Analytical Techniques for Microscale Analysis

Thesis (Ph.D.)--University of Washington, 2014Over the years, there has been a rapid rise in the use of microfluidics in the application of single cell studies. The ability to have low dilution and high throughput compartmentalization of cells has made this a promising platform for studying cellular responses. The most common method for assembling these devices is based on soft photolithography. In this dissertation, we report the challenges encountered in the development of diagnostic devices using traditional soft lithography. To overcome these obstacles, we examined alternative strategies including hard casting substrates such as polyurethane-methacrylate (PUMA) in place of commonly used soft substrates, such as poly(dimethyl)siloxane (PDMS). Furthermore, we investigated cost effective and rapid methods to assess the quality of our fabricated structures through a white-light interferometer constructed in a collaborative effort by the Chiu group. Preliminary data from an investigation targeted toward trapping single cells for biological analysis using a microwell array will be presented. Additionally, we will present two methods for coupling microfluidic devices with mass spectrometry for protein analysis. The first method will involve fabricating an interconnect junction for the direct insertion of a fused silica capillary emitter. In the second method, we will couple a soft polymer microchannel with a planer method of ionizing samples called surface acoustic wave nebulization. Lastly, we will investigate methods for genetic analysis using alternative platforms that do not rely heavily on traditional soft lithography for device fabrication. We will present the generation of reaction containments for polymerase chain reactions (PCR) using hydrophilic and hydrophobic patterning and by agitating an immisciblebiphase to form water-in-oil droplets