Recent Advances in Nanogenerator-Driven Self-Powered Implantable Biomedical Devices

Implantable medical devices (IMDs) have experienced a rapid progress in recent years to the advancement of state-of-the-art medical practices. However, the majority of this equipment requires external power sources like batteries to operate, which may restrict their application for in vivo situations. Furthermore, these external batteries of the IMDs need to be changed at times by surgical processes once expired, causing bodily and psychological annoyance to patients and rising healthcare financial burdens. Currently, harvesting biomechanical energy in vivo is considered as one of the most crucial energy-based technologies to ensure sustainable operg, pacemaker energizing, nerve-cell stimulating, orthodontic treatment and real-time biomedical monitation of implanted medical devices. This review aims to highlight recent improvements in implantable triboelectric nanogenerators (iTENG) and implantable piezoelectric nanogenerators (iPENG) to drive self-powered, wireless healthcare systems. Furthermore, their potential applications in cardiac monitorinoring by scavenging the biomechanical power within the human body, such as heart beating, blood flowing, breathing, muscle stretching and continuous vibration of the lung are summarized and presented. Finally, a few crucial problems which significantly affect the output performance of iTENGs and iPENGs under in vivo environments are addressed.