title: Mid-infrared quantum cascade laser based off-axis integrated cavity output spectroscopy for biogenic nitric oxide detection.
abstract: Tunable-laser absorption spectroscopy in the mid-IR spectral region is a sensitive analytical technique for trace-gas quantification. The detection of nitric oxide (NO) in exhaled breath is of particular interest in the diagnosis of lower-airway inflammation associated with a number of lung diseases and illnesses. A gas analyzer based on a continuous-wave mid-IR quantum cascade laser operating at approximately 5.2 microm and on off-axis integrated cavity output spectroscopy (ICOS) has been developed to measure NO concentrations in human breath. A compact sample cell, 5.3 cm in length and with a volume of < 80 cm3, that is suitable for on-line and off-line measurements during a single breath cycle, has been designed and tested. A noise-equivalent (signal-to-noise ratio of 1) sensitivity of 10 parts in 10(9) by volume (ppbv) of NO was achieved. The combination of ICOS with wavelength modulation resulted in a 2-ppbv noise-equivalent sensitivity. The total data acquisition and averaging time was 15 s in both cases. The feasibility of detecting NO in expired human breath as a potential noninvasive medical diagnostic tool is discussed.
authors.affiliation: Department of Electrical and Computer Engineering, Rice University, 6100 South Main Street, Houston, Texas 77005-1892, USA.
authors.forename: Yury A
authors.initials: YA
authors.lastname: Bakhirkin
authors.forename: Anatoliy A
authors.initials: AA
authors.lastname: Kosterev
authors.forename: Chad
authors.initials: C
authors.lastname: Roller
authors.forename: Robert F
authors.initials: RF
authors.lastname: Curl
authors.forename: Frank K
authors.initials: FK
authors.lastname: Tittel
mesh_terms: D045853:Exhalation / Q000502:physiology; D005240:Feasibility Studies; D007834:Lasers; D008904:Miniaturization; D009569:Nitric Oxide / Q000032:analysis* / Q000378:metabolism; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013055:Spectrophotometry, Infrared / Q000295:instrumentation* / Q000379:methods*; D014159:Transducers
chemical_list: D009569:Nitric Oxide