Quasi-Adiabatic Thermoacoustic Sound Sources

Thermoacoustic sound source (TASS) shows great potential for flexible electronics and medical devices due to its broad frequency range and ease of integration. However, its sound pressure level (SPL) remains inadequate due to low thermoacoustic conversion efficiency. In this study, a double-sided laser-induced graphene (d-LIG) TASS is demonstrated to create a quasi-adiabatic structure. By applying identical currents to both sides, this design minimizes heat transfer to the substrate, closely approximating adiabatic conditions. The d-LIG TASS achieves an SPL of 80 dB at 15 kHz, with a sound pressure 3 times higher than the single-sided counterpart. Its thermoacoustic conversion efficiency reaches 4.88 × 10^-5 at 15 kHz, representing a substantial improvement compared to typical porous graphene TASS. Furthermore, as a universal strategy, a quasi-adiabatic indium tin oxide-based transparent screen is proposed, which can be applied as a front speaker for mobile phone. This research demonstrates a simple and effective way to enhance the performance of TASS.