Gigantic triboelectric power generation overcoming acoustic energy barrier using metal-liquid coupling

Hermetically sealed titanium (Ti) packaging provides protection for implantable medical devices, but it hinders reliable wireless power transfer to these devices. We present a miniaturized device that utilizes ultrasound-induced vibrations in Ti, mediated by liquid space, for efficient triboelectric energy harvesting. Unlike the conventional ultrasound-driven triboelectric nanogenerator, which induces contact electrification through multiple modes, the Ti-packaged device generates vibrations of the triboelectric membrane in a single mode, facilitating effective energy transfer. The incorporation of the Ti packaging leads to a significant increase in power density, up to 310% compared with the absence of it when measured under a tissue-mimicking material, and it enables long-term stability and Bluetooth communication in vivo. These findings represent the first technology that enhances power transmission characteristics through a Ti layer. We believe that this technology will accelerate the development of smaller, multifunctional, and long-lasting implantable medical devices.