MEMS and smart sensors and actuators

Abstract

In this chapter we look at some additional aspects of sensors and actuators, aspects that could not have been discussed in conjunction with the principles of conventional devices. First, we discuss a class of devices called microelectromechanical systems (MEMS). The term MEMS relates more to the method of production of sensors and actuators, whereas the sensors and actuators themselves are some of the devices discussed previously as well as others. We discuss them here because they are unique not only in the methods used to produce them, but at least some of them can only be produced as MEMS. One can imagine an electrostatic actuator, at least in principle. But only as a MEMS device does it become a useful, practical device. Then there is the issue of scale of fabrication. Using techniques borrowed from semiconductor production, enhanced by micromachining techniques, it became possible to mass-produce sensors such as accelerometers and pressure sensors, and actuators such as microvalves and pumps. Many of these devices have been developed for the automotive industry, but they have found their way into others areas, including medicine. Although MEMS devices are unique, they may be viewed as simply a miniaturization of macroscopic sensors and actuators to the microscopic scale, meaning the devices or components of devices have dimensions between 1 and 100 μm. Their production is based on the basic methods employed in electronic microcircuits and because of that can be easily integrated with additional circuitry to obtain smart sensors and actuators.