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Proceedings Paper

Real time detection of exhaled human breath using quantum cascade laser based sensor technology
Author(s): Frank K. Tittel; Rafal Lewicki; Lei Dong; Kun Liu; Terence H. Risby; Steven Solga; Tim Schwartz
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Paper Abstract

The development and performance of a cw, TE-cooled DFB quantum cascade laser based sensor for quantitative measurements of ammonia (NH3) and nitric oxide (NO) concentrations present in exhaled breath will be reported. Human breath contains ~ 500 different chemical species, usually at ultra low concentration levels, which can serve as biomarkers for the identification and monitoring of human diseases or wellness states. By monitoring NH3 concentration levels in exhaled breath a fast, non-invasive diagnostic method for treatment of patients with liver and kidney disorders, is feasible. The NH3 concentration measurements were performed with a 2f wavelength modulation quartz enhanced photoacoustic spectroscopy (QEPAS) technique, which is suitable for real time breath measurements, due to the fast gas exchange inside a compact QEPAS gas cell. A Hamamatsu air-cooled high heat load (HHL) packaged CW DFB-QCL is operated at 17.5°C, targeting the optimum interference free NH3 absorption line at 967.35 cm-1 (λ~10.34 μm), with ~ 20 mW of optical power. The sensor architecture includes a reference cell, filled with a 2000 ppmv NH3 :N2 mixture at 130 Torr, which is used for absorption line-locking. A minimum detection limit (1σ) for the line locked NH3 sensor is ~ 6 ppbv (with a 1σ; 1 sec time resolution of the control electronics). This NH3 sensor was installed in late 2010 and is being clinically tested at St. Luke's Hospital in Bethlehem, PA.

Paper Details

Date Published: 23 February 2012
PDF: 8 pages
Proc. SPIE 8223, Photons Plus Ultrasound: Imaging and Sensing 2012, 82230E (23 February 2012); doi: 10.1117/12.912273
Show Author Affiliations
Frank K. Tittel, Rice Univ. (United States)
Rafal Lewicki, Rice Univ. (United States)
Lei Dong, Rice Univ. (United States)
Kun Liu, Rice Univ. (United States)
Terence H. Risby, The Johns Hopkins Bloomberg School of Public Health (United States)
Steven Solga, St. Luke's Hospital (United States)
Tim Schwartz, St. Luke's Hospital (United States)


Published in SPIE Proceedings Vol. 8223:
Photons Plus Ultrasound: Imaging and Sensing 2012
Alexander A. Oraevsky; Lihong V. Wang, Editor(s)

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