Mass General Brigham Researchers Develop Ingestible Biosensor Pill for At-Home Monitoring of Intestinal Inflammation

A new swallowable device called PRIM (Pill for ROS-responsive Inflammation Monitoring) could someday make tracking inflammatory bowel disease (IBD)—a chronic condition that causes inflammation in the digestive tract—as simple as checking the color of your stool. Researchers from Mass General Brigham and the University of Toronto designed and tested the device in preclinical models. In their proof-of-concept study, the pill correctly detected gut inflammation about 78% of the time. The researchers estimate the device would cost less than 50 cents to make, making it a promising option for widespread, regular at-home use. Their findings are published in Device.

Currently, monitoring gut inflammation often requires unpleasant or expensive procedures like colonoscopies or sending stool samples to a lab—steps that can be difficult or cumbersome for many patients to do regularly.

“Millions of people around the world live with IBD, and many struggle with the burden of frequent, invasive monitoring,” said co-senior author Yuhan Lee, PhD, an investigator in the Innovative Biomaterials Lab at Brigham and Women’s Hospital (BWH), a founding member of the Mass General Brigham health care system. “This paper introduces a simple and affordable solution: an ingestible ‘biosensor pill’ that could be swallowed, like any other pill. With further development and testing in humans, this swallowable sensor could help patients and doctors catch flare-ups earlier, adjust treatments more effectively, and ultimately improve quality of life without the hassle of stool handling or hospital visits.”

Researchers designed the PRIM pill as a small capsule coated with a special polymer that reacts to inflammation. When levels of reactive oxygen species (ROS)—a chemical marker of inflammation—are elevated in the gut, the polymer breaks down and releases a blue dye. This visible signal can then be detected in the stool, signaling intestinal inflammation. The device was tested both in laboratory settings and in a rat model of colitis, using 36 capsules across healthy and inflamed conditions to evaluate its performance.

In rats with colitis, the miniaturized PRIM device successfully identified intestinal inflammation with 78% sensitivity and 72% specificity. The blue dye it released was clearly visible in the animals’ stool, while the device remained unopened and inactive in healthy rats, confirming its stability under non-inflammatory conditions.

The research team is now working to adapt the PRIM pill for human use. This includes testing it in larger animal models and fine-tuning its sensitivity to detect even mild-to-moderate inflammation. The device has an estimated production cost of just $0.38 per unit.

“This innovative device could transform how physicians monitor IBD by giving patients a clear, visual signal they can check at home,” said co-senior author Caitlin L. Maikawa, PhD, a former postdoctoral researcher in Lee’s lab at BWH. Maikawa is now an assistant professor at the University of Toronto’s Institute of Biomedical Engineering. “It’s designed to be low-cost, easy to use, and accessible for patients at home.”

Authorship: In addition to Lee and Maikawa, Mass General Brigham authors include Zile Zhuang, Lucia L. Huang, Bo Chan Seo, Subhashini Pandey, and Jeffrey M. Karp.

Disclosures: Karp has been a paid consultant and or equity holder for multiple biotechnology companies (listed here). Lee has been a paid consultant and or equity holder for AltrixBio inc. and One Fun inc. Maikawa, Lee, Karp Huang, and Zhuang have a patent application on the described work.

Funding: Supported by the Schmidt Science Fellows program, the Rhodes Trust, and the Natural Sciences and Engineering Research Council of Canada, and R01 (R01EB035790) from the National Institute of Biomedical Imaging and Bioengineering (NIBIB) at the National Institutes of Health (NIH).

Paper cited: Zhuang, Z. et al. “A Radically Simple Ingestible Colourimetric Biosensor Pill for Cost-Effective, Non-Invasive Monitoring of Intestinal Inflammation.” Device. DOI: 10.1016/j.device.2025.100865