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, has shown that by sampling a person’s breath with laser light they can detect molecules in the breath that may be markers for diseases like asthma or cancer.
While many studies have been done to showcase the potential of optical technologies for breath analysis, the JILA approach takes an important step toward demonstrating the full power of optics for this prospective medical application. Their findings are published in the latest issue of the Optical Society of America’s open-access journal Optics Express.
The technique, called cavity-enhanced direct optical frequency comb spectroscopy, may one day allow doctors to screen people for certain diseases simply 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.
Optical frequency comb spectroscopy was developed in the 1990s by 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). In the paper, Michael Thorpe, a graduate research assistant, Ye, and their colleagues describe the novel application of this technique to breath analysis. 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.
Some of these tracer breath molecules are biomarkers of disease. 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. When many breath molecules are detected simultaneously, highly reliable and disease-specific information can be collected. For instance, asthma can be detected much more reliably when carbonyl sulfide, carbon monoxide, and hydrogen peroxide are all detected in parallel with nitric oxide. The reported approach offers exactly this kind of potential.
In the experiments performed by Ye and his colleagues, optical frequency comb spectroscopy was used to analyze the breath of several student volunteers. They showed that they could detect trace signatures of gasses like ammonia, carbon monoxide, and methane on their breath. In one of these measurements, they detected carbon monoxide in a student smoker and found that it was five times higher when compared to a non-smoking student.
The researchers had the students breathe into an optical cavity—a space between two standing mirrors. The optical cavity was designed so that when they aimed a pulsed laser light into it, the light bounced back and forth so many times that it covered a distance of several kilometers by the time it exited the cavity. This essentially allowed the light to sample the entire volume of the cavity, striking all the molecules therein. In addition, this lengthens the light-molecule interaction time thereby increasing the sensitivity. By comparing the light coming out of the cavity to the light that went in, Ye and his colleagues could determine which frequencies of light were absorbed and by how much. This information told them which molecules were present in the breath from the start. The remarkable combination of a broad spectral coverage of the entire comb and a sharp spectral resolution of individual comb lines allows them to sensitively identify many different molecules, as they show in their paper.
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. Existing approaches to breath analysis are limited, because the equipment is either not selective enough to detect a diverse set of rare biomarkers, or it is not sensitive enough to detect trace amounts of the molecules exhaled in human breath. The biggest shortcoming of existing approaches is their inability to provide rapid and reliable breath measurements for many biomarkers. The new technique addresses these problems with its capability to rapidly, simultaneously, sensitively, and accurately detect many breath biomarkers. The results can qualitatively change the field of breath analysis, realizing its real potential as a low-cost, rapid, robust, and non-invasive method for health screening.
Colleen Morrison | EurekAlert!
XXL computed tomography: a new dimension in X-ray analysis
17.05.2018 | Fraunhofer-Gesellschaft
Why we need erasable MRI scans
26.04.2018 | California Institute of Technology
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.
Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...
A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.
Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
18.05.2018 | Power and Electrical Engineering
18.05.2018 | Information Technology
18.05.2018 | Information Technology