Harnessing acoustic energy with liquid metal triboelectric nanogenerators: A promising approach for moving-parts-free power generation

Abstract

Heat-driven acoustic engines (HDAEs) offer a promising approach to energy generation without solid moving parts. However, integrating linear alternators for acoustic-to-electric conversion introduces moving components, diminishing this advantage. To tackle this issue, we investigate using an acoustically-driven liquid–metal triboelectric generator (LM-TEG) within HDAEs for acoustic-to-electric conversion. Experiments were conducted in three settings: mechanically-driven LM-TEGs under atmospheric and pressurized gas conditions, and acoustically-driven LM-TEGs. Results from mechanically-driven LM-TEG tests show that using FEP material, increasing LM-TEG contact area, stacking TEGs in parallel, and using pressurized gas enhance performance. Acoustically-driven LM-TEG experiments demonstrate significant improvements with pressurized nitrogen, achieving a short-circuit current approximately 4.5 times higher than with helium at equivalent pressures. Notably, charge and power densities reached 388 μC/m² and 1.7 W/m², respectively, surpassing typical values from conventional TEGs. Importantly, these results were obtained with a complete, fully integrated acoustically driven LM-TEG system. This study represents the first investigation in the literature of acoustically driven LM-TEGs, offering a distinct power generation system with no solid moving parts. The findings validate the feasibility of integrating LM-TEGs with HDAEs and suggest their potential for large-scale power generation, moving beyond the small-scale applications that have dominated prior TEG research.