The research team from the University of Cambridge say that the device – about the size of a AA battery – uses the microscopic organism synechocystis, which photosynthesizes sunlight to create an electrical current.
While the current generated is very small, it is still enough to power a microprocessor. The researchers say the system, which has been running continuously for a year, could be used to power small devices in remote locations
“The growing Internet of Things needs an increasing amount of power, and we think this will have to come from systems that can generate energy, rather than simply store it like batteries,” said Professor Christopher Howe, from the university’s Department of Biochemistry, and a joint senior author of the paper. “Our photosynthetic device doesn’t run down the way a battery does because it’s continually using light as the energy source.”
The non-toxic algae requires no feeding, because it creates its own food as it photosynthesises. Even though photosynthesis requires light, the device continues to produce power during periods of darkness, the team said.
The researchers believe this is because the algae processes some of its food when there’s no light, and so continues to generate an electrical current.
To test the system, the researchers hooked up the device to an Arm Cortex M0+ microprocessor, a highly efficient processor which is typically used in IoT devices. It operated in a domestic environment and semi-outdoor conditions under natural light.
“We were impressed by how consistently the system worked over a long period of time — we thought it might stop after a few weeks but it just kept going,” said lead author Paolo Bombelli.
The hope is that systems like this could one day replace expensive lithium-ion batteries or traditional photovoltaic systems which use environmentally hazardous materials, particularly in IoT devices.