Width variations of hydrodynamically focused streams in low to moderate Reynolds number
Multi-scale and/or multi-disciplinary approach to process-product innovation
Nanotechnology: New Developments (T3-6)
Keywords: microfluidics, hydrodynamic focusing
Hydrodynamic focusing is a technique relying on squeezing one of the streams in a four channel intersection by two side streams, reshaping it downstream into a thin, sheathed film.
This technique is utilized in many chemical engineering and Lab-on-a-Chip applications including micromixers, microreactors, patterning and fabrication inside capillaries, flow adressing, two phase flow generation, rheometry and microPIV flow visualization.
The last publications however, show the complexity of this phenomenon. The focused sheet leaving the system shows significant width deviations. This effect is clearly visible in case of non symmetrical hydrodynamical focusing, where the sheet no longer resides in the centre of the channel. In such a case the focused sheet looses its planar behavior with displacement.
The observed non-uniform sheet width grows with higher overall velocities changing drastically the flow pattern. The growing accuracy needed in many novel microfluidic applications of hydrodynamic focusing shows the urgent necessity of closer look into this aspect.
This paper describes a focused stream shape deviation aspect in hydrodynamic focusing.
To analyze the problem the Confocal Laser Scanning Microscopy (CLSM) was used for 3D flow pattern visualization. The investigation was done in PMMA channels of cross sections 260 x 200 µm, within the downstream velocities range from 0,1 to 4 cm/s.
The possible impact on existing applications and theirs modifications is discussed. This leads to conclusion that the detailed description of such a 3D behavior can be a very valuable tool for improving the hydrodynamic focusing technique.
See the full pdf manuscript of the abstract.
Presented Tuesday 18, 11:20 to 11:40, in session Nanotechnology: New Developments (T3-6).
