Emerging Triboelectric Nanogenerators for In-Body Implantation

Emerging implantable medical devices (IMDs) collect critical health data for individualized treatment strategies, providing noninvasive, real-time monitoring to efficiently manage diseases. However, their reliance on conventional batteries introduces surgical risks and operational limitations, necessitating the exploration of alternative energy solutions, such as triboelectric nanogenerators (TENGs). As these implantable TENGs develop, they are increasingly used to power medical devices and function as IMDs themselves. Despite improved design flexibility and compatibility with various functional materials, TENGs still face challenges in maintaining stable operation within the fluid environment in-body. This review provides an in-depth look at functional implantable TENGs in biomedical settings, highlighting the basic mechanism of TENGs and covering their electricity generation process, commonly used material combinations, and design methods. The review classifies implantable TENGs into four types: stretchable, bioadhesive, on-demand biodegradable, and stimuli-responsive, to address challenges after implantation. Additionally, this article discusses current developments and future possibilities, aiming to showcase new research avenues and opportunities by evaluating both existing applications and potential innovations.