Researchers at the University of Maryland have developed smart underwear, the first wearable device specifically designed to measure flatulence in humans. The tiny sensor tracks hydrogen in farting, allowing scientists to reconsider long-held assumptions about how often people pass gas. This technology also provides a new way to observe gut microbial metabolism in daily life.
For many years, doctors had limited tools to evaluate patients with intestinal gas problems. Michael Levitt, a gastroenterologist widely known in the field as the “King of Farts,” highlighted this challenge when he wrote in 2000 that “it is virtually impossible for physicians to objectively document the presence of excess gas using currently available tests.”
Wearable sensor that tracks intestinal gas
To address this problem, a research group led by Brantley Hall, assistant professor in UMD’s Department of Cell Biology and Molecular Genetics, has developed smart underwear, a compact wearable device that discreetly clips onto regular underwear. The device contains an electrochemical sensor that continuously monitors intestinal gas production throughout the day and night.
In a study published in Biosensors and bioelectronics: Xa study led by UMD Assistant Research Scientist Santiago Botasini used the device to measure flatulence in healthy adults. Participants had an average of 32 farts per day. This is approximately double the 14 (±6) times per day often cited in early medical literature. However, results varied widely between individuals, ranging from a total of as few as 4 flatus events per day to as many as 59 flatus events per day.
Older estimates were likely lower because previous studies relied on invasive measurement techniques performed in small groups or relied on self-reporting. Both approaches can miss events or rely on incomplete memory, and cannot record gas production during sleep. Furthermore, the sensitivity of internal organs varies greatly from person to person. This means that two people can produce the same amount of flatulence but perceive it completely differently.
“Objective measurements offer an opportunity to increase scientific rigor in areas that have traditionally been difficult to study,” said Hall, lead author of the study.
Tracking intestinal microbial activity using hydrogen gas
In most people, intestinal gas consists primarily of hydrogen, carbon dioxide, and nitrogen. Some individuals also produce methane. Since hydrogen is produced exclusively by microorganisms living in the intestines, continuous measurement of hydrogen in the intestine provides a direct signal of microbial fermentation activity as intestinal bacteria break down food components.
“Think of this like a continuous blood sugar monitor for intestinal gas,” Hall said, explaining that the device detected an increase in hydrogen production after participants ingested the prebiotic fiber inulin. The sensor identified these increases with 94.7% sensitivity.
Human Intestinal Gas Atlas aims to define what is normal
Scientists have established normal ranges for many health indicators, such as blood sugar and cholesterol. However, when it comes to flatulence, there is no universally accepted baseline.
“We actually don’t know what a normal occurrence of flatus looks like,” Hall says. “Without that baseline, it’s difficult to know when someone’s gas production is truly excessive.”
To address this gap, Hall’s lab is launching a large-scale project called the Human Fratus Atlas. The study will use smart underwear to continuously measure the flatulence patterns of hundreds of participants, while also analyzing their diet and the composition of their gut microbiota. Devices will be shipped directly to volunteers, allowing adults across the U.S. to participate from the comfort of their own homes. The goal is to determine the normal range of intestinal gas in Americans age 18 and older.
Study of different types of intestinal gas producers
To capture the full range of variation, researchers are recruiting volunteers who fit into several categories identified in earlier studies.
Zen Digesters are people who eat a high-fiber diet (25 to 38 grams of fiber daily) but have very low flatus. Studying them may help researchers understand how the microbiome adapts to a fiber-rich diet.
Hydrogen overproducers are individuals who frequently emit gas. Investigation of this group may reveal biological factors that cause large amounts of gas production.
Ordinary people represent people who are between these two extremes.
To better understand the microorganisms responsible for these differences, the team plans to collect stool samples from Zen Digesters and Hydrogen HyperProducers for microbiome analysis.
“We’ve learned an enormous amount about which microbes live in our gut, but we don’t know much about what they’re actually doing at any given moment,” Hall says. “The Human Gut Bacteria Atlas establishes an objective baseline of gut microbial fermentation, which is an important basis for assessing how dietary, probiotic, or prebiotic interventions alter microbiome activity.”
How to participate in Human Fratus Atlas research
If you are interested in participating, please visit flatus.info for more information. Registration is open to adults 18 years and older in the United States. Participants will receive a smart underwear device and will wear it day and night for the duration of the study. Registration is limited.
A patent has been filed for the technology, with Brantley Hall and Santiago Botasini listed as inventors. Both are also co-founders of Ventoscity LLC, which licensed the device.
This research was supported by the University of Maryland, Maryland Innovation Initiative Phase I, and the UM Ventures Medical Device Development Fund.
