Nature gives us a charge from the possible use of electric eel generating systems to power replacement organs:
The prototype, described in Nature on 13 December, runs on a solution of salt and water, but researchers hope that future versions might get their energy from bodily fluids.
“Our artificial electric organ has a lot of characteristics that traditional batteries don’t have,” says Thomas Schroeder, a chemical engineer at the University of Michigan in Ann Arbor, who co-led the research. As well as its desirable physical features, “it isn’t as potentially toxic, and it runs on potentially renewable streams of electrolyte solution”.
To design a biocompatible power source, Schroeder and his colleagues took inspiration from the knifefish, or electric eel (Electrophorus electricus), which defends itself and stuns prey with electrical discharges of up to 600 volts. The eel generates these powerful shocks using specialized cells called electrocytes, in organs that run along most of the length of its body.
Schroeder’s team mimicked the anatomy of electrocytes using four different hydrogels made of polyacrylamide and water, then stacked around 2,500 of these units together. This synthetic system generated a potential difference of 110 volts. But its total power output was between two and three orders of magnitude smaller than that achieved by an electric eel, whose cells are thinner and thus lower-resistance.
In theory, the power generated by the artificial battery could be enough to run existing ultra-low-power devices, including some cardiac pacemakers, says Schroeder. But the team thinks it should be possible to improve the system’s performance dramatically, for example by making the hydrogel membranes thinner to reduce their resistance.