Lasers for analyzing our breath?
According to the Optical Society of America (OSA), U.S. researchers have shown it is possible to use lasers to analyze our breath to detect diseases such as asthma or cancer. This technique -- hold your breath -- is called 'cavity-enhanced direct optical frequency comb spectroscopy.' It is based on research done in the 1990s and which led to the 2005 Nobel Prize in Physics. The researchers add that 'while the efficacy of this technique has yet to be evaluated in clinical trials, monitoring the breath for such biomarkers is an attractive approach to medicine because breath analysis is the ultimate non-invasive and low-cost procedure.' I'm not sure that I would like a laser blasting in my mouth, but read more...
You can see above a "schematic of the cavity-enhanced direct-frequency-comb spectrometer, along with the gas handling system for breath analysis." (Credit: JILA) This really looks complicated, isn't?
But on the picture above, you can see "CU-Boulder physics doctoral student Michael Thorpe holds a detection chamber next to a novel laser apparatus at JILA." (Credit: University of Colorado at Boulder) And it looks really less complex...
This research work has been conducted at the Joint Institute for Laboratory Astrophysics (JILA), a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado (CU) at Boulder. Jun Ye, a fellow of JILA, a fellow of NIST and a professor adjoint at CU-Boulder’s Department of Physics, led the research effort with other members of his group, including Michael Thorpe.
Let's forget for a while the optical technology and let's look at the human aspect. How is it possible to detect health markers in our breaths? Here is OSA's answer. "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."
And these breath molecules can show that we're ill. "Just as bad breath may indicate dental problems, excess methylamine can be used to detect liver and kidney disease, ammonia on the breath may be a sign of renal failure, elevated acetone levels in the breath can indicate diabetes, and nitric oxide levels can be used to diagnose asthma."
Now, it's time to learn why this new technology includes the word 'comb.' A University of Colorado at Boulder news release, Scientists Using Laser Light To Detect Potential Diseases Via Breath (February 18, 2008) gives additional details. "The optical frequency comb is a very precise laser for measuring different colors, or frequencies, of light, said Ye. Each comb line, or 'tooth,' is tuned to a distinct frequency of a particular molecule's vibration or rotation, and the entire comb covers a broad spectral range -- much like a rainbow of colors -- that can identify thousands of different molecules. Laser light can detect and distinguish specific molecules because different molecules vibrate and rotate at certain distinct resonant frequencies that depend on their composition and structure, he said. He likened the concept to different radio stations broadcasting on separate radio frequencies.
For more information, this research work has been published in Optics Express under the title "Cavity-enhanced optical frequency comb spectroscopy: application to human breath analysis" (Volume 16, Issue 4, Pages 2387-2397, February 18, 2008). Here is a link to the abstract, which itself provides a link to the full paper (PDF format, 11 pages, 1.22 MB). The top image in this post has been extracted from this article.
Here is a short excerpt of the conclusions of this paper about future work. "Although these future developments promise to make more dramatic advances, we note that our current system can already be used for clinical trials to gather statistics for the feasibility and cost effectiveness of breath measurements for noninvasive health screening tests."
Sources: Optical Society of America (OSA) news release, February 18, 2008; and various websites
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