCEs modified with (1) gold nanoparticles (AuNP), (2) carboxylic acid-functionalized multiwalled-carbon nanotubes (MWCNT) and AuNP or using (3) carboxylic acid-functionalized magnetic beads. The antibody-antigen interaction was detected using an antibody labelled with alkaline phosphatase and 3-indoxyl phosphate and silver ions as the enzymatic substrate. The signal of the enzymatically generated metallic silver was recorded by linear sweep voltammetry (LSV). The total assay time was 2h20min. The obtained LODs were 8.5 ng/mL for SPCE-AuNP, 0.16 ng/mL for SPCE-MWCNT/AuNP and 2.8 ng/mL for SPCE-MBs. Full article

Mechanical stresses of materials are generally coupled with temperature variations and then, monitoring such variations can help gaining information about the material behavior under the applied loads. This can be accomplished with an infrared imaging device, which can be advantageously exploited to sense the thermal radiation associated with mechanical stresses and to obtain a legible explicative temperature map. In the present paper, glass/epoxy is used as material case study to show that thermal signatures visualized during the load application can be decoded into knowledge, which can contribute to the material characterization. In particular, glass/epoxy specimens are subjected to three types of tests: cantilever beam alternate bending, quasi-static bending and low velocity impact. Thermal images are acquired in time sequence during each test and after post-processed and analyzed. It is possible to get data about the damage initiation and its evolution under either quasi-static bending, or impact. In particular, a cute analysis of thermal images supplies information about damage types (matrix cracks, or fibers breakage) and extension of delamination, as well of the impact duration and the time to reach peak contact force. It is also possible to well depict the harmonic cantilever beam oscillations through the associated small temperature variations. Full article

Electrochemical molecularly imprinted polymers (e-MIP) are MIP specially designed to detect aromatic organic molecules without redox properties. The detection is based on the electrochemical answer of a redox probe inserted inside the binding cavities of cross-linked MIPs. Microbeads of e-MIP were synthesized from vinylferrocene or ferrocenylmethyl methacrylate as functional monomer/redox probe with or without 4-vinylpyridine functional as co-monomer, benzo[a]pyrene or bisphenol A as the target and ethylene glycol dimethacrylate of divinylbenzene as cross-linker. After physico-chemical characterization, e-MIP microbeads were incorporated in a graphite paste to prepare modified electrode or screen-printed carbon electrodes (SPCE). Full article

We report, to our knowledge, the first optical detection of the main isotopologues of short-chained hydrocarbons. The sensor system is based on photoacoustic (also known as optoacoustic) spectroscopy (PAS, OAS). This technique takes advantage of the fact that absorbed electromagnetic radiation is partially transferred into kinetic energy via inelastic molecular collisions. This is equivalent to a temperature increase of the irradiated volume. If the radiation is modulated, a pressure wave with an amplitude proportional to the concentration of the absorbing molecules is generated, the so called PA (OA) signal. Two continuous wave (cw), thermoelectrically cooled (TEC), distributed feedback interband cascade lasers (DFB-ICLs) with emission wavelengths around 3.33 and 3.38 μm, respectively, serve as light sources. The PA signal is detected with a microphone and phase-sensitively amplified. The new sensor is applied for the stable carbon isotope-selective analyses of methane (CH₄), ethane (C₂H₆) and propane (C₃H₈). We report first measurements of ¹²C₂H₆, ¹³C¹²CH₆ and ¹³C₂H₆ as well as of ¹²C₃H₈ and ¹³C¹²C₂H₈, all at approximate room temperature and atmospheric pressure. The listed isotopologues were selected because of their importance for numerous applications from atmospheric and planetary research to natural gas exploration. Full article

Triclosan (TCS), a bacteriostatic detected in water bodies, have inauspicious effects in human and biota. Consequently, there is a critical need of monitoring these type of compounds in aqueous matrices. In this sense, sensors, based on polyethyleneimine and polysodium 4-styrenesulfonate layer-by-layer thin-films adsorbed on supports with gold interdigitated electrodes deposited, were developed. The aim was analyze the sensitivity of discrimination of TCS (10⁻¹⁵ M to 10⁻⁵ M) in deionized water, Luso^® and in an effluent, by measuring the impedance spectra. LbL films can distinguish TCS concentrations in EF, while in LW was achieved an acceptable sensibility when interdigitated electrodes without films were used. Full article

The electronic tongue concept based on layer-by-layer (LbL) films can be used to the detection in water of triclosan (TCS), a pernicious molecule used in personal care products and widely released in the environment. In this work, we analyzed the adsorption of TCS on poly(allylaminehydrochloride) (PAH) and poly[1-[4-(3-carboxy-4hydroxyphenylazo) benzenesulfonamido]-1,2-ethanediyl, sodium salt] (PAZO) layers of PAH/PAZO LbL films. We demonstrate that the adsorbed amount is strongly dependent of pH, the efficiency of adsorption of TCS on PAH layer is higher, and, when PAZO is the outmost layer, the electrical parameters can discriminate the ionic strength on solutions of TCS. Full article

We clarify that, unlike time-domain techniques, slope-assisted Brillouin optical correlation-domain reflectometry has a trade-off relation between the strain dynamic range and the spatial resolution. This trade-off is shown to be caused by its unique bell-shaped noise floor, which is inherently unavoidable in correlation-domain systems. Subsequently, we experimentally show that, at the cost of lowered spatial resolution, the strain dynamic range can be 3 times wider than the previously reported value. Full article

The combination of micro- and nano-technologies with micro-mechanic, photonic, electronic and (bio)chemical approaches is producing completely new, compact and effective tools for diagnostics and therapeutics, which can be disposable, wearable, implantable or tattooable. These new technologies are opening the way to closed loop theranostics, i.e., device integrating advanced sensing and diagnostic capabilities and therapeutic response. In order to enable these new class of transducers for continuous and real time health monitoring, ultrathin and compliant non-intrusive smart technologies are required. Full article

In this work, we report a systematic investigation about the sensitivity of arc-induced Long Period Gratings in standard SMF28 fiber. Several gratings were fabricated with period Λ in range 330–630 µm and characterized towards changes in the surrounding refractive index (SRI), temperature and strain conditions. Wide tuning of the sensitivities is reported, with maximum values of -6391.7 nm/RIU, 95.5 pm/°C and 2.0 pm/με, respectively, for SRI, temperature and strain. These results permit the proper selection of the fabrication parameters in order to have the desired sensing features for a specific application. Full article

We introduce wavelength-scanning coherent optical time domain reflectometry (WS-COTDR) for dynamic vibration sensing along optical fibers. The method is based on spectral shift computation from Rayleigh backscatter spectra. Artificial neural networks (ANNs) are used for fast and high-resolution strain computation from raw measurement data. The applicability of the method is demonstrated for vibration monitoring of a reinforced concrete bridge. We demonstrate another application example for quasi-static and dynamic measurement of ground deformation and surface wave propagation along a dark fiber in a telecommunication cable. Full article

This paper presents the design of a new force/tactile sensor for robotic applications. The sensor is suitably designed to provide the robotic grasping device with a sensory system mimicking the human sense of touch, namely, a device sensitive to contact forces, object slip and object geometry. This type of perception information is of paramount importance not only in dexterous manipulation but even in simple grasping task, especially when objects are fragile and deformable, such that only a minimum amount of grasping force can be applied to hold the object without damaging it. Full article

We present an immunosensor for the rapid and sensitive detection of the p53 oncosuppressor protein and of its mutated form p53_R175H, which are both valuable cancer biomarkers. The sensor is based on the accurate measurement of the source-drain current variation of a metal oxide semiconductor field-effect transistor, as due to the gate potential changing arising from charge release upon the selective capture of a biomarker by the partner immobilized on a sensing surface connected to the gate electrode. A suitable microelectronic system is implemented to combine high current resolution, which is needed to be competitive with standard immunoassays, with compact dimensions of the final sensor device. Full article

A novel sensor for measuring viscoelastic properties of sodium alginate (SA) in distilled water of concentration (1.0, 1.5, 2.0, 2.5, and 3.0 w/w%) has been tested. The sensor used is an FBG (Fiber Bragg Grating) fibre optic sensor. It has seen that there is a linear response in terms of area of the peak as the concentration of SA increases and the FWHM increases linearly with a small error bar, indicating the precision of the present sensor. The system proposed will substitute the mechanical Maxwell method for measuring viscoelasticity of polymers, with a mechano-optic sensor. Full article

We use here a carbon nanomaterial as the electroactive label for the development of a low-cost and easy-to-miniaturize non-optical polymerase chain reaction (PCR). To this aim, graphene oxide nanocolloids (GONCs) were first conjugated to the DNA primers either by physical adsorption or by the formation of a covalent bond. Subsequently, GONC-modified primers were hybridized to their complementary counterpart to obtain GONC-modified double stranded DNA (GONC-dsDNA). The electrochemical signal, due to the reduction of the electrochemically reducible oxygen functionalities on GONC surface was then measured and correlated to the concertation of GONC-dsDNA. Full article

We use as optical waveguide a green composite, based on bacterial cellulose (BC). More specifically, we have sputtered a thin gold film on this innovative slab waveguide for obtaining a Localized Surface Plasmon Resonance (LSPR) sensor. Experimental results confirm the possibility of using the BC based composite as an environmental friendly optical sensor platform with plasmonic capabilities, which could be exploited for realizing disposable biosensors. The new optical sensor has been used by combining it with optical fibers. The fibers connect the green disposable optical sensor with a light source and with a spectrometer. The device has been tested by measuring the refractive index of different water-glycerin solutions. Full article

Due to the non-electroactivity of carcinogenic organic compound acrylamide, an indirect electrochemical detection by using molecularly imprinted polymer is proposed as a detection method. Polyaniline was chosen due to the conductivity, interesting properties and wide usage in the field of sensors. Polyaniline was prepared by the different electropolymerisation process to achieve different morphologies, properties. Cyclic voltammetry was further chosen for electropolymeristion of polyaniline, in which propanamide was imprinted as a template molecule. Due to the same size, shape and functional groups, so imprinted polyaniline presents a proof of concept molecule for further acrylamide bonding. Successful imprinting was confirmed by surface analysis technique (FTIR) and simple electrochemical measurements of polyaniline response. Full article

For the omnidirectional measurement, the collected images of large-angle fisheye lens need to be corrected and spliced before next procedure, which is complicated and inaccurate. In this paper, a direct position measurement method based on fisheye imaging is proposed for large-angle imaging without any image correcting and splicing. A nonlinear imaging system of fisheye lens is used to acquire the sequence images based on its distortion model, and the critical distortion features of the sequence images are extracted, which contains the position information. And a BP neural network is trained with the extracted image features of previous standard experimental dataset. Finally, the trained BP neural network is employed to measure the object’s distance. Experimental results demonstrate show that the proposed method achieves simple close-object distance measurement with high robustness and a measurement error of ±0.5cm. The proposed method overcomes the shortcomings of conventional measurement methods and expands the fisheye applications filed for omnidirectional measurement. Full article

For Chinese traditional musical instruments, the general subjective evaluation method by experts is not cost-effective and is limited by fewer and fewer experts, but a clear physical law is very hard to established by physicists. Considering the effectiveness of artificial neural networks (ANNs) for complex system, for a Chinese lute case, a neural network based 8-microphone array is applied to correlate the objective instrument acoustic features with expert subjective evaluations in this paper. The acoustic features were recorded by a microphone array sensor and extracted as the constant-Q transform coefficients, Mel-frequency cepstral coefficients and correlation coefficients between each microphone for ANNs input. The acoustic library establishment, acoustic features extractions, and deep learning model for Chinese lutes evaluation are reported in this paper. Full article

In-liquid biosensing is the new frontier of cells real time monitoring and biomarkers detection. In order to improve the stability and electrical properties of an Electrolyte Gated Organic Field Effect Transistor (EGOFET) biosensor, in this study we investigate the effect of the solvent and of the substrate modification on thin films of organic semiconductor Poly(3-hexylthiophene) (P3HT). The studied surface is the relevant interface between the P3HT and the electrolyte acting as gate dielectric for in-liquid detection of an analyte. AFM and XPS characterizations were employed to study the effect of two solvents (toluene and 1,2-dichlorobenzene) and of the adhesion promoter (Ti prime) on the morphological structure and electronic properties of P3HT film. Combining the results from the surface characterizations with electrical measurements, we investigate the changes on the EGOFET performances and stability in DI water with an Ag/AgCl gate electrode. Full article