MEMS sensors

Micro-electromechanical systems (MEMS) have been in the industry since they were first produced in the 1980s; however, the origin of the first MEMS pressure sensor dates back to the 1960s at Kulite Semiconductor, who developed a piezoresistive pressure sensor. Essentially, they incorporate miniaturized mechanical structures that interact with electronic controls. Typically, these sensors are in the 1 to 100 um geometry range. Unlike the other sensors mentioned in this chapter, MEMS mechanical structures can spin, stretch, bend, move, or alter form, which in turn affects an electrical signal. This is the signal captured and measured by one particular sensor. 

MEMS devices are manufactured in a typical silicon fabrication process using multiple masks, lithography, deposition, and etching processes. MEMS silicon dies are then packaged with other components such as operational amplifiers, analog to digital converters, and support circuitry. Typically, MEMS devices will be fabricated in the relatively large 1 to 100-micron range, whereas typical silicon structures are fabricated at 28 nm or below. The process involves a thin layer deposition and etching to create the 3D structures for a MEMS device.  

Besides sensor systems, MEMS devices can be found in the heads of inkjet printers and modern overhead projectors such as digital light processor (DLP) projectors. The ability to synthesize MEMS sensing devices into packages as small as a pinhead has and will allow IoT growth into billions of connected things.