CO Gas-Induced Resonance Frequency Shift of ZnO-Functionalized Microcantilever in Humid Air

Lia Aprilia,Makoto Hosoda,Dwi Gustiono,Ratno Nuryadi,Nurmahmudi Nurmahmudi,Hidenori Mimura,Arief Udhiarto,Brian Yuliarto,Yoichiro Neo,Djoko Hartanto

doi:10.1155/2017/4824607

Abstract

Resonance frequency shift of a zinc oxide- (ZnO-) functionalized microcantilever as a response to carbon monoxide (CO) gas has been investigated. Here, ZnO microrods were grown on the microcantilever surface by a hydrothermal method. The measurement of resonance frequency of the microcantilever vibrations due to the gas was carried out in two conditions, that is, gas flow with and without air pumping into an experiment chamber. The results show that the resonance frequency of the ZnO-functionalized microcantilever decreases because of CO in air pumping condition, while it increases when CO is introduced without air pumping. Such change in the resonance frequency is influenced by water vapor condition, and a possible model based on water-CO combination was proposed.

Highlights

Microcantilever-based sensors could replace conventional sensors because of the ability to detect ultrasmall mass with fast response time
zinc oxide (ZnO) microrods were successfully grown on silicon microcantilevers as a sensitive layer
The same condition occurs if the ZnO surface is modified with a hydrophobic coating, in which the water vapor should not be adsorbed on the ZnO surface, and in case of carbon monoxide (CO) adsorption, the gas will be adsorbed on the hydrophobic layer

Summary

Introduction

Microcantilever-based sensors could replace conventional sensors because of the ability to detect ultrasmall mass with fast response time. The working principle of this sensor is based on deflection of microcantilever (MC) due to an object attached on its surface (static mode) or resonance frequency shift of the MC vibration due to an object (dynamic mode). Gas detection on metal oxide surfaces, such as zinc oxide (ZnO) which has a great potential in sensing applications, is especially influenced by the presence of humidity [12]. The water-CO combination should be considered as a model system for gas detection on metal oxide surfaces. We have grown ZnO microrods on the microcantilever surface as sensitive layers for gas detection and studied the effect of carbon monoxide (CO) on resonance frequency of the MC at a room temperature. The possible model is proposed to explain the experimental results

Experimental Details

Results and Discussions

Resonance Frequency Shift due to Gas Adsorption

Conclusions