3D printed molds for non-planar PDMS microfluidic channels

•Development of 3D printed molds for rapid fabrication of complex microchannel.•Quantification of technological limits of 3D printed molds.•Microfluidic networks in monolithic polydimethylsiloxane (PDMS) blocks. This article introduces the use of three-dimensionally (3D) printed molds for rapid fabrication of complex and arbitrary microchannel geometries that are unattainable through existing soft lithography techniques. The molds are printed directly from computer-aided design (CAD) files, making rapid prototyping of microfluidic devices possible in hours. The resulting 3D printed structures enable precise control of various device geometries, such as the profile of the channel cross-section and variable channel diameters in a single device. We report fabrication of complex 3D channels using these molds with polydimethylsiloxane (PDMS) polymer. Technology limits, including surface roughness, resolution, and replication fidelity are also characterized, demonstrating 100-μm features and sub-micron replication fidelity in PDMS channels.