Vibration energy harvesting device using P(VDF-TrFE) hybrid fluid diaphragm

We designed and realized a novel vibration energy harvester based on a P(VDF-TrFE) membrane. The mechanical arrangement consists in an incompressible fluid confined between two thin P(VDF-TrFE) piezoelectric membranes. It is called piezoelectric hybrid fluid diaphragm (PHFD). Compared with conventional vibration harvester, this solution appears to be simple and suitable for miniaturization and integration. The fluid-structure interaction allows a drastic reduction of the resonant frequency of the membrane whose mechanical tension is used to generate electrical power. Consequently, the realization of compact generators for low frequencies excitation (typically under 100 Hz) using membranes is possible. Moreover, nonlinear hardening behavior offers wideband capability. A theoretical model is established and allows the performance of the generator to be estimated. A first prototype has been fabricated and tested. The influence of the electric load, the amplitude and the frequency of the excitation on the voltage and the generated power have been investigated. A maximum output power of 158.33 μW per cubic centimeter of active material was obtained at 119.56 Hz for 40 m/s2 amplitude acceleration.