Diseases May Be Identifiable By Laser

Testing a person’s breath with laser light can identify molecules which may serve as markers for diseases like asthma or cancer, according to a team of scientists at JILA, a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado (CU) at Boulder. Their findings are published in the latest issue of the Optical Society of America’s open-access journal Optics Express.

Cavity-enhanced frequency comb spectroscopy, as the technique is called, may one day permit doctors to screen patients for certain diseases by sampling their breath. "This technique can give a broad picture of many different molecules in the breath all at once," says Jun Ye, who led the research. He is a fellow of JILA, a fellow of NIST and a professor adjoint at CU-Boulder’s Department of Physics.

Ye’s JILA colleague John L. Hall and Theodor W. Hänsch of Germany’s Max-Planck Institute (they shared the 2005 Nobel Prize in Physics with Roy J. Glauber for their invention), developed optical frequency comb spectroscopy in the 1990’s. Optical comb spectroscopy is powerful enough to sort through all the molecules in human breath, Ye says, but it is also sensitive enough to find those rarest molecules that may be markers of specific diseases.

Every time we breathe in, we inhale a complex mixture of gasses—mostly nitrogen, oxygen, carbon dioxide, and water vapor, but also traces of other gasses, such as carbon monoxide, nitrous oxide, and methane. Each time we exhale, we blow out a slightly different mixture with less oxygen, more carbon dioxide, and a rich collection of more than a thousand types of other molecules—most of which are present only in trace amounts.

Source: Optics Express, Vol. 16, Issue 4, February 18, 2008.

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