Edible Batteries Made From Cuttlefish Ink Could Solve Power Problem For Medical Devices
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A new suite of medical devices coming onto the market can be swallowed and used to release drugs over time or monitor the progression of diseases. But these devices require batteries to keep them going, and conventional power sources often contain toxic chemicals. Now scientists in Pittsburgh say they have a solution: cuttlefish.
It has long been known that pigment, like the melanin that colors your skin, can be used as an anode in a battery. (The anode is the negatively charged half of the battery — the thing that releases the electrons.) Researchers at Carnegie Mellon University have now identified the pigment in cuttlefish ink as having "the right chemistry and nanostructure to power tiny electronic devices," the institution said. Common anode materials include lithium, carbon, or tin.
"Instead of lithium and toxic electrolytes that work really well but aren't biocompatible, we chose simple materials of biological origin," Chris Bettinger, a biomedical engineer at the university, told MIT Technology Review. He said the kinds of devices that people would ingest aren't like pacemakers that have to hold out for a decade or more. They're just small, simple units that only last for a day or so. "The performance of melanin anodes is comparable to many commonly available synthetic organic electrode materials," the researchers wrote in their paper, published last month in Proceedings of the National Academy of Sciences of the United States of America.
Edible "smart drugs" are a growing branch of medical research and hold incredible promise for people with chronic illness. According to MIT Technology Review, pills containing sensors and circuits could help doctors learn about conditions inside patients' bodies or tell athletes information about their internal fluids. Those kinds of pills could also contain drugs or supplements that would only be released after passing through the highly acidic stomach and into the more hospitable intenstines.
"Using natural materials in energy storage devices increases the likelihood for use in powering devices that operate in sensitive environments such as the human body," Bettinger says. "We found that the melanin pigments in cuttlefish ink make it a perfect fit for use in battery electrodes that would ultimately be used in devices that operate in close proximity to sensitive living tissue."
The cuttlefish is a squid-like animal that lives in waters off Asia, Europe, and Africa, and its ink and flesh are used in the cuisine of those places. This, however, appears to be the first time anybody has harvested the natural energy of its ink for power. But it's not the first material to be tested as a medicinal power source. According to John Rogers, a materials scientist unaffiliated with the research, scientists have explored a range of other sources, including degradable solar cells. "This new system appears to offer a scalable route to high power output," he told the Materials Research Society. "Successful integration of these batteries with electronics and sensors and wireless communication components, all of which now appear possible due to rapid advances in chemistries and materials, can enable devices that go into the body and then naturally disappear."
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