Coin-Sized Hydrogen Sensor Clipped to Underwear Provides Objective Measurement of Flatulence Frequency

A coin-sized hydrogen-detecting device that clips to underwear adjacent to the perineum has shown that people have a poor grasp of how often they fart. Brantley Hall at the University of Maryland designed the sensor, which is the size of a medium-sized coin such as a nickel or two-pence piece and a couple of coins thick.

It measures the frequency of farts to provide objective data on intestinal gas production.

Hall and his colleagues had 37 people use the device to record flatulence after consuming lactose or sucrose. The researchers first placed participants on a low-fibre diet for two days to establish a baseline of farting. On the morning of the third day, each participant received either 20 grams of lactose or 20 grams of sucrose, then consumed the other sugar on the fourth morning.

The study was double-blind so that participants and research teams did not know who was getting lactose or sucrose on which day. Of the 37 participants, 24 were sensitive to lactose. 5 times more than their baseline during the day after consuming lactose.

For 22 of the 24 lactose-sensitive participants, the day with higher gas production corresponded to lactose consumption. An accompanying survey showed that the lactose-sensitive participants correctly guessed which day they were gassier only 50 per cent of the time. “It’s literally like a coin flip.

People aren’t reliable narrators about their flatulence patterns,” Brantley Hall said. Producing excess intestinal gas is a hallmark of lactose intolerance because microbes ferment undigested lactose and produce hydrogen. About one-third of people with lactose intolerance don’t report symptoms.

The device is intended to objectively determine how much gas people are producing to help diagnose conditions like irritable bowel syndrome and to study how well drug treatments to reduce intestinal gas production are working. Hall will present the results at the Digestive Disease Week 2026 conference in Chicago on 4 May.

In healthy adults, daily fart count ranges between 4 and 59, with the average being 32.

Hall said the average figure of 32 is likely to go down over time because studies are probably biased towards people who are farting a lot. Hall and colleagues are trying to establish the baseline of healthy human flatulence patterns, including how many times a day people fart and what foods are the major causes. Tom van Gils at University of Gothenburg in Sweden reviewed the approach.

“Measuring flatulence right where the gas leaves the body by using non-invasive smart-underwear is interesting, especially given the good acceptability of the technique,” Tom van Gils said. @NewScientist reported that the smart underwear can help spot gut-related conditions that might otherwise go undiagnosed, such as lactose intolerance.

The work builds on earlier research from Hall’s team that documented the wide range in daily fart counts among healthy adults.

Hall views the device as a tool for both clinical diagnosis and evaluating therapies aimed at reducing gas.