When printed in a precise pattern onto carbon nanotubes on paper, these photosynthetic bacteria can produce electricity from sunlight, which could power biodegradable environmental and medical sensors.
A breakthrough in creating simple paper-based bio-solar panels could lead to a greener way to power air quality sensors and other small devices, as these microbial biophotoltaics (BPV) are completely biodegradable. Although bacterial batteries, such as in the form of a microbial fuel cell, are showing promise, others are working toward biological solar cells, which harvest the electricity produced by cyanobacteria during photosynthesis.
Cyanobacteria, which are thought to have been instrumental in the oxygenation of the Earth due to oxygen production by photosynthesis, are found in almost every habitat, and are nitrogen-fixers (and now ethanol-producers), along with fulfilling vital functions in the ecology of the oceans. They're also responsible for both the production of cyanotoxins that can kill humans and animals, as well as a tasty popcorn topping and potential superfood, so these microorganisms really get around.
A team of researchers has just demonstrated that cyanobacteria can be used to create living, breathing, and electricity-producing devices that run on sunlight, and that these bio-solar panels can be printed using existing technology. The team, which includes researchers from Imperial College London, the University of Cambridge and Central Saint Martins, successfully used an off-the-shelf inkjet printer to print precise patterns of carbon nanotubes, which are electrically-conductive, onto paper, and to then print on top of that with the cyanobacterium Synechocystis as the ink. The resulting bio-solar panel, which is merely a proof-of-concept at this point, was able to 'harvest' the electricity from the bacteria's photosynthesis process over a 100-hour period.
"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." - Dr Marin Sawa, Department of Chemical Engineering at Imperial College London
According to Imperial College, cyanobacteria can not only produce electricity during the day, but can also "carry on producing it even in the dark from molecules produced in the light." This ability is a plus for applications that require only small amounts of electricity, but which needs to be supplied around the clock, and a cyanobacteria bio-solar panel could essentially act as a bio-battery as well. Although previous attempts at microbial biophotoltaics (BPV) have been deemed too expensive to make, the team's choice of using a standard inkjet printer to create their cell is meant to also demonstrate that the concept could be "easily" scaled up using today's technology.
One other potential application for this cyanobacteria bio-solar technology could be monitoring medical patients:
"Paper-based BPVs integrated with printed electronics and biosensor technology could usher in an age of disposable paper-based sensors that monitor health indicators such as blood glucose levels in patients with diabetes. Once a measurement is taken, the device could be easily disposed of with low environmental impact and its ease of use could facilitate its direct employment by the patients. Furthermore, this approach has the potential to be very cost-effective, which could also pave the way for its use in developing countries with limited healthcare budgets and strains on resources." - Dr Andrea Fantuzzi, Department of Life Sciences at Imperial College London
The team's study is published in the journal Nature Communications under the title "Electricity generation from digitally printed cyanobacteria."