How does a piezo-electric accelerometer work?
Piezo-electric crystals are man-made or naturally occurring crystals that produce a charge output when they are compressed, flexed or subjected to shear forces. The word piezo is a corruption of the Greek word for squeeze. In a piezo-electric accelerometer a mass is attached to a piezo-electric crystal which is in turn mounted to the case of the accelerometer. When the body of the accelerometer is subjected to vibration the mass mounted on the crystal wants to stay still in space due to inertia and so compresses and stretches the piezo electric crystal. This force causes a charge to be generated and due to Newton law F=ma this force is in turn proportional to acceleration. The charge output is either is converted to a low impedance voltage output by the use of integral electronics (example: in an IEPE accelerometer) or made available as a charge output (Pico-coulombs /g) in a charge output piezo-electric accelerometer.
