Self-Powered Medical Implants Using Triboelectric Technology

ConspectusElectronic medicines represent a class of biomedical technology that exploits electrical impulses to achieve diagnostic and therapeutic purposes. They allow patients to identify their physiological conditions themselves through effortless diagnosis methods, no longer confining treatment solely to medical examinations by physicians. Their clinical practices also operate as an alternative therapeutic approach to pharmacological interventions, wherein the electrical impulses are directly administered to biological tissues with minimal adverse effects. However, unlike wearable electronic medicines that offer the convenient replacement of their energy storages, medical implants require surgical removal for recharging energy storages, thereby imposing substantial physical and psychological burdens on patients. To address these challenges, many efforts are widely conducted to develop self-powered medical implants by utilizing energy harvesting technologies to extend the lifetime of energy storages.Compared to their applications in wearable devices, energy harvesting technologies for powering implantable electronics encounter technical constraints, because the human body exhibits the limited depth penetration of light sources and hemostasis reactions on body temperature. Triboelectric energy harvesting technologies have been highlighted as a promising energy solution of medical implants, exploiting diverse mechanical energy sources to generate electrical energy in vivo. Benefitting from the simple device structure favorable for device miniaturization, triboelectric nanogenerators (TENGs) are extensively explored. Herein, we introduce self-powered medical implants driven by the triboelectric mechanism, providing an exposition on their recent research trends. First, we describe the varying device structures and energy generation performances of TENGs, upon their mechanical energy sources with various frequency ranges. Most devices powered by high-frequency energy sources exhibit superior electrical output performances compared to those powered by low-frequency energy sources. However, the current status indicates that these energy solutions still fall short of meeting the energy consumption demands for their instantaneous application in commercialized electronic medicines. As potential solutions to meet the energy consumption demand, we describe material design strategies to aim for high output performance of triboelectric nanogenerators. Beyond their conventional role as mere power supplies for commercialized medical implants, battery-less electronic medicines based on TENGs hold the great potential for diverse clinical applications. This Account also presents our previous studies of self-powered electronic medicines to carry out clinical practices such as wound healing, tissue engineering, neurostimulation, neuroregeneration, and antibacterial activity. Lastly, we illustrate advanced technologies in materials and devices design with their applicability based on the implantation sites and clinical timeline of self-powered electronic medicines. We anticipate that this Account, by sharing our insights, will contribute to the future generation of outstanding achievements for potential readers engaged in the fields of bioelectronics, self-powered systems, and biomedical engineering.