Bragg gratings based on hybrid polymers for analytical sensor technologies

• Applicants: Professor Dr. Lothar Frey (†); Professor Dr. Ralf Hellmann
• Subject Area: Microsystems
• Term: from 2013 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 244990912

The objective of this proposal is the development of an optical sensor system for the qualitative and quantitative analysis of liquids and gases. For this purpose, the photonic structure of a Bragg grating will be used as its feasibility in Ormocer® hybrid polymers has already been proven within the scope of the DFG-projects.The striven concept is based on an optical splitter system, which is molded into hybrid polymers via the innovative UV enhanced substrate conformal imprint lithography (UV-SCIL). This compact system of waveguides and couplers, covering only few square centimeters, comprises a matrix of volume type Bragg gratings with different periodicity. The gratings are induced by using static phase mask technology combined with a KrF-Excimerlaser. Introducing a broad banded incident spectrum of light into the sensor system, a polychromatic reflection is created as sum of the individual reflections of each inscribed Bragg grating. To compensate possible cross sensitivities (e.g. due to temperature fluctuations) individual Bragg gratings could be isolated. Further on, the targeted concept allows a selective sensitization of single elements aiming for a general or analyst specific increase in sensitivity. Due to the fact of using Bragg gratings as sensor elements, a singular connection of the sensor suffices, realized by the coupling of a single-mode fiber to the system. To characterize and improve the system integration, an analysis and optimization of several coupling strategies is striven within this project.

• DFG Programme: Research Grants