Algae features heavily in green technologies of the future, in many different ways. It shows promise in producing hydrogen, purifying wastewater, removing carbon dioxide from the atmosphere, forming the basis of biofuels, and generating electricity through photosynthesis.

It's that last point that the Cambridge team has focused on. Algae is an efficient natural solar cell, converting sunlight into chemical energy and water and carbon dioxide into organic molecules. Electrons are produced in the process, and these can be collected and used to power electronic devices.

The new algae energy harvester placed a species of blue-green algae in a small container with some water, with the entire unit being about as big as a AA battery. Electrons are collected by an aluminum electrode and shuttled out to run an Arm Cortex M0+, a low-power microprocessor that's commonly used in Internet of Things (IoT) devices.