Acoustic energy harvesting metasurface based on surface wave conversion

In this work, we propose and demonstrate an acoustic gradient metasurface with phase modulation that can convert the propagating waves into surface bounded waves for energy concentration. Due to the periodic design, multiple surface waves can form the standing wave in the case of normal incidence. Then, all piezoelectric composite sheets (PCSs) are placed in the antinode regions for acoustic energy harvesting and the output voltage of different PCS keeps the same phase. Numerical simulation and experimental results confirm that the sound pressure is 5 times larger than the incident waves, and the output power is increased by 8 times for single PCS. Our work provides an alternative way to reduce the incident noise in an enclosed space like machine room and work as a power source with a simplified design.