Scalable, Transparent, and Micro: 3D‐Printed Rapid Tooling for Injection Molded Microfluidics

Abstract

The fast‐growing 3D printing industry is improving its hardware at an accelerated pace. This includes higher‐resolution printing combined with a wider range of photosensitive resins. The parallel development of rapid tooling (RT) for injection molding enables upscaling 3D‐printed designs. Within microfluidics, where prototyping and scalability are key, the development of 3D‐printed RT for injection molding can prove a competitive alternative to more traditional tooling methods. Herein, the dominating parameters impacting 3D‐printed RT for injection molding are investigated, enabling the delivery of durable, high‐resolution, and optically transparent microfluidics. It is found that reducing the sidewall waviness to 1.9 ± 0.4 μm and the interlocking angle to 1.9 ± 0.8° enhances the mold release success rate to 100 ± 0.0%. The surface roughness is reduced from 1.1 ± 0.1 μm to 0.2 ± 0.0 μm by increasing layer exposure during printing. In turn, this improves the optical transparency of molded replicas to >228 lp mm−1 line resolution and increased image contrast and amplitude. Ultimately, the established procedure proves capable of running a small‐scale production (≈500 parts) of a droplet generator with 50 μm channels, with a lead production time of under 3 h from computer‐aided design to a functional device.