Tympanic membrane metamaterial inspired multifunctional low-frequency acoustic triboelectric nanogenerator

This study introduces the Tympanic Membrane Metamaterial inspired acoustic Triboelectric Nanogenerator (TMM-TENG), which exhibits subwavelength structural dimensions and effective sound absorption within low-frequency ranges. The performance of acoustic energy harvesting is increased by replacing rigid bottom of the acoustic cavity with an elastic part and introducing a point-surface mechanism. Experimental tests employing the proposed mechanism are then conducted. The obtained results show a remarkable 2220% increase in the output voltage of the TMM-TENG compared with the traditional approach. As for the acoustic energy harvesting performance, for a sound pressure level (SPL) of 95 dB, the peak-to-peak value of the output voltage reaches 500 V, with a measured current of 40 μA and a maximum output power of 3.05 mW. Moreover, the incorporation of an elastic part into the TMM-TENG proves advantageous in the manipulation of low-frequency sound waves. The acoustic performance of the device can also be regulated by adjusting the thickness of the elastic part. In addition, multiple TMM-TENGs with varying elastic part thicknesses are placed on a duct, and band-limited white noise is generated to evaluate the sound reduction ability without limiting the air ventilation. Furthermore, the mounted TMM-TENG allows to perform of self-powered wireless temperature sensing and acoustic telecommunication functionalities.