Electric eels inspire new Oxford ‘droplet battery’

Inspired by the way electric eels generate a charge, the design uses an ionic gradient across a chain of tiny hydrogel droplets to produce electricity. According to the Oxford team, the work is a significant step towards realising miniature bio-integrated devices, capable of directly stimulating human cells. The study is published in Nature.  

“The miniaturised soft power source represents a breakthrough in bio-integrated devices,” said lead author Dr Yujia Zhang, from Oxford’s Department of Chemistry.  

“By harnessing ion gradients, we have developed a miniature, biocompatible system for regulating cells and tissues on the microscale, which opens up a wide range of potential applications in biology and medicine.”

The miniature battery was produced by depositing a chain of five nanolitre-sized droplets of a conductive hydrogel. Each droplet has a different composition, resulting in a salt concentration gradient created across the chain. Droplets are separated from their neighbours by lipid bilayers, which provide mechanical support while also preventing ions from flowing between the droplets.