Sheets of virus generate electricity when squished

Squishing a stack of virus sheets generates enough electricity to power a small liquid crystal display. With increased power output, these virus films might one day use the beating of your heart to power a pacemaker, the researchers behind them say.
Piezoelectric materials build up charge when pushed or squeezed. These materials may be familiar to you: they generate the spark in a gas lighter, and motors powered by such materials vibrate some cell phones. Piezoelectric materials made of metals or polymers require large inputs of energy to build up a charge. Bone, DNA, and protein fibers are weakly piezoelectric, but it’s hard to efficiently organize these materials on a large scale to yield electricity.
To handle this organizational issue, Seung-Wuk Lee, of the University of California in Berkeley and the Lawrence Berkeley National Laboratory, and his colleagues looked for a biomaterial that had intrinsic order and was easy to make. They settled on the M13 bacteriophage, a rod-shaped virus that only infects bacteria. One bacterium can produce one million copies of the virus within four hours, so starting material isn’t a problem. And the virus neatly arranges itself in stacked rows when spread on a surface.
The researchers first tested the virus to see if it was piezoelectric. Instead of pushing on the virus and measuring a current, they looked for the opposite effect. They electrified a film made with the virus and watched for mechanical motion. The scientists saw the helical proteins covering the virus twist.
To understand why the virus is piezoelectric, we need to look at its structure. About 2700 copies of a helical protein stretch along the length of the virus, tipping out from that central axis about 20°. Each helix has a positively charged end and a negatively charged end. The amount of this charge difference and the distance between the two charged areas sets up an electric dipole, which runs along each helix.