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

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 mu m and the interlocking angle to 1.9 +/- 0.8 degrees enhances the mold release success rate to 100 +/- 0.0%. The surface roughness is reduced from 1.1 +/- 0.1 mu m to 0.2 +/- 0.0 mu m 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 (approximate to 500 parts) of a droplet generator with 50 mu m channels, with a lead production time of under 3 h from computer-aided design to a functional device.