Advanced implantable energy storage for powering medical devices

Implantable electronic medical devices (IEMDs) are revolutionary advancements in healthcare, enabling continuous health monitoring and disease treatments. To support their further development, IESDs that include supercapacitors (SCs) and batteries are now garnering intensive worldwide research efforts. In this review, we discuss and analyze the research advancements and challenges associated with batteries and SCs in the realm of IESDs. First, we summarize the main components of IESDs, including electrodes, electrolytes, and encapsulation materials. Subsequently, we elucidate the main application scenarios of multifunctional energy storage devices, specifically biosafe, stretchable/self-healing, biodegradable, miniaturized, injectable, and edible IESDs. We then summarize research progress to date on the integration of IESDs with energy harvesters and wireless charging. State-of-the-art studies of IESDs categorized by human organ systems are covered in depth, including cardiovascular, nervous, gastrointestinal, musculoskeletal, vision, and systemic recording and stimulation. We close by briefly outlining the challenges and future prospects for IESDs.