Optical chemical sensor technology in the mid-infrared (MIR) spectral range (3-20 µm) is gaining importance in process monitoring, environmental analysis, and the biomedical field due to the increasing demand for versatile and robust sensor technology with inherent molecular specificity. Interfacing IR transducers with continuous measurement or surveillance situations becomes increasingly feasible with the advent of appropriate waveguide technology (e.g., MIR transparent optical fibers, planar semiconductor waveguides and resonators, etc.), innovative surface coatings (e.g., functionalized polymers, diamond-like carbon, etc.), and the availability of advanced light sources such as e.g., room-temperature operated tunable quantum cascade lasers (QCLs) next to conventional FT-IR spectrometers.
Our fundamental research interests focus on the development of innovative infrared sensing concepts with particular emphasis on system miniaturization/integration, concepts for increased sensitivity in liquid and gas phase sensing applications, and medical applications of IR diagnostics. Recently, we have been extending our efforts into the far-infrared/terahertz spectral regime (THz, 20-300 µm) with main emphasis on nearfield imaging techniques, and integrated sensing platforms for the label-free detection of biomolecular interactions (e.g., DNA hybridization).
Furthermore, we develop deep-sea deployable MIR sensing techniques enabling molecularly selective detection at extreme environmental conditions (e.g., gas hydrates, diamandoids, marine sediments, etc.). These efforts are complemented by the development of novel concepts in multivariate data analysis for autonomous sensor operation and data mining.
- Evanescent field sensors based on quantum cascade laser
- Trace gas analysis with hollow waveguides
- Planar MIR semiconductor waveguides and resonators
- Deep sea MIR sensor technology and spectroscopy
- MIR sensors and spectroelectrochemistry with DLC-coated waveguides
- Integrated nearfield THz technology
- Virtual MIR sensors - Modeling and simulation
- New concepts in multivariate data analysis
Biomimetic recognition schemes utilizing molecularly templated/imprinted polymers (MIPs) have proven their potential as synthetic receptors in numerous applications including liquid chromatography, solid phase extraction, biomimetic assays, and sensor technology. The inherent advantages of synthetic receptors and functionalized membranes in contrast to biochemical/biological recognition and immobilization schemes include their robustness, synthetic versatility, and low cost, thereby rendering MIPs and related materials ideal molecular capture or scavenger matrices tailorable for selective recognition or immobilization of a wide range of target molecules.
We have successfully demonstrated this concept for a variety of molecular species including flavones/flavonoids, mycotoxins, herbicides/pesticides, nitrophenoles, and endocrine disrupting compounds (e.g., estradiol derivatives). More recently, our research focuses on biomedical and biotechnological applications of MIPs including selective scavengers for contrast agents and proteins. However, tailoring synthetic recognition elements to a target analyte requires thorough analysis and fundamental understanding of the molecular interactions governing the imprinting process. An ultimate goal of our research is the rational prediction and design of optimized synthetic strategies leading to molecular capture, recognition, and immobilization schemes with superior control on their physical properties and molecular selectivity. Hence, we focus on combining the analysis of the governing principles in molecular templating by NMR, IR, UV/VIS, MS, ITC, and XRD studies for elucidating the nature of the molecular interactions with fundamental molecular (dynamics) simulations enabling predictive modeling.
In addition to MIPs, a wide variety of (functionalized) polymer and sol-gel membranes are studied with particular emphasis on their molecular enrichment properties for volatile organic target analytes (VOCs) including e.g., benzene, chlorinated hydrocarbons, etc. for use in chemical sensors.
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