Ingestible electronics are giving their first full tours of the gas in people’s guts.
Newly constructed capsules, described online January 8 in Nature Electronics, sense various gases while traveling through a person’s digestive tract, revealing how the gut’s chemical composition reacts to factors like diet.
What exactly each person’s gut gas could reveal about his or her health “is still to be determined,” says William Bentley, a bioengineer at the University of Maryland in College Park. But using capsules to gather gas fingerprints of many people with different diets or disorders could help researchers better characterize gut problems and improve disease diagnoses as well as boost monitoring of the effects of dietary or medication changes.
Kourosh Kalantar-Zadeh, an engineer at the Royal Melbourne Institute of Technology in Australia, and his colleagues built plastic capsules about 2.5 centimeters long — about as long as a Jolly Rancher hard candy — that sniff out carbon dioxide, hydrogen and oxygen gas molecules in the gut. Such molecules are primarily generated when microbes feast on undigested food. These battery-powered capsules continuously relay gas updates to a smartphone until expelled from a person’s body.
The researchers studied how these ingestible electronics, similar to capsules previously tested in pigs (SN: 2/20/16, p. 5), worked inside six healthy people. By watching a capsule pass through the gut with an ultrasound, the researchers found that oxygen concentrations varied in different regions of the gut, for example between the stomach and the small intestine. This result indicates that oxygen readouts could be used to trace the capsule’s location in the gastrointestinal tract and clock digestion time.
Kalantar-Zadeh’s team also found that dietary changes noticeably altered people’s digestion rates and gas profiles. For instance, higher dietary fiber intake increased a capsule’s time in the small intestine and led to a slight increase in hydrogen concentration in the colon, compared with the hydrogen decrease seen on a low fiber diet.
“The data here — even though it was a very small cohort — are encouraging” that smart, swallowable capsules can provide new insight into gastrointestinal goings-on, says Giovanni Traverso, a gastroenterologist and biomedical engineer at Brigham and Women’s Hospital in Boston. “This really amplifies the field of ingestible sensors.”