Fully Bioabsorbable Capacitor as an Energy Storage Unit for Implantable Medical Electronics

: Implantable medical electronic devices are usually powered by batteries or capacitors, which have to be removed from the body after completing their function due to their non-biodegradable property. Here, a fully bioabsorbable capacitor (BC) is developed for life-time implantation. The BC has a symmetrical layer-by-layer structure, including polylactic acid (PLA) supporting substrate, PLA nanopillar arrays, self-assembled zinc oxide nanoporous layer, and polyvinyl alcohol/phosphate buffer solution (PVA/PBS) hydrogel. The as-fabricated BC can not only work normally in air but also in a liquid environment, including PBS and the animal body. Long-term normal work time is achieved to 30 days in PBS and 50 days in Sprague-Dawley (SD) rats. The work time of BC in the liquid environment is tunable from days to weeks by adopting different encapsulations along BC edges. Capacitance retention of 70% is achieved after 3000 cycles. Three BCs in series can light up 15 green light-emitting diodes (LEDs) in vivo. Additionally, after completing its mission, the BC can be fully degraded in vivo and reabsorbed by a SD rat. Considering its performance, the developed BC has a great potential as a fully bioabsorbable power source for transient electronics and implantable medical devices.