It’s Called the ‘Fitbit for farts’—and it’s No Joke
As I type this, a battery-powered computer tucked in my, er, swimsuit area is monitoring for my next flatus. Yes, flatus means “fart.” Don’t judge me—it’s for science.
This sensing device, which would have been impossible to make until very recently, sits at the intersection of some of the most important technology trends of the past decade, including miniaturization, continuous monitoring and edge—as opposed to cloud—computing.
And the data it’s designed to collect could help the 40% of U.S. adults whose lives are regularly interrupted by digestive troubles. The frequency and volume of flatulence is a major reason people quit healthy, fiber-rich diets, which can be key to heading off gastrointestinal disorders and colon cancer.
One day, millions of Americans might wear sensors like this one, which I found surprisingly unobtrusive. Playfully referred to by its creators as a “Fitbit for farts,” it’s the core of the University of Maryland’s Human Flatus Atlas study. Developed using some of the same components found in smart rings and wireless earbuds, devices like this could eventually share a stage with blood-glucose monitors and heart-monitoring Apple Watches.
For now, it’s a prototype. The researchers are sending out the first 800 to study participants all over the U.S. Close to 4,000 people have already applied, so the researchers plan to make more.
“We desperately need to understand what the baseline of human flatulence patterns are,” says Brantley Hall, the study’s principal researcher at UMD. Hall is also co-founder of Ventoscity, a startup launched to commercialize the sensor. “It’s 2026 and we don’t know how many times the average American is farting every day.”
A portal to the gut
Despite the prevalence of digestive-health issues, flatulence researchers have been limited to either invasive laboratory studies or self-reporting, which has proven unreliable. Most of us just don’t know how often we pass gas, or how much.
This new tech could be instrumental in untangling the mystery of why two people can eat the same thing and react to it in such different ways, says Sean Gibbons, an associate professor who studies the gut microbiome at the Institute for Systems Biology in Seattle. “I think having a way to continuously monitor this stuff will lead to improved knowledge,” he adds. (Gibbons isn’t affiliated with the UMD study.)
The sensor works by sampling the stream of hydrogen we emit. Its genesis dates back to September 2020, when a member of Hall’s team at UMD wanted to measure the hydrogen production of gut bacteria in an anaerobic chamber, to learn about the anaerobic metabolism that happens in our own digestive systems.
The researcher tried a commercial hydrogen sensor, but it didn’t work. Hall, frustrated, told his colleagues, “I bet if I fart on it, it will work.” He took the expensive, bulky sensor home and gave it a try.
“The signal was enormous, and the rest is history,” he says.
The team recently published a paper on the results of studies using an earlier, more ungainly version of their wireless sensor. So far, the record-holder passed gas 175 times in a single day, while another subject broke wind only four times.
Going from a bulky commercial hydrogen sensor to a smart device about the size of a stack of three nickels was a technical challenge like that of any consumer-health wearable. The team went through 12 iterations before landing on the current design.
“We had to come up with a completely custom solution,” says Hall. Using a tiny battery required adopting the newer kind of chips found in so-called internet-of-things devices. Users charge the sensor every 24 hours with a custom magnetic charger sourced from China’s smart-ring supply chain. He says such electronics have become far cheaper and more plentiful only recently. “This would have been impossible three years ago,” he adds.
When the device is charging, it transmits data to the Human Flatus Atlas app on your phone. (Hall says participants’ data remains confidential.) The sensor sits outside your underwear and can be cleaned with alcohol wipes. Though it’s not waterproof, you can wear it during most workouts. But no cycling!
An ‘artificial butt’
Before the “Fitbit for farts” could be sent into the field, the research team needed a way to test it in the lab. The sensor is mostly dormant, but it also needs to record every emission, so the team needed a way to generate a flatus on command. Enter the “artificial butt.”
In Hall’s lab, near the 3-D printers that are mass-producing the sensor casings, sits a collection of mannequin buttocks attached to gas canisters. They’re designed to emit lab-made, synthetic flatuses.
One problem: “Farts have an illegal amount of hydrogen, about 20%, and I’m not allowed to have 20% hydrogen in my lab,” says Hall. “It’s one reason flatuses are flammable.” (In testing, he compromised by using a lower concentration of hydrogen over a longer period of time.)
The extreme concentration of hydrogen in a flatus does make it easier to detect with a tiny sensor. Today, those same simulated posteriors are essential to making sure new sensors are in good working order.
“We calibrate and validate each device in this butt,” says Hall, who calls it the “key innovation” that made developing the sensor possible.
The quest for fiber
The ultimate goal of Hall’s five-year quest is to gather enough data to craft some kind of intervention for those suffering from gas and bloating. A pill, perhaps. But creating a workable intervention can’t happen until scientists know just how much the average person flatulates, and why.
In the current study, the Human Flatus Atlas app asks participants to take a picture of everything they eat and drink. Researchers could analyze that data, seeking correlations between diet and the sensor’s main metric: the total volume of gas passed in a day.
The top 3% of gas passers who enroll in Hall’s study will have an opportunity to have their gut microbiome sequenced, which could help identify which bacteria contribute to intestinal distress. They’ll also get a small plaque declaring them a “Prodigious Hydrogen Producer.” (The least gassy will get a “Zen Digester” accolade.)
In the meantime, would-be participants from all over America are filling up the inbox of the UMD team. “There are people who are like, ‘I fart constantly, I will break your sensor, please let me be in your study,’” says Hall. “I am saying yes to all those people.”
