Choosing energy sources for battery-free pacemakers

Battery-free cardiac pacemakers can overcome the limitations of traditional battery-dependent devices. This perspective discusses recent progress in developing energy-harvesting solutions for pacemakers, focusing on triboelectric, piezoelectric, thermoelectric, photovoltaic, biofuel cell, and wireless energy transfer mechanisms that harness biomechanical energy, body heat, ambient light, ultrasound, biochemical energy, and electromagnetic fields. These technologies eliminate the need for battery replacements, reducing surgical risks and enhancing patient comfort and quality of life. We also discuss future directions and challenges of these systems, such as energy conversion efficiency, biocompatibility, long-term reliability, safety and clinical concerns, and opportunities for additional functionalities, such as real-time feedback and control. Battery-free pacemaker technology can eliminate the need for battery replacement surgeries of traditional pacemakers. Various energy harvesting and transmitting technologies can help realize this, such as utilizing energy from body movement, body heat, chemical energy in body fluids, and externally applied electromagnetic fields and ultrasound waves. However, these devices are not yet competitive with the mature technology of battery-operated pacemakers. Existing challenges include energy efficiency, biocompatibility, durability, and stability. Some of these technologies also provide opportunities for integrating additional functionalities, such as the real-time monitoring of biological signals. The development of battery-free pacemaker technology has potential to change implantable devices in general. Depending on the specific requirement and local operating environment of the implanted device, similar technologies can be developed based on the lessons learned here. Zheng et al. explore a wide range of energy-harvesting strategies for powering battery-free cardiac pacemakers, which include the use of piezoelectric, triboelectric, thermoelectric, photovoltaic, biofuel cell, and wireless energy transfer mechanisms. For each of these approaches, challenges in energy conversion efficiency, biocompatibility, and long-term reliability are discussed.