Direct Molding of Luer Connections in PDMS Microfluidic Devices: Comparison with Conventional Interface Methods

Reliable world-to-chip connections remain a critical challenge in PDMS-based microfluidic devices, particularly under high-pressure flow conditions. In this work, we present a simple, low-cost, and reproducible method to directly mold male Luer cone fittings into PDMS devices during fabrication, without compromising the geometry of microchannels. To evaluate the effectiveness of this approach, we compared the performance of three connection types-PTFE tubing, metal pipes, and molded Luer adaptors-by measuring the infusion pressure at which fluid leakage occurred. Devices with integrated Luer adaptors consistently withstood higher pressures (up to 1555 mbar) with reduced variability across repeated connection cycles, while PTFE and metal connections failed at lower pressures and showed inconsistent leakage behavior. As a biological proof of concept, Staphylococcus aureus biofilms were grown in the microfluidic channels under continuous perfusion and subsequently exposed to flow rates of 50, 83.3, and 116.7 µL/min. Image analysis showed an initial biofilm-covered area of 14.22% of the analyzed channel area, while the biofilm areas remaining after exposure to 50, 83.3, and 116.7 µL/min were 1.39, 0.85, and 0.32%, respectively. The final measurement represented a reduction of approximately 97.7% relative to the initial biofilm coverage. The molded Luer connections maintained stable fluid delivery during biofilm cultivation and flow-induced detachment, supporting their use in biological microfluidic applications. Overall, this molding strategy provides a robust and reusable Luer-compatible interface for integrating standardized connections into soft-lithography-based microfluidic platforms.