SAW Filter Technology on POI for Sensor Applications

Pieozelectric-On-Insulator (POI) wafers are representing the new generation of engineered substrates for the development of advanced SAW devices. These materials combining single crystal sub-micron layers and Silicon substrates allow for the design of frequency filters with minimum insertion losses, coupling factor in the range 7-11% and quality factor times frequency Q×f products equal to or in excess of 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> Hz. Although quite obvious for filter applications, the advantages of SAW-on-POI did not find yet a supported interest for sensing applications. In this paper, we are showing some examples of the use of SAW-on-POI for sensor development. We particularly show how it is possible to develop temperature or stress differential sensors with only one device upon specific design and selected operation conditions.