Highly Sensitive Surface Acoustic Wave NH3 Gas Sensor based on TiO2 Film

Lei Zhao,Qingqing Cao,Ruili Wang

doi:10.18494/sam.2020.3139

Abstract

Highly Sensitive Surface Acoustic Wave NH3 Gas Sensor based on TiO2 Film

Highlights

NH3, an important industrial gas, is widely used in some traditional industrial fields such as fertilizers, rubber, and refrigeration.[1,2,3,4] In addition, NH3 plays a critical role in some advanced areas of semiconductor technology, such as the LED and solar cell manufacturing industries.[5,6,7] It is a source of atmospheric pollution and can cause various respiratory diseases even at low concentrations.[8,9,10] when the concentration of NH3 is higher than 500 ppm, it can even cause death.[11]
These advantages are due to the fact that any physical and chemical changes on the surface of the surface acoustic wave (SAW) device can induce a perturbation of the velocity of a SAW, which leads to changes in the working frequency of the SAW sensor.[16]. To further enhance the sensitivity of SAW gas sensors, sensitive films are usually deposited on the devices
It was found that the positive responses of the sensor were caused by the change in the elastic modulus of the sensitive film, which was induced by the condensation of the hydroxyl groups on the film catalyzed by NH3

Summary

Introduction

NH3, an important industrial gas, is widely used in some traditional industrial fields such as fertilizers, rubber, and refrigeration.[1,2,3,4] In addition, NH3 plays a critical role in some advanced areas of semiconductor technology, such as the LED and solar cell manufacturing industries.[5,6,7] It is a source of atmospheric pollution and can cause various respiratory diseases even at low concentrations.[8,9,10] when the concentration of NH3 is higher than 500 ppm, it can even cause death.[11]. Sensors based on various techniques have been used for NH3 monitoring, such as electrochemical sensors,(12) semiconductor sensors,(13,14) and surface acoustic wave (SAW) sensors.[15] Among these sensors, SAW sensors have the advantages of high sensitivity, reliability, and accuracy These advantages are due to the fact that any physical and chemical changes on the surface of the SAW device can induce a perturbation of the velocity of a SAW, which leads to changes in the working frequency of the SAW sensor.[16] To further enhance the sensitivity of SAW gas sensors, sensitive films are usually deposited on the devices. We fabricated a SAW NH3 gas sensor based on a TiO2 sensitive film This sensor had a detection limit of 1 ppm, as well as excellent selectivity and stability. It was found that the positive responses of the sensor were caused by the change in the elastic modulus of the sensitive film, which was induced by the condensation of the hydroxyl groups on the film catalyzed by NH3

Experimental Details

Results and Discussion

Conclusion