ABSTRACT
A sensor is a device for detecting the presence of a physical, chemical, or biological property and, by appropriate transduction, transforming the detected quantity into an electrical signal. Sensors, in general, are of many types, based on sensing mechanisms that may be electrical, optical, acoustic, magnetic, etc. in nature. We limit the discussion here to acoustic sensors, which are devices where the environmental property perturbs the acoustic wave. Traditionally, sensors have varied in size from very small to very large instruments. We make a further distinction here in that we will concentrate almost exclusively on acoustic microsensors, that is, those fabricated by microelectronic techniques and integrated into silicon or hybrid circuits. Some of the more common microsensors that will be discussed in this chapter are based on acoustic waveguide geometries discussed in Chapter 10.
