Biophotonic fluorescence excitation with integrated polymer waveguides

Abstract

All-organic chips with integrated optical waveguides and microfluidic channels were built for fluorescence excitation of biological samples. These optofluidic systems were made out of poly (methyl methacrylate) (PMMA) with lithographically generated or micro machined fluidic structures. Integration of the waveguides was based on photodegradation of PMMA through deep ultraviolet (DUV) radiation. Two types of demonstrators were created in order to show the applicability of the integrated optical waveguides. In one set free space illumination via the waveguide and thus fluorescence excitation of biological samples located inside or flowing through a microfluidic channel could be shown. In another set fluorescence excitation via evanescent field coupling of biological samples located on top of an embedded optical waveguide was simulated and could be experimentally proven. As biological samples stained living animal cells (L929 mouse fibroblasts with DiD membrane staining), fluorophore labeled proteins (Cy3), or phospholipids (rhodamine) were used with the optofluidic micro systems. Emitted fluorescence was observed with a microscope. The experiments serve as a proof of concept for the layout of a cell based optofluidic microsensor built as a monolithic polymer device with potential use as a Lab-on-a-Chip system.