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

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 mu m 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.