Biosensor reacts to light

Scientists at Oxford University and Duke University in the US have used tiny water droplets to build a unique microscopic light sensor.

To do it, the scientists took a protein called bacteriorhodopsin that is normally used by bacteria to produce energy, and incorporated it into a network of water droplets.

The protein reacts to green light by pumping protons across a cell membrane, which creates a positive electrical charge. By piercing the droplets with hair-thin electrodes the current generated can be measured with a sensitive amplifier.

In the future such droplets might possibly be arranged to form ‘pixels’ in an imaging array – acting as an artificial eye.

‘Using protocells, or empty artificial cells that can be filled with different cellular components, to simulate biological systems offers significant advantages to working with live cells, where there is far less control over their contents, size and function,’ said Dr Matthew Holden of Oxford University’s Department of Chemistry who conducted the research with Oxford’s Professor Hagan Bayley and Professor David Needham at Duke University.