Surface modification of micro-fluidic devices

The surface modification, fabrication and characterization of microfluidic sensor systems for oxygen and glucose measurements with the use of polymeric materials were investigated in this dissertation. This dissertation is prepared in publication format. The first manuscript focuses on the surface modification of SU -8 layer to enhance the wettability. The improvement of wettability is critical since biofouling can be minimized during bioanalysis. A novel in situ photopattemable grafting technology was used to attach biocompatible polymer layers on SU-8 surface, changing its property from hydrophobicity to hydrophilicity. The results were confirmed by contact angle measurement and Fourier Transform Infrared (FTIR) spectra. The second manuscript demonstrates the use of modified SU-8 for applications to microfluidic sensors for dissolved oxygen measurements based on quenching behavior of fluorophore. A new chemical anchoring method was introduced to lithographically pattern sensing elements inside a complete SU-8 microfluidic channel. A stable Stem-Volmer relationship between oxygen content and fluorescent intensity was observed for two months. The third manuscript is about the fabrication and characteristic of fluorescent glucose microfluidic sensor by using an optically transparent dry film, PerMX 3050. It was possible to determine the glucose concentrations by the normalized initial reaction rates, derived from the fluorescent intensity change caused by enzymatic oxygen consumption. Novel polymer materials and surface modification technologies introduced in this dissertation have been successfully applied to optical microfluidic sensors and exhibit a large potential for many other biomolecules assay --Abstract, page iv