An ingestible electronic capsule that can sense O2, H2 and CO2 levels in the gut has been trialled in humans. The capsule was shown to be an accurate tool for monitoring the effects of diet and could have potential in diagnosing gastrointestinal disorders such as IBS and malabsorption.
Prompted by a challenge several years ago, Kourosh Kalantar-Zadeh and colleagues attempted to improve tests that measure gases in the gut via the breath; however, they concluded that a lack of information about the point of gas production in the gut was responsible for the unreliability of these tests. “As such, we started developing our swallowable gas-sensing capsule for measuring gases 'directly' where they are generated in the gut,” explains Kalantar-Zadeh.
The team — a collaboration between RMIT and Monash Universities, Australia — developed a capsule that incorporated electronic components for measuring H2, CO2 and O2 levels, with gas selectivity and sensitivity obtained by modulating the heating elements of the sensor. Data on the concentrations of gases and temperature are then transmitted to a monitor that displays the profiles in real time on a mobile phone.
After conducting tests in pigs, human volunteers (total n = 6) were recruited to trial the capsules. Here, gas profiles of the gastrointestinal tract were obtained while modulating the fermentative activities of the gut microbiota by altering the intake of dietary fibre in crossover studies.
The capsules were found to be reliable and well tolerated by the volunteers. Using ultrasonography to locate the capsule, the researchers found they could reliably assess bowel motility using O2 levels. “We could see step changes in the oxygen sensor when the capsule was moving from one segment of the gut to another,” reports Kalantar-Zadeh.
In the crossover studies, fibre intake was associated with variations in intestinal transit time as well as regional fermentation patterns defined using H2 profiles. “New clinical observations could also be seen, including a possible oxidative immune system in the stomach against foreign objects, and that a high content of oxygen could be pushed down into the colon area by taking a very high fibre diet,” adds Kalantar-Zadeh.
The investigators are now preparing for phase II trials of the technology and envision that the capsules could provide a potentially powerful diagnostic technique or be used as a monitoring tool to help develop individualized diets.
Kalantar-Zadeh, K. et al. A human pilot trial of ingestible electronic capsules capable of sensing different gases in the gut. Nat. Electronics https://doi.org/10.1038/s41928-017-0004-x (2018)
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Dickson, I. Gas-sensing gut capsules. Nat Rev Gastroenterol Hepatol 15, 131 (2018). https://doi.org/10.1038/nrgastro.2018.3