Stomach Acid powered battery created by researchers

A voltaic cell that is powered from the acid in the stomach was invented from researchers at MIT and Brigham and Women’s Hospital. It has enough energy to power small sensors or drug delivery systems that can stay in human’s stomach.

The cell can offer a cheaper and safer alternative to the batteries used now for those purposes.

“We need to come up with ways to power these ingestible systems for a long time,” says Giovanni Traverso. “We see the GI tract as providing a really unique opportunity to house new systems for drug delivery and sensing, and fundamental to these systems is how they are powered.”

Traverso, a gastroenterologist and biomedical engineer is one of the main authors of the study, along with Robert Langer, a professor at MIT.


Powered by acid fluids


The team have build before many devices like this one that can monitor heart rate, temperature or breathing rate.

“This work could lead to a new generation of electronic ingestible pills that could someday enable novel ways of monitoring patient health and/or treating disease,” Langer says.

They are powered by tiny batteries that can possess a health risk. In order to find a better alternative, the authors teamed with Nadeau and Chandrakasan, who specialize in building low-power electronic.

They gained insight from a simple voltaic cell called “lemon battery”.It consists of two electrodes stuck in a lemon.  The acid found in the lemon causes a small electric current between the  electrodes.

Copying this model, they used zinc and copper electrodes attached to their sensor. The zinc emits ions that power the device, that can power a temperature sensor and a 900 MHz transmitter.

They tested it firstly in pigs, where it took 6 days to travel to the stomach. It had enough energy to power the temperature sensor and transmit information to 2 meters away every 12 seconds.

When the device moved to the small intestine, it could only generate a hundredth of what it produced in the stomach. “But there’s still power there, which you could harvest over a longer period of time and use to transmit less frequent packets of information,” Traverso says.


Decreasing its size


The size of the cell is 4 cm in length and 1,2 cm in diameter, but the researchers believe they can reduce the size three times. They’ll build and integrated circuit that hosts the energy harvester, a microprocessor and a transmitter.

“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,” Chandrakasan says.

When they are able to decrease it in size, they are going to develop it for other applications like long-term watching of vital signs. This kind of device can also be used as an drug deliverer,.

“You could have a self-powered pill that would monitor your vital signs from inside for a couple of weeks, and you don’t even have to think about it. It just sits there making measurements and transmitting them to your phone,” Nadeau says.

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