An Introduction to mems (Micro-electromechanical Systems)
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| An Introduction to MEMS
Prime Faraday Technology Watch – January 2002 32
unable to be fabricated by any other method than MEMS is an implantable piezoresistive strain gauge to measure forces in heart and brain tissue.
b) Accelerometer - accelerometers sense acceleration by using a suspended proof mass on which external acceleration can act (Figure 30). Upon acceleration (or deceleration), a force (F=ma) is generated on the proof mass resulting in displacement. The force or displacement is usually measured by piezoresistive and capacitive methods.
Figure 30. Suspended proof mass in a piezoresistive accelerometer (not to scale).
c) Gyroscope – a gyroscope is a device that measures the rotation rate and detects inertial angular motion. As a result it can be found, for example, in transportation, navigation and missile guidance applications. It relies on measuring the influence of the Coriolis force on a body in a rotating frame. MEMS gyroscopes typically use vibrating structures because of the difficulty of micromachining rotating parts with sufficient useful mass.
d) Pressure sensor - MEMS pressure sensors are usually based around thin membranes with sealed gas or vacuum-filled cavities on one side of the membrane and the pressure to be measured on the other side. Piezoresistive and capacitive membrane deflection measurement techniques are most commonly used in commercial pressure sensors.
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