(Phys.org)—Researchers have used a simple inkjet printer to print a “bio-ink” of cyanobacteria onto a conductive surface, creating a biophotovoltaic cell. Unlike conventional photovoltaic cells that operate only when exposed to light, the cyanobacteria can generate an electric current both in the dark and in response to light. The researchers expect that the cell may serve as an environmentally friendly power supply for low-power devices such as biosensors, and can even be scaled up to print a bioenergy wallpaper.