Optimization of an analytical SAW microsystem for organic gas detection

Starting from a recently developed automatic working, compact analytical microsystem for organic gas detection which uses modified commercially available SAW devices, a new approach is presented to improve its sensitivity and selectivity. The choice of low-loss SAW devices using horizontally polarized surface transverse waves instead of Rayleigh-type waves allows an increased thickness of sensitive coatings resulting in a higher sensitivity and larger freedom of choice towards the sensitive material deposited. An example for taking advantage of this freedom is the choice of polysiloxanes which show very good sensitivities and ageing properties. In addition, their selectivity could be easily controlled by choosing appropriate side groups.