Wearable sensors are typically worn on the wrist, but we’ve written about sensors pinned to clothing, carried in a pocket, woven into garments, and even ingested. For example, in 2017 we wrote about Abilify MyCite, the first FDA cleared ingestible sensor. That same year we covered Brigham and Women’s Hospital and MIT’s work with tapping stomach acid to power smart ingestibles. Brigham and Women’s Hospital Division of Medical Toxicology also developed an ingestible opioid monitor to measure outpatient usage.

Recent work at MIT on an ingestible Jell-O-like pill may play a transportation and protection role for a wide range of ingestible sensors in the future. Current ingestible sensors can only last in the stomach for a few days, but the MIT design is patterned after the rapidly-inflating pufferfish and can stay in place up to a month. Initially designed to monitor stomach health, the pill expands after ingestion. It is made up of two hydrogel-based layers: one that swells quickly and the second that protects the contents from the stomach’s corrosive acid storm.

After ingestion, the pill expands rapidly to the size of a ping-pong ball. It relies on the same sodium polyacrylate material that is commonly used in highly absorbent diapers. In testing, the MIT engineers found that the pill inflated to 100 times its starting size in roughly 15 minutes. The first use cases for the expanding pill are to track ulcers, cancers, and other GI conditions over time.

According to the MIT group, the pill payload could include sensors to measure pH levels, certain bacteria or viruses, or even to carry tiny embedded cameras to monitor ulcers and tumors. Another potential application could use the expanding pill as a safer alternative to gastric balloon diets.