New device can identify diseases through exhalation

BOULDER, Colo. Scientists have revealed that they have produced a machine that uses a person’s breath to identify single molecules that are associated with specific diseases, according to published reports.

People exhale a complex mixture of gases, including oxygen, nitrogen, carbon dioxide, and others, according to physicist Jun Ye, leader of the research team. In fact, more than 1,000 different compounds are contained in a human breath. But along with those common gases and compounds, people also exhale certain molecules that are considered biomarkers indicating specific conditions like diseases.

Normal breath consists of trillions of molecules, only a few of which are actual biomarkers. And finding just one isn’t enough. There needs to be a pattern consisting of several different types of biomarkers that are all associated with a particular medical problem.

What’s necessary, Ye said, is to create a device that will find a few molecules in a sea of background noise consisting of trillions of harmless molecules. He calls it “seeing the forest all at once, but also seeing individual trees extremely clearly.”

The technology that he has helped develop builds on the device that won a Nobel Prize in 2005, called optical frequency comb. Ye and his group applied the technology to spectroscopy, which is used to identify distinct molecules by their emission and absorption of light.

The heart of Ye’s machine is a cavity between two curved mirrors. Laser pulses are shot into the cavity and reflect back and forth between the mirrors tens of thousands of times, bombarding any molecules in their way, before finally escaping. To test the device, the researchers recruited several students and had them breathe into the cavity.

The bouncing laser beam interacted with the billions of exhaled molecules, identifying the entire composition of the breath. The findings were very precise, Ye said. One of the participants was a smoker, and his test revealed five times the normal level of carbon monoxide.

“If you have asthma, your breath will have nitrous oxide, but nitrous oxide does not necessarily mean you have asthma,” he said. “But if you see several different molecules all at once, and they are associated with asthma, then you have found a real fingerprint of a certain disease.”

The technology can now identify a single molecule among billions. The next goal will be to find a single molecule among trillions. That would broaden its application even further.