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C. Gasser, B. Lendl:
"Application of tunable MEMS-based Fabry-Pérot filters and pulsable thermal infrared sources in MIR spectroscopy";
Poster: 12th Martin and Willis student meeting, Glasgow; 12.09.2013 - 13.09.2013.

With increasing demand of PAT (Process Analytical Technology) for on- or inline monitoring of chemical as well as pharmaceutical processes, the need for powerful, robust and low priced sensors increases. Most reasonable priced online techniques offer simple access to parameters such as pH or redox potential. However, they often fail when specific information about chemical composition and condition is required. IR spectroscopy represents a technique, which is chemically selective towards different compounds and therefore well suited for analysis of different processes. Nonetheless, most IR spectrometer are relatively expensive and bulky.
We present a novel, simple, small-sized and cheap technique for IR spectroscopy of liquids. The combination of pulsable thermal IR sources with tunable Fabry-Pérot (FP) filters with integrated pyrodetectors allows the construction of a classical transmission setup using a flow cell. We are able to show that this way IR spectra of different analytes in aqueous solution can be collected and quantification is possible. For the problem at hand, the tunable FP filter shows similar performance to the FTIR spectrometer.