How to put piezoelectric and hitting device together

The major limitations of harvesting the
energy from piezoelectric devices are not
only providing low power, but also the
difficulty to investigate their behaviour
when applying to some applications such
as prosthetic legs. Thus, the investigating
of the output voltage waveforms when hitting
the upper arm of the piezoelectric
PZT was shown.

Reference:

Piezoelectrics in Prosthetics: Energy Harvesting

Slow Contact Opening Circuit Breakers