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How do piezoelectric accelerometers measure motion?

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Figure 1: Ferroelectric properties of barium titanate (BaTiO3). (Left) Above 120° C the structure of the BaTiO3 crystal is cubic, and there is no net polarization of charge; (right) below 120° C the structure changes to tetragonal, shifting the relative positions of the ions and causing a concentration of positive and negative charges toward opposite ends of the crystal. — capacitor dielectric and piezoelectric ceramics Figure 1: Ferroelectric properties of barium titanate (BaTiO₃). (Left) Above 120° C the structure of the BaTiO₃ crystal is cubic, and there is no net polarization of charge; (right) below 120° C the structure changes to tetragonal, shifting the relative positions of the ions and causing a concentration of positive and negative charges toward opposite ends of the crystal.

Piezoelectric accelerometers measure motion by utilizing the direct piezoelectric effect, where certain materials generate an electric voltage when subjected to mechanical stress.12

In these devices, a reference mass is typically arranged to exert pressure on a piezoelectric ceramic or crystal element. When the object to which the accelerometer is attached undergoes acceleration, inertia causes the internal mass to exert a varying force on the piezoelectric material. Because the induced polarization—and thus the resulting voltage—is proportional to the applied stress, the device produces an electrical signal that corresponds to the acceleration of the object.341

These nonresonant devices are highly effective for applications such as vibration monitoring and seismic detection, as they provide a reliable method for converting mechanical motion into a measurable electrical output.34