MEMS (Micro Electrical Mechanical Systems) is a comparatively new and little known class of semiconductor chips. They are physical devices, mostly sensors, built with standard semicon technologies so that they are small and cheap. Amazing new sensors are opening up all kinds of low-cost measurements, and when/if the IoT world materializes, MEMS sensors will be ubiquitous.
An early application was accelerometers to measure what happens during an auto crash. Precisely calculating when to set off the airbags and how much force to use substantially reduced the incidental injuries caused by airbags expanding at 100 mph or faster. Another early application was the Wii’s wand. Now they are common in many products such as phones and toys. They also play key roles in “lab on a chip” technologies. In the future, household appliances may include MEMS microphones, vibration sensors, chemical sensors, and many other.
So MEMS is one of the multitude of “important but invisible” technologies that make the world work. As an aside, too many of my students look for jobs only with companies they have heard of, ie. they completely miss industries like MEMS.
Many years ago I helped Analog Devices with some manufacturing problems. ADI was a MEMS pioneer, so of course it had many new problems to deal with. Their fab (plant) was in Cambridge, MA, right next to MIT! Now the technology is more widely diffused, so the industry is more competitive and apparently not very profitable. This article has a short discussion of price pressure and product directions. Semiconductor Engineering .:. The Trouble With MEMS
A short description of the technology itself is at MEMS Motion Sensors: The Technology Behind the Technology.