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Sahu V.,University of Delhi | Shekhar S.,University of Delhi | Ahuja P.,University of Delhi | Gupta G.,National Physical Laboratory India | And 3 more authors.
RSC Advances | Year: 2013

We report the low-temperature (250 °C) synthesis of high-performance hydrophilic carbon black for application as a conducting filler in supercapacitor electrodes. Increased water content, due to the hydrophilicity, maintained the uniform hydration level of MnO2/carbon composite electrodes, with good protonic conduction. This results in an increase in the total specific capacitance by 24%. This journal is © 2013 The Royal Society of Chemistry.

Singh H.,Solid State Physics Laboratory DRDO | Raj V.B.,University of Delhi | Kumar J.,Solid State Physics Laboratory DRDO | Durani F.,Solid State Physics Laboratory DRDO | And 3 more authors.
Process Safety and Environmental Protection | Year: 2016

A functionalized polymer (SXFA: fluoroalcoholpolysiloxane) coated single surface acoustic wave (SAW) sensor E-Nose is proposed for the detection of harmful vapors by operating at different temperature. The polymer coated SAW sensor is used along with a reference SAW device in dual Colpitt's oscillator configuration. The sensor is tested with four different classes of vapors at different concentrations in an environmental chamber whose temperature can be varied in the range -20 to +70 °C. The sensor showed variation in response with exposure to benzene, methanol, diesel and DMMP vapors at different temperatures. The polymer coated SAW sensor was giving frequency shifts of 0.21-1.12 kHz for methanol (1000-4000 ppm), 0.3-2.69 kHz for benzene (400-1600 ppm), 0.81-7.39 kHz for diesel (12-48 ppm) and 4.27-8.07 kHz for DMMP (1-10 ppm) vapors at 30 °C operating temperature. Principal component analysis and artificial neural network algorithms are successfully implemented to classify and detect the target vapors. © 2016 Institution of Chemical Engineers.

Raj V.B.,University of Delhi | Nimal A.T.,Solid State Physics Laboratory DRDO | Tomar M.,University of Delhi | Sharma M.U.,Solid State Physics Laboratory DRDO | Gupta V.,University of Delhi
Sensors and Actuators, B: Chemical | Year: 2015

Abstract A new method has been devised for obtaining fast NO2 gas sensing characteristics by using detuned SnO2/SAW sensor oscillator. The deposited SnO2 thin films were polycrystalline showing XRD reflections corresponding to (1 0 1) and (2 1 1) planes of rutile structure. The frequency of the sensor remained tuned for SnO2 layer of small thickness (< 90 nm), and sensing response was moderate (< 140 kHz) with relatively slow response time and recovery time. However with increase in thickness (≥ 90 nm), the frequency of SAW sensor detuned resulting in enhanced sensing response (≥ 16 MHz) along with fast response time and recovery time. Independent experiments confirmed the change in elasticity of the sensing layer as the dominant sensing mechanism for SnO2/SAW sensor towards NO2 gas. © 2015 Elsevier B.V.

Hasan P.M.Z.,Jamia Millia Islamia University | Islam S.S.,Jamia Millia Islamia University | Islam T.,Jamia Millia Islamia University | Azam A.,Aligarh Muslim University | Harsh,Solid State Physics Laboratory DRDO
Sensor Review | Year: 2010

Purpose - The purpose of this paper is to present the dependence of capacitive sensing of organic vapours by porous silicon (PS) on its molecular structure for the realization of a organic vapour sensor, compatible with existing silicon technology, with desired miniaturization and selectivity. Design/methodology/approach - The method introduces large surface area of PS obtained by electrochemically etching of silicon wafer for characterization of organic vapours through capacitive sensing. Findings - The method provides a comparative study of sensor response for organic vapour molecules of different structures and leads to an insight into the sensing mechanism. Research limitations/implications - The surface of PS has been stabilized by thermal oxidation process. Practical implications - The method is useful for the development of a simple, cost-effective sensor for selective gas analysis. Originality/value - The result is an outcome of regular experimental work carried out to observe the capacitive sensing behavior of PS for different organic vapours. © 2010 Emerald Group Publishing Limited. All rights reserved.

Singh H.,Solid State Physics Laboratory DRDO | Raj V.B.,University of Delhi | Kumar J.,Solid State Physics Laboratory DRDO | Mittal U.,Solid State Physics Laboratory DRDO | And 4 more authors.
Sensors and Actuators, B: Chemical | Year: 2014

An Electronic nose (E-nose) made up of an array of metal oxide thin film based SAW sensors is proposed as a detection system for the binary mixture of DMMP (simulant of nerve agent) and methanol at room temperature. The SAW devices are one port surface acoustic wave (SAW) resonators having center frequency of 433.9 MHz. The E-nose sensor array has SAW sensors coated with four different chemical sensitive coatings of ZnO, TeO2, SnO2 and TiO2 in order to recognize the individual components in a binary mixture of DMMP (in ppb levels) and methanol (in sub ppm levels). Principal Component Analysis (PCA) as a data pre-processing technique and Artificial Neural Network (ANN) as a pattern classification technique have been applied for obtaining a clear discrimination and correct classification. © 2014 Elsevier B.V.

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