Preparation and Performance Analysis of Ag/ZnO Humidity Sensor.

Peng Li,Hongyan Zhang,Shuguo Yu

doi:10.3390/s21030857

Abstract

Highly sensitive silver (Ag) modified zinc oxide (ZnO) humidity sensors were prepared by hydrothermal synthesis and the mechanism was studied. Experimental results show that Ag-modified ZnO can effectively enhance the performance of a humidity sensor. Large number of oxygen vacancies and many active sites are generated on the surface when molar ratio of Ag+ to Zn2+ is 1:100, which can accelerate the decomposition of water molecules on surface of the material, thereby improving the response of humidity sensor. Moreover, the linearity of ZnO humidity sensor is greatly improved by silver nanoparticles. Compared with previously reported ZnO-based humidity sensors, Ag/ZnO humidity sensors have a better response (151,700%), good linearity, low hysteresis (3%), and short response/recovery time (36/6 s). At the same time, it is found that the light had little effect on the performance of Ag/ZnO. Therefore, this kind of ZnO sensor with stable performance and excellent performance is expected to be used in the detection of relative humidity in conventional environments.

Highlights

Humidity sensors have been developed rapidly and have attracted much attention in many fields such as agriculture, food safety, industrial production, medical treatment and so on [1,2,3]
Experimental results show that an Ag/zinc oxide (ZnO) humidity sensor exhibits high sensitivity, low hysteresis and short response/recovery time when a molar ratio of Ag+ to Zn2+ is 1:100
We found that the performance of humidity sensor became worse with the increase of Ag+

Summary

Introduction

Humidity sensors have been developed rapidly and have attracted much attention in many fields such as agriculture, food safety, industrial production, medical treatment and so on [1,2,3]. In terms of the structure of the resistance humidity sensor, the selection of sensitive materials is still the key to improving the performance of the relative humidity sensor. Silver particles have good electrical conductivity, which is beneficial to improve linearity of the sensor, so Ag/ZnO composite material can provide a new idea for the preparation of high-performance humidity sensors. Experimental results show that an Ag/ZnO humidity sensor exhibits high sensitivity, low hysteresis and short response/recovery time when a molar ratio of Ag+ to Zn2+ is 1:100. This is mainly because in this case there are a large number of oxygen vacancies and active sites on the surface of ZnO. The electrochemical characteristics of the humidity sensor were tested on the Zennium workstation (CIMPS-2, Zahner, Kronach, Germany)

Preparation of ZnO Microparticles

Findings

Conclusions