Solar panels come in all shapes and sizes, whether they are printed, sprayable, flexible, or integrated in the pavement, roof tiles or windows. Generally, however, they are made of inorganic and non-biodegradable materials, just like the batteries they use to store energy. Researchers at the Imperial College London have developed a bio-battery and solar panel, by printing living cyanobacteria and circuitry onto paper, creating living wallpaper.

Cyanobacteria are photosynthetic micro-organisms that have been on Earth for billions of years. They are thought to be the primary reason why the Earth’s atmosphere is oxygen rich.

The team discovered that cyanobacteria can be used as an ink and printed them from an inkjet printer in precise patterns onto electrically conductive nanotubes, also printed by inkjet. The bacteria survive the printing process and are able to perform photosynthesis so that small amounts of electrical energy are generated, which is then harvested.

One of the advantages of using these solar panels to harvest energy from cells like cyanobacteria is that they can produce small amounts electricity in daylight and carry on producing it even in the dark from molecules produced in the light.

A bio-solar panel with the size of an iPad could power a simple digital clock, or a small LED light bulb.

The invention could lead to new types of electrical devices that are made from paper and printed photosynthetic bacteria. These could include disposable power supplies integrated into paper-based sensors.

The team says their approach of using an off-the-shelf inkjet printer to construct BPVs demonstrates a potential method for easily scaling up the technology, which may pave the way for its wider use. The current paper-based solar panel is a palm size. The next step will see the team scale up their proof-of-concept to A4 size to determine the electrical output on a larger scale.

Photos: Imperial College London/Marin Sawa