IrSens: Integrated sensing platform for gases and liquids in the near and mid-infrared range

Edoardo Charbon of EPFL/IC/LAP/AQUA, expert in SPAD Sensors. Silicon detectors and signal processing

Lukas Emmenegger of EMPA, expert in Gas spectroscopy

Hans Peter Herzig of EPFL/STI/IMT/OPT , expert in micro-optics and photonic crystal-based sensors

Daniel Hofstetter of UniNE/Institut de Physique, expert in mid-infrared III-V detectors

Alexandra Homsy of EPFL/STI/IMT/SAMLAB, expert in Micro-fluidics

Eli Kapon of EPFL/SB/IPEQ/LPN, expert in VCSELs

Herbert Looser of FHNW/IGN, expert in nonlinear optics

Markus Sigrist of ETHZ/D-PHYS/IQE/LSSL, expert in Gas and liquid spectroscopy

The aim of this project is to create a photonic sensor platform with high performance and reliability. This platform will leverage on the new source, detector and interaction cell technologies to create a new sensor element with vastly improved performance and lowered cost. These improvements will be demonstrated further by the incorporation into two pilot applications, the first one aiming at the demonstration of the sensing in the gas phase, the second one in the liquid phase. The two sensors will be developed in parallel and they will share some common points, namely the optical absorption spectroscopy technique, the compactness of the sensor, and an integrated approach concerning the components of the sensor (source, interaction region and detection) resulting in an integrated sensing platform.

The first sensor will be dealing with breath analysis: extensive studies have been carried out in recent years to apply this technique to clinical diagnosis. Most of these studies made use of mass spectrometry with or without prior separation by gas chromatography. The current trend goes towards other techniques that are ideally small, affordable and accurate. A prime candidate for modern breath analysis is infrared spectroscopy. We intend to build a compact gas sensing platform, based on QCLs as a compact and powerful light source in the mid-infrared. QCL absorption spectroscopy (QCLAS) can be used to detect a wide variety of gases. To demonstrate its suitability for breath analysis, the first part of this project is focused on the detection of helicobacter pylori by means of isotopic ratio measurements in exhaled CO₂. Helicobacter pylori has been linked to over 80 % of gastric ulcers with an infection rate of around 25 % in Western Europe. The infection can be detected based on an increase of ¹³CO₂ following ingestion of ¹³C-labeled urea. Thus, isotopic ratio breath analysis is an excellent tool for its medical diagnosis.

The second main objective of this project consists in developing an integrated sensing platform for fluids based on infrared laser spectroscopy in silicon based systems. The basic idea is to develop a multiwavelength semiconductor laser source based on either mid-infrared QCLs or on near-infrared VCSELs and to couple them to a silicon based optical module where the liquid analyte will flow through a built-in micro-fluidic channel. The integrated approach to this sensor will imply the development of a broadband silicon based detection element being responsible also for the data acquisition. The described platform is intended to be used mainly in bio-medical applications with a particular emphasis on drugs and doping agents detection in human fluids, and it would take advantage of a high sensitivity performance together with the very small volume of specimen needed for the analysis. A first targeted demonstrative application for this sensor would be the cocaine detection in human saliva.

The project will be organized around the three key elements of the photonic sensor platform: optical source, interaction cell and detectors. The selected groups will assemble complementary expertise of the highest caliber from Swiss institutions.

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