A simple all-parylene in-channel pop-up checkvalve with controllable cracking pressure

We present here a new surface-micromachined, all-parylene (para-xylylene), in-channel, normally-closed pop-up checkvalve with a designable cracking pressure. The cracking pressure is created by the mechanical residual tensile stress introduced by a popping mechanism. Moreover, an even higher cracking pressure can be achieved by thermal annealing before popping, which adds another degree of freedom to control the cracking pressure. The checkvalves can be easily micro machined combined with parylene channels to form a fully independent micro fluidic regulating system. A testing chip is designed to test the fabricated device sealed with photoresist which can be released by acetone afterward. This work demonstrated a cracking pressure of 0.17 psi by the popping and 0.32 psi by the combined thermal annealing (at 140°C) and popping. The final device is designed as 6 mm long, which is useful for heath care or any biomedical applications.