To integrate or not to integrate

For almost 50 years, silicon sensors and actuators have been on the market. Early devices were simple sand-alone sensors and some had wide commercial success. There have been many examples of success stories for simple silicon sensors, such as the Hall plate and photo-diode. The development of micromachining techniques brought pressure sensors and accelerometers into the market and later the gyroscope. To achieve the mass market the devices had to be cheap and reliable. Integration can potentially reduce the cost of the system so long as the process yield is high enough and the devices can be packaged. The main approaches are; full integration (system-on a-chip), hybrid (system-in-a-package) or in some cases separate sensors with remote electronics. The last can be the case when the environment is unsuitable for the electronics. The critical issues are reliability and packaging if these devices are to find the applications. This paper examines the development of the technologies, some of the success stories and the opportunities for integrated Microsystems as well as the potential problems and applications where integration is not the best option.