MEM is chip-based technology where Sensors are composed of a suspended mass between a pair of capacitive plates. When the sensor is tilted, a difference in electrical potential is created by this suspended mass. The created difference is then measured as a change in capacitance.

Current Mems devices include accelerometers for airbag sensors, inkjet printer heads, computer disk drive read/write heads, projection display chips, blood pressure sensors, optical switches, microvalves, biosensors. MEMS sensors can be used to measure physical parameters such as acceleration, temperature and pressure. Electronic components can be constructed on the same chip to measure the output of the sensors, perform signal processing and provide wireless communication.

There are two basic types of MEMS switch technology: capacitive and ohmic. A capacitive MEMS switch is developed using a moving plate or sensing element, which changes the capacitance.

Due to the ultra-low power consumption of MEMS accelerometers, wired systems can now be replaced with wireless solutions, single-axis bulky piezo sensors can be replaced with small, lightweight triaxial analog components, and a wider range of machines can now be monitored continuously in a cost-effective way. Some of the metals used within MEMS systems include gold, nickel, aluminium, copper, chromium, titanium, tungsten, platinum, and silver, and the methods of choice for creating these devices are usually electroplating, evaporation and sputtering. Today’s mobile devices are packed with nearly 14 sensors that produce raw data on motion, location and the environment around us. This is made possible by the use of micro-electromechanical systems (MEMS). MEMS are mechanical systems built into tiny semiconductor chips. The original iPhone, and first-generation iPod touch, use the LIS302DL 3-axis MEMS based accelerometer.

The key limitations of MEMS sensors were noise, bandwidth, and g range. Low noise is key to detect low level vibrations, potentially enabling earlier fault detection or even prediction. Bandwidth is key because a lot of asset/motor faults, such as cavitation, bearing issues, and gear meshing often occur earliest at frequencies above 5 kHz and of course time is critical in detecting faults. The g range is important as larger assets can produce shocks or impacts up to hundreds of g, potentially destroying MEMS sensors designed for less harsh operation.

Bosch continues to be the MEMS leader, with an exceptional business and growth. Similarly, STMicroelectronics and TDK sales grew significantly in 2021. Broadcom’s. Fabrication and assembly unit costs can be very high for low quantities. Therefore, MEMS are not suitable for niche applications unless cost is not an issue. Testing equipment to characterise the quality and performance can also be expensive. Silicon is an ideal substrate material for MEMS because of the following reasons: It is mechanically stable and it is feasible to be integrated into electronics on the same substrate.

Each sensor device has unique packaging requirements to meet specific functions for interacting with external devices or the environment. For example, speakers, microphones and pressure sensors must have sound or pressure inlets integrated using MEMS and sensor packaging techniques. Optical devices may require certain types of materials to be used so that the desired optical wavelengths may be detected. MEMS and sensor packages can be further differentiated into mold type, air type with lead frame/organic substrate/ceramic substrate and metal/plastic packages and wafer-level packaging, providing comprehensive solutions for sensor and device protection according to the type of application and the commercial/reliability requirements.

Integrated sensor hub/sensor fusion has become more and more important in the latest cell phones and wearable devices.

Micro-Electro-Mechanical System (MEMS) gyroscopes are motion sensors that detect and measure the angular motion of an object. They measure the rate of rotation of an object around a particular axis: 1-axis, 2-axis, and 3-axis.

MEM accelerometer is an electromechanical device that is used to measure linear acceleration and the force producing it.

All MEMS accelerometer sensors commonly measure the displacement of a mass with a position-measuring interface circuit. That measurement is then converted into a digital electrical signal through an analog-to-digital converter (ADC) for digital processing. Gyroscopes, however, measure both the displacement of the resonating mass and its frame because of the Coriolis acceleration.

Today, everyone carries MEMS devices on themselves in the form of smartphones, smartwatches and fitness trackers. In the past, an aeronautic gyroscopic system used to determine roll, pitch and yaw in the cockpit of aircraft weighed several kilograms and measured several inches in length, whereas nowadays, MEMS gyroscopes in our smartphones weigh less than a milligram and are equivalent in size to a grain of sand. With miniaturisation in size also comes a significant reduction in manufacturing cost and improved scales of economy. This is like the continued miniaturisation and reduction in cost seen in the semiconductor industry.

Some common commercial applications of MEMS include:

•  Accelerometers in modern cars for a large number of purposes including airbag deployment and electronic stability control.
•  MEMS gyroscopes in remote controlled, or autonomous, helicopters, planes and multirotor (also known as drones), used for automatically sensing and balancing flying characteristics of roll, pitch and yaw.
• Accelerometers in consumer electronics devices such as game controllers (Nintendo Wii), personal media players / cell phones (virtually all smartphones, various HTC PDA models), augmented reality (AR) and virtual reality (VR) devices, and a number of digital cameras (various Canon Digital IXUS models). Also used in PCs to park the hard disk head when free-fall is detected, to prevent damage and data loss.
• Bio-MEMS applications in medical and health related technologies including lab-on-a-chip (taking advantage of microfluidics and micropumps), biosensors, chemosensory as well as embedded components of medical devices e.g. stents.
• Micromachined ultrasound transducers.
• MEMS-based loudspeakers focusing on applications such as in-ear headphones and hearing aids.
• Here MEMS are used in attitude adjustment, propellant gauging, propellant flow management, leakage testing thermal and environmental control and in onboard life-support systems.

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