Thin Film Gas Sensors Based on Zinc Oxide Nanoinks
Date
2021-12-22
Authors
Duan, Pengjun
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Abstract
Planetary ball milling (PBM) is a high-energy ball milling technology that was used in this study to fabricate zinc oxide (ZnO) nanoinks via nano grinding, followed by the fabrication of thin film chemiresistive gas sensors via the doctor blading method, which operated at room temperature. In order to create the different thin film gas sensor samples (with different particle sizes and porosity), the ZnO nanoinks were prepared by changing the grinding parameters, such as grinding time, grinding speed and solvents (ethylene glycol (EG) and deionized (DI) water). To study the gas sensing performance, we tested these gas sensor device samples using dry air/oxygen against hydrogen, argon and methane target gases, in addition to different temperatures and relative humidity, under ambient light conditions. In this report, the particle size and RMS film roughness were measured by atomic force and scanning electron microscopy; the purity and structure of ZnO nanoparticles are confirmed by Raman spectroscopy, photoluminescence, and x-ray analysis. At room temperature, the gas sensor response of thin film samples reached a peak for nanoinks milled at 400 rpm and 30 min. This can be related to the increase of film porosity and the enhancement of electron concentration change, caused by oxygen ion adsorption/desorption on the surface of zinc oxide nanoparticles. In addition, research also indicated that the sensor response and dynamic behaviour improves with increasing temperature, reaching a maximum value between 100 – 150 ºC. Our study demonstrates the application of low-cost PBM nanoink as an active material for solution processed thin film gas/humidity sensors, and provides some suggestions to improve gas sensors in future study, such as measuring system, ZnO nanomaterials with different morphologies, and doping.
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Keywords
Planetary Ball Milling, Nanoinks, ZnO