Timelapse of the pill expanding. Source: Massachusetts Institute of TechnologyTimelapse of the pill expanding. Source: Massachusetts Institute of TechnologyEngineers at MIT have developed a pill that once ingested expands to roughly the size of a ping pong ball and monitors stomach health for up to 30 days.

The ingestible pill is outfitted with sensors that monitor the health of a patient’s stomach, according to researchers. After an estimated 30 days, the pill dissolves and leaves the body. To expel the pill early, patients can drink a calcium solution that will shrink the pill to a size that can safely pass through the body.

The pill design was inspired by the puffer fish. Composed of two different hydrogels containing polymers and water, the pill expands in the stomach while withstanding prolonged exposure to stomach acid, which is an improvement on current ingestible sensors that are typically composed of hard plastics or metals that can only withstand a few days in the stomach before being expelled.

To swell the pill, the engineers added sodium polyacrylate particles to the inside of the pill, which are the super-absorbent particles found in products like diapers that expand as they quickly absorb liquid. The engineers added a second layer to the pill to envelop the super-absorbent particles so that they wouldn’t immediately break apart upon ingestion. The protective layer is composed of nanoscopic, crystalline chains woven to create an extremely robust membrane.

In the lab, the engineers determined that the pill would expand to 100 times its original size in just 15 minutes after introduction to solutions that resembled gastric juices. Additionally, the team tested the strength and durability of the pill under conditions and forces that resemble typical stomach contractions.

"The stomach applies thousands to millions of cycles of load to grind food down," Lin explained. "And we found that even when we make a small cut in the membrane, and then stretch and squeeze it thousands of times, the cut does not grow larger. Our design is very robust."

The team of engineers envisions a number of additional possible applications for the pill, including embedding tiny cameras into the pills so that tumor or ulcer progress can be monitored. The team also believes that the pill might one day be a safer alternative to the gastric balloon diet.

The research is published in Nature Communications.

To contact the author of this article, email mdonlon@globalspec.com