Pressurized photobonding for 3D-printed inertial and droplet microfluidics.

Microfluidics has transformed scientific and industrial applications by leveraging fluid dynamics at small scales, yet limitations in fabrication techniques continue to impede scalability and design flexibility. This study introduces a novel 3D-printing-based fabrication method, termed "press-cure", which enables the creation of microfluidic devices with high resolution, strong bonds, and solvent resistance using commercially available stereolithography printers. By applying uniform pressure and ultraviolet curing to 3D-printed components, the press-cure method achieves sub-100-micrometer channel dimensions, robust bonding, and structural fidelity under pressures exceeding 300 psi. We demonstrate the versatility of this technique through several microfluidic applications, including scalable step emulsifiers for droplet generation, crescent-shaped particle fabrication, and inertial focusing nozzles. The press-cure method overcomes conventional limitations of PDMS and other fabrication materials, offering enhanced geometric complexity, mechanical robustness, and chemical compatibility. This accessible and scalable approach expands the capabilities of additive manufacturing in microfluidics, paving the way for innovative designs in fields such as flow cytometry, microparticle fabrication, and droplet-based assays.