Government scientists say they have uncovered a way to produce electricity by harnessing the power from simple every day tasks, such as walking or shutting a door.
The scientists use a virus benign to humans to accomplish the ingenuous technology, which relies on the piezoelectric properties of a biological material.
Piezoelectricity works on the premise that electrical charge can accumulate in a solid in response to mechanical stress. To test their approach the researchers — all from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) — created a generator that is charged by tapping a finger on a postage stamp-sized electrode coated with specially engineered viruses. The researchers said that repetitive taps were converted by the viruses into an electric charge sufficient to operate a small liquid-crystal display.
The researchers said the viruses — M13 bacteriophages which only attack bacteria — could also be employed in the building of microelectronic devices since they have the capacity to self-organize, arranging themselves into an orderly film that enabled the generator to work.
The piezoelectric effect was first noticed in 1880 and has been observed since in crystals, ceramics, bone, proteins and DNA. Some modern applications like electric cigarette lighters and scanning probe microscopes take advantage of piezoelectricity, but it has mostly remained a niche technology in large part because many of the materials needed are toxic and difficult to work with.
In order to first establish if the M13 viruses were piezoelectric, the research team applied an electrical field to a film of the viruses. Under microscope they observed the helical proteins that coat the viruses twisting and turning under the effect of the field — a clear sign the viruses would work as a power source.
Next they attached genetically engineered, negatively charged amino acid residues to one end of the helical proteins to increase the positive/negative differential between the two ends of the protein, and therefore increase the electrical charge of the viruses.
To make the virus-based piezoelectric energy generator the lab team set it up so that the genetically engineered viruses organized themselves into a multilayered film that measured about one square centimeter. Pressed between two gold-plated electrodes connected by wires to a liquid-crystal display, when pressure was applied the viruses were able to generate enough power to flash the number “1” on the LCD display. That’s roughly equivalent to about a quarter the voltage of a triple A battery.
This video from the lab outlines the process of converting the force of a finger tap into electricity, and shows the “viral-electric” generators in action, first by pressing only one of the generators, then by pressing two at the same time, which produces more current:
The results of the Berkeley Lab research were published in Nature Nanotechnology.
Seung-Wuk Lee, a faculty scientist in Berkeley Lab’s Physical Biosciences Division and a UC Berkeley associate professor of bioengineering, headed the research team. In a statement, the professor said: “More research is needed, but our work is a promising first step toward the development of personal power generators, actuators for use in nano-devices, and other devices based on viral electronics.”