Surface infusion micropatterning of elastomeric substrates

Surface infusion micropatterning (SIM) is a novel microfabrication process for simultaneous topographical and chemical patterning of elastomeric substrates. The SIM process involves three steps: (1) infusion of a monomer into the substrate, (2) photopolymerization through a patterned contact mask, and (3) drying. For the first time, SIM is demonstrated to create wells and channels (typical depth 5–22 μm, width 20–200 μm) in two substrate materials, a crosslinked polydimethylsiloxane elastomer and a thermoplastic polyurethane elastomer. High-resolution surface features produced include a “checkerboard” well pattern and a microfluidic channel system. The surface micropatterns have been characterized by scanning electron microscopy, optical microscopy, and optical profilometry to quantify channel depth and shape. Because of wall curvature effects, SIM is most suitable for producing shallow (aspect ratio <0.5) microfluidic channels in soft elastomeric materials. Due to the different chemical composition of the interpenetrating polymer network formed in the exposed regions, SIM also produces surface chemical patterning, as illustrated by selective dye-staining experiments. The potential for SIM to impact emerging technologies is discussed in the light of process advantages and limitations.