MEMS Accelerometers are manufactured using microelectronics fabrication techniques. MEMS-based accelerometers measure physical parameters such as vibration or acceleration through the combination of microscopic mechanical sensing structure, typically silicone, coupled with microelectronics circuit. Unlike IEPE accelerometer, MEMS accelerometers are generally used for measuring low frequency vibration down to 0 HZ (DC acceleration) , motion and constant acceleration. Therefore, MEMS accelerometers can also be termed as DC accelerometers.
There are two types of DC Accelerometers that are available in the market: Variable Capacitance Accelerometers and Piezoresistive Accelerometers. These two accelerometers operate based on MEMS technology and differ in terms of sensitivity, measuring ranges and types of applications. In this article, we will discuss Variable capacitance Accelerometers in more details.
Variable capacitance accelerometer provides DC response. Therefore, they are ideal for measuring low frequency vibration down to 0 Hz, motion and steady state acceleration. The Variable Capacitance Accelerometers are known for their high sensitivities, narrow bandwidths and an outstanding temperature stability. They offer accurate and precise measurement results and are ideal in measurement highly sensitive environments such as in seismic or underground applications. Due to their DC responding feature, variable capacitance accelerometers are greatly useful in measuring centrifugal forces or measuring the accelerations or decelerations experienced by devices such as elevators.
The sensor element operates based on the principle of Differential Capacitance, which is a voltage-dependent capacitance. As soon as the sensor experiences acceleration or mechanical force, the silicone structure displaces which results in a change in capacitance. This change in capacitance is detected by the CMOS circuit and it is then transformed into an output voltage proportional to acceleration. To attain the maximum benefit from the DC response generated by this accelerometer, the readout device must also be in a DC coupled state. A VC MEMS accelerometer Sensor consists of a voltage regulator inbuilt in it, to ensure that the sensor is powered by any unregulated DC voltage source.
The Variable Capacitance Accelerometers have some unique characteristics which makes them capable of providing a highly stable and accurate measurement.
Due to their ability to operate under constant acceleration and broad temperature range, there are many industries and applications where variable MEMS Accelerometers are used. Let’s look at these different applications:
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