A multistage optimization method is developed yielding Tesla valves that are effiicient even at low flow rates,characteristic,e.g.,for almost all microfluidic systems,where passive valves have intrinsic advantages over active ones.We report on optimized structures that show a diodicity of up to 1.8 already at flow rates of 20 pl s-1 corresponding to a Reynolds number of 36.Centerpiece of the design is a topological optimization based on the fiinite element method.It is set-up to yield easy-to-fabricate valve structures with a small footprint that can be directly used in microfluidic systems.Our numerical two-dimensional optimization takes into account the finite height of the channel approximately by means of a so-called shallow-channel approximation.Based on the threee-dimensionally extruded optimized designs,various test structures were fabricated using standard,widely available microsystem manufacturing techniques.The manufacturing process is described in detail since it can be used for the production of similar cost-effective microfluidic systems.For the experimentally fabricated chips,the efficiency of the different valve designs,i.e.,the diodicity defined as the ratio of the measured pressure drops in backward and forward flow directions,respectively,is measured and compared to theoretical predictions obtained from full 3D calculations of the Tesla valves.Good agreement is found.In addition to the direct measurement of the diodicities,the flow profiles in the fabricated test structures are determined using a two-dimensional microscopic particle image velocimetry(μPIV)method.Again,a reasonable good agreement of the measured flow profiles with simulated predictions is observed.
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机译:EXPERIMENTAL INVESTIGATIONS ON THE INTERACTIONS BETWEEN LIQUIDS AND STRUCTURES TO PASSIVELY CONTROL THE SURFACE-DRIVEN CAPILLARY FLOW IN MICROFLUIDIC LAB-ON-A-CHIP SYSTEMS TO SEPARATE THE MICROPARTICLES FOR BIOENGINEERING APPLICATIONS
机译:Clinical immunofluorescence comparison analysis of microfluidic chips for highly efficient detection of CTCs with colorectal cancer and other cancers
机译:amelioration de la perfusion des organes vitaux par la valve d'valve inspiratoire et le concept de pompe respiratoire:rationnel physiologique et application clinique(通过呼吸泵改善生命器官灌注:生理学和临床使用)。