Pill-Size Sensor Sniffs Out Gases as It Passes Through Your Gut

A swallow-able, pill-size sensor that can sense gases as it travels through the human digestive tract may one day help doctors diagnose patients' gut conditions, such as lactose intolerance and irritable bowel syndrome, a new, small study finds. 

Researchers tested the electronic sensor in seven healthy people and found that the device could accurately detect the concentrations of hydrogen, carbon dioxide and oxygen in real time as it passed through the body, according to the study, published online yesterday (Jan. 8) in the journal Nature Electronics.

Although the sensor's results still need to be tested in a larger group of people, including in individuals who have gut conditions, use of the sensor could one day lead to fewer invasive procedures, such as colonoscopies, the researchers said.

The capsule is about the size of a large pill — just 1 inch by 0.4 inches (2.6 centimeters by 1 centimeters). From the moment it's swallowed to the time it's excreted between one and two days later, the capsule sends data about the gut's gas concentrations every 5 minutes to a handheld device outside of the body. This device, in turn, uses Bluetooth to send the data to a smartphone application. 

A 3D drawing (A) shows how the gas-sensing capsule is designed; a photo (B) of the packaged gas capsule and its receiver device.

Credit: Kalantar-zadeh K. et al., Nature Electronics, 2018.

Sensor surprise

Beyond relaying real-time data about gas concentrations throughout a person's gut, the capsule trial revealed that the human stomach has a previously unknown protection system. This system kicks into gear if foreign compounds stay in the stomach for too long, triggering the stomach to release oxidizing chemicals to break down and destroy them, the researchers found. 

"Such an immune mechanism has never been reported before," lead study author Kourosh Kalantar-zadeh, a professor in the School of Engineering at the Royal Melbourne Institute of Technology, in Australia, said in a statement.

Moreover, the capsule showed that the colon, or large intestine, may contain oxygen, as people on a high-fiber diet had high concentrations of oxygen in their colons. "This contradicts the old belief that the colon is always oxygen-free," Kalantar-zadeh told Live Science.

This oxygen-related finding may help researchers understand how certain conditions, such as colon cancer, develop, he said.

If it's approved, the capsule could revolutionize the way doctors diagnose gut disorders, and even help them assess a patient's diet, he said. That's because each disease likely has its own signature of gas concentrations, so capsule readouts would allow doctors to identify any problems a patient is having, he said.

A larger trial with more than 300 patients is expected to be completed in 2019, Kalantar-zadeh noted. It's unclear how much the capsule will cost if it's brought to market, but the researchers "hope to deliver it to patients under $200 in the first stage," he said.

The dimensions (C) of the capsule; and (D) a drawing showing gas penetrating the membrane, allowing the gas to reach the sensing elements.

Credit: Kalantar-zadeh K. et al., Nature Electronics, 2018.

A better breath test

The scientists made the electronic sensor after a gastroenterologist (a doctor who specializes in the gastrointestinal tract and liver) asked whether the researchers could make diagnostic breath tests more reliable for gut conditions, as most breath tests are reliable just 60 percent to 70 percent of the time, Kalantar-zadeh said. Such breath tests are used to diagnose conditions such as small intestine bacterial overgrowth and irritable bowel syndrome, by measuring gas concentrations.

However, the researchers weren't able to produce a better breath test, he said. That's because the amount and concentrations of gases produced in the gut change by the time they get to the lungs, he said. 

"So, we started making a device, our capsule, to measure gases 'directly' where they are generated in the gut," Kalantar-zadeh said.

Outside opinions

The capsule is a "novel tool which can help us decipher the complex interactions between the host, gut bacteria and diet that ultimately determine our health or disease," said Dr. Premysl Bercik, an associate professor in the Department of Medicine at McMaster University, in Canada, who was not involved with the study.

It's intriguing that the capsule found high oxygen values in the colon, Bercik told Live Science, but added that "we have to be cautious when interpreting these results … more data is needed to understand the complex chemistry happening in our bowels."

In the meantime, this device may be beneficial in patients with irritable bowel syndrome or small intestinal bacterial overgrowth, said Dr. Priya Kathpalia, an assistant professor of medicine at the University of California, San Francisco's Division of Gastroenterology. That's because the capsule could help patients learn whether they need to make dietary changes or seek medical treatment, Kathpalia told Live Science.

Original article on Live Science.