Virus power

Rather than just being something that can infect you, your dog or your computer and make you all sick, a new breed of viruses is able to generate harnessable electricity.

A virus called M13 is being hailed as a bug that will change the world because it can generate electricity. It is also claimed to be quite safe and pose no threat to humans but its future influence could be enormous.

However, M13 goes one step further because it can organise itself into tiny invisible sheets of film that can be pasted on to the casings of devices, such as portable computers, which can then be powered by the microbes. Every time the keyboard is pressed the viruses convert the finger presses into electricity that then charges the battery.

Researchers at the Lawrence Berkeley National Laboratory in the US have genetically engineered the viruses that have generated enough electricity to power a small LCD screen. The secret of the virus, that is technically a bacteriophage and 880 nm long by 6.6 nm wide, relies on the piezoelectric effect which, of course, is the creation of electricity by certain crystals when they are twisted or squeezed. The effect is a well-established phenomenon of crystals being widely used in oscillators and of course the ignition source for cigarette lighters.

It is a versatile system as any kind of motion can set the viruses going so that a phone battery coated with the film could be kept constantly fully charged just by its movement in a pocket.

Although M13 is a natural power source, researchers have enhanced its output by genetically engineering the virus, adding some negatively charged amino acids to one end of its tough outer shell. This modified version is a better voltage generator because it has a separate negative and positive end.

The film that has been created measures about a square centimetre. This was then sandwiched between two gold-plated electrodes connected by wires to an LCD. Stacks of 20 layers of the virus were needed to generate the current for the display.

When pressure was applied, the generator produced up to 6 nA at 400 mV, enough to flash the number ‘l’ on the display. This was about a quarter of the voltage of a normal AAA battery.

On a wider front, it is possible that these modified batteries could be used to control some aspects of pollution. One scenario envisages specially designed microbes living within the emission-control systems of a coal-fired power station, consuming its pollution of carbon dioxide.

Other microbes could be used to reduce water pollution or minimise the effects of toxic nuclear waste.

“Much more research is needed but our work is a promising first step towards the development of personal power generators, actuators for use in nano devices and other devices based on viral electronics,” said Dr Seung-Wuk Lee at Berkeley.

The newly constructed microbe is a replica of the phiX virus that occurs naturally and infects bacteria, never humans.

It is only the second time that a virus has been constructed from scratch in the lab but the new effort is said to produce substantially quicker results.