Implantable and bio-compatible Na-O2 battery. Credit: Chem/Lv et al.
Key points:
- Researchers developed a new implantable battery that uses oxygen in the body to deliver stable power.
- The team implanted the battery under the skin on the backs of rats and found that it produced stable voltages without triggering inflammatory reactions, metabolic issues or poor healing.
- Researchers hope to optimize and scale up their battery design for uses ranging from energy production to biotherapies.
Implantable medical devices need batteries to function, but these batteries eventually run low and require invasive surgeries to replace. Now, researchers have developed an implantable battery that can run on oxygen. The study, published in Chem, details how their design delivered stable power while being biologically compatible.
Researchers made the battery’s electrodes from a sodium-based alloy and a nanoporous gold. These electrodes undergo chemical reactions with oxygen in the body to produce electricity. The team then encased the battery and its electrodes within a protective porous polymer film.
After developing the battery, researchers implanted it under the skin on the backs of rats and measured is electricity output. They found that the battery produced stable voltages between 1.3V and 1.4V and a maximum power density of 2.6mW/cm3 two weeks after implantation. This output is not sufficient to power medical devices, but the design shows promise for harnessing oxygen in the body to produce energy.
The team also examined biological compatibility by assessing inflammatory reactions, metabolic changes, and tissue regeneration around the battery. They found that rats had no apparent inflammation and any byproducts of the battery – sodium ions, hydroxide ions, hydrogen peroxide – were easily metabolized. The rats healed well after implantation with the hair on their back regrowing at four weeks and their blood vessels regenerating.
In the near future, the team plans to increase the battery’s energy delivery by testing more efficient electrodes and optimizing the battery structure and design. They hope to both scale up production of their design and identify purposes beyond powering medical devices.
“Because tumor cells are sensitive to oxygen levels, implanting this oxygen-consuming battery around it may starve cancers,” explained study author Xizheng Liu of Tianjin University of Technology, “It’s also possible to convert the battery energy to heat cancer cells. From a new energy source to biotherapies, the prospects for this battery are exciting.”