An accelerometer is a device that is utilized to measure acceleration, which is the rate of change of velocity of a body traveling in each direction. It is a microelectromechanical (MEMS) device created using microfabrication technology.
Accelerometers are produced using a multilayer wafer process and work by detecting the displacement of a mass in relation to fixed electrodes. The sensing approach used in accelerometers is capacitance, which measures acceleration by detecting the change in capacitance of a moving mass. This method is highly accurate, stable, and has lower power dissipation and simpler construction. Capacitive accelerometers are not prone to noise and variations with temperature, but the bandwidth is limited to a few hundred Hertz due to the physical geometry of the device.
The capacitance sensing structure can be a single-sided or a differential pair, which is a movable mass on either side of a fixed electrode. To achieve a greater change in capacitance, multiple movable and fixed electrodes are connected in parallel, since the change in capacitance for a single mass/electrode pair is usually small. This approach improves the accuracy of measurement and makes it easier to detect changes in capacitance.