Acoustic energy harvesting based on topological states of multi-resonant phononic crystals

Recently, topological phononic crystals can be well utilized to design acoustic energy harvesting devices, and the properties of topological state can improve the robustness. However, these devices generally have excessively high operating frequencies. Aiming at this problem, this work designs a novel acoustic energy harvesting device based on the topological edge state of a multi-resonant phononic crystal, in which topological edge states can improve robustness and operating frequency can be cut down by introducing the multiple resonant cavities. In this work, a theoretical model of acoustic energy harvesting device is established and the robustness of edge states is verified by finite element method (FEM). It is proved by simulation and experiments that the device can collect acoustic energy very well. Experiments show that the device has the maximum output voltage at the incident acoustic frequency of 718 Hz, with a maximum voltage amplitude of 132.5 mV. Meanwhile, the device still has good acoustic energy collection capability with a maximum voltage of 96.5 mV at 707 Hz when it contains point defects. It can be concluded that the topological edge state of a multi-resonant phononic crystal can be designed as an excellent acoustic energy harvesting device because it can provide lower operating frequency and better design robustness.