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Gas Sensor Based on Surface Acoustic Waves Using Zinc Oxide Piezoelectric Thin Films

Gas sensor based on surface acoustic wave (SAW) using piezoelectric zinc oxide (ZnO) thin film was simulated with COMSOL. The gas sensor is designed with an inter-digital transducer (IDT) on a ZnO substrate and covered with a thin polyisobutylene (PIB). The results show that there are the resonant frequency and ant-resonant frequency of SAW in the ZnO substrate arising from the electrode effect of the IDT, and deformed shape of the resonance SAW mode is different with that of anti-resonance SAW mode. The effect of the dichloromethane (DCM) on the gas sensor was also researched. Because the mass of the PIB film increases with PIB selectively adsorbing DCM in air, a shift in resonance to a slightly lower frequency was found.