A chest X-ray and lab test might not always be the first stop for checking pneumonia in the future.

Researchers at MIT have developed a portable sensor prototype that they say could detect pneumonia and other lung-related diseases from a person’s breath. The device, called PlasmoSniff, has so far only been tested in mice, not humans, but the team says it could eventually offer a faster way to pick up signs of disease without relying on laboratory-grade electronics typically found in hospitals.

The system starts with nanoparticles that a patient inhales. When those nanoparticles are later exhaled, they carry attached biomarkers that can show evidence of disease from deep inside the body.

“In practice, we envision that a patient would inhale nanoparticles and, within about 10 minutes, exhale a synthetic biomarker that reports on lung status,” mechanical engineer Aditya Garg said.

“Our new PlasmoSniff technology would enable detection of these exhaled biomarkers within minutes at the point of care.”

The nanoparticles used in the system have been in development for several years. The biomarkers, or chemical tags, attached to them break away when they come into contact with specific protease enzymes linked to certain diseases.

That gives researchers a signal to track. The challenge is that those biomarkers are exhaled only in very small amounts.

To pick up those traces, the new sensor uses plasmonics, the study and manipulation of light. That is where the name PlasmoSniff comes from.

More specifically, the sensor uses Raman spectroscopy, a technique that uses light to measure the vibrations of a molecule. Those vibrations act as signatures for the movement of atoms within chemical bonds, allowing researchers to identify molecules.

The sensor uses gold nanoparticles suspended over a thin gold film. The team says gold is an ideal metal for plasmonics. Inside the sensor, water-coated microscopic gaps trap the target biomarkers and amplify their vibrations enough for the device to detect them.

Human breath contains volatile organic compounds, or VOCs, that can show everything from the state of the gut microbiome to how efficiently the body’s metabolic processes are running. But the newly designed sensor is built to isolate only a very small fraction of the chemicals a person exhales.

“This is a needle-in-a-haystack problem,” mechanical engineer Loza Tadesse said.

“Our method detects that needle that would otherwise be embedded in the noise.”

For now, the research remains at the prototype stage. The team tested the sensor in mice rather than people, and it looked for only one specific biomarker.

The next steps are more complicated. The researchers say testing on human breath will be harder, and they still need to build a mask-like attachment that can analyse a patient’s breath over about five minutes.

That mask would work with a device similar to an asthma inhaler, which would deliver the nanoparticles into the body. In healthy people, the nanoparticles would simply circulate out of the body without being broken down by disease.

The researchers say that if development and scaling go well over the coming years, the technology could become a new option for monitoring and detecting disease. They also say it could be adapted for a wide range of uses beyond respiratory conditions such as pneumonia.

Tadesse said the platform may also have uses outside human health in situations where portable sensors need to detect small traces of chemicals in the air.

“It’s not just limited to these biomarkers or even diagnostic applications,” Tadesse said.

“It can sniff out industrial chemicals or airborne pollutants as well. If a molecule can form hydrogen bonds with water, we can use its vibrational fingerprint to detect it. It’s a pretty universal platform.”

The research has been published in Nano Letters.