Quantum cascade laser-based sensors for the detection of exhaled carbon monoxide

摘要: Carbon monoxide (CO) is an important biomarker as it originates in the human body from heme (component of hemoglobin) degradation. Tunable laser absorption spectroscopy mid-infrared wavelength region used for sensitive trace gas sensing exhaled carbon (CO). Based on a quantum cascade emitting at 4.61 µm, two different spectroscopic methods are investigated: off-axis integrated cavity output (OA-ICOS) and modulation 2f/1f (WMS). The optical sensors integrate slow feedback system to correct drifts improving their stability over days. Both approaches demonstrate high reproducibility sensitivity during online measurements breath. Considering detection limit be equal standard deviation background fluctuations, noise-equivalent both OA-ICOS WMS 7 ppbv (1-s averaging time), leading 3.1 × 10−7 cm−1 Hz−1/2, which sufficient CO (eCO). Collection eCO samples were investigated, exhalation flow rates breath-holding time explored, provide reliable sampling method future medical investigations.