Microelectromechanical systems (MEMS) are a valuable technology in many applications and have been used for many years now to perform a range of functions. While they are now an older technology, advances in fabrication technologies are yielding smaller features and smaller components, and this is enabling MEMS to be made with more and more materials. The ability to create more features, structures, and components with a greater range of materials has opened MEMS to a wide array of applications.
What Are MEMS?
MEMS are small integrated systems that combine both mechanical and electrical components into functional devices. There are many different methods use to fabricate the different components of MEMS, as well as to pattern and manipulate the structure of materials used in each of the components. These range from using integrated circuit batch processing methods for creating the electronics components to a variety of advanced micromachining, lithography, and deposition methods used to fabricate the mechanical components.
MEMS devices contain many components and can be quite complex systems. The different components can be made of many materials, from silicon to various metals, ceramics, and polymeric materials. The components that make up the MEMS device are fabricated on the micrometer level, but the overall device can still be at the millimeter scale if they contain a multitude of components.
Key Application Areas of MEMS
MEMS devices contain a wide range of mechanical microstructures, microsensors, microactuators and microelectronics integrated on a silicon chip. The extensive components in MEMS means that any devices created with them can be designed to sense, control, and actuate at the micro level but provide macro-level effects and functions. For example, a lot of different actuators have been developed using MEMS, including optical, radiation, thermal, magnetic, chemical, and mechanical actuators. Given the wide scope of MEMS devices and the number of components and materials that can be utilized, there are numerous key application areas for MEMS, most notably across the industrial, automotive, photonic, life science, and RF sectors.
When it comes to sensing applications, MEMS have been used to create pressure sensors, accelerometer radiation sensors, thermal sensors, magnetic sensors, mass flow sensors, gas sensors, chemical sensors, and biological sensors. In specific industries, pressure sensors have been used in high temperature industrial environments and for medical applications. Certain automotive applications use accelerometer sensors as airbag deployment sensors, whereas gas sensors are used to measure the levels of carbon monoxide.
Looking towards more specific applications in the industrial sector, MEMS have been used in fluid nozzles, hinge mechanisms, thermal inkjet printer heads, micromachined valves, micropumps, and micropositioners in data storage systems. MEMS have also been used widely in optic and photonic applications, including in displays, infrared imaging applications, projection displays, fiber optic communication devices, tunable lasers, optical switches, photonic switches, and wavelength locking devices.
As for medical and life science applications, MEMS are used for a broad range of purposes. MEMS are used in microfluidic devices as part of the mixing and pumping components, in microelectrode arrays that can analyze cell cultures and DNA (and their hybridization), and in PCR-on-a-chip and electrophoresis-on-a-chip devices.
The other specific area where MEMS have found plenty of use is in RF applications. MEMS devices have been used in micromachined capacitors and inductors, microelectromechanical resonators, comb-drive resonators, beam resonators, coupled-resonator bandpass filters, microelectromechanical switches, membrane shunt switches, and cantilever switches.
The scope of MEMS applications goes beyond what we’ve detailed here, and quite frankly, beyond MEMS in their truest definition. While there are defined features that set MEMS apart from other complex systems, there is some overlap with other integration technologies that use micron-sized components—and the application areas where they are used. In this regard, MEMS and other similar integration systems often fall under the banner of microsystems technologies (MST). An example of this is micro-opto-electromechanical systems (MOEMS), which are similar to MEMS, but instead of only using mechanical and electronic components, MOEMS also use miniaturized optics to perform specific functions and give the device different macro properties, effects, and functionalities.
Conclusion
MEMS are complex but versatile systems that contain many different electronic and mechanical components and perform different bulk functions based on the components within. The range of materials and components available to MEMS has enabled them to be designed and developed for a wide array of applications across many different industries―including industrial manufacturing, automotive, life science, RF, optics, and photonics. As advances in fabrication methods continue to make smaller features and components, it’s likely that the application scope of MEMS will continue to grow, even though it has been an established technology for many years.
