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Detection of toxic and flammable gases and volatile organic compounds (VOCs) released from Li-ion batteries during thermal runaway can generate an early warning. A submicron (∼0.15 μm)-thick poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) sensor film is coated on a platinum electrode through a facile aqueous dispersion. The resulting sensor reliably detected different volatile organic compounds (VOCs) released during the early stages of thermal runaway of lithium-ion batteries (LIBs) even at low concentrations. The single-electrode sensor utilizes impedance spectroscopy to measure ethyl methyl carbonate and methyl formate concentrations at 5, 15, and 30 ppm independently and in various combinations using ethanol as a reference. In contrast to DC resistance measurement, which provides a single parameter, impedance spectroscopy provides a wealth of information, including impedance and phase angle at multiple frequencies as well as fitted charge transfer resistance and constant-phase elements. Different analytes influence the measurement of different parameters to varying degrees, enabling distinction using a single sensing material. The response time for ethyl methyl carbonate was measured to be 6 s. Three principal components (PCs) preserve more than 95% of information and efficiently enable discrimination of different classes of analytes. Application of low-power PEDOT:PSS-based gas sensors will facilitate cost-effective early detection of VOCs and provide early warning to battery management systems (BMS), potentially mitigating catastrophic thermal runaway events.

We herein present the Au and Ag NPs synthesized via chemical reduction with green synthesized carbon nano lights (CNL) as a visible light photosensitizer for TiO2 nanofibers (TNFs) towards photoelectrochemical water splitting. The synthesized photoanodes (PA1: TNFs, PA2: Ag@CNLs/TNFs and PA3: Au@CNLs/TNFs) were probed ex-situ for morphological, structural, optical and electronic properties before being used for the PEC experiments. We first show the efficient photocatalytic activity of these photoanodes for the degradation of methylene blue under visible light irradiation. Followed by the photoelectrochemical (PEC) water splitting investigation, which reveals the substantially improved photocurrent density to 13 mA/cm2 and 18 mA/cm2, for PA2 and PA3, respectively under simulated AM 1.5 solar illumination at 1.36 V vs RHE, ~15 fold enhancement compared to that obtained for a PA1. This improvement we attributed to the synergic consequence, improved absorption and effective charge carrier separation & transport due to surface plasmonic effect, which is well evident in the decrease of measured charge transfer resistance (Rct), for PA2 (15.1 Ω) and PA3 (6.71 Ω), as compared to PA1 (139 Ω).

The multiplexed resistive arrays simplify the data collection with reduced connections and circuit complexity. However, the effect of crosstalk in these cases becomes inevitable. The crosstalk is caused due to the leakage currents in the multiplexer channels as well as the parasitic paths among the non-selected elements in the array. This paper analyses a circuit arrangement capable of suppressing crosstalk in 2D resistive sensor arrays. The proposed circuit employs transistors and diodes to modify simple voltage feedback commonly used for crosstalk reduction. The paper includes simulation results, approximate mathematical model for the “element under measurement” and other practical aspects of the circuit arrangement, such as the array size or the bias resistance. Finally, the circuit is compared (based on the simulation results) with two known circuit arrangement from the literature. The suggested circuit is clearly capable of eliminating crosstalk better than previously known methods. The analysis also reveals that the circuit is sensitive to temperature variations and must be modeled with temperature calibration factors for better model accuracy.

Modern electronic nose and such systems, typically employ gas sensors in arrays. Access to the individual elements in an m × n resistive sensor array requires m + n interconnect lines and effect of crosstalk becomes inevitable. The crosstalk is caused due to the leakage currents in the multiplexer channels as well as the parasitic paths among the non-selected elements in the array. Here, the authors present a novel circuit arrangement to suppress crosstalk in two-dimensional chemo-resistive sensor arrays. The proposed circuit employs a transistorised bypassing scheme, diodes in series and voltage feedback to non-selected elements of an array for crosstalk elimination. Simulation results of a resistive sensor array are presented. Finally, the proposed arrangement has been applied on an 8 × 2 sensor array and the result has been compared with the same array with a normal feedback arrangement for data acquisition. The work can also be extended for general resistive sensor arrays.

This article demonstrates an optical fiber sensor probe coated with hierarchical nanostructures of zinc oxide (ZnO) for trace level detection of volatile amines. The nanostructure is grown by hydrothermal process on a multimode optical fiber probe coated with ZnO nanofibrous mat prepared by electrospinning technique. The high surface area of the hierarchical structures facilitated diffusion of amines, which, on interaction with ZnO surface, changes the effective refractive index of the optical fiber probe. The modulation of the transmitted intensity through the optical sensor probe in presence of the target analyte is monitored for sensing the amine. An increase in absorbance is observed in proportion to amine concentrations with the emergence of a broad peak at around 500nm. The sensor is able to detect as low as 25ppb of different volatile amines such as ammonia, triethylamine, aniline, and ethylenediamine with responses of 1, 0.65, 0.75, and 0.5, respectively. The sensor is further demonstrated for detection of volatile amines released during protein degradation in salmon fish to show its usability for real time applications.

In this work, a multimode optical fiber sensor probe coated with polypyrrole-polyethylene oxide (PPO) nanofibrous mat is investigated to detect volatile compounds such as ammonia, triethylamine, methanol, ethanol and acetone vapours. The fibrous mat on the fiber cladding is deposited using electrospinning method followed by vapour phase polymerization. The affinity of PPO towards different volatile compounds changes the effective refractive index of optical fiber cladding, modulating the intensity of the transmitted spectrum. The intensity variation in presence of volatile vapours of different concentration is investigated to determine the responses of the sensor probe. The sensor probe shows different detection limit such as 0.1 ppm, 2 ppm, 2 ppm, and 1 ppm and recovery time of 10 min, 54.4s, 21.06 s and 11.08 s for ammonia, ethanol, methanol and triethylamine vapours respectively. Thus, the electrospinning technique can be used for coating optical fiber cladding with special material such as PPO to develop optical fiber based sensor to detect trace amount of volatile compound.

Electronic nose systems have been recently in use for various applications ranging from environmental monitoring to biomedical applications. This paper introduces a compact electronic nose system integrating conducting polymer sensors with data acquisition, data processing and storage unit. The data acquisition system presented here is equipped with a graphical user interface (GUI) to control the acquisition parameters as well as perform analysis on obtained data. The real-time data acquisition system is capable of collecting data from an 8X8 resistive sensor array as per the parameters passed by the GUI. Finally, the paper is concluded with results and discussion obtained using the proposed electronic system. The result shows with proper classification algorithm, the system is capable of identifying various amine and alcohol groups.

Sarcoidosis is a chronic, multisystemic, granulomatous disease of unknown aetiology characterised by the formation of non-caseating granuloma. It shows slight female predominance and has a bimodal age distribution. Lungs, skin, eye and liver are commonly affected. The oral lesion, though uncommon, may present as submucosal nodule, papule or superficial ulceration. Occasionally, oral lesion may be the first manifestation of underlying systemic disease. This case is interesting because it emphasises that dental practitioners may play a key role in early recognition of the clinical presentation of this multifaceted disease, and thereby aid in the diagnosis of the systemic condition. The present report deals with a case of sarcoidosis affecting the buccal mucosa in a 48-year-old woman. The patient was treated with oral prednisolone and within 4 months of corticosteroid therapy, the oral lesion regressed with no recurrence or new lesion noted over a period of 1 year.

This paper reports the impedance spectroscopy of the ZnO-polypyrrole composite as a sensor used for the detection of ammonia. The frequency response of the sensor is studied using Nyquist plot in the frequency range of 100 mHz to 1 MHz. Sensitivity of the sensor is observed using DC measurement method. The impedance spectroscopy is performed for the ammonia vapors with the concentration ranging from 5 ppm to 115 ppm. The equivalent circuit is proposed based on the impedance response of the sensor. Based on the Nyquist plot observed, different elements contributing the changes in the overall impedance of the sensor are discussed.

Herein, we report noble metal free, cathodically co-electroreduced rGO/MnO2 nanohybrid (NH) on glassy carbon electrodes for arsenite (As (III)) detection in water by square wave anodic stripping voltammetry (SWASV). Cyclic voltammetry, scaning electron microscopy, X-ray diffraction, trasnsmission electron microsocpy and Fourier transform infra-red (FT-IR) spectroscopy were used to probe the rGO/MnO2/GCE surface, revealing the formation of NHs. The arsenite sensing parameters such as deposition potential and time was optimized allowing a detection range of 0.1 ppb to 50 ppb in 0.1 M acetate buffer. This in-situ fabricated NHs electrodes exhibit favourable sensitivity of 0.175 μA/ppb with a theoritical limit of detection of 0.05 ppb for arsenite, which is well below the levels set by World Health Organization. Moreover, the fabricated electrode exhibited good selectivity, stability and reproducibility, in near alkaline condition without using any noble metal as sensing electrode component, desirable for practical application. These findings suggest the possibility of a cost effective electrochemical sensing electrode for a portable embedded system to determine As (III) in water.

Instability dependent electrospinning process has been controlled to obtain tin oxide nanofibers with morphological variation. The effect of spinning parameters such as viscosity, conductivity, flow rate, distance and applied voltage on growth rate of different instabilities was simulated and different deposition conditions were defined from the simulation results. The structural morphology was analyzed using X-Ray Diffraction (XRD) and Scanning Electron microscope (SEM). The sensing behavior of different structures was investigated. The branched structure obtained due to axisymmetric instabilities exhibited best sensing performance owing to high surface to volume ratio.

In the present work nanofibers has been prepared by electrospinning method. Zinc Oxide nanofibrous thin film were electrospun on ITO substrate from a solution containing Poly Ethylene Oxide (PEO) and Zn(CH3COO)2.2H2O. Calcination process of ZnO/PEO composite at 600oC forms a random network of poly crystalline ZnO nanofiber. Surface morphology of the electrospun ZnO thin film, studied using FE-SEM shows a uniform, continous parallel aligned sharp nanofibers. The crystal structure and orientation of ZnO thin film was determined by X-ray diffraction (XRD). Gas sensing characteristics were studied on a custom made chamber based on two probe resistance measurement method. The film shows a good sensitivity towards organic vapours such as methanol, ethanol, acetone and propanol.

Tin oxide (SnO2) thin films for gas sensing applications were prepared using electrostatic spray deposition method under optimum deposition conditions. It is shown in the paper that desired film morphology can be obtained by controlling different spray parameters (liquid properties, applied voltage, nozzle-substrate distance and substrate temperature). The spray parameters were optimized with respect to droplet diameter and applied voltage. An empirical relationship between critical voltage and different spray parameters was established for optimization. The morphology of the films prepared using these optimized spray parameters were investigated using X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM).

In this work, an artificial lipid membrane was synthesized using tetra-dodecyl ammonium bromide (TDAB) and doped with gold nanoparticles (AuNP). The taste sensor designed using artificial lipid membrane is composed of tetradodecylammonium bromide (TDAB) as a lipid, dioctylphenyl phosphonate (DOPP) as a plasticizer, and polyvinyl chloride (PVC) as a supporting polymer in the ratio of 1:3:2. The lipid/polymer membrane acts as the recognition element which transforms the taste information generated by the chemical substances into an electric potential change. The fundamental taste analytes (like fructose for sweetness, HCl for sourness, NaCl for saltiness, MgCl2 for bitterness and MSG for umami) were used to study the effect of doping on taste sensing at different concentrations (10μM to 10mM). The study was based on the open circuit potential (OCP) change of the membrane with the analytes. The observations implicate that the doping increases the specificity of the artificially synthesized lipid membrane taste sensor for the sweet analytes, particularly for fructose.

Fiber optic sensor coated with polypyrrole fiber mats is demonstrated for triethylamine vapours detection. The sensor exhibits sensing response, 34.3% for 100ppm concentration. Enhanced interaction is due to high surface area of polypyrrole mats.

Tin oxide-polypyrrole composites have been widely studied for their enhanced sensing performance towards ammonia vapours, but further investigations are required for an understanding of the interaction mechanisms with different target analytes. In this work, polypyrrole coated tin oxide fibers have been synthesized using a two-step approach of electrospinning and vapour phase polymerization for the sensing of ammonia, ethanol, methanol, 2-propanol and acetone vapours. The resistance variation in the presence of these vapours of different nature and concentration is investigated for the determination of sensor response. A decrease in resistance occurred on interaction of tin oxide-polypyrrole with ammonia, as opposed to previous reported works. Partial reduction of polypyrrole due to interfacial interaction with tin oxide has been proposed to explain this behavior. High sensitivity of 7.45 is achieved for 1 ppm ammonia concentration. Furthermore, the sensor exhibited high sensitivity and a faster response towards ethanol vapours although methanol has the highest electron donating capability. The catalytic mechanism has been discussed to explain this interesting behavior. The results reveal that interaction between tin oxide and polypyrrole is crucial to control the predominant sensing mechanism.