ZnO Based Film Bulk Acoustic Resonator for Environment Monitoring

Different environmental factors, such as ultraviolet radiation (UV), relative humidity (RH) and the presence of reducing (acetone) or oxidizing (ozone) gases, play an important role in the daily life of human beings. Traditionally, semiconductor metal oxide sensors are the major candidates employed to monitor these factors. However, they suffer from low sensitivity, poor selectivity and huge power consumption. In this paper, Zinc Oxide (ZnO) based Film Bulk Acoustic Resonator (FBAR) was developed to monitor UV, RH, acetone and ozone in the environment. FBAR generally consists of a sputtered piezoelectric thin film sandwiched between two electrodes. It has been well developed both as filters and as high sensitivity mass sensors in recent years. FBAR offers high sensitivity and excellent selectivity for various environment monitoring applications. As the sensing signal is in the frequency domain, FABR has the potential to be incorporated in a wireless sensor network for remote sensing. This study extended our current knowledge of FBAR and pointed out feasible directions for future exploration.