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Bio Inspired Materials: The Electric Eel

Posted on January 11th, 2018 by in New Materials & Applications

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When it comes to designing new materials, it’s often worth turning to nature for inspiration. After millions of years of evolution there’s a vast array of complex materials all around us.

A team made up of members from the University of California San Diego, the University of Michigan and the University of Fribourg have done just that.

They set out to reverse-engineer the process eels use to generate electricity inside their body.

Their aim is to develop an electrical power source that is biocompatible and mechanically flexible, which is also able to harness the chemical energy available inside the body (or other biological system). A device like this could be used to power medical sensors, or additional health support systems inside the body, without the need to connect to any external power source.

Electrophorus Electricus (aka The Electric Eel)

The electric eel, which was the inspiration for this research, has an organ which acts as an electrical power source inside its body. This organ can generate potential differences of 600 volts and currents of 1 amp.

To generate this voltage, eels essentially have a bank of cells which they are able to polarize and depolarize. They are able to positively charge the sodium and potassium in their bodies, which once charged, move towards the eel’s head.

This process, known as transmembrane transport, sets up a potential difference of around 150 millivolts across each cell in the chain. These small voltages add up to give a significant difference between the head and tail of the eel, which it can use to shock its prey.

The Man Made Eel

The team has produced a series of hydrogels – made up of water-based polymer blends – in their man-made version of the electric eel. These hydrogels have been designed to mimic the behaviour of an eel’s cells, copying the transmembrane transport process, which is outlined in a recently published paper.

Instead of potassium, the team used NaCl to enable a charge to move through the structure. After dissolving the salt in a hydrogel, the team then printed a pattern onto a sheet (alternating between the hydrogel containing salt and a “freshwater” hydrogel).

When this sheet comes in contact with a second sheet, which has been designed to control the flow of charged particles, the resulting structure is a flexible array of very small cells with a small potential difference across each of them, just like in the electric eel. When these cells are put together end-to-end, a difference of more than 100V can be achieved.

What’s Next?

High on the priority list for the team is to develop a way to recharge the artificial organ. At the moment, an external power source is required to force all of the charged particles back to their starting positions, after the particles have been charged.

The hope is that this sort of device will be able to harness chemical energy available inside the body to reset itself. It’s possible that this could be done by capitalizing on natural occurring charge separations inside the body (like the stomach, for example, which is often relatively positively charged compared to  the surrounding tissue), but that is an idea which will take further research to determine its viability.

At the moment, the device would only be able to drive small, low-powered devices (like a pacemaker). But while this technology is still in its early days, it could one day power other implanted devices.

Access to a reliable, internal power source could open up all sorts of possibilities for sensors and other systems to operate from inside the body.


All opinions shared in this post are the author’s own.

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