THEORY, DESIGN AND OPERATION OF A SURFACE-ACOUSTIC-WAVE HYDROGEN-SULFIDE MICROSENSOR

The theory, design and operation of a surface acoustic wave (SAW) hydr ogen sulfide (H2S) sensor that uses a gold-doped semiconducting metal oxide, tungsten trioxide (WO3:Au), film as the gas sensing element is described. It is shown experimentally that the dominant property chang e that occurs in the film when exposed to H2S is the electrical conduc tivity. Finally, it is pointed out that upon exposure to a target gas, a properly designed SAW gas sensor that monitors large changes in fil m electrical conductivity is much more sensitive than a similar sensor that monitors mechanical properties such as mass loading.