Rapid, low-cost fabrication of circular microchannels by air expansion into partially cured polymer

This paper reports a simple fabrication process for microfluidic channels with circular cross-sectional shapes using a polydimethylsiloxane (PDMS) master and thermal air expansion. This technique can be easily used to generate circular microchannels with a wide range of diameters from 25 to 150 μm through a simple bench-top fabrication process. By controlling the gelation time of the PDMS, we can obtain circular microchannels in a variety of diameters. This technique does not require plasma-activated bonding or any alignment processes. We can apply this technique to fabricate networks of circular microchannels to simulate the vascular system, micro-concave platforms for culturing microspheroids, micronozzles for droplet-generation devices, and micro-sized patch clamps for cell immobilization.