There is significant motivation for making MEMS out
of CMOS. Leveraging foundry CMOS for MEMS is fast,
reliable, repeatable, and economical. Electronics can be
placed directly next to microstructures, enabling arrayed
systems on chip. In CMOS MEMS, multiple conductors
can be placed inside of the microstructures, which enables
placement of multiple electrically isolated capacitive sensors
and electrostatic actuators. The gate polysilicon can be
embedded in the microstructures as heater resistors,
piezoresistors, or thermocouples.