The mature MEMS accelerations are divided into three kinds: piezoelectric, capacitive and heat sensitive. The piezoelectric MEMS accelerometer is applied to the piezoelectric effect, and there is a rigid block supporting mass inside it. Under the condition of motion, the mass will generate pressure, and the rigid body will produce strain and transform acceleration into electrical signal output.
There is also a mass block inside the capacitive MEMS accelerometer. From a single unit, it is a standard flat plate capacitor. The change of acceleration drives the movement of moving mass blocks, thereby changing the distance between two poles of the plate capacitor and the positive area. The acceleration is calculated by measuring the capacitance change.
Thermal MEMS accelerometer has no internal mass, there is a heating body which is the central, peripheral temperature sensor, which is sealed gas chamber, when working in the heating body under the action of gas to form a cloud of hot gas inside, and the proportion of air around air mass is different, change the thermal field moves through the inertial air mass formed so that the sensor detects the acceleration value.
Because of the existence of rigid support in the piezoelectric MEMS accelerometer, usually, the piezoelectric MEMS accelerometer can only induce “dynamic” acceleration, but can not sense the “static” acceleration, that is what we call the acceleration of gravity. The capacitive and thermal induction accelerations can not only induce the “dynamic” acceleration, but also the “static” acceleration.