Development of a gas sensing platform for environmental and industrial applications

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Multipass cell comprising six spherical mirrors. Examples for a ray traced pattern (top) and a measured light pass (bottom).

Progress in sensor technologies and their applications has become one of the key ingredients in the technological development of the industrialized world. Furthermore, sensors are essential to address some of the major challenges of today's society such as monitoring and control of our environment. Techniques based on optical absorption offer the possibility to realize a non-invasive and highly sensitive detection.

With Nanotera-Irsens we pool together the know-how of leading groups of Switzerland to establish a technology platform for optical chemical sensing. The groups of ETH (Faist) and EPFL (Kapon) tackle the infrared laser sources (QCL and VCSEL); EMPA (Emmenegger) and ETH (Sigrist) the gas sensing; UNINE (Herzig and DeRooij) and ETH (Sigrist) the liquid sensing; UNINE (Hofstetter) and EPFL (Charbon) detectors and signal processing.

The IrSens gas sensing platform promises to be compact, fast, sensitive and versatile to serve industrial, medical and environmental applications. One key element of this platform is the optical cell which, in combination with quantum cascade lasers, can be used to detect a wide range of gas molecules that have their fundamental absorption lines in the mid-IR. The current cell design is suitable for direct absorption, wavelength modulation, and photoacoustics. First results indicate that the achievable precision for ambient CO2 and N2O concentrations is well below 1 ‰ at 1 second averaging time, and that real time data acquisition and processing of up to 200Hz can be achieved.