Batteries for miniature bio-integrated devices and robotics are a critical area of research and development due to the unique requirements of these systems. These devices, which could include biomedical implants, wearable sensors, or small-scale robots designed to interact with biological systems, require batteries that are compact, lightweight, flexible, and capable of providing long-lasting power in often constrained environments. The ideal batteries for these applications should also be biocompatible or safe for integration into the human body, in cases of biomedical applications.
Researchers created a small soft lithium-ion battery that might be used as a defibrillator to regulate cardiac rhythm during surgery. The flexible lithium-ion battery is made by assembling biocompatible hydrogel droplets. The cutting-edge technology boasts the tiniest soft lithium-ion battery with the maximum energy density. The study paves the door for the development of tiny bio-integrated devices with a variety of applications in robotics, biology and medicine.
Researchers at the University of Oxford have taken a big step in developing microscopic, soft batteries for use in a wide range of biomedical applications, including defibrillation and heart tissue pacing. The work was published in the journal Nature Chemical Engineering.
We used the droplet battery to power the movement of charged molecules between synthetic cells and to control the beating and defibrillation of mouse hearts. By including magnetic particles to control movement, the battery can also function as a mobile energy carrier.
Dr Yujia Zhang
The development of tiny smart devices, smaller than a few cubic millimeters, demands equally small power sources. For minimally invasive biomedical devices that interact with biological tissues, these power sources must be fabricated from soft materials. Ideally, these should also have features such as high capacity, biocompatibility and biodegradability, triggerable activation, and the ability to be controlled remotely. To date, there has been no battery that can fulfil these requirements all at once.
To address these requirements, researchers fromthe University of Oxford’s Department of Chemistry and Department of Pharmacology have developed a miniature, soft lithium-ion battery constructed from biocompatible hydrogel droplets. Surfactant-supported assembly (assembly aided by soap-like molecules), a technique reported by the same group last year in the journal Nature, is used to connect three microscale droplets of 10 nanolitres volume. Different lithium-ion particles contained in each of the two ends then generate the output energy.
‘Our droplet battery is light-activated, rechargeable, and biodegradable after use. To date, it is the smallest hydrogel lithium-ion battery and has a superior energy density’ said Dr Yujia Zhang (Department of Chemistry, University of Oxford), the lead researcher for the study and a starting Assistant Professor at the École Polytechnique Fédérale de Lausanne. ‘We used the droplet battery to power the movement of charged molecules between synthetic cells and to control the beating and defibrillation of mouse hearts. By including magnetic particles to control movement, the battery can also function as a mobile energy carrier.’
Proof-of-concept heart therapies were conducted in the laboratory of Professor Ming Lei (Department of Pharmacology), a senior electrophysiologist specializing in cardiac arrhythmias. He stated, ‘Cardiac arrhythmia is the biggest cause of death worldwide. Our proof-of-concept use in animal models offers a promising new option for arrhythmia control with wireless and biodegradable devices.
Professor Hagan Bayley (Department of Chemistry), the study’s research group leader, stated that: “The tiny soft lithium-ion battery is the most sophisticated in a series of microscale power packs developed by Dr Zhang and points to a fantastic future for biocompatible electronic devices that can operate under physiological conditions.”
