24 January 2011 Real time ammonia detection in exhaled human breath using a distributed feedback quantum cascade laser based sensor
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Abstract
A continuous wave, thermoelectrically cooled, distributed feedback quantum cascade laser (DFB-QCL) based sensor platform for the quantitative detection of ammonia (NH3) concentrations present in exhaled human breath is reported. The NH3 concentration measurements are performed with a 2f wavelength modulation quartz enhanced photoacoustic spectroscopy (QEPAS) technique, which is very well suited for real time breath analysis, due to the fast gas exchange inside a compact QEPAS gas cell. An air-cooled DFB-QCL was designed to target the interference-free NH3 absorption line located at 967.35 cm-1 (λ~10.34 μm). The laser is operated at 17.5 °C, emitting ~ 24 mW of optical power at the selected wavelength. A 1σ minimum detectable concentration of ammonia for the line-locked NH3 sensor is ~ 6 ppb with 1 sec time resolution. The NH3 sensor, packaged in a 12"x14"x10" housing, is currently installed at a medical breath research center in Bethlehem, PA and tested as an instrument for non-invasive verification of liver and kidney disorders based on human breath samples.
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Rafał Lewicki, Rafał Lewicki, Anatoliy A. Kosterev, Anatoliy A. Kosterev, David M. Thomazy, David M. Thomazy, Terence H. Risby, Terence H. Risby, Steven Solga, Steven Solga, Timothy B. Schwartz, Timothy B. Schwartz, Frank K. Tittel, Frank K. Tittel, "Real time ammonia detection in exhaled human breath using a distributed feedback quantum cascade laser based sensor", Proc. SPIE 7945, Quantum Sensing and Nanophotonic Devices VIII, 79450K (24 January 2011); doi: 10.1117/12.874887; https://doi.org/10.1117/12.874887
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