Polymer tube embedded in-plane micropump for low flow rate

This paper presents the design, analysis, and fabrication of a novel polymer tube embedded in-plane micropump. The key component of the proposed micropump is a Parylene polymer tube that is embedded into the silicon die. Advantages of embedding a Parylene polymer tube are biocompatibility and leakage free environments. The issue of leakage of fluid presented Sin, Lee and Stephanou (2004) is eliminated by inserting the polymer tube. The tube itself acts as a diaphragm, which transfers the force and motion of thermal actuators to fluid. The structural analysis and the fabrication of the Parylene tube shows that better deflection is achieved with higher aspect ratio tubes. Coupled-field multiphysics analysis of the electrothermal actuators is done to modify the actuator to avoid melting of the Parylene tube. 4 μm thick Parylene is conformally deposited on the nickel coated DRIE processed silicon wafer, and peeled off and two Parylene layers are bonded together to form a tube. The maximum deflection achieved for the Parylene diaphragm is 5.4 μm and the computed value of flow rate for the pump is 160 nl/min. This fabrication process can fabricate Parylene tubes with aspect ratios up to 1:3 by a novel technique of chemical release.