3D-printed microfluidic systems: Recent advances and emerging analytical applications

3D printing techniques, such as fused deposition modelling, stereolithography, digital light processing, MultiJet, and PolyJet printing, have become commonplace in chemical laboratories in recent years, playing a pivotal role in the fabrication of microfluidic platforms. 3D printing can frequently replace technically and operationally demanding manufacturing approaches such as soft lithography or laser ablation, thereby enabling the simple, cost-effective, and rapid production of customized devices. This review highlights recent developments and applications of 3D-printed microfluidics over the past three years. It focuses on advances in microfluidic manufacturing, such as the direct fabrication of PDMS microchips with enclosed channels, the introduction of multi-material stereolithography printers, and the production of channels with miniature cross-sections down to 1.9 × 2 μm. Furthermore, it discusses the application of microfluidics in microchip electrophoresis for monitoring preterm birth peptides, in microchip liquid chromatography, and in online sample preparation for HPLC and MS analysis. Beyond analytical separations, 3D-printed architectures play vital roles as droplet generators, encapsulation tools for the preparation of controlled-release tablets, and devices for sorting nanoparticles or cells by size. In the field of microfluidic sensors, point-of-care devices, non-invasive collection of clinical samples, and the integration of smartphones as optical detectors have gained significant traction. Finally, molecular biology applications of 3D-printed microfluidics are highlighted, including field-deployable DNA isolation for the detection of bacterial contamination and the controlled cultivation of cells and tissues within organ-on-a-chip systems.