From pacemakers to neurostimulators, implantable medical devices rely on batteries to, for example, keep the heart beating or continue the selected therapy. But the batteries eventually run out and require invasive surgeries to replace. To address these challenges, researchers in China came up with an implantable battery that runs on oxygen in the body. The study, published in Cell, shows in rats that The design can give stable energy and is compatible with the biological system.
“If you think about it, oxygen is essential for life,” explains study leader Xizheng Liu, from Tianjin University of Technology. “If we can take advantage of the continuous supply of oxygen in the body, Battery life will not be limited by materials of conventional batteries.
To build a safe and efficient device, Liu's team made the electrodes from a nanoporous sodium-gold-based alloy, a material with pores thousands of times smaller than the width of a hair. Gold is known for its compatibility with living systems and sodium is an essential and ubiquitous element in the human body. The electrodes generate chemical reactions with the body's oxygen to produce electricity. To protect the battery, the researchers encased it within a porous polymer film that is soft and flexible.
They then implanted the battery under the skin of rats' backs and measured its electricity production. Two weeks later, they discovered that the battery could produce stable voltages between 1.3 V and 1.4 V. Although the power is insufficient to power medical devices, the design shows that it is possible to use the body's oxygen to obtain energy.
Liu's team also evaluated inflammatory reactions, metabolic changes, and tissue regeneration around the battery. The rats showed no apparent inflammation. The byproducts of the battery chemical reactions, including sodium ions, hydroxide ions, and low levels of hydrogen peroxide, were easily metabolized by the body and did not affect the kidneys or liver. The rats They healed well after implantation and the hair on his back completely grew back after four weeks. To the researchers' surprise, blood vessels also regenerated around the battery.
“We were surprised by the electricity production immediately after implementation – adds Liu -. It turned out that we had to give the wound time to heal, for the blood vessels to regenerate around the battery and supply oxygen, before the battery could provide stable electricity. “This is a surprising and interesting finding because it means that the battery may help control wound healing.”
Next, the team plans increase battery power supply, exploring more efficient materials for the electrodes and optimizing its structure and design. In fact, the uses could extend beyond powering medical devices.
“Because tumor cells are sensitive to oxygen levels, implanting this oxygen-consuming battery around them can help starve cancers – concludes Liu -. It is also possible Convert battery power into heat to kill cancer cells. “From a new energy source to potential biotherapies, the prospects for this battery are exciting.”