A Battery You Swallow Does Its Job, Then Disappears

A battery smaller than a shirt button can power a device from inside the stomach for about three days, then fall apart. Swallowing a battery is normally a trip to the emergency room.

The team, led by MIT engineer and gastroenterologist Giovanni Traverso, built it from materials the body can tolerate in small amounts: magnesium on one side, molybdenum trioxide on the other and a gel electrolyte in between. Plant-derived cellulose fibers bind it into something closer to paper than to a battery. The results appear in Nature Chemical Engineering.

Delivered into pigs' stomachs, the battery started at 1.84 volts, a little more than a standard AA, and kept working for up to three days as its output slowly sagged. Within a few weeks it had broken apart. The team built two sizes: a disc 7.5 millimeters (0.3 inches) across and a bar 24 millimeters (about 1 inch) long. The disc powered a tracking tag that broadcast continuously from inside the stomach at up to 1.5 meters (about 5 feet). The bar powered a capsule that sends a small current into the stomach lining; in the new tests, 20 minutes of stimulation raised levels of the hunger hormone ghrelin by about 50 percent.

The new battery made nearly that entire stimulation device bioresorbable. Nearly. The printed circuit board did not dissolve; pigs passed it on their own.

Ingestible devices often run on small lithium or silver oxide coin batteries, which become a safety risk if their protective coating is damaged in transit.

None of this has been tested in humans. The team still has to get the batteries performing consistently from one unit to the next.

So far, every one of these results comes from pigs and lab tests. The first human volunteers are about two years out.

Read the full story at MIT News, September 21, 2026

Hot Take: The battery dissolves and the capsule mostly dissolves, but the circuit board leaves the old-fashioned way, which puts the most sophisticated part of the device on the same exit plan as corn.