Self-driven flow loop in microscale

This study proposes a conceptual design of three-dimensional self-driven loop and the concept is demonstrated as a passive control of pumping liquids within networks. Surface tension imbalance through appropriate combination of cross section change of the flow channel and channel surface hydrophilic property provides sufficient self-driven force to drive the liquid flow with no moving part. Numerical simulations using first principle equations and experimental visualizations are performed to demonstrate the success of this concept. A complete circulation flow loop and a quarter of the loop are constructed as three-layer and two-layer structures respectively by MEMS technology and the flow circulations inside the constructed flow loops are photographed by high-speed camera with frame rates of 1000 to 250 frames per second.