Capillary Flow in PDMS Cylindrical Microfluidic Channel Using 3-D Printed Mold

This letter investigates the capillary filling in polydimethylsiloxane (PDMS) microchannels using 3-D printed molds to produce channels with circular cross sections. The circular cross sections are prevalent in biology and anatomy, yet they cannot readily be mimicked with existing soft-lithography techniques. The molds are printed directly from computer-aided design files, making rapid prototyping of microfluidic devices possible in hours, demonstrating microscale features in PDMS channels. The PDMS channels with variable channel diameters ranging from 200 to 1000 μm in a single device that are obtained from four different 3-D printers are compared in terms of capillary flow. Technology limits, including surface roughness and resolution, are also characterized, and estimated as an equivalent contact angle which is a fit parameter dependent on the 3-D printer.