Itsy bitsy

MEMS now big in consumer electronics

By Gabriela Ehrlich

MEMS, tiny electromechanical systems, are now an indispensable component of portable consumer electronics where they increase the performance, accuracy and reliability of existing technologies in ways that are not possible with traditional electronics. At CES 2012 literally hundreds of devices now include sensors, gyroscopes, accelerometers that enable innovative services on smart phones and tablets and allow for the miniaturization of projectors and other devices.

This text includes extracts of an article by IDG News Service, James Nicolai - shortened and published with permission – full article available here.

MEMS are miniaturized mechanical and electro-mechanical elements (Photo: NXP) MEMS are miniaturized mechanical and electro-mechanical elements (Photo: NXP)

From industrial applications to consumer electronics

MEMS (Micro electromechanical systems) were all over the 2012 Consumer Electronics Show, though you might not know it unless someone told you. While MEMS have been used in automobiles, PCs, medical devices and industrial applications for years, their widespread use in portable consumer electronics is relatively new, propelled by reductions in the cost, size and their power consumption. 

They've become vital for a multitude of consumer electronics including remote controllers, gaming devices, smartphones and tablets as well as printers, pico-projectors, digital cameras, microphones and hundreds of other products.

Progressively, MEMS incorporating one or several different functions such as accelerometers, altimeters, magnetometers (compasses), inclinometers, gyroscopes, and pressure sensors are built into a rapidly increasing number of consumer hardware that work in combination with apps on smart phones and tablets.

Processing motion

MEMS motion sensors detect the orientation of any device, where it is heading and its absolute location in three-dimensional space. By fusing the data streams from different MEMS (accelerometers, altimeters, inclinometers, etc.) they are for example used to control the hardware of game consoles or inform software such as security protocols or location-based services. MEMS are increasingly small, inexpensive and low-power enough for use in even the tiniest mobile devices. In 2012, mobile device makers will begin integrating navigation accelerometers, gyros and magnetometers allowing augmented reality and device tracking. Smartphones will soon know not only where you are but what floor of a building you or your device are on.

Sharper images in millions of shades

The MEMS micro mirror chip (DMD) is frequently used in consumer electronics and particularly in video projectors and televisions. This chip uses microscopic moving mirrors to improve the image quality and reliability of these products. In a way it is like a light-switch composed of millions of hinge-mounted mirrors, each of which measures approximately 1/5 of a human hair and corresponds to one dot or pixel in a projected image. The mirrors are mounted on tiny hinges that allow them to tilt either towards the light source to reflect the light or away from it to block the light. The length of time the mirror faces the light determines the brightness of each dot. They are able to produce over 16 million shades of colour and an image quality that enables them now to replace film projectors in movie theatres.

More storage and better sound

MEMS are revolutionizing mass data storage in the computer industry by miniaturizing components for disk drives, servers and peripherals.

Acoustic MEMS chips are changing the way sound reaches the human ear. They provide less distortion and higher clarity and quality of sound. For this reason they are built into cell phones, music devices but also hearing aids.

Increasing safety

In the automotive industry MEMS accelerometers are a key element of modern airbag systems. These MEMS contain a central mass that moves in response to the vehicles acceleration. The mass is mounted on a hinge that allows it to move during driving, returning it to its original position when the car stops. Sensible electronic circuitry read the mass’s movement and relates its data to a connected micro-processor. When the mass’s movement changes at an unsafe speed, the airbags are deployed protecting passengers from impact. Previously airbag systems were composed of numerous electronic components: today, two small chips suffice to operate this complex system. This not only decreases cost but also increases operational accuracy and reliability.

Opening the way for new applications

In medical applications, in addition to improving speed and reliability, MEMS open the way for novel innovations: MEMS chips inserted under the skin of patients are able to release an exact amount of drug over time; built into a scalpel they measure the length and depth of incisions during delicate operations. Environmental sensors (for temperature, humidity and air quality), medical sensors (such as in blood-pressure monitors, glucose meters, weight scales and pulse oximeters) and wearable sensors that can invoke a personal emergency response system, all use MEMS sometimes connected wirelessly to the Internet.

Sensing danger

MEMS low-power nano sensors are also used to detect gas leaks or saturation levels. They are so small that they can be sewn into clothing to be worn by soldiers in the field or by the elderly at home. Increasingly these MEMS sensors are placed along pipelines, around factory perimeters and in workspaces where they help increase safety and enable early warning systems.

IEC work for MEMS

IEC SCs (Subcommittees) 47E and 47F prepare a multitude of International Standards that enable manufacturers to build better, more resistant, efficient and reliable sensors and MEMS. They cover terms and mechanical properties, basic characteristics, essential and optimal operating ratings, as well as a multitude of testing methods for materials such as bonding strengths in composites, resistance to stress or bending or thermal expansion. Together they facilitate the design, manufacture and use and reuse of micro electromechanical systems.

What are MEMS and how are they made?

According to the MEMS Industry Group MEMS are tiny machines that include elements in size from 1 to 100 microns, approximately the thickness of a human hair. They are generally divided into two categories: sensors and actuators. Sensor devices gather information from their surroundings; actuators execute given commands or act through highly controlled movements.

MEMS contain both mechanical and electrical components. To make them, thin layers of material are deposited onto a base and then selectively etched away, leaving a microscopic three-dimensional structure. The electrical elements process data while the mechanical elements act in response to that data. An integrated circuitry provides the thinking part of the system while the MEMS component complements the system with active perception and control functions.

Known as MST (Micro systems technology), MEMS devices, which were invented in the 1980s, are now used in a huge and broadening number of products, where they help improve existing technologies in ways that are not possible with traditional electronics, offering increased performance, higher accuracy and reliability as well as faster response time. 

MEMS are miniaturized mechanical and electro-mechanical elements (Photo: NXP) MEMS are miniaturized mechanical and electro-mechanical elements (Photo: NXP)
Pico cameras/projectors are some of the many electronic devices that make use of MEMS (Photo: 3M) Pico cameras/projectors are some of the many electronic devices that make use of MEMS (Photo: 3M)
MEMS are also used in motion sensors (Photo: STMicroelectronics) MEMS are also used in motion sensors (Photo: STMicroelectronics)