Review of recent passive wireless SAW sensor and sensor-tag activity

During the past several years, work has been ongoing at corporate, goverment laboratory, and university research group to develop passive wireless surface acoustic wave (SAW) sensors and sensor-tags. These efforts have led to SAW sensors that operate wirelessly in enviroments coosiderably more extreme than those in which silicon-based sensors can operate. Advances have also been made in sensor coding, allowing production of small sets of sensors that can be individually read. The use of SAW devices as wireless interfaces to external impedance varying and voltage producing sensors and devices has also been demonstrated. This article provides a brief overview of recent advances made in this technology by several companies.