Are biological materials poor conductors?

A world without electricity is becoming harder and harder to even imagine. No laptops, espresso machines or smartphones. To transport that electricity, we need conductors. And to create them, you need a lot of energy and rare metals. The result is lots and lots of waste. The impact on our planet is huge. Until recently, scientists assumed that biological – and therefore biodegradable – materials are poor conductors of electricity. But after a discovery on the ocean floor, Filip Meysman's research team (dept. of Biology) achieved a real breakthrough.

 

What are 'good conductors'?

 

The measure of a "good" conductor is a measurement of the electrical resistance of the material. Well-conducting materials, such as metals, have low resistance. In general, biological materials do not score well; they have too high a resistance.

 

Ultra-thin cables 

 

A few years ago, scientists discovered so-called cable bacteria in the ocean floor. These bacteria form strings of up to 10,000 cells, several centimetres long, but a hundred times thinner than a human hair. 

 

In the same places where those cable bacteria were found, electric currents ran through the seabed. Researchers therefore began to suspect that cable bacteria were able to conduct electric currents, just like copper wire. But proving that was rather difficult, because cable bacteria die as soon as they are exposed to air. 

 

An incredible discovery

 

Enter Filip Meysman's research team, whose research at the University of Antwerp led to a breakthrough. They developed a tiny voltage meter and attached it to a long cable bacterium, which allowed them to measure electric current over a distance of just over one centimetre. This was the first proof that cable bacteria can conduct electricity. 

 

But the actual results of the measurement were truly astonishing. The cable bacteria were found to contain protein filaments that are extremely conductive – even more so than the materials currently used to make computer chips! 'This is very impressive, because biological materials are usually very poor conductors,' says Meysman.

 

'Until recently, the longest recorded distance of biological electron transport was about 1 micrometre (one ten-thousandth of a centimetre),' explains Meysman. 'But as it turns out, cable bacteria can transport an electrical charge efficiently over a distance of several centimetres.' The resistance of the fibers in these cable bacteria is about a million times lower than that of the best conducting biomaterial known to date.

 

Cable bacteria in your phone ... and in your body?

 

So cable bacteria in the seabed have developed a special and unique fibre material that allows them to send electrical signals very efficiently. Meanwhile, the team is investigating the structure of the molecules that enable this 'superconductivity'. This is crucial if we want to use those super fibres in new materials and technologies.

 

Revolutionary

 

Take smartphones, for instance. 'Today, it takes a lot of energy and rare metals to manufacture smartphones. And often, those phones end up in landfills after just a few years. That's a double blow to the environment,' Meysman says. 'But suppose we could use the super fibres from cable bacteria as conductors in our smartphones ... Those fibres are biodegradable, and you don't need fossil fuels to produce them.'

 

In other words, this discovery could be a huge revolution in the fight for a livable planet. For now, this is still a long way off, but Meysman's research team is working hard on the next big breakthrough.​