Methods for the functionalization of polymer biosensor surfaces are applied for the binding of receptors and the sensing of biological particles. In many cases the same biosensor polymer has to perform transduction mechanisms as in the case of optical waveguides. The effects of the functionalization process on the sensor transduction properties like absorption and surface roughness loss should be minimal. In this work we investigate the formation of functional groups by oxygen plasma treatment as a method of precise surface modification for PMMA and SU-8 waveguide materials. Oxygen groups were analyzed by contact angle measurements, XPS, chemical derivatization XPS and fluorescence labeling
We report the nanoimprinting of a microring resonator (MRR) and the development of a functional nanoimprint polymer as route toward selective MRR biosensors. A hybrid, residual layer-free, UV assisted nanoimprint technique was used to pattern freestanding polymer waveguides with a resolution of 300nm and an aspect ratio of 4:1. A low viscous, functional UV nanoimprint polymer was formulated with a hydroxyl functional acrylate monomer (4-hydroxyl butyl acrylate, HBA). The functional polymer was characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The added hydroxyl groups were found on the polymer surface and were accessible for selective binding of a fluorine tag (trifluoroacetic anhydride, TFAA). The density of the hydroxyl groups was tuned by the HBA concentration. A maximum hydroxyl group density of 8.4% was reached for 33.75wt% HBA. The RMS surface roughness was 1.2-2.2nm. Polymeric photonic MRR with superficial chemical functio nalities for a subsequent biomolecule binding and application as a biosensor
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