Design, fabrication and evaluation of a Quad-Finger multimodal vibration energy harvester utilizing MFC generators

This study develops a Quad-Finger structure as a multimodal vibration energy harvester using macro fiber composites (MFCs). Comprising piezoelectric fibers in a polymer matrix, MFCs offer enhanced mechanical robustness and address the brittleness of traditional piezoceramics, making them ideal for vibration energy harvesting applications. The proposed Quad-Finger structure is consisting of a primary plate, four smart beams embedded with MFC patches, and proof masses. To assess the harvester's performance in real applications, a read-out circuit is integrated to measure the electrical outputs. A finite element (FE) model is developed using COMSOL Multiphysics (R) 6.0 to simulate the harvester's performance. The read-out circuit is also simulated in LTspice, allowing the FE results to be validated and the circuit to be optimized. Following the simulations, a prototype of the harvester is fabricated, and experimental tests are conducted to verify the simulation results and demonstrate practical performance. The FE model enables extensive numerical analysis, showing that the device effectively harvests vibrational energy from its first four modes within a 10 Hz bandwidth, highlighting its potential for broadband vibration energy harvesting. Notably, MFCs prove to be significantly more efficient for energy harvesting compared to traditional piezoceramics. Furthermore, power output analysis suggests that the harvester operates optimally when a tunable load resistance is employed.