New Properties of SAW Gas Sensing

摘要

An analytical expression for the SAW sensor gas response versus gas concentration (calibration curve) is deduced, at low gas concentrations. It is shown that the value of the SAW response as well as the calibration curve, the sensitivity (its slope) and the detection limit (threshold concentration) for a given gas and sorbent membrane, can be controlled by a proper choice of the SAW propagation on anysotropic piezoelectric substrate, allowing to change the partial contributions to the SAW response through mechanical displacements, coupling constant and temperature coefficient of velocity (TCV). The theoretical predictions are experimentally verified on the integrated array of SAW gas sensors imoplemented on ST-quartz, using Pd as a sorbent film and humid air as testanalyte.