Enhancing sound pressure output in graphene-based hybrid bone conduction hearing aids through electromagnetic and electrostatic integration

Bone conduction hearing aids (BCHA) actively serve patients with conductive hearing loss or external auditory canal problems, including auditory canal atresia, ossicular dislocation, etc. They are typically categorized into surgically implanted devices, embedded directly into the skull, and adhesive devices, which transmit sound through the skin. The latter are advantageous for being non-invasive and suitable for children under five. However, adhesive devices, due to their sound transmission method, require enhanced sound output performance compared to implanted devices. Graphene, known for its low mass density yet excellent mechanical and electrical properties, finds application in various electronic fields. Currently, it serves as a diaphragm in electroacoustic transducers, enabling stable vibrations across broad frequency ranges. The electroacoustic transducers of BCHA are typically driven by electromagnetic methods, which may be effective in low-frequency ranges but not in high-frequency ranges. This study successfully introduced a hybrid approach that combines the complementary advantages of both electromagnetic and electrostatic modes by utilizing a graphene sheet as the diaphragm for a hybrid graphene BCHA. The electrostatic mode, which performs better in high-frequency ranges compared to the electromagnetic mode, was implemented in this hybrid structure. According to the measured frequency response data, the hybrid mode showed up to an 11 dB improvement compared to the electromagnetic mode and up to a 21 dB improvement compared to the electrostatic mode, exhibiting a relatively flat shape over a wide frequency range. Subsequently, the device’s effectiveness as a BCHA is confirmed through experiments on rabbits, showcasing its potential in auditory aid advancement.