Transforming Fragile Hydrogel Chips Into Standardized Cartridges via Contact Line Pinning for Robust Microfluidics.

Hydrogel-based microfluidic chips have gained significant attention in various fields, including drug delivery, tissue engineering, and biosensing. However, the practical implementation of hydrogel chips often faces challenges related to connection methods due to the inherent fragility and wet properties of hydrogels, which limit their broader applications as testing platforms. In this context, we present a novel approach to transform hydrogel chips into standard cartridges that are low-cost, convenient to use, and suitable for mass production, effectively addressing these challenges and enhancing usability. Our cartridge design utilizes a hydrogel-plastic bonding scheme to provide mechanical support to the chip and incorporates a contactless connection method for efficient, tubing-free chip-to-world interfacing. This contactless connection method allows for a gap width tolerance between the hybrid chip and chip holder of 60-600 µm, while accommodating static fluid pressures of up to approximately 9.5 kPa. We demonstrate the applications of cartridges produced using this method in antibiotic susceptibility tests and 2D cell culture experiments. These results indicate that our method presents a viable and accessible alternative for hydrogel-based microfluidic chips, enhancing their applicability across diverse biomedical applications.