New Edible Batteries Could Power Tiny Medical Devices

An edible battery that could safely pass through the human body could open up a whole new form of ingestible medicine. Yagi Studio/Getty

About two decades ago, scientists invented an ingestible camera that takes pictures as it moves through the gastrointestinal tract and relays data back to doctors. There was just one problem: The components of the camera, as well as the battery that powers it, were not designed for use in the body and contained potentially toxic materials. If the device got stuck as it made its way through the patient's gastrointestinal tract, it could pose a danger and would have to be removed, most likely with surgery.

"That's kind of the first generation. They use materials and components you might find at a RadioShack," says Christopher Bettinger, an associate professor of materials science at Carnegie Mellon University. The risk of a complication is palatable for one-time use of an ingestible device, but "if you have to take that every single day, the risk starts accumulating."

Bettinger and his colleagues have developed an edible battery using nontoxic materials found in the body. The key ingredient is melanin, the kind of pigment found in the eyes, hair and skin. Melanin can bind and unbind ions, like a battery does. It can serve as either the positive or the negative terminal, with a mineral like magnesium (also found in the body) at the other end. An additive like starch or another carbohydrate holds them together. When the battery comes into contact with fluid inside the body, the circuit is completed and turns on the battery, just as the light on a life vest from an airplane would come on when it touches water, Bettinger says.

A pill containing an edible battery, created by Christopher Bettinger and his team at Carnegie Mellon University. Stephanie Strasburg

This edible battery is roughly 2 millimeters thick and up to half an inch in diameter, and it provides roughly half a volt of power, equal to about one-third of a standard AA battery. At this size, it could power a device for about 20 hours. If it were to get stuck, the battery would simply degrade in the body in a matter of weeks.

The battery has potential for a range of devices. One of the most promising is targeted drug delivery, which could release medicine wherever it is absorbed most effectively. Another might be to add sensors to determine what kind of bacteria are in different parts of a patient's gut, which might play a role in issues like obesity, diabetes and inflammatory bowel disease.

"A lot of people feel comfortable with popping a pill," says Bettinger, and in the future that daily pill might have more than medicine in it.