Reduction of Humidity Effect in WO3 Thin Film-Based NO2 Sensor Using Physiochemical Optimization

Ghosh, S and Ilango, MS and Prajapati, CS and Bhat, N (2020) Reduction of Humidity Effect in WO3 Thin Film-Based NO2 Sensor Using Physiochemical Optimization. In: Crystal Research and Technology . (In Press)

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Abstract

In this work, the effect of humidity on WO3 thin films is studied. Two thin films of higher and lower oxidation states are characterized and studied for their interaction with water molecules on the metal oxide sensing surface. The film with higher oxidation is found to be more immune to humidity effect and hence, further used to reduce the same effect using absorbent filters and Nichrome deposited heater mesh. With the use of a Nichrome heater mesh, by increasing mesh temperature from 30 to 90 °C, there is a 63 reduction in absolute humidity at the sensor die. This in turn stabilizes the NO2 sensor response, by decreasing the humidity dependent (40 RH to 90 RH) peak current variation for 3 ppm NO2 exposure, from 65 to 26. High-temperature ageing at a temperature of 90 °C and 90 RH is found to be effective in significantly reducing humidity effect on sensor current output and only 8.4 change in peak current is observed for 3 ppm NO2 at variable humidity, which stabilizes the sensor current drift due to humidity variation. © 2020 Wiley-VCH GmbH

Item Type:	Journal Article
Publication:	Crystal Research and Technology
Publisher:	Wiley-VCH Verlag
Additional Information:	Copyright for this article belongs to Wiley-VCH Verlag
Keywords:	Mesh generation; Metals; Molecules; Nitrogen oxides; Oxide films; Tungsten compounds, Absolute humidity; High-temperature ageing; Humidity effects; Nichrome heater; Oxidation state; Physio-chemical; Sensing surface; Sensor current, Thin films
Department/Centre:	Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	15 Mar 2021 05:21
Last Modified:	15 Mar 2021 05:21
URI:	http://eprints.iisc.ac.in/id/eprint/67213

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