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Piezoresistive accelerometer

The piezoresistive accelerometer is a variant of the strain gauge accelerometer, where piezoresistive sensors are used instead of strain gauges. These sensors behave similarly to strain gauges, but allow more extended elongation and sensitivity, despite having some stability problems with the temperature variation.

A piezoresistive accelerometer has a stable structure composed of a silicon chip created by micromachining and semiconductor production technology. A mass and a beam on which a set of the piezo-resisters are created on a silicon chip. A set of electrical bridged is formed by such piezo-resistive resisters to generate signals proportional to the applied acceleration.

The key benefits of piezoresistive accelerometers are:

• measurements are possible over the wide frequency range covering down from the ultra-low up to the high frequency as of several kHz
• compact and lightweight
• high sensitivity
• highly acceleration resistant

Instead of sensing the capacitance changes in the seismic mass, a piezoresistive accelerometer takes advantage of the resistance change of piezoresistive materials to convert mechanical strain to a DC output voltage. Most of the Piezoresistive designs are either MEMS type (gas damped) or bonded strain gauge type (fluid damped) and they are suitable for impact measurements where frequency range and g level are considerably high.

Piezoresistive accelerometers are widely used in automobile safety testing including anti-lock braking systems, safety air-bags, and traction control systems as well as weapon testing and seismic measurements. Besides, micromachined accelerometers are available and used in various applications, such as submillimeter piezoresistive accelerometers in extremely small dimensions used for biomedical applications.