COMPARISON BETWEEN BAW AND SAW SENSOR PRINCIPLES

A comparison is given between piezoelectrically excited bulk acoustic wave (BAW) and surface acoustic wave (SAW) elements with respect to th eir primary sensitivity functions and principal capabilities for senso r applications. The importance of mode purity for high dynamic range s ensors is emphasized. Characteristic sensor examples are reviewed, and the special demands on the electronics for BAW and SAW elements in th e sensor field are described (e.g., cable problem, wireless SAW sensor s). For a fair evaluation, a performance figure, SQ, defined as the pr oduct of reduced sensitivity S and resonator Q-value, is introduced. T he potential of alternative piezoelectric materials for future sensor developments is discussed briefly.