Research of Novel Benzene Vapor Sensor and Theoretical Model

Abstract

A novel benzene vapor sensor based on the swelling effect of polymer film is proposed, which is composed of a Si Bridge embedded with piezoresistive Wheatstone bridge and a gas-sensitive thin polymer layer. The sensor relies on the swelling of the thin polymer layer due to the uptake of organic vapor molecules from ambient condition. The swelling of the thin polymer layer leads to bending of the Si Bridge which causes the piezoresistive Wheatstone bridge to produce an output voltage. In this paper silicon rubber as sensing film with good sensitivity and selectivity for benzene is used in the novel vapor sensor. A theoretical model of the interaction between Si Bridge and polymer layer is presented based on elastic mechanics theory. An equivalent transverse gas load is presented. The output expression of the sensor is obtained. The model of the sensor is verified by the experimental results. The relationship between the parameters of thin polymer layer and the sensitivity of the sensor is studied. The effects of ambient temperature on the sensitive character are investigated. The experimental results show that the benzene vapor sensor has good linearity, sensitivity, selectivity and reproducibility.