Research Projects

Human exhaled breath (HEB) gas analysis holds great promise as a versatile framework for general bio-monitoring applications. More recently, due to the advancements in detection and sensing technologies, researchers have found that there are biomarkers, including volatile organic compounds (VOCs) and other trace gases, that may be present because of regular metabolic activity in the body, pathological disorders, and exposure to drugs and they can act as biomarkers of various diseases For example, HEB contains methane (CH4) (2-10 ppm), acetone (C3H6O) (0-2.5 ppm), ammonia (NH3) (100-278 ppb), carbon monoxide (CO) (1-10 ppm), nitric oxide (NO) (1-20 ppb), etc. as biomarkers. Depending on the pathological conditions, the concentrations of some of the biomarkers vary significantly. Although HEB analysis techniques provide a promising non-invasive, real-time diagnostic platform, they are not yet routinely used in hospitals and clinics. The traditional analysis methods are based on offline blood sample analysis. Gas Chromatography (GC) based separation coupled with Mass Spectrometry (MS) remains the ‘gold standard technique’ for trace gas analysis. However, these techniques involve manual sampling procedures and sample preparation. The need for point-of-care medical instrumentation is increasing for diagnostic and monitoring purposes. Human exhaled breath consists of many VOCs, which are significant biomarkers. Laser spectroscopic-based non-invasive human exhale analysis is useful for real-time analysis without discomfort to the subject. Most of these approaches involve complex tunable laser systems and spectrometer systems in the mid-infrared (Mid IR) range. Alternatively, the proposed quartz-enhanced photoacoustic spectroscopy combined with the supercontinuum laser source and broadband tunable filter can be used to demonstrate measurement of trace gases from breath and can also be extended to the measurement of many other biomarkers selectively. Different research groups are working towards measuring ethane, nitric oxide, carbonyl sulfide, ethylene, etc. However, to the best of our knowledge, there are no reports on the application of the quartz-enhanced photoacoustic technique using a broadband/tunable light source for breath gas analysis to measure biomarkers, such as NH3 (associated with liver/kidney diseases), CH4 (gastrointestinal activity), CO (oxidative stress), NO (respiratory inflammation), and C3H6O (glucose/diabetic activity). The proposed study will focus on the development of a compact health monitoring system based on the quartz-enhanced photoacoustic spectroscopy technique combined with a broadband optical source for the selective detection of biomarkers like acetone, carbon monoxide and ammonia in real-time towards hospital and clinical applications. Further, the sensor output will be processed using Artificial Neural Networks to determine the concentration of the biomarker under consideration and improve the sensitivity of the system and reduce cross-interference from other gases (CO2, H2O) in the breath matrix. The broadband tunable source allows tuning the laser to a particular absorption band of a target gas with multiple absorption lines and the absorption allows enhanced photoacoustic signal strength. This proposal aims to work towards the development of a compact QEPAS-based biomarker concentration sensor using a broadband mid-infrared light source for a real-time application in hospital/clinical applications.