The Ubiquitous MEMS

Micro-electro-mechanical systems, or MEMS, are present in almost every electronic system that we use daily. They can be found in smartphones, cameras, automobiles, and all other kinds of electronic gadgets. MEMS act as microscopic components that enable our devices to become smaller, faster and lighter.

MEMS were first used in the early 80s, one of their first applications was as ink-jet printer heads and as sensors: later on MEMS technology advanced and nowadays we see MEMS successfully applied in the medical, automotive, aerospace, entertainment and other fields.

The development of MEMS made possible the fabrication of very small devices. MEMS production became practical once semiconductor IC devices manufacturing became widespread and common. A modification of the traditional semiconductor fabrication technologies made possible MEMS production on large scale since the technologies and processes used in MEMS fabrication are very similar to those adopted in IC fabrication. MEMS are made of various materials such as silicon, polymers, ceramics, and metals and their processing requires several techniques, including deposition, patterning, etching, and dicing.

MEMS have many applications, but one of their most important uses involves their role as very small mechanical switches to control the flow of electricity. This apparently simple role is very significant as it is one of the fundamental principles around the actuators and sensors in modern electronics. Examples of these sensors and actuators that utilize MEMS switches are the head of the inkjet printer, the accelerometer in a smartphone, the gyroscope in a game console controller, and the sensor in the car that controls the airbag release

Essentially, MEMS work in the same way mechanical switches work, but have the advantage of being very small. Chris Keimel, a Process Development Engineer at GE, says that a switch can be made to work faster if it is smaller. The smaller the mass of the switch, the faster it can be moved. This is very important for a switch operating on the order of microseconds and it is essential for faster and more compact electronic devices.

A mechanical switch has a switch arm that moves to turn the flow of electricity on or off, MEMS also have a switch arm that is usually much thinner than a human hair and it would not be able to oscillate quickly as needed if it were thicker than that. Micro-switches speed is not limited by the laws of classical physics, such as inertia, but by other factors such as wetting and electrostatic forces. Their small size means that they can be accelerated further via electrostatic forces due to their relatively large surface areas.

Aside from acting as switches, the fast oscillation of MEMS is also utilized in other applications. Movie projectors that use digital light projection utilize thousands or hundreds of thousands of minuscule mirrors that oscillate at very fast rates. The oscillation rate can be controlled to adjust the intensity of the light reflected.

Given that the current technological trend is toward miniaturized, commoditized electronics systems, MEMS switches will continue to play a bigger role in technology advancement. While we may even not notice this revolution coming, the effects will be just under our eyes.

About the Author-

This article was written by Matteo Martini, author and CEO of Martini Tech, a company that provides nanoimprinting, PSS patterning, MOCVD deposition, sputtering, MEMS foundry, GaN wafer, GaN LED Technology and other microfabrication-related services. Please have a look at our blog.