The world’s smallest lithium bio-battery for medical use

A research team at Oxford University, UK, developed a soft, compact lithium-ion battery for the biomedical field such as powering tiny robots, defibrillators, pacemakers, Interesting Engineering reported on October 25. “To date, this is the smallest lithium-ion hydrogel battery and has outstanding energy density,” said Dr. Yujia Zhang at the University of Oxford’s Department of Chemistry, lead author of the new study.

Developing tiny smart devices, often smaller than a few millimeters, requires a correspondingly small energy source. For biomedical devices that interact directly with biological tissue, the power supply battery must be made from soft materials to ensure safety and minimal invasiveness. Ideally, batteries should have high capacity, biocompatibility, biodegradation, and activation. They also need remote control capabilities to enhance functionality and adaptability in complex environments. However, combining all these features into one battery is difficult.

To solve the problem, a team of scientists from Oxford University developed a small, flexible lithium-ion battery using biocompatible hydrogel droplets. Using a “surfactant-assisted assembly” process, the new battery combines three microdroplets, each with a volume of 10 nanoliters, with the help of soap-like molecules. Two of the drops contain lithium-ion particles with the ability to interact to generate energy.

The new battery is light-activated, rechargeable and biodegradable. In the study, the battery powered electrically charged molecules moving between synthetic cells, as well as controlling the heartbeat and defibrillating the heart of mice. By integrating magnetic particles, it can serve as a portable power source.

According to the team, animal heart treatment trials show the potential of the new battery as a promising biodegradable and wireless solution. This innovative design helps solve key challenges in powering biomedical devices, providing a biocompatible, safe and effective solution. The group has now applied for a patent.