ACOUSTIC FIELDS IN TRAPEZOIDAL CAVITIES

In recent years the growing demand for miniaturised transducers and se nsors, and the widespread use of silicon technology, has focused inter est on the design of devices on silicon chips. Usually at the heart of these devices is a small, fluid-filled cavity whose characteristics, such as its geometry and dimensions, are unavoidably determined by the crystallographic properties of silicon and the etching process. To be precise, these physical processes determine that the cavity be trapez oidal having an angle between adjacent walls close to 55 degrees. We d iscuss some aspects of the problems which arise when designing on sili con and present analytical and experimental results concerning the pro perties of acoustic fields in trapezoidal cavities.