Viruses seem like an improbable way to generate electricity. But scientists at UC Berkeley have built what is possibly the smallest biological power plant by harnessing viruses to turn motion into electrical current.
It’s not much—400 millivolts, equivalent to one-fourth of a AAA battery—but enough to turn on a tiny LCD screen and open up possibilities for a future powered by trillions of tiny viruses, harmless to humans, that convert every vibration into a very little spark. It’s a remarkable achievement for scientists developing piezoelectric (that’s electricity created by pressure) materials.
That certain substances can turn mechanical energy into electricity has been known for more than a century. Ceramics and crystals, most commonly, may accumulate a charge when physically stressed. This means the materials release energy when changing shape, or may move in response to an electrical charge. You’ve heard of a few applications. Loudspeakers, guitar tuners, and electric cigarette lighters all work on piezoelectric principles.
But the problem has been that most piezoelectric materials are expensive, toxic, or difficult to manage (let alone pronounce), curtailing the more promising applications. While tiny road vibrations or faint breezes may one day power, say, billions of tiny air-quality sensors, that moment has remained on the horizon for decades. If self-powered electrical devices can be manufactured cheaply and efficiently, that could change.
Seung-Wuk Lee, Ramamoorthy Ramesh, and Byung Yang Lee, researchers at Berkeley’s biosciences and engineering divisions, reasoned that viruses—if they were piezoelectric—might prove to be a remarkably cheap and efficient way to power tiny devices. Viruses are densely packed coils of proteins and RNA well known for infecting humans, but they share properties with other excellent piezoelectric materials. They also do things that no other materials do, including replicating by the billion in a matter of hours, for free.
In a study published this month in the journal Nature Nanotechnology, the researchers showed they could coax a harmless bacteria-hunting virus known as a bacteriophage to assemble in neatly ordered layers, genetically inserting a few amino-acids to strengthen the viruses’ piezoelectric properties, and produce a charge. The viral films were stacked 20 deep then sandwiched between two gold-plated electrodes the size of postage stamps. Like jumper cables on a car battery, the electrodes were hooked up to a liquid-crystal display that, when pressed, squeezed out enough current to flash the number "1" on an LCD screen.
"We’re now working on ways to improve on this proof-of-principle demonstration," says Lee in a statement. "Because the tools of biotechnology enable large-scale production of genetically modified viruses, piezoelectric materials based on viruses could offer a simple route to novel microelectronics in the future."
Bioenergy may be the future in ways we never expected.