Design of polymer tube embedded in-plane micropump

This paper presents a design of micropump, which is an assembly of silicon micromachined actuator with a polymer tube diaphragm. The pump actuation principle is electrothermal expansion of a silicon V-beam structure, and its expansion is amplified through a lever structure to create greater diaphragm stroke as presented in J. Sin et al. (2004). Diffuser/nozzle structures are applied to direct the flow from an inlet to outlet port while the actuator provides pumping motion. Deep RIE (reactive ion etching) process is used to fabricate the pump structure on a SOI (silicon on insulator) wafer. Polymer tube is fabricated from Parylene conformal deposition process using a DRIE silicon mold and the tube structure is assembled with the silicon actuator module. FEM analysis is performed on the tube structure and the simulation results show that the stroke of the tube diaphragm becomes much smaller than original actuator stroke, mainly due to the constrained tube geometry in silicon structure. When the tube stroke is combined with the diffusion/nozzle flow mechanism, the resultant flow rate of the pump was about 160nl/min, which will be suitable for low flow rate and high precision applications. Further study is on going to build prototype of the pump.