Scientists Invent a Digestible, Paper-Based Battery That Can Power Swallowed or Implanted Medical Devices

Ingestible sensors provide a helpful way to monitor a person’s health from the inside. But finding effective ways to power them has been a challenge. They typically use either standard batteries, which contain harmful chemicals, or external sources that provide energy wirelessly.

Now, scientists have created digestible, paper-based batteries that can power medical devices inside the body and eventually get broken down. The technology, described in the journal Nature Chemical Engineering on September 21, has so far been tested only in pigs. If further studies confirm its safety in humans, it could one day power all sorts of medical devices.

In fact, we need little bits of these elements for essential bodily functions. A biodegradable liquid salt serves as the electrolyte, a substance that transfers charge-carrying particles between the electrodes. One of the electrodes—the cathode—is bound together with cellulose fibers, which are found in plant cells and mean the system is paper-based.

Edible rice-paper wrappings on certain candies inspired this design, reports Katherine Bourzac for Nature. The entire battery is encased in natural waxes to prevent premature degradation in the stomach. Exposing them to an acidic liquid similar to gastric fluid revealed they would function normally in the stomach for about three days.

After that, their performance waned, and the tech completely degraded within a few months. The researchers then tested the batteries in two devices: an RFID tag that transmitted information from the stomach to a receiver outside the body, and a capsule that produces an electrical current to tell the body to make a hunger hormone called ghrelin. Both types of devices were inserted in the stomachs of live pigs, which have gastrointestinal tracts similar to humans.

The RFID tag worked in the animal, sending data to an external reader around five feet away. Meanwhile, 20 minutes of stomach tissue stimulation with the electrical current-producing capsule raised ghrelin levels by about 50 percent. Nobel Prize-winning technology In 2019, the Nobel Prize in Chemistry went to three scientists whose work contributed to lithium-ion batteries, the rechargeable power sources in devices like your smartphone and laptop.