Researchers at the University of Tokyo have developed what they call the first photoconducting nanostructures, nanocables that convert light into electricity.

The cables, 16 nanometers in diameter and several micrometers long, resemble the light-harvesting antennae used by some bacteria and transform light into electricity in a similar way to the semiconductors in solar panels. According to NewScientist.com:

Each time a photon hits the cable from outside it passes through the outer layer and knocks an electron loose from the inner layer. This causes the electron to jump to the outer layer and leave behind a positively charged "hole". These separated charges can then generate a current.

To test the nanocables, the researchers placed one on a silicon surface and applied a voltage across it. When light was shone onto the surface, a current began flowing down the cable between two electrodes. When the light was switched off, the current stopped.

The nanocables could be fitted to nano-sized robots or micro-machines and power their movements, suggests Franz Würthner at the University of Würzburg in Germany. Their similarity in size and function to the antennae used by bacteria for photosynthesis means it might also be possible to connect them to such organisms, creating hybrid devices, he says. (fiber optic cable pictured)