Photoresist‐Assisted 3D Printing for Rapid Fabricating Circular Microchannel

Abstract While 3D printing‐based microchannel fabrication is advantageous in terms of simple and time‐saving, the rough surface of the fabricated channel limits its wide application. To address this problem, this paper introduces a photoresist‐assisted 3D printing technique for fabricating circular master molds tailored for soft microchannel fabrication. The effects of photoresist spin‐coating speeds and 3D‐printed convex microstructure sizes on surface roughness and the sizes of the fabricated microchannel are investigated. It is found that after photoresist spin‐coating, the surface roughness of the printed microstructure is reduced to 15.44 nm. The thickness of the coated photoresist film and the bottom width of the microchannel decreased with the increase in spin‐coating speed, while the channel height is the same as that of 3D‐printed microstructures. Parallel microchannels with a separation distance of 65.75 µm are fabricated. This technique is further applied for fabricating a pneumatically actuated microvalve and a straight microchannel with variable heights for real‐time detection and counting of living microalgae.