QCLASER NOSE

Ultrasensitive Quantum Cascade Laser spectroscopy for the heterodyne detection of exhaled biomarkers

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 Obiettivo del progetto (Objective)

'This proposal is designed to combine high-performance Quantum Cascade Lasers with the most advanced cavity-enhanced spectroscopic methods in order to develop new trace-gas methods. This project will lead to a non-invasive and compact, diagnostic tool for the real-time analysis of trace gas concentrations in human breath. The detection in human breath of gases with medical relevance, and particularly of hydrogen peroxide (H2O2), and hydrogen cyanide (HCN), will be our main challenge. The first innovative step of this research will be the development of a continuous wave mid-infrared External Cavity Quantum Cascade Lasers (EC-QCL), offering broad frequency tuning range in the 4-11 micrometer infrared region, high tuning speed, and high output power. This laser source will be able to probe a vast majority of molecular gases exhibiting strong or fundamental vibrational absorption bands in the mid-infrared. For this project the detection sensitivity has to be pushed to extreme limits. Therefore, as a second step, Frequency Modulation of the EC-QCL source will be developed, to perform for the first time with QCLs, Noise Immune Cavity Enhanced Optical Heterodyne Molecular Spectroscopy (NICE-OHMS). Based on the use of high-finesse optical cavities, it will enable the tracing of molecules at the low part-per-trillion volume: the required sensitivity to trace exhaled biomarkers from humans.'

Introduzione (Teaser)

Most laser setups used to identify molecules in the air can only identify one at a time. Scientists developed a small, simple system to rapidly detect multiple molecules in exhaled breath with high accuracy.

Descrizione progetto (Article)

An increase in hydrogen peroxide (H2O2) concentration in exhaled breath is considered a reliable indicator of lung diseases such as asthma and chronic obstructive pulmonary diseases. It has also been linked to exposure to air pollutants such as ozone (O3). Sensitive and accurate measurement and monitoring of biomarkers in exhaled breath is a non-invasive way to obtain reliable information relevant to the diagnosis and treatment of disease processes.

Infrared (IR) lasers (in particular, continuous wave quantum cascade lasers (cw-QCLs)) with specialisation for spectroscopic use have been widely used to determine the contents of samples for medical, military and environmental purposes. However, the specialisation imposes a narrow tuning restriction on the spectral range that requires the use of multiple QCLs to detect multiple molecules.

EU support of the project 'Ultrasensitive quantum cascade laser spectroscopy for the heterodyne detection of exhaled biomarkers ' (QCLASER NOSE) enabled scientists to develop a small, A4-size instrument capable of detecting several medically relevant molecules.

Consisting of a QCL chip in an external cavity (EC) of wide tuning range, the instrument exhibits fast tuning speed and high resolution as well as exploiting a novel technique, integrated cavity output spectroscopy (ICOS). The inherent flexibility of the design facilitates use of the instrumentation with other QCLs at other wavelengths without changing the EC configuration. Scientists demonstrated its ability to detect any absorption in the mid-IR wavelength region of 8 micrometres that is characteristic of numerous biologically relevant molecules.

The QCLASER NOSE sensor was able to detect a variety of gases within a few seconds. ICOS makes it particularly useful for the detection of trace concentrations of biomarkers in exhaled breath. Eventual commercialisation of the small and easy-to-use system could have important impact on disease diagnosis and even in preventive medicine.