Solar Innovation: Scientists Have Printed Bio-Solar Cells Onto Paper With An Inkjet Printer
A team of scientists from Imperial College London, University of Cambridge and Central Saint Martins have created a two-in-one solar bio-battery and solar panel by printing circuitry and living cyanobateria onto paper.
Cyanobacteria are micro-organisms that gain their energy from photosynthesis. These micro-organisms have been on Earth for billions of years and produce oxygen via photosynthesis. It is thought that cyanobacteria contributed to the Great Oxygenation Event where the Earth’s atmosphere was converted from an oxygen-deficient atmosphere to the oxygen-rich one we have today.
By harnessing the power of photosynthesis that occurs within these cyanobacteria in bio-solar cells, scientists can generate power. These types of biological solar cells are known as biophotovoltaics. These typically work by placing the cyanobacteria onto an anode in a chamber. Within the chamber, the anode and cathode, the two electrodes, just like those in a battery are separated by a membrane that only allows protons through. The anode side of the chamber is filled with water and the electrodes are connected by an external circuit. There is also a chamber on the cathode side (see figure below). Whilst the cyanobacteria photosynthesize, electrons, protons, and oxygen are produced in the anode chamber. Oxygen produced in the anode chamber is released out and oxygen is pumped into the cathode chamber. The protons pass through the membrane and travel towards the cathode chamber. The electrons cannot pass through this membrane so travel along the external circuit to recombine with the proton and oxygen. As a result, water is made in the cathode chamber. This movement of the electrons is what is most commonly known as a current and this is used to generate electricity.
The researchers demonstrated that these cyanobacteria could be made into an ink and printed from a standard inkjet printer onto pieces of paper. They found that the printing process did not harm the cyanobacteria and they were able to continue photosynthesizing. A bio-solar panel made in this way that is the size of an iPad could power a simple digital clock.
One of the main advantages of these bio-solar cells is that even when there is no light they can continue to produce current. Unfortunately, they are expensive to manufacture, have a low power output and have short lifespans. They can typically last for about 100 hours after printing.
Dr Marin Sawa, a co-author from the Department of Chemical Engineering at Imperial College London, said in a statement: “We think our technology could have a range of applications such as acting as a sensor in the environment. Imagine a paper-based, disposable environmental sensor disguised as wallpaper, which could monitor air quality in the home. When it has done its job it could be removed and left to biodegrade in the garden without any impact on the environment.”
By using an inkjet printer and paper, the team of scientists hopes to reduce the cost of manufacturing bio-solar cells. These bio-solar cells could be used, for instance, in developing countries with low healthcare budgets and limited resources as part of disposable and paper-based blood glucose monitors. They’ll be easy to use, so patients could even use them themselves. Watch this space, you could be seeing these bio-cells in hospitals or in our homes. The work was published in Nature Communications and can be found here.