The University of Oxford has developed the smallest soft lithium-ion battery ever created, consisting of three tiny droplets made from a silk-based hydrogel. This innovative battery has the capability to deliver defibrillator electric shocks to beating mouse hearts, as well as provide pacemaker-style control. The potential applications of this technology extend to powering biomedical implants and wearable electronics for humans in the future.
Lead researcher Yujia Zhang envisions the battery being used as an implantable microrobotic battery that can be directed to specific locations using a magnetic field, where it can then release energy for medical treatments. The design of the battery involves three interconnected droplets that self-assemble in a liquid solution. One droplet serves as the negative electrode with lithium manganese oxide particles, another as the positive electrode with lithium titanate particles, and a central droplet filled with lithium chloride acts as a separator. Activation of the battery is achieved through UV light, which ruptures the layers between the droplets, allowing lithium ions to flow freely.
Measuring just 600 micrometers in length, the droplet batteries are significantly smaller than previous soft lithium-ion batteries, making them about six times the width of a human hair. They are also 1000 times smaller in volume than similar flexible lithium-ion batteries. Additionally, the incorporation of magnetic nickel particles in the central droplet enables remote control of the batteries via an external magnetic field.
Wei Gao from the California Institute of Technology commends the energy density of these miniature batteries, stating that it surpasses that of other similar-sized batteries. Testing on mouse hearts demonstrated the effectiveness of the droplet batteries as defibrillators and pacemakers, successfully restoring normal heartbeats and regulating heart rhythms. The batteries also exhibited a capacity retention of 77% after 10 charge and discharge cycles.
Gao highlights the simplicity and scalability of the droplet battery manufacturing process as a potential advantage over traditional methods. He envisions these batteries powering minimally invasive biomedical implants and biodegradable medical devices in the future. However, considerations for safety and biocompatibility of the materials used in the battery are crucial, especially as the technology advances towards commercialization or further research applications.
Overall, the soft lithium-ion droplet battery showcases a promising future in the realm of biomedical technology, with its unique hydrogel-based composition mirroring the aqueous environment of human tissue. As researchers continue to explore the capabilities of this innovative energy storage solution, the potential for transformative applications in healthcare and wearable electronics remains high.
