In this work, a separated-electrode piezoelectric sensor（SEPS）, constructed by a naked quartz crystal mounted between two electrodes, is reported for applications in a corrosive gaseous phase. The response of SEPS was measured by an impedance analysis method. It was shown that SEPS has an excellent frequency stability because its quality factor is in the order of 10^5. The SEPS can be operated even with the electrode gap in air larger than 1 cm. Compared with a conventional quartz crystal microbalance, the resonant frequency of the SEPS is independent of the mass change in the electrode. The SEPS was applied to monitor the adsorption of iodine on quartz surface and zeolitic-imidazolate framework-8（ZIF-8） film as well as in the transfer of iodine between two ZIF-8 films. The SEPS offers the advantages of easy preparation, corrosion-resistant and convenience in combination with mass and optical measurements.
Da-Zhong ShenTing-Ting CaiXi-Lei ZhuXiao-Long MaLing-Qiang KongQi Kang
