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25 Nov, 2021 / BY Neil Sharp

What is MEMS?

A MEMSMEMS = Micro-Electro-Mechanical System

Over the past 20 years, the term MEMS has evolved in meaning. Today, MEMS describes both a type of device or sensor and a manufacturing process. 

As a device, MEMS refers to something that is considered to be “a microscopic device” featuring “electrical functionality” and “moving parts”. This combination of both electrical and mechanical functions allows products to be developed, such as microphones, loudspeakers, pressure sensors, and acceleration sensors. 

MEMS manufacturing processes provide an alternative to conventional macro-scale machining and assembly techniques.

In this blog, we talk mainly about the device rather than the manufacturing process.

How does MEMS technology work?

Microsensors detect changes in the system’s environment by measuring mechanical, thermal, biological, optical, magnetic, chemical, or electromagnetic information or phenomena. Microelectronics systems process this information and signal the microactuators to react and cause a change in the environment—by moving, positioning, regulating, pumping, or filtering. 

MEMS, therefore, allow the environment to be controlled for a desired outcome or purpose. 

Where can you find MEMS technology?

MEMS are everywhere. They are found in everyday consumer electronic devices, such as mobile phones, tablets, digital cameras, and drones. But they are also key parts of more critical applications that ensure our safety, such as activating the airbags in our cars, ensuring insulin pumps deliver the correct amount, and controlling building heating and cooling systems. 

Generally, MEMS technology is applied mainly to five separate areas:

  1. Car industry: including vehicle security systems
  2. Consumer purchases: including sports training devices
  3. Industrial applications: including earthquake detection
  4. Military: including vehicles for soldiers
  5. Biotechnology: including biochips to detect hazardous chemical and biological agents

A brief history of MEMS

The first MEMS device, a pressure sensor, was made in the 1960s. While there was only an academic interest in MEMS during the1980s, large-scale commercial development and manufacturing only began in the1990s. 

Today, everyone carries multiple MEMS devices on them—smartphones, smartwatches, and fitness trackers. And they have got smaller. Twenty years ago, for example, an aeronautic gyroscopic system used in aircraft cockpits weighed several kilograms and was ten cm long. Today, however, we carry this technology in our pockets. The MEMS gyroscopes in our smartphones weigh less than a milligram and are the same size as a grain of sand. 

How small are MEMS?

Perhaps it’s easiest to understand MEMS as a miniature machine with both electrical and mechanical components. MEMS can range in size from several mm to an impossibly small size: less than 1 micrometre or 1000 of a millimetre. At this size, it is not even visible to the human eye.

Despite their small size, MEMS are made up of parts such as microsensors, microprocessors, and microactuators—which either process data or are built to interact with exterior pieces.

With ever-changing technologies, MEMS are becoming even smaller, requiring less power, and become less expensive. 

A MEMS is not always a MEMS

As if MEMS aren’t as complicated enough already, sometimes they are referred to by a different term. In Japan, for example, MEMS is more commonly known as Micro Machines, while in European countries, MEMS is more commonly referred to as microsystems technology. 

Furthermore, some MEMS devices convert a measured mechanical signal into an electric or optical signal, so they may also be referred to as transducers. And there are also different classes of MEMS altogether, known as optical MEMS or MOEMS that feature interaction of MEMS actuation and light. This class is commonly used in technology such as bar code scanning and projection.

How are MEMS manufactured?

Manufacturers make MEMS with processing tools and materials that are used in integrated-circuit (IC) manufacturing. 

Layers of polycrystalline silicon are generally deposited along with what is known as sacrificial layers of silicon dioxide. The layers are then patterned and etched before the sacrificial layers are dissolved to reveal three-dimensional structures, including microscopic cantilevers, chambers, nozzles, wheels, gears, and mirrors. 

These structures are built using the same batch-processing methods used in IC manufacturing: many MEMS can be put on a single silicon wafer. Because of this, manufacturers have achieved significant economies of scale. Also, the MEMS components do not need any further assembly, which is not the case for conventional mechanical devices.

8 benefits of MEMS devices

  1. They are very small in size, mass, and volume
  2. They have a very low power consumption
  3. They have a low cost
  4. They are easy to integrate into systems or modify
  5. They have a small thermal constant
  6. They can be highly resistant to vibration, shock, and radiation
  7. They can be batch fabricated in large arrays
  8. They have improved thermal expansion tolerance

Examples of commonly used MEMS products

  1. Biosensors
  2. Accelerometers for airbag sensors
  3. Blood and tire pressure sensors
  4. Optical Cross Connects
  5. Mirror Arrays for Televisions and Displays
  6. High-Performance Steerable Micromirrors
  7. Optical switches
  8. Disposable Medical Devices
  9. High Force, High Displacement Electrostatic Actuators
  10. MEMS Devices for Secure Communications

MEMS and the future

From 2019 to 2024, the MEMS market will grow 8.3% annually in value. The recent shift towards personalised products embodied by Industry 5.0, for example, requires ever more devices to be manufactured—ones that depend on MEMS technology. 

Scientists are constantly trying to overcome challenges, particularly medical ones, including restoring vision and hearing and overcoming Parkinson’s disease. MEMS can help measure electrical signals in the brain and then use those signals to activate other parts of the body that might have been paralysed due to injury or illness.

Scientists borrow from mechanical, electrical, and thermal engineering and fluidic systems to try and create one single device that uses MEMS to measure an element of interest. 

One of the largest global manufacturers has already made over 10 billion MEMS and this number will continue to grow. It is estimated that the MEMS market will be worth $18.2B by 2026.

MEMS might be getting smaller, but the market is definitely growing.

Value Engineering guide for manufacturing

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