Advancing modular microfluidics: Stereolithographic 3D printing of reconfigurable connectors for bioanalytical applications

Traditional monolithic microfluidic devices are constrained by their inability to accommodate modifications to circuit elements, necessitating complete redesign and refabrication. To address these limitations, this study introduces modular microfluidic connectors fabricated via stereolithographic (SL) 3D printing. We designed and evaluated three distinct connector types-tessellated, sponge, and solid-walled-using tailored photoresins to enhance reusability, flexibility, and sealing performance. The tessellated connectors, printed with poly(ethylene glycol) diacrylate (PEGDA, Mw ~258) and incorporating an Octet Unit cell structure, reduced the rigidity of PEGDA prints, improving reusability under moderate conditions. The sponge connectors, fabricated from a PEGDA and 2-hydroxyethyl acrylate (2-HEA, Mw ~116) blend (2-HEA-co-PEGDA), exhibited greater flexibility; however, swelling in aqueous environments may limit their long-term utility. In contrast, the solid-walled connectors, produced with commercial Asiga Soft Resin, demonstrated superior reliability and adaptability, as validated in a reconfigurable concentration gradient generator (CGG) with scalable output capabilities. Cytocompatibility tests confirmed that PEGDA-printed devices, following isopropanol (IPA) and UV post-processing, are suitable for bioanalytical applications that do not require incubation. These findings establish SL 3D printing as a promising method for developing flexible, reconfigurable microfluidic platforms, with potential uses in material synthesis, chemical analysis, and point-of-care diagnostics. While challenges related to environmental durability persist, these advances lay the foundations for developing more robust and adaptable microfluidic systems with versatile applications.