P2.5 - High sensitivity optoelectronic sensor for nitric oxide detection in exhaled air

Abstract

Certain gases in human breath are known to be indicators of the presence of diseases. These gases have been identified as biomarkers using different instruments, mainly based on chemical methods, e.g. gas chromatography or chemiluminescence. The article describes an application one of the most sensitive optoelectronic method – Cavity Enhanced Absorption Spectroscopy (CEAS) to investigation of fractional exhaled nitric oxide (FeNO). Measurement of FeNO concentration is a quantitative, non-invasive, simple, and safe method of respiratory inflammation and asthma diagnosis. For detection of NO the vibronic molecular transitions were used in our optoelectronic sensor. The wavelengths of these transitions are situated in the spectral range of 5.23 μm – 5.29 μm. A setup of the sensor consists of a pulsed quantum cascade laser (QCL), optical cavity, high sensitivity photoreceiver and a digital signal processing system. The optical cavity was built of spherical mirrors of high reflectance. The leakage optical signal from the cavity output was detected with specially developed low noise detection module. In the sensor, the detection limit of 75 ppb (parts per billion) was obtained.