Department of Electrical and Electronics Engineering

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Subject: search.filters.subject.Gas sensor

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    Microheater Material Selection Framework for Micro-Electromechanical System (MEMS)-Based Gas Sensor
    (IEEE, 2023-09) Gupta, Navneet
    This article describes the material selection for microheater in micro-electromechanical systems (MEMS)-based gas sensors. The analysis was done using multicriteria decision-making (MCDM) approaches: Ashby’s technique, Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), and VlseKriterijumska Optimizacija I Kompromisno Resenjein in Serbian (VIKOR). All possible materials for heating element used in MEMS gas sensors are considered. Various material properties, such as thermal expansion, melting point, resistivity, and thermal conductivity, are investigated to find out the most promising microheater material. Analysis was done using materials chart in Ashby’s approach and ranking system using TOPSIS and VIKOR approaches. The analysis shows that tungsten and molybdenum are the best materials to be used in microheater. The results show very good agreement among all the three material selection methodologies that confirms the validity of our proposed result.
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    Plasma Oxidized Suspended Core-Shell Nanostructures for High Performance Metal Oxide Gas sensors
    (IEEE, 2019) Benedict, Samatha
    We report on the novel technique of creating core-shell metal-metal oxide high performance gas sensors using plasma oxidation of a suspended metal thin film. We demonstrate that this technique is very generic by realizing Pt-PtOx and W-WOx nanostructured sensors. The optimization technique for plasma oxidation is elucidated. We also propose an improvisation technique to create nano discs on top of suspended core-shell metal-metal oxide sensor to further enhance the performance.
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    Low power gas sensor array on flexible acetate substrate
    (IOP, 2017-06) Benedict, Samatha
    In this paper, we present a novel approach of fabricating a low-cost and low power gas sensor array on flexible acetate sheets for sensing CO, SO2, H2 and NO2 gases. The array has four sensor elements with an integrated microheater which can be individually controlled enabling the monitoring of four gases. The thermal properties of the microheater characterized by IR imaging are presented. The microheater with an active area of 15 µm  ×  5 µm reaches a temperature of 300 °C, consuming 2 mW power, the lowest reported on flexible substrates. A sensing electrode is patterned on top of the microheater, and a nanogap (100 nm) is created by an electromigration process. This nanogap is bridged by four sensing materials doped with platinum, deposited using a solution dispensing technique. The sensing material characterization is completed using energy dispersive x-ray analysis. The sensing characteristics of ZnO for CO, V2O5 for SO2, SnO2 for H2 and WO3 for NO2 gases are studied at different microheater voltages. The sensing characteristics of ZnO at different bending angles is also studied, which shows that the microheater and the sensing material are intact without any breaking upto a bending angle of 20°. The ZnO CO sensor shows sensitivity of 146.2% at 1 ppm with good selectivity.
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    Comprehensive modeling of gas sensor based on Si3N4-passivated AlGaN/GaN Schottky diode
    (IEEE, 2014) Kumar, Rahul
    A physics-based analytical modeling for the gas sensor application of AlGaN/GaN heterostructure Schottky diode has been investigated for high linearity and sensitivity of the device. The heterointerface and surface properties are exploited here. The dependency of 2DEG on the surface charge, which is dependent on the Si 3 N 4 passivation layer, is mainly utilized to model the device. The simulation of Schottky diode has been performed in the TCAD tool and I-V curves are generated. From the I-V curves, 54% response has been recorded in presence of 500 ppm gas and at biasing voltage of 0.95 Volts.
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    Development of CdS-doped TiO2 nanocomposite as acetone gas sensor
    (Elsevier, 2021-09) Hazra, Arnab
    In recent years, much interest has been shifted towards the design and development of gas sensing devices for use of detecting and identifying toxic gases. In this work, a CdS doped TiO2 nanocomposite, with 1–2 wt % CdS, is prepared in the form of films as a gas sensor. The results are described with X-ray diffraction (XRD) and atomic force microscopic (AFM) images. The response of the fabricated sensor is measured with exposure to acetone, propanol, and LPG of varied concentrations (0–5000 ppm) in ambient air at room temperature. It is found that an optimized 2 wt% CdS-doping extends the highest response, i.e. 71% for 5000 ppm acetone, which is more selective over propanol or LPG, and also superior than reported ever for TiO2 based sensors. The response and recovery times are improved from 85 s to 190 s for undoped TiO2 sensor to 55 s–115 s for acetone (5000 ppm). Possible mechanisms of finely tuned sensing properties are described in light of the microstructure.