MIT Makes a Battery That's Safe to Swallow

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CC BY-NC-ND 3.0. Diemut Strebe

Medical technology in many ways has moved away from what can be done from the outside to focusing on what can be done from the inside. Medical implants and tiny sensors and electronics that can be used to deliver precise treatment within the body are being developed around the world.

Researchers at MIT and Brigham and Women’s Hospital have recently invented a breakthrough device that could make that super-targeted treatment much safer. It's an ingestible battery. Yes, it can be swallowed, unlike the button cell batteries of death all around your house. And more than that, it is actually powered by the acids in the stomach, allowing it to reside safely in your gastrointestinal tract for several days.

“A big challenge in implantable medical devices involves managing energy generation, conversion, storage, and utilization. This work allows us to envision new medical devices where the body itself contributes to energy generation enabling a fully self-sustaining system,” said Anantha Chandrakasan, head of MIT’s Department of Electrical Engineering and Computer Science.

Engineers at MIT have previously built other ingestible devices that can be used to monitor vital signs like heart rate, temperature and breathing as well as drug delivery systems that treat diseases like malaria, but those devices were powered by conventional batteries that not only discharge overtime, but also pose a safety risk if the chemicals within the battery were to leak into the human body.

The team were inspired to make the new pill-like ingestible battery from a simple lemon battery -- a voltaic cell consisting of two electrodes like a copper penny and a nail stuck inside a lemon where the acid from the lemon carries a small electric current between the electrodes.

For the ingestible battery, the researchers attached a copper and zinc electrode to a sensor. Once swallowed, stomach acid stands in place of the lemon and sustains the battery, providing enough electricity to power the temperature sensor and a wireless transmitter.

In tests with pigs, the device took six days to make its way through the entire digestive tract with a signal being wirelessly sent to a base station every 12 seconds.

As the researchers continue to work on the device, they hope to make it smaller and optimize it for medical uses like monitoring vital signs over a two-week period while sending data to your smartphone or delivering drug treatment over a span of time.