Performance of a piezoelectric bimorph for scavenging vibration energy

We analyze the performance of a piezoelectric bimorph in the flexural mode for scavenging ambient vibration energy and evaluate the dependence of the performance upon the physical and geometrical parameters of the model bimorph. The analytical solution for the flexural motion of the piezoelectric bimorph shows that the output power density increases initially, reaches a maximum, and then decreases monotonically with increasing load impedance, which is normalized by a parameter that is a simple combination of the physical and geometrical parameters of the scavenging structure, the bimorph, and the frequency of the ambient vibration, underscoring the importance for the load circuit to have the impedance desirable by the scavenging structure. The numerical results illustrate the considerably enhanced performances achieved by adjusting the physical and geometrical parameters of the scavenging structure.