A room-temperature bonding technique for the packaging of hydrogel-based hybrid microfluidic devices

Abstract

We present a room-temperature bonding technique which enables the sealing of micromolded water-swollen poly-2-hydroxy ethyl methacrylate (PHEMA)-based hydrogel modules to thermoplastic and elastomeric platforms. The core mechanism of the proposed method is to favor the formation of hydrogen bonds at the interface between the surface-reactive hydrated hydrogel components and the functionalized hydrophobic materials, by contacting the polymeric layers via a mild compression. Plasma oxygen and silanization processes using 3-amino-propyl trimethoxy silane have been optimized to generate surface hydroxyl functionalities on poly-methyl methacrylate (PMMA) and poly-dimethyl siloxane (PDMS) platforms which can react with the OH groups’ enriched surface of the microstructured PHEMA. The resulting microsystems can operate in a continuous perfusion mode while being soaked in water to keep the hydrogel hydrated. The method could also be applied to bond PHEMA thin layers (300 μm thick) to PMMA and PDMS microfluidic components. The sealing properties of the produced devices were demonstrated by liquid leakage tests and further validated by hydration–dehydration cycles of the systems and by monitoring methylene blue diffusion through the hydrogel matrix at the modules interface. The presented technique is suitable for cells-based hybrid materials microfluidic devices rapid prototyping.