Screen printing technique for DUV patterning of PMMA substrates

Plastics and Poly-Methyl-Methacrylate (PMMA) is becoming the choice of microfluidic components in medical diagnostic systems these days. These materials offer excellent flexibility in manufacturing processes and also make the technology economical compared to traditional glass and silicon based devices. Deep-UV exposure based PMMA microfluidic devices fabrication has been reported in the past. However it utilizes a fairly expensive metal deposition step and standard photoresist based lithographic process steps. While this demonstrates a direction toward economical processing of PMMA microfluidic parts, a more cost effective process needs to be developed to address ultra economical process for PMMA parts fabrication. In this context, this thesis proposes the utilization of the ubiquitous silk screen printing process to pattern PMMA surface for producing microfluidic components. The ink utilized in the silk screen printing process is inherently opaque to DUV. Further screen printed and dried ink is readily dissolved in isopropyl alcohol (IPA) which is the standard developing and etching solution for PMMA. These features allow us to configure a process sequence to ultra economically pattern PMMA substrates and produce microfluidic components. This thesis outlines this novel technique and also analyses the fabricated components for bio-compatibility by studying the fabricated surface using XPS.