ZnO Nanostructure Based QCM Sensor to Detect Ethanol at Room Temperature Fabricated by All Wet Process

Takeshi Ito,Noriyoshi Yamanishi,Shoso Shingubara,Tomohiro Shimizu

doi:10.3390/proceedings1040397

Abstract

QCM is one of major sensing methods for volatile organic compounds (VOC) at room temperature. Nanostructure is effective to increase the sensitivity because of its large surface area. We introduced ZnO nanostructure to detect ethanol gas. ZnO nanostructure was fabricated by all wet process such as electrodeposition and chemical bath deposition (CBD). In this case, seed layer was obtained by electrodeposition, and nanostructure was formed by the CBD. The thickness of seed layer was controllable by charge amount on the electrodeposition, and that of nanostructure was controllable by deposition time on the CBD. As the results, the sensitivity increased with the thickness of the seed layer when the deposition time on CBD was set as 30 min. These results indicate that we can obtain high sensitive VOC sensor by using all wet process which is fit to large scale production with cost-effective.

Highlights

Volatile organic compounds (VOC) are one of the major targets for gas sensing, since they are known as air pollutants and marker of some diseases such as diabetes and kidney failure
quartz microbalance methods (QCM) type sensor monitors the frequency changes of resonance frequency corresponding to the gas adsorption on the electrode and works at room temperature
The seed layer was obtained by electrodeposition, and nanostructure was formed by Chemical Bath Deposition (CBD)

Summary

Introduction

Volatile organic compounds (VOC) are one of the major targets for gas sensing, since they are known as air pollutants and marker of some diseases such as diabetes and kidney failure. Semiconductor type gas sensor monitors the resistance changes corresponding to the gas adsorption on the electrode and works at high temperature over 200 °C. ZnO has been used for a sensor material for VOC on a semiconductor device [1,2]. QCM type sensor monitors the frequency changes of resonance frequency corresponding to the gas adsorption on the electrode and works at room temperature. QCM with scaly ZnO surface, which was obtained at −0.8 V vs Ag/AgCl, showed high frequency changes on exposing to ethanol gas. This result indicated that highly specific surface would be effective to improve the sensor sensitivity. The seed layer was obtained by electrodeposition, and nanostructure was formed by Chemical Bath Deposition (CBD)

Experimental

Morphology of ZnO Nanostructures

Sensor Characteristics