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Materials and Applications for Sensors and Transducers

A special issue of Sensors (ISSN 1424-8220).

Deadline for manuscript submissions: closed (31 August 2017) | Viewed by 85411

Special Issue Editors


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Guest Editor
Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 11635 Athens, Greece
Interests: optical materials; nanocomposites; nanomaterials; photonics; optoelectronics; devices; sensors; biosensing; industrial applications
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Guest Editor
Department of Economics, University of Peloponnese, 22100 Tripolis, Greece
Interests: complex systems; machine learning; variational integrators; econo-physics
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

It is our pleasure to announce this Special Issue that will host selected and peer-reviewed papers from the 6th International Conference on Materials and Applications for Sensors and Transducers (27–30 September, 2016, Athens, Greece). The IC-MAST conference covers a board thematic area of sensor technology and related applications, but is also especially focused on material research that enables sensors and transducers development. Guest Editors also invite individual researchers in addition to IC-MAST 2016 participants to contribute original research papers or timely reviews in those thematic areas.

The research and development activities of sensing devices and transducers has become an interdisciplinary technological field, combining research in a number of diverse thematic areas and technologies, ranging from materials, nanotechnology, processing techniques, mathematical modeling, optimization strategies, and electronics integration to name just a few. New disruptive technologies are exploited towards the identification of new potential sensing and monitoring applications, while demanding and established application areas often impose strict operational requirements in current technologies for the enhancement of sensing performance and functionality in a number of application areas like industry, environment, defence, biomedical, health, etc.

The current Special Issue seeks to strengthen this interdisciplinary connection by hosting representative original contributions, aiming to relate, by characteristic examples, the key issues of basic research and materials development with sensing and transuding technology in the frame of emerging and demanding applications.

The Special Issue would include the following topics:

  • Functional materials: optical, magnetic, electronic, semiconducting, nanostructured, etc.
  • Sensors and transducers design
  • Sensors and transducers fabrication
  • Optical and photonic sensors
  • Chemical sensors
  • Gas sensors
  • Nanosensors
  • Sensing methods and technologies
  • Sensor systems and applications
  • Modelling and computational methods for sensors and transducers design
  • Interrogation techniques and devices characterization
  • New demanding applications in industry, defence, space, and biomedical areas
  • Sensing requirements and solutions for new emerging ICT applications: Wireless Sensor Networks, Internet of Things (IoT), etc.

Dr. Christos Riziotis
Prof. Evangelos Hristoforou
Prof. Dimitrios Vlachos
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Materials for sensors
  • Transducers
  • Sensors Fabrication
  • Photonic Sensors
  • Magnetic Sensors
  • Applications
  • Physical sensors
  • Chemical Sensors
  • Biosensors

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Published Papers (14 papers)

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Research

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2418 KiB  
Article
Mn-Doped CaBi4Ti4O15/Pb(Zr,Ti)O3 Ultrasonic Transducers for Continuous Monitoring at Elevated Temperatures
by Makiko Kobayashi, Taiga Kibe and Hajime Nagata
Sensors 2017, 17(12), 2740; https://doi.org/10.3390/s17122740 - 27 Nov 2017
Cited by 2 | Viewed by 3617
Abstract
Continuous ultrasonic in-situ monitoring for industrial applications is difficult owing to the high operating temperatures in industrial fields. It is expected that ultrasonic transducers consisting of a CaBi4Ti4O15(CBT)/Pb(Zr,Ti)O3(PZT) sol-gel composite could be one solution for [...] Read more.
Continuous ultrasonic in-situ monitoring for industrial applications is difficult owing to the high operating temperatures in industrial fields. It is expected that ultrasonic transducers consisting of a CaBi4Ti4O15(CBT)/Pb(Zr,Ti)O3(PZT) sol-gel composite could be one solution for ultrasonic nondestructive testing (NDT) above 500 °C because no couplant is required and CBT has a high Curie temperature. To verify the high temperature durability, CBT/PZT sol-gel composite films were fabricated on titanium substrates by spray coating, and the CBT/PZT samples were tested in a furnace at various temperatures. Reflected echoes with a high signal-to-noise ratio were observed up to 600 °C. A thermal cycle test was conducted from room temperature to 600 °C, and no significant deterioration was found after the second thermal cycle. To investigate the long-term high-temperature durability, a CBT/PZT ultrasonic transducer was tested in the furnace at 600 °C for 36 h. Ultrasonic responses were recorded every 3 h, and the sensitivity and signal-to-noise ratio were stable throughout the experiment. Full article
(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)
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2504 KiB  
Article
Experimental Investigation on the Detection of Multiple Surface Cracks Using Vibrothermography with a Low-Power Piezoceramic Actuator
by Changhang Xu, Jing Xie, Wuyang Zhang, Qingzhao Kong, Guoming Chen and Gangbing Song
Sensors 2017, 17(12), 2705; https://doi.org/10.3390/s17122705 - 23 Nov 2017
Cited by 25 | Viewed by 4567
Abstract
Vibrothermography often employs a high-power actuator to generate heat on a specimen to reveal damage, however, the high-power actuator brings inconvenience to the application and possibly introduces additional damage to the inspected objects. This study uses a low-power piezoceramic transducer as the actuator [...] Read more.
Vibrothermography often employs a high-power actuator to generate heat on a specimen to reveal damage, however, the high-power actuator brings inconvenience to the application and possibly introduces additional damage to the inspected objects. This study uses a low-power piezoceramic transducer as the actuator of vibrothermography and explores its ability to detect multiple surface cracks in a metal part. Experiments were conducted on a thin aluminum beam with three cracks in different orientations. Detailed analyses of both thermograms and temperature data are presented to validate the proposed vibrothermography method. To further investigate the performance of the proposed vibrothermography method, we experimentally studied the effects of several critical factors, including the amplitude of excitation signal, specimen constraints, relative position between the transducer and cracks (the transducer is mounted on the same or the opposite side with the cracks). The results demonstrate that all cracks can be detected conveniently and simultaneously by using the proposed low-power vibrothermography. We also found that the magnitude of excitation signal and the specimen constraints have a great influence on detection results. Combined with effective data processing methods, such as Fourier transformation employed in this study, the proposed method provides a promising potential to detect multiple cracks on a metal surface in a safe and effective manner. Full article
(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)
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4434 KiB  
Article
Research on the Optimum Water Content of Detecting Soil Nitrogen Using Near Infrared Sensor
by Yong He, Shupei Xiao, Pengcheng Nie, Tao Dong, Fangfang Qu and Lei Lin
Sensors 2017, 17(9), 2045; https://doi.org/10.3390/s17092045 - 7 Sep 2017
Cited by 24 | Viewed by 4550
Abstract
Nitrogen is one of the important indexes to evaluate the physiological and biochemical properties of soil. The level of soil nitrogen content influences the nutrient levels of crops directly. The near infrared sensor can be used to detect the soil nitrogen content rapidly, [...] Read more.
Nitrogen is one of the important indexes to evaluate the physiological and biochemical properties of soil. The level of soil nitrogen content influences the nutrient levels of crops directly. The near infrared sensor can be used to detect the soil nitrogen content rapidly, nondestructively, and conveniently. In order to investigate the effect of the different soil water content on soil nitrogen detection by near infrared sensor, the soil samples were dealt with different drying times and the corresponding water content was measured. The drying time was set from 1 h to 8 h, and every 1 h 90 samples (each nitrogen concentration of 10 samples) were detected. The spectral information of samples was obtained by near infrared sensor, meanwhile, the soil water content was calculated every 1 h. The prediction model of soil nitrogen content was established by two linear modeling methods, including partial least squares (PLS) and uninformative variable elimination (UVE). The experiment shows that the soil has the highest detection accuracy when the drying time is 3 h and the corresponding soil water content is 1.03%. The correlation coefficients of the calibration set are 0.9721 and 0.9656, and the correlation coefficients of the prediction set are 0.9712 and 0.9682, respectively. The prediction accuracy of both models is high, while the prediction effect of PLS model is better and more stable. The results indicate that the soil water content at 1.03% has the minimum influence on the detection of soil nitrogen content using a near infrared sensor while the detection accuracy is the highest and the time cost is the lowest, which is of great significance to develop a portable apparatus detecting nitrogen in the field accurately and rapidly. Full article
(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)
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2431 KiB  
Article
Response of a Zn2TiO4 Gas Sensor to Propanol at Room Temperature
by Ibrahim Gaidan, Dermot Brabazon and Inam Ul Ahad
Sensors 2017, 17(9), 1995; https://doi.org/10.3390/s17091995 - 31 Aug 2017
Cited by 23 | Viewed by 5942
Abstract
In this study, three different compositions of ZnO and TiO2 powders were cold compressed and then heated at 1250 °C for five hours. The samples were ground to powder form. The powders were mixed with 5 wt % of polyvinyl butyral (PVB) [...] Read more.
In this study, three different compositions of ZnO and TiO2 powders were cold compressed and then heated at 1250 °C for five hours. The samples were ground to powder form. The powders were mixed with 5 wt % of polyvinyl butyral (PVB) as binder and 1.5 wt % carbon black and ethylene-glyco-lmono-butyl-ether as a solvent to form screen-printed pastes. The prepared pastes were screen printed on the top of alumina substrates containing arrays of three copper electrodes. The three fabricated sensors were tested to detect propanol at room temperature at two different concentration ranges. The first concentration range was from 500 to 3000 ppm while the second concentration range was from 2500 to 5000 ppm, with testing taking place in steps of 500 ppm. The response of the sensors was found to increase monotonically in response to the increment in the propanol concentration. The surface morphology and chemical composition of the prepared samples were characterized by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The sensors displayed good sensitivity to propanol vapors at room temperature. Operation under room-temperature conditions make these sensors novel, as other metal oxide sensors operate only at high temperature. Full article
(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)
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2796 KiB  
Article
Transformation from a Single Antenna to a Series Array Using Push/Pull Origami
by Syed Imran Hussain Shah and Sungjoon Lim
Sensors 2017, 17(9), 1968; https://doi.org/10.3390/s17091968 - 26 Aug 2017
Cited by 11 | Viewed by 5576
Abstract
We propose a push/pull origami antenna, transformable between a single antenna element and a three-element array. In limited space, the proposed origami antenna can work as a single antenna. When the space is not limited and a higher gain is required, the proposed [...] Read more.
We propose a push/pull origami antenna, transformable between a single antenna element and a three-element array. In limited space, the proposed origami antenna can work as a single antenna. When the space is not limited and a higher gain is required, the proposed origami antenna can be transformed to a series antenna array by pulling the frame. In order to push the antenna array back to a single antenna, the frame for each antenna element size must be different. The frame and supporting dielectric materials are built using a three-dimensional (3D) printer. The conductive patterns are inkjet-printed on paper. Thus, the proposed origami antenna is built using hybrid printing technology. The 10-dB impedance bandwidth is 2.5–2.65 GHz and 2.48–2.62 GHz for the single-antenna and array mode, respectively, and the peak gains in the single-antenna and array mode are 5.8 dBi and 7.6 dBi, respectively. The proposed antenna can be used for wireless remote-sensing applications. Full article
(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)
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6129 KiB  
Article
Aspheric Surface Measurement Using Capacitive Sensors
by Daocheng Yuan, Huiying Zhao, Xin Tao, Shaobo Li, Xueliang Zhu and Chupeng Zhang
Sensors 2017, 17(6), 1355; https://doi.org/10.3390/s17061355 - 11 Jun 2017
Cited by 6 | Viewed by 5003
Abstract
This paper proposes a new method for the measurement of spherical coordinates by using capacitive sensors as a non-contact probe solution of measurement of aspheric surfaces. The measurement of the average effect of the capacitive probe and the influence of capacitive probe tilting [...] Read more.
This paper proposes a new method for the measurement of spherical coordinates by using capacitive sensors as a non-contact probe solution of measurement of aspheric surfaces. The measurement of the average effect of the capacitive probe and the influence of capacitive probe tilting were studied with respect to an eccentric spherical surface. Based on the tested characteristic curve of the average effect of the sphere and probe, it was found that nonlinear and linear compensation resulted in high measurement accuracy. The capacitance probe was found to be trying to fulfill a need for performing nm-level precision measurement of aspheric electromagnetic surfaces. Full article
(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)
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1190 KiB  
Article
Concentric-Electrode Organic Electrochemical Transistors: Case Study for Selective Hydrazine Sensing
by Sébastien Pecqueur, Stéphane Lenfant, David Guérin, Fabien Alibart and Dominique Vuillaume
Sensors 2017, 17(3), 570; https://doi.org/10.3390/s17030570 - 11 Mar 2017
Cited by 12 | Viewed by 6730
Abstract
We report on hydrazine-sensing organic electrochemical transistors (OECTs) with a design consisting of concentric annular electrodes. The design engineering of these OECTs was motivated by the great potential of using OECT sensing arrays in fields such as bioelectronics. In this work, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based [...] Read more.
We report on hydrazine-sensing organic electrochemical transistors (OECTs) with a design consisting of concentric annular electrodes. The design engineering of these OECTs was motivated by the great potential of using OECT sensing arrays in fields such as bioelectronics. In this work, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based OECTs have been studied as aqueous sensors that are specifically sensitive to the lethal hydrazine molecule. These amperometric sensors have many relevant features for the development of hydrazine sensors, such as a sensitivity down to 10−5 M of hydrazine in water, an order of magnitude higher selectivity for hydrazine than for nine other water-soluble common analytes, the capability to entirely recover its base signal after water flushing, and a very low operation voltage. The specificity for hydrazine to be sensed by our OECTs is caused by its catalytic oxidation at the gate electrode, and enables an increase in the output current modulation of the devices. This has permitted the device-geometry study of the whole series of 80 micrometric OECT devices with sub-20-nm PEDOT:PSS layers, channel lengths down to 1 µm, and a specific device geometry of coplanar and concentric electrodes. The numerous geometries unravel new aspects of the OECT mechanisms governing the electrochemical sensing behaviours of the device—more particularly the effect of the contacts which are inherent at the micro-scale. By lowering the device cross-talk, micrometric gate-integrated radial OECTs shall contribute to the diminishing of the readout invasiveness and therefore further promote the development of OECT biosensors. Full article
(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)
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8679 KiB  
Article
Characterization of Industrial Coolant Fluids and Continuous Ageing Monitoring by Wireless Node—Enabled Fiber Optic Sensors
by Alexandros El Sachat, Anastasia Meristoudi, Christos Markos, Andreas Sakellariou, Aggelos Papadopoulos, Serafim Katsikas and Christos Riziotis
Sensors 2017, 17(3), 568; https://doi.org/10.3390/s17030568 - 11 Mar 2017
Cited by 12 | Viewed by 6224
Abstract
Environmentally robust chemical sensors for monitoring industrial processes or infrastructures are lately becoming important devices in industry. Low complexity and wireless enabled characteristics can offer the required flexibility for sensor deployment in adaptable sensing networks for continuous monitoring and management of industrial assets. [...] Read more.
Environmentally robust chemical sensors for monitoring industrial processes or infrastructures are lately becoming important devices in industry. Low complexity and wireless enabled characteristics can offer the required flexibility for sensor deployment in adaptable sensing networks for continuous monitoring and management of industrial assets. Here are presented the design, development and operation of a class of low cost photonic sensors for monitoring the ageing process and the operational characteristics of coolant fluids used in an industrial heavy machinery infrastructure. The chemical, physical and spectroscopic characteristics of specific industrial-grade coolant fluids were analyzed along their entire life cycle range, and proper parameters for their efficient monitoring were identified. Based on multimode polymer or silica optical fibers, wide range (3–11) pH sensors were developed by employing sol-gel derived pH sensitive coatings. The performances of the developed sensors were characterized and compared, towards their coolants’ ageing monitoring capability, proving their efficiency in such a demanding application scenario and harsh industrial environment. The operating characteristics of this type of sensors allowed their integration in an autonomous wireless sensing node, thus enabling the future use of the demonstrated platform in wireless sensor networks for a variety of industrial and environmental monitoring applications. Full article
(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)
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3884 KiB  
Article
Humidity Sensing Properties of Paper Substrates and Their Passivation with ZnO Nanoparticles for Sensor Applications
by Georgios Niarchos, Georges Dubourg, Georgios Afroudakis, Markos Georgopoulos, Vasiliki Tsouti, Eleni Makarona, Vesna Crnojevic-Bengin and Christos Tsamis
Sensors 2017, 17(3), 516; https://doi.org/10.3390/s17030516 - 4 Mar 2017
Cited by 52 | Viewed by 7041
Abstract
In this paper, we investigated the effect of humidity on paper substrates and propose a simple and low-cost method for their passivation using ZnO nanoparticles. To this end, we built paper-based microdevices based on an interdigitated electrode (IDE) configuration by means of a [...] Read more.
In this paper, we investigated the effect of humidity on paper substrates and propose a simple and low-cost method for their passivation using ZnO nanoparticles. To this end, we built paper-based microdevices based on an interdigitated electrode (IDE) configuration by means of a mask-less laser patterning method on simple commercial printing papers. Initial resistive measurements indicate that a paper substrate with a porous surface can be used as a cost-effective, sensitive and disposable humidity sensor in the 20% to 70% relative humidity (RH) range. Successive spin-coated layers of ZnO nanoparticles then, control the effect of humidity. Using this approach, the sensors become passive to relative humidity changes, paving the way to the development of ZnO-based gas sensors on paper substrates insensitive to humidity. Full article
(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)
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2925 KiB  
Article
Sensing Properties of a Novel Temperature Sensor Based on Field Assisted Thermal Emission
by Zhigang Pan, Yong Zhang, Zhenzhen Cheng, Jiaming Tong, Qiyu Chen, Jianpeng Zhang, Jiaxiang Zhang, Xin Li and Yunjia Li
Sensors 2017, 17(3), 473; https://doi.org/10.3390/s17030473 - 27 Feb 2017
Cited by 17 | Viewed by 4683
Abstract
The existing temperature sensors using carbon nanotubes (CNTs) are limited by low sensitivity, complicated processes, or dependence on microscopy to observe the experimental results. Here we report the fabrication and successful testing of an ionization temperature sensor featuring non-self-sustaining discharge. The sharp tips [...] Read more.
The existing temperature sensors using carbon nanotubes (CNTs) are limited by low sensitivity, complicated processes, or dependence on microscopy to observe the experimental results. Here we report the fabrication and successful testing of an ionization temperature sensor featuring non-self-sustaining discharge. The sharp tips of nanotubes generate high electric fields at relatively low voltages, lowering the work function of electrons emitted by CNTs, and thereby enabling the safe operation of such sensors. Due to the temperature effect on the electron emission of CNTs, the collecting current exhibited an exponential increase with temperature rising from 20 °C to 100 °C. Additionally, a higher temperature coefficient of 0.04 K−1 was obtained at 24 V voltage applied on the extracting electrode, higher than the values of other reported CNT-based temperature sensors. The triple-electrode ionization temperature sensor is easy to fabricate and converts the temperature change directly into an electrical signal. It shows a high temperature coefficient and good application potential. Full article
(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)
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3916 KiB  
Article
The Influence of Different Partial Pressure on the Fabrication of InGaO Ultraviolet Photodetectors
by Sheng-Po Chang, Li-Yang Chang and Jyun-Yi Li
Sensors 2016, 16(12), 2145; https://doi.org/10.3390/s16122145 - 15 Dec 2016
Cited by 17 | Viewed by 5463
Abstract
A metal–semiconductor–metal ultraviolet photodetector has been fabricated with a radiofrequency (RF)-sputtered InGaO thin film. Results for the devices fabricated under different oxygen partial pressure are here in discussed. Under low oxygen partial pressure, the devices work in the photoconductive mode because of the [...] Read more.
A metal–semiconductor–metal ultraviolet photodetector has been fabricated with a radiofrequency (RF)-sputtered InGaO thin film. Results for the devices fabricated under different oxygen partial pressure are here in discussed. Under low oxygen partial pressure, the devices work in the photoconductive mode because of the large number of subgap states. Therefore, the devices exhibit internal gain. These defects in the films result in slow switching times and lower photo/dark current ratios. A higher flow ratio of oxygen during the sputtering process can effectively restrain the oxygen vacancies in the film. The responsivity of the photodetector fabricated under an oxygen flow ratio of 20% can reach 0.31 A/W. The rise time and decay time can reach 21 s and 27 s, respectively. Full article
(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)
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4758 KiB  
Article
A Photoactivated Gas Detector for Toluene Sensing at Room Temperature Based on New Coral-Like ZnO Nanostructure Arrays
by Li-Ko Yeh, Jie-Chun Luo, Min-Chun Chen, Chih-Hung Wu, Jian-Zhang Chen, I-Chun Cheng, Cheng-Che Hsu and Wei-Cheng Tian
Sensors 2016, 16(11), 1820; https://doi.org/10.3390/s16111820 - 31 Oct 2016
Cited by 9 | Viewed by 6475
Abstract
A photoactivated gas detector operated at room temperature was microfabricated using a simple hydrothermal method. We report that the photoactivated gas detector can detect toluene using a UV illumination of 2 μW/cm2. By ultraviolet (UV) illumination, gas detectors sense toluene at [...] Read more.
A photoactivated gas detector operated at room temperature was microfabricated using a simple hydrothermal method. We report that the photoactivated gas detector can detect toluene using a UV illumination of 2 μW/cm2. By ultraviolet (UV) illumination, gas detectors sense toluene at room temperature without heating. A significant enhancement of detector sensitivity is achieved because of the high surface-area-to-volume ratio of the morphology of the coral-like ZnO nanorods arrays (NRAs) and the increased number of photo-induced oxygen ions under UV illumination. The corresponding sensitivity (ΔR/R0) of the detector based on coral-like ZnO NRAs is enhanced by approximately 1022% compared to that of thin-film detectors. The proposed detector greatly extends the dynamic range of detection of metal-oxide-based detectors for gas sensing applications. We report the first-ever detection of toluene with a novel coral-like NRAs gas detector at room temperature. A sensing mechanism model is also proposed to explain the sensing responses of gas detectors based on coral-like ZnO NRAs. Full article
(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)
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Review

Jump to: Research

19592 KiB  
Review
Micro and Nanostructured Materials for the Development of Optical Fibre Sensors
by Cesar Elosua, Francisco Javier Arregui, Ignacio Del Villar, Carlos Ruiz-Zamarreño, Jesus M. Corres, Candido Bariain, Javier Goicoechea, Miguel Hernaez, Pedro J. Rivero, Abian B. Socorro, Aitor Urrutia, Pedro Sanchez, Pablo Zubiate, Diego Lopez-Torres, Nerea De Acha, Joaquin Ascorbe, Aritz Ozcariz and Ignacio R. Matias
Sensors 2017, 17(10), 2312; https://doi.org/10.3390/s17102312 - 11 Oct 2017
Cited by 50 | Viewed by 8569
Abstract
The measurement of chemical and biomedical parameters can take advantage of the features exclusively offered by optical fibre: passive nature, electromagnetic immunity and chemical stability are some of the most relevant ones. The small dimensions of the fibre generally require that the sensing [...] Read more.
The measurement of chemical and biomedical parameters can take advantage of the features exclusively offered by optical fibre: passive nature, electromagnetic immunity and chemical stability are some of the most relevant ones. The small dimensions of the fibre generally require that the sensing material be loaded into a supporting matrix whose morphology is adjusted at a nanometric scale. Thanks to the advances in nanotechnology new deposition methods have been developed: they allow reagents from different chemical nature to be embedded into films with a thickness always below a few microns that also show a relevant aspect ratio to ensure a high transduction interface. This review reveals some of the main techniques that are currently been employed to develop this kind of sensors, describing in detail both the resulting supporting matrices as well as the sensing materials used. The main objective is to offer a general view of the state of the art to expose the main challenges and chances that this technology is facing currently. Full article
(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)
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832 KiB  
Review
Identification of Chinese Herbal Medicines with Electronic Nose Technology: Applications and Challenges
by Huaying Zhou, Dehan Luo, Hamid GholamHosseini, Zhong Li and Jiafeng He
Sensors 2017, 17(5), 1073; https://doi.org/10.3390/s17051073 - 9 May 2017
Cited by 51 | Viewed by 8413
Abstract
This paper provides a review of the most recent works in machine olfaction as applied to the identification of Chinese Herbal Medicines (CHMs). Due to the wide variety of CHMs, the complexity of growing sources and the diverse specifications of herb components, the [...] Read more.
This paper provides a review of the most recent works in machine olfaction as applied to the identification of Chinese Herbal Medicines (CHMs). Due to the wide variety of CHMs, the complexity of growing sources and the diverse specifications of herb components, the quality control of CHMs is a challenging issue. Much research has demonstrated that an electronic nose (E-nose) as an advanced machine olfaction system, can overcome this challenge through identification of the complex odors of CHMs. E-nose technology, with better usability, high sensitivity, real-time detection and non-destructive features has shown better performance in comparison with other analytical techniques such as gas chromatography-mass spectrometry (GC-MS). Although there has been immense development of E-nose techniques in other applications, there are limited reports on the application of E-noses for the quality control of CHMs. The aim of current study is to review practical implementation and advantages of E-noses for robust and effective odor identification of CHMs. It covers the use of E-nose technology to study the effects of growing regions, identification methods, production procedures and storage time on CHMs. Moreover, the challenges and applications of E-nose for CHM identification are investigated. Based on the advancement in E-nose technology, odor may become a new quantitative index for quality control of CHMs and drug discovery. It was also found that more research could be done in the area of odor standardization and odor reproduction for remote sensing. Full article
(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)
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