Today’s batteries are full of limitations that make it a challenge to use them inside the body to power medical devices. They are rigid and are typically made of toxic materials, are difficult to recharge once implanted, and have a lifetime that requires replacement. Researchers at the University of Fribourg, University of Michigan, and University of California San Diego have teamed up to develop an electric eel-inspired power source that would remain inside the body, completely alleviating the need to use batteries.
In an electric eel, special cells called electrocytes are essentially wired in serial to generate hundreds of volts of electrical current. Each electrocyte, absorbing sodium ions and releasing potassium ions, produces very little voltage on its own, but when thousands of them are lined up and triggered at the same time, the effect is shocking.
The research team took this basic design principle and build their own tiny hydrogel cell-like units that produce electric current due to the different in the concentration of salt. One side of each of these units is salt water and on the other is fresh water, the two separated by an ion-selective membrane. Many of these individual current generating units are strung together in a serial-like arrangement using a 3D printer.
To release the current at the same time, an eel uses the brain, but this part is impossible to replicate in a lab. The research team instead made their device foldable, so that when it is folded, connections are established at the same time that release the built-up current.
The result is that up to 110 volts can be generated at the same time, which is quite impressive and should be sufficient to power all kinds of cardiac implants.
There are a bunch of improvements that can be made to the system, including adding additional ways to generate electricity that would increase the storage capacity and potential energy that can be delivered.
Study in Nature: An electric-eel-inspired soft power source from stacked hydrogels…
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