Pill-sized electronic monitor rapidly detects GI disease

By John Murphy, MDLinx
Published July 6, 2018

Key Takeaways

Scientists at Massachusetts Institute of Technology (MIT) have developed an ingestible, capsule-sized, electronic monitor that can detect disease in hard-to-reach areas of the gastrointestinal (GI) tract. In a proof-of-concept study, the biosensor-in-a-pill detected intestinal bleeding in a pig within an hour, and wirelessly relayed the data to investigators in near real time. The researchers reported in Science that the swallowable sensor could also be used to detect infectious and inflammatory GI conditions.

“The goal with this sensor is that you would be able to circumvent an unnecessary procedure by just ingesting the capsule, and within a relatively short period of time you would know whether or not there was a bleeding event,” said co-lead author Mark Mimee, a graduate student in microbiology.

Other researchers are investigating ingestible biosensors in animal studies, but these devices rely on “cumbersome analysis” of bacterial gene expression or DNA in stool samples, the MIT investigators noted.

The biosensor prototype used in this study is a capsule about 1.5 inches long equipped with biological sensors meshed with low-power electronics. The sensors are bioengineered, bioluminescent bacterial cells that light up when exposed to a targeted stimulus.

“Our idea was to package bacterial cells inside a device,” said co-lead author Phillip Nadeau, PhD, a former MIT postdoctoral researcher in electrical engineering. “The cells would be trapped and go along for the ride as the device passes through the stomach.”

The capsule is covered by a semipermeable membrane that allows small molecules from the GI environment to diffuse through and reach the bacterial cells. The MIT scientists placed these bacterial cells on top of a low-power luminometer chip that converts the bacteria’s light response into wireless signals received by a nearby laptop or smartphone.

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The 2.7-volt battery that powers the device could keep it going for about 1.5 months of continuous use, the researchers estimated. Alternatively, it may be powered by a voltaic cell sustained by acidic fluids in the stomach, using technology that the investigators previously developed.

To advance the device toward possible clinical use in humans, the researchers anticipate that further engineering could reduce both the size of the capsule and its power consumption.

In this proof-of-concept study, the researchers showed that the biosensor identified gastric blood in pigs within 52 minutes of ingestion. The device’s blood-sensing ability improved with time, with a sensitivity and specificity of 83.3% at 60 minutes and 100% at 120 minutes.

“Although cost-effective fecal occult-blood testing is available, diagnosis of acute bleeding in the upper gastrointestinal tract often requires endoscopic observation, and ingestible micro-bioelectronic devices could offer a rapid, minimally invasive, and cost-effective means of detection,” the authors wrote.

The investigators also adapted the device to sense biomarkers of gut infection and inflammation, such as Crohn’s disease or other inflammatory conditions.

The ingestible biosensor enables “new opportunities for gastrointestinal biomarker discovery and could transform the management and diagnosis of gastrointestinal disease,” the authors concluded.

This research was funded by Texas Instruments, the Hong Kong Innovation and Technology Fund, the Office of Naval Research, the National Science Foundation, the Center for Microbiome Informatics and Therapeutics, Brigham and Women’s Hospital, a Qualcomm Innovation Fellowship, and the Natural Sciences and Engineering Council of Canada. Chip fabrication was provided by the TSMC University Shuttle Program.

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