Method to fabricate round cross‐sectional channel using thermal expansion of air for passive flow regulators

Abstract

We present a novel method for fabricating round cross‐sectional channels for autoregulatory pressure regulators. The application of previously reported methods in multilayered soft lithography using three‐dimensional printed molds is challenging. Herein, we used a thermal expansion technique to create round cross‐sectional channels in replica layers using air in the cavity space of a master mold. The width and height of the round channel in the replica could be adjusted in the range of 80–300 and 3–57 µm, respectively, by varying the precuring time of the replica in the gel state and adjusting the cavity size of the master mold. We successfully fabricated a pressure regulator with a round cross‐sectional channel, achieving a constant output pressure at a low threshold input pressure. Our device exhibited superior performance, with a constant output pressure at a threshold input pressure of less than 77%, compared to a device with a rectangular cross‐sectional channel. Our method has significant potential for application in the fabrication of integrated microfluidic systems with round cross‐sectional channels.