Building “Smart Food” to Sense Digestive Health

For people with eosinophilic esophagitis, finding out whether the disease is active can mean an uncomfortable medical procedure. Eosinophilic esophagitis, or EoE, is an inflammatory condition of the esophagus often triggered by food or environmental allergens. When the disease is active, immune cells called eosinophils accumulate in the tissue, causing inflammation that can make swallowing difficult and, over time, narrow the esophagus.

Diagnosing active EoE typically requires an endoscopy. A doctor inserts a flexible camera down the throat and takes tissue samples for analysis. Researchers at Carnegie Mellon University have proposed a swallowable sensor that could measure the esophagus, noninvasively, from the inside. In their paper, “NFCapsule: An Ingestible Sensor Pill for Eosinophilic Esophagitis Detection Based on Near-field Coupling,” researchers built a smart sensor pill that is designed to detect changes in the electrical properties of esophageal tissue as it passes through the body.

“Our NFCapsule offers a new way to detect active EoE by measuring changes in the electrical properties of esophageal tissue without relying on an invasive endoscopy,” explains Swarun Kumar, the Sathaye Family Foundation Professor of Electrical and Computer Engineering and lead author of the paper. “It is essentially a wireless sensor disguised as a pill.”

The Carnegie Mellon University research team recently received funding from the National Science Foundation for further miniaturizing the form-factor of their sensing system into a new paradigm “smart food” – embedding esophagus and digestive tract sensing capabilities into the size of everyday food. 

Digestive health conditions change the electrical properties of the digestive system. For example, active EoE changes the microscopic structure of digestive tissue. In particular, inflammation can increase the spacing between cells. Those changes affect how the tissue responds to an electrical signal. The researchers propose embedding tiny circuits into everyday food. As the food moves through the digestive tract, the surrounding tissue changes the circuit's electrical behavior and an external reader wirelessly sends energy to the capsule and measures how the sensor responds. From those measurements, the system estimates the tissue's electrical properties.

“Our work doesn't need to see the inflammation,” says Kumar. “It detects the electrical pulses.”

The proposed SmartFood platform will be designed to lower the barriers to digestive health monitoring, making sensing as effortless as consuming regular food, with data collected wirelessly in a home setting. As SmartFood devices traverse the body, they will detect various impairments affecting the esophagus, stomach, and intestines, wirelessly transmitting the data to an external reader. The project will specifically focus on monitoring inflammation, acidity, and bloating, three common conditions impacting the digestive system. In doing so, the project will explore new avenues for clinical solutions and broader STEM education surrounding health sensing.

“The project will enable us to explore the design space of battery-free, ingestible sensors to detect changes in the digestive system wirelessly, opening the door to a less invasive approach to monitoring our digestive health,” says Kumar.