Energy-harvesting techniques may offer opportunities for powering implantable and wearable devices. Citing Walt Whitman’s “I Sing the Body Electric,” Charles Q. Choi in The Washington Post writes, “More than 150 years later, MIT materials scientist and engineer Canan Dagdeviren and colleagues are giving new meaning to Whitman’s poem with a device that can generate electricity from the way it distorts in response to the beating of the heart.”
Choi cites some specs: “The bellows-like motions that a person makes while breathing, for example, can generate 0.83 W of power; the heat from a body, up to 4.8 W; and the motions of the arms, up to 60 W.”
Choi notes that Dagdeviren and colleagues have developed flat piezoelectric devices that can be affixed to organs and muscles and have tested the devices on cows, sheep, and pigs. He quotes her as saying, “When these devices mechanically distort, they create positive and negative charges, voltage and current—and you can collect this energy to recharge batteries. You can use them to run biomedical devices like cardiac pacemakers instead of changing them every six or seven years when their batteries are depleted.”
The piezoelectric devices needn’t be implanted. Choi writes that they can be worn in shoes, trousers, or underwear to power external devices.
Dagdeviren is also experimenting with thermoelectric materials. “In principle, the heat from a human body can generate enough electricity to power wireless health monitors, cochlear implants, and deep-brain stimulators to treat disorders such as Parkinson’s disease,” Choi writes.
The triboelectric effect also shows promise. Choi quotes nanotechnologist Zhong Lin Wang of Georgia Tech as saying, “The more I work with triboelectricity, the more exciting it gets, and the more applications it might have. I can see myself devoting the next 20 years to it.”
Offering yet another possibility are biofuel cells, which can generate electricity through chemical reactions involving blood and sweat. Choi reports that scientists in France have created a biofuel cell based on enzyme-coated carbon nanotubes. The biofuel cells, he adds, could be woven into garments or even inserted into the body, where they would dissolve after their useful life.
Choi quotes Dagdeviren as saying, “Imagine having a device inserted into your body, and after it works for a while, it dissolves away down to the molecular level in your bodily fluids. And you don’t have to open your chest to take it out.”
