Piezoelectrically Driven Self-Excited Microbridge VOCs Sensor

Piezoelectrically driven microbridge gas sensors have been fabricated by MEMS process. We have used the resonant frequency change of the microbridge transducer upon mass increase. The sol-gel derived Pb(Zr0.52,Ti0.48)O3 (PZT) film capacitor as an actuating part was integrated into the thin SiN x bridge structure. The resonant frequency of the microbridge was in the range of 250 kHz to 260 kHz. The microbridge exhibited a mass sensitivity and gravimetric sensitivity factor of ca. 7.27 pg/Hz and 345 cm 2 /g, respectively. With the PMMA polymer sensing layer, the microbridge showed the gas sensitivity of 1.67 ppm/Hz for ethanol vapor.