A bi-polymer micro one-way valve

We have developed an in-plane bi-polymer check-valve for controlling microfluidic flow and preventing contamination between solutions by utilizing the elastic force of a swollen hydrogel. The valve was created using microfluidic tectonics, a fabrication procedure that allows construction of microscale components and autonomous systems using liquid-phase photopolymerization and in situ fabrication. The valve is composed of rigid parts (poly isobornyl acrylate) that provide a base frame, and compliant parts (hydrogel) that seal off the channel. The rigid part was fabricated by filling a polycarbonate cartridge with the isobornyl acrylate based prepolymer followed by UV light exposure through a photomask forming a chamber. To obtain well-defined chamber walls, a double exposing method (first exposure under lower UV dosage, then second exposure after filling the formed channel with DI water) was applied. Next, the chamber was filled with the hydrogel prepolymer mixture and exposed to UV light through a valve mask to define the compliant component of the device, resulting in an in-plane bi-polymer structure. The valve is actively assembled in situ providing precise sealing using low resolution lithography fabrication methods. Valve performance can be adjusted by varying the device geometry. Due to its in-plane structure and in situ fabrication process, microfluidic devices incorporating microvalves can be designed and fabricated conveniently.