Watch a cigarette lighter spark into flame. You are witnessing the piezoelectric effect, the ability of certain materials to produce electricity when squeezed, rubbed, bashed together or, in scientific terms, under mechanical stress.
Harvesting energy from natural processes, such as heat and vibration, is not new (think windmills). But ever since 1880, when French physicist brothers Pierre and Jacques Curie discovered the piezoelectric effect, others found a variety of materials that could generate small amounts of electricity when stressed. It’s a strange mix, including silk, wood, certain crystals (even common sugar) bone and DNA, the building block of life.
It was DNA that encouraged scientists at the Lawrence Berkeley National Laboratory in California to create a tiny generator—a sandwich of specially engineered viruses and gold plates—that produces enough current to light up a small liquid crystal display (LCD). Announced this week, the virus-powered device is a significant first step in generating electricity for critical healthcare needs using living matter.
Seung-Wuk Lee, the lead researcher and associate professor of bioengineering at the University of California, Berkeley—where this week I finished a five-month stint as visiting lecturer—calls this new paradigm “virotronics”, designing new materials and devices using genetically engineered viruses. “Through virotronics, I envision solving some of the most challenging science and engineering problems,” Lee told me.
Little more than bits of DNA, viruses are nature’s smallest living creatures. They are very efficient at what they do, which is invading living cells and cloning themselves. Now, what if viruses could be used as a nano-material, built from invisibility—they are too small to be seen in a common, optical microscope—by using their ability to self-replicate, self-assemble and self-evolve?
That is what Lee and his colleagues did, using a benign virus called M13, known for several decades to science. Using a DNA-based language, they programmed M13 to speed up its natural evolution, as it self-replicated itself within a bacteria. Within hours, a single virus cloned itself millions of time. “Basically we want to build a nanobot (nano-robot) through our virotronic approach, like (the) cloned soldiers of Star Wars 2,” said Lee, referring to the movie Star Wars 2: Attack of the Clones.
This act of high-speed cloning generates energy. The details are more complicated. To determine if M13 was piezoelectric, Lee turned to Berkeley colleague Ramamoorthy Ramesh, a Berkeley professor (who with 14,000 citations is one of the most cited scientists in physics).
Patches of DNA were added to the virus to boost its voltage. The scientists created a stack of 20 films, each crawling with the replicated virus, then sandwiched it between two gold-plated electrodes (or conduits for electricity), from which wires snaked out to LCD. The little generator measures only 1 sq. cm.
For now, the virus-and-gold sandwich generates one-fourth of the voltage of a triple-A battery. “We believe that we can achieve power enhancement 10-100 times (greater) and generate the personal power generator in (the) near future,” said Lee, who envisages pacemakers, hearing aids and other personal health sensors without batteries.
It is the inability of batteries to keep up with the relentless advances in electronics that has, in great measure, encouraged scientists such as Lee to probe new sources of piezoelectricity.
Though piezoelectricity was discovered in the 19th century, and the first practical application was sonar (developed during World War I), scientists seriously started research into harvesting it for the new age of electronics more than a century later, in the 1990s. Specialized piezoelectric devices are used in industrial applications, including the automotive industry, which applies it to car ignitions.
It remains a frontier, emerging technology. The US army has explored generating electricity from combat boots. A company called Bionic Power generates electricity from a generator attached to the legs (at two pounds per leg, it’s just too heavy). Another device—sold-out when it hit the market last year—called the nPower PEG, generates enough electricity to power a phone for a minute, from 15 minutes of walking. A major problem with some of these personal piezoelectric devices is the discomfort they cause from additional weight, so, as energy needs become more specialized, devices must become lighter and smaller.
Zhong Lin Wang, a professor at the Georgia Institute of Technology, is about two years away from a power suit made of a fabric that generates a charge through wrinkles in clothing. Nano wires, one-thousandth the width of a human hair, are embedded in the fabric, which, as it moves, creates energy that can be harvested.
Work continues apace on the great piezoelectric frontier: generating electricity from personal biological processes. Last year, two scientists at the University of Wisconsin—Madison demonstrated a material that could capture energy from the simple act of breathing. Even the flow of blood could produce enough electricity to power the minuscule devices aimed at enhancing your life.
I always think: “How do they ever get these ideas?” I put the question to Lee. He replied: “As Steve Jobs said, ‘Think different’.”
Samar Halarnkar is consulting editor, the Hindustan Times and Mint. He is currently a visiting lecturer at the University of California-Berkeley. This is a fortnightly column that explores the cutting edge of science and technology.
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