A View from Nidhi Subbaraman
A Watch That Runs On Two Live Lobsters
What two crustaceans and a timepiece have to do with the future of medical electronics.
In Evgeny Katz’s vision of the future, medical implants will use the human body as a battery. They’ll just run on the same juice that powers us human beings. His lab at Clarkson University has been building a biofuel cell—an energy harvester–that has successfully drawn electrical energy from glucose coursing the blood streams of snails, clams, and now, lobsters.
Human medical implants powered by what we eat are a long way away, but in a new paper, Katz and his team demonstrate how their technology is maturing towards such a reality. That’s where the lobsters come in. Researchers from Clarkson University and the University of Vermont College of Medicine explain how they’ve powered a watch using glucose from two lobsters, connected as batteries would be, in series. They also show that it’s possible to keep a pacemaker ticking with glucose levels usually seen in the human body.
The key to this setup is an enzyme stationed at implanted electrodes made of carbon nanotubes. Together, the two efficiently convert chemical energy from glucose in an animal’s circulatory system to electricity.
In the past, these energy-harvesting biofuel cells have been tested in the ear of rabbits, in the abdomen of insects, in the body cavity of snails and clams. But the lobsters are different. It’s the first time living organisms have powered up a piece of electronics.
With electrodes in their abdomen, the two lobsters powered the watch for an hour, until the lobsters’ glucose levels near the electrode dropped. (They don’t feel any pain, a member of the team has explained, because they don’t have nerve endings where the electrodes were implanted.) The voltage picked up though, and the crustaceans powered the watch for as long as they remained alive in the lab.
People with pacemakers are ideal bio-battery candidates. As an early test of the idea, the team hooked up a pacemaker to an artificial setup resembling the human circulatory system. It contained serum spiked with glucose at different levels–to represent glucose levels in the blood immediately after you hit the gym, or while sitting at your desk at work, or if you’re diabetic. (Serum is blood with the proteins and cells filtered out.)
With its battery removed, the pacemaker became the first of its kind to run solely on glucose derived from body fluid for five hours. It won’t be the last though, Katz and co. have a list of other medical devices waiting their turn.