Patterning of a nanoporous membrane for multi-sample DNA extraction

A novel method for patterning a nanoporous aluminum oxide membrane was developed using SU-8 to allow for extraction of DNA from multiple samples simultaneously. To facilitate the patterning process, the spin curve for SU-8 2015 on the membrane was determined. The correlation profile of the SU-8 spin curve was similar in form to curves of SU-8 spun on silicon wafers, but with a uniform decrease in thickness across the curve. Characterization of the patterned SU-8 regarding step height and surface roughness was determined using pin-based surface profilometry. The patterned aluminum oxide membrane displayed acceptable flatness and precise pattern replication. Thickness uniformity was also observed to be approximately +/-2.8% for a 29.3 mum thick pattern. SEM imaging was used to examine the exposed membrane surface for any visible changes or damage to the membrane caused by the patterning process, with none observed. DNA extraction was performed on the patterned membrane using multiple wells to show the ability of collecting multiple DNA samples simultaneously. DNA, marked with a fluorescent dye, was collected on the membrane and successfully observed using a fluorescence microscope. The techniques developed in this work have application to lab-on-a-chip type systems that include DNA extraction steps.