This "Smart Pill" Sensor Grabs Your Body's Glucose to Power Long-Term Monitoring of Your Guts

Researchers from UC San Diego and the VA San Diego Healthcare System have developed a sensor system you swallow for insights into your gut health — and that runs on a glucose-harvesting fuel cell to avoid having to eat batteries.

"In our experiments, the battery-free biosensor technology continuously monitored glucose levels in the small intestines of pigs 14 hours after ingestion, yielding measurements every five seconds for two to five hours," explains Ernesto De La Paz, UC San Diego nanoengineering graduate student and co-first author of the team's paper. "Our next step is to reduce the size of the pills from the current 2.6 cm in length so they will be easier for human subjects to swallow."

Aimed at those who suffer from gastrointestinal disorders — around 20 per cent of people, the researchers say — the pill-like sensor system uses a glucose biofuel cell (BFC), which harvests energy from the digestive tract as it passes through. “It uses glucose present in the intestines as a biofuel to power the device," explains Patrick Mercier, professor of electrical and computer engineering and co-lead of the project. "Making this all work with ultra-low-power electronics and with a stable yet small glucose biofuel cell were major technical challenges that were addressed here."

The device not only uses glucose as a power source but as a monitoring metric: as it passes through the subject it tracks changing glucose concentrations, transmitting the resulting data using a magnetic human body communication (mHBC) system between 40-200MHz — chosen for its low power requirements and the ability to transmit even while inside a subject's body.

The team's next step, beyond miniaturization, is to increase the number of sensors available in the device — expanding from glucose monitoring to gathering data on a range of other gut-health metrics. "“Given that the gastrointestinal tract possesses dynamic changes of pH, temperature and oxygen concentrations," De la Paz explains, "future work envisions the integration of additional sensing modalities to account for these differences."

"With our battery-free smart pill approach, we have opportunities to monitor the small intestine for much longer than just a moment," adds co-lead Joseph Wang, nanoengineering professor. "We also plan to add additional sensors to the system.

"Our goal is to develop a sensing platform for the intestine that allows for the collection of many different kinds of information over longer periods of time. We are working to show that there is so much opportunity to discover what is really happening in the small intestine. I hope this kind of information will be useful for better understanding the role that changes in the small intestine environment play in health and disease."

The team's work has been published under open-access terms in the journal Nature Communications.

Main article image courtesy of David Ballot/UC San Diego.