Ultrasound-Driven Highly Stable Implantable Triboelectric Nanogenerator with Human-Tissue Acoustic Impedance-Matched Polyether Ether Ketone

Implantable electrical neurostimulators offer a promising avenue for treating neurological disorders. However, their dependency on a finite battery life limits their long-term utility. Emerging transcutaneous ultrasound-driven triboelectric nanogenerator (TENG) techniques provide solutions for converting external ultrasound waves into internal electricity. This study proposes an implantable ultrasound-driven TENG (IU-TENG) using polyether ether ketone (PEEK) for its exceptional stability inside a human body and acoustic impedance compatibility with human tissues. This IU-TENG remarkably surpasses traditional titanium-based encapsulation, resulting in a 99.94% efficiency in ultrasound transmission. In addition, PEEK contains numerous electron-donating functional groups, making it suitable for TENG applications, particularly as a positive triboelectric layer. The device exhibits robust voltage outputs, reaching up to 11.50 and 8.75 V in water and in vivo, respectively, under body-safe ultrasound intensities. Moreover, its ability to sustain a stable electrical output for over 300 min emphasizes the durability and mechanical resilience of PEEK. In vivo mouse models and ex vivo porcine tissue trials demonstrate the effectiveness of the IU-TENG in nerve stimulation, showing its potential in medical treatments, enhancing the functionality and longevity of implantable medical devices.