How do you extract the maximum amount of energy from a piezoelectric element? (For energy harvesting purposes.)
The maximum power theorem would seem to say that you need to load it with a resistance equal to the piezo's internal resistance, but a piezo's internal impedance is capacitive rather than resistive. So the load would have to be an inductor? Or a resistance tailored for a specific frequency of vibration? How would you use this to do something more normal, like charge a capacitor for powering other circuitry?