A MEMS (micro-electromechanical system) is a miniature machine that has both mechanical and electronic components. The physical dimension of a MEMS can range from several millimeters to less than one micrometers, a dimension many times smaller than the width of a human hair.
Some MEMS do not even have mechanical parts, yet they are classified as MEMS because they miniaturize structures used in conventional machinery, such as springs, channels, cavities, holes and membranes. Because some MEMS devices convert a measured mechanical signal into an electrical or optical signal, they may also be referred to as transducers. In Japan, MEMS are more commonly known as
micromachines, and in European countries, MEMS are more commonly referred to as microsystems technology (MST).
How MEMS are constructed:
MEMS are composed of parts such as microsensors, microprocessors, microactuators, units for data processing and parts that can interact with exterior pieces.
Unlike conventional mechatronics devices, MEMS are often manufactured with the same batch fabrication techniques used to create integrated circuits (ICs) and many commercial MEMS products are integrated and packaged together with ICs. MEMS fabrication allows micro-sensors, which gather data, and micro-actuators, which convert energy into motion, to integrate on the same substrate.
Although MEMS have a low per-device production cost, packaging can be a challenge. Each MEMS must be packaged so that electrical or optical circuitary and other device components remain free from air and
water contamination, while still being able to interact with the surrounding environment and accommodate motion.
History of MEMS:
The idea of creating MEMS started in the 1980s; however, the means to produce MEMS (the designing and manufacturing infrastructure) was not available enough until the 1990s. One of the first few types of MEMS produced were for air-bag controllers and inkjet printheads. In the late 1990s, a projector was made using micromirrors (which utilizes MEMES). Much of the original support for MEMS came from the Defense Advanced Research Projects Agency Research and Development Electronics Technology Office.
Over time, microsensors began being used for a large number of sensortypes, including sensors for temperature, pressure, magnetic fields andradiation. In many cases, sensors that used MEMS were much moreefficient performance wise when compared to larger counterparts. Today, most people interact with MEMS daily.
Today, most people interact with MEMS daily. Each new automobile that rolls off an assembly line has at least 50 MEMS; they are essential components in various mandated safety systems, including airbags,
electronic stability control (ESC) and tire pressure monitoring systems (TPMS).
MEMS vs. NEMS
While MEMS stands for micro-electromechanical system, NEMS stands for nano-electromechanical system. NEMS would be used in Nanotechnology, which is a technology that can manipulate matter at a nanoscale (around the atomic or molecular level). A top-down approach to nanotechnology uses devices that share many similar techniques to MEMS. MEMS and NEMS are sometimes referred to as separate technologies but can be considered as dependent on one another as NEMS technologies are required for NEMS. As an example, a scanning tunneling-tip microscope (STM), which can detect atoms, is a MEMS device.
Examples of MEMS
The small system on a chip (SOC) that automatically adjusts screen orientation on a smartphone is an example of a MEMS many people interact with each day. As MEMS become smaller, require less power and are less expensive to manufacture, they are expected to play an important part in the wireless internet of things (IoT)and homer automation.
Other commercial applications of MEMS include:
- Sensor-driven heating and cooling systems for building
- Micro-mirror arrays for high definition projection systems.
- Smart dust for the detection of environmental changes in
molecular manufacturing (nanotechnology) clean rooms.
- Micronozzles to control the flow of ink in inkjet printers.
- Tiny gyroscopes, barometers, accelerometers and microphones to
support Mobile apps.
- Disposable pressure sensors for use in healthcare.
- Optical switching devices that allow one optical signal to control
another optical signal.
The MEMS below is a disposable, wearable insulin pump for managing diabetes, designed by Debiotech and STMicroelectronics. According to Debiotech, the chip is a stack of 3 layers bonded together: a silicon on insulator (SOI) plate with micromachined pump structures and two silicon cover plates with through-holes. A piezoelectric actuator on the chip moves the membrane in a reciprocating movement to compress and decompress fluid in the pumping chamber.
WHAT IS MEMS USED FOR ?
Micro-electromechanical systems (MEMS) is a process technology used to create tiny integrated devices or systems that combine mechanical and electrical components. They are fabricated using integrated circuit (IC) batch processing techniques and can range in size from a few micrometers to millimetres.
FUTURE OF MEMS:
From 2019 to 2024 the MEMS market will grow 8.3% annually in value driven by pressure (for TPMS), RF (for V2X 5G communications), inertial (for ADAS) and future MEMS (such as PMUT for ultrasonic fingerprint) (Source: Status of the MEMS Industry report, Yole Development, 2019).
Emerging application trends in MEMS :
The main growth is coming from traditional MEMS devices (microphones, RF, inertial, optical) found across a multitude of applications such as wearables & hearables (especially sensor-packed TWS), 5G smartphones, ADAS, industrial monitoring, and many others.
The development of microelectromechanical systems (MEMS) based on micromachining and microelectronics technologies has been significant for almost a decade. However, it is unrealistic to consider micromachining technology as a micro version of conventional machining technology. As a matter of fact, micromachining technology stemmed from the planar technology of silicon and is basically a two-dimensional processing technology.
On the other hand, it is obvious that a micromachine cannot compare with a conventional machine in strength and power. For the successful development of MEMS in the future, a simple rule is suggested by the experience gained in the past few years: try to avoid as much as possible mechanical coupling with the outside world while trying hard to improve the MEMS technology to enhance the mechanical power of the devices. In addition to that, the strategy proven to be correct for the development of solid-state
sensors also applies: MEMS devices should mainly be developed for new applications with a vast market.
Their substitution for traditional applications should not be considered as a main strategy of development. Based on these arguments, the future development of MEMS devices and technologies is further discussed in the paper.
The MEMS market is year after year growing faster than the average semiconductor industry. Over that time the largest technology driver for MEMS changed from automotive applications to consumer electronics dominated by smartphones. Beyond that, MEMS sensors become the heart of whole classes of new devices like fitness trackers, smart watches, virtual reality glasses and smart sensor nodes for the Internet of Things. Silicon chips are only one part of the MEMS story, you need as well special mixed
signal circuitry, low power data processing, smart algorithms and connectivity to transform raw signals into meaningful information. Multisensory applications & modules are playing an increasingly important role.