Swallowable sensor offers simpler way to monitor gut inflammation

Researchers at the University of Toronto, Mass General Brigham and Harvard Medical School have developed a swallowable, low-cost device that changes colour in the presence of inflammation in the gut.

Designed for people with inflammatory bowel diseases (IBD) such as Crohn’s disease or ulcerative colitis, the “PRIM” pill (Pill for ROS-responsive Inflammation Monitoring) could offer an easy, at-home alternative to current monitoring tools such as colonoscopies or lab-analyzed stool samples. With further development, this technology could help doctors and patients detect flare-ups earlier and adjust treatments more effectively.

This study was published in Device, a journal by Cell Press. The work was co-led by Professor Caitlin Maikawa at the Institute of Biomedical Engineering at the University of Toronto with Professor Yuhan Lee and Professor Jeffrey Karp both at Harvard Medical School and Brigham and Women’s Hospital.

IBD affects over seven million people worldwide and is often marked by unpredictable episodes of inflammation in the digestive tract. While long-term management depends on keeping inflammation under control, current methods for monitoring gut health are either invasive, expensive or underused. Colonoscopies remain the gold standard but are not practical for frequent use. Stool-based tests are less invasive, but many patients are unwilling to collect or send in samples, which limits long-term tracking.

“There’s a clear need for a tool that can make routine inflammation monitoring easier and more accessible for patients,” said Maikawa, co-corresponding author of the study. “Our goal was to design something simple, affordable and patient-friendly that makes it possible to detect inflammation without needing a lab.”

The PRIM device uses a chemical marker called reactive oxygen species (ROS), which increases in the intestines during inflammation. The pill is coated with a specially designed polymer that remains intact in healthy conditions but breaks down when ROS levels are high. When this occurs, the pill releases a harmless blue dye. If inflammation is present, the dye colours the stool and toilet water blue, providing a clear visual signal that can be observed at home without handling stool or using specialized equipment.

The team tested the device in rats with induced gut inflammation and found that the pill detected inflammation with approximately 78 percent accuracy. Because the materials used to make the device are inexpensive, researchers estimate it could cost less than 50 cents to manufacture at scale. The simplicity of the design makes it more accessible to a broader population, including those in lower-resource settings.

The team continues to work on refining the pill design to bring the technology closer to clinical use. Lucia Huang, co-lead author on the study and an MSc student on Maikawa’s team, is working developing new polymer materials that will more sensitively detect inflammatory markers like ROS. Future studies will also test the device in larger animal models that better mimic humans.

“We are working on refining the pill design, including improving the pill’s accuracy and exploring how our pill could interface with digital health technologies,” said Maikawa. “Our long-term aim is to make regular inflammation monitoring as easy as possible.”