MicrosensorsA transducer is a device that converts from one physical quantity to another. The change in refractive index of some crystals under an applied magnetic field is one example (magneto-optic effect). Deformation of a piezoelectric crystal under an applied electric field is another. Sensors and actuators special types of transducer. In the present context, a sensor is a device that converts one physical or chemical quantity to an electrical one, for processing by the microsystem. Similarly, an actuator is a device which converts an electrical quantity into a physical or chemical one.Many of the sensors described below have been developed within the microelectronics industry; and do not involve any special micromachining techniques. However, some of these sensors can be enhanced by the use of micromachining techniques (e.g. for thermal isolation). |