Theoretical Analysis of Acoustoelectrical Sensitivity in SAW Gas Sensors

The theoretical studies on acoustoelectrical (AE) sensitivity in SAW gas sensors are presented. The analysis was based on normalized parameter xi=sigma/v(0)C(s) (where: as is the film's electrical surface conductivity, vo SAW velocity, Cs sum of the substrate's and environment's electrical permittivities) which determines the value of AE sensitivity. The electrical surface conductivities in the bi-layer structure are correlated by the cyst= x cyst dependence. The investigations revealed that for single and bi-layer sensor structures the maximum value of AE sensitivity is obtained for xi(max)= 0.6. For bi-layer structures this sensitivity is lower. However we also found the positions of the maximum values in a function of x parameter dependent on different values of normalized conductivity of the second film. (C) 2015 article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-ric-nd/4.0/) Peer-review under responsibility of the organizing committee of EUROSENSORS The Authors. Published by Elsevier Ltd. This is an open access