Their broadest use is in the sensor area. There exist MEMS sensors to measure vibrations, temperature, light, movement (1,2 and 3 axis), linear and rotational acceleration. They are integrated in ink jet printers, video games, cell phones, alarms, cars, etc.
In the medical field, they are used as biosensors, pressure sensors, in studies related to drug delivery and other kinds of physical sensors.
In the automotive area they are integrated in intelligent airbags and used in vibration detection and in many other applications.In telecommunications they are used all along the transmission line. MEMS are used in the implementation of tunable lasers, tunable filters, optical switches, dynamic gain equalizers, attenuators, etc. as it is shown in the following image.