Direct Measurements of Velocity Profiles in Flows of Polymer Solutions through a Rectangular Microchannel with a PDMS Surface

Abstract

Velocity profiles of polymer solutions were directly measured in a microchannel with rectangular cross sections. The test fluids are 0.2 wt% aqueous solutions of polyacrylamide whose molecular weights are 6 × 10 6 (fluid A) and 1.5 × 10 7 (fluid B). The microchannel was made of PDMS and it was mounted on the glass plate. The velocity profile in the depth direction is discussed as a function of the flow rate and shear stress on the wall. Consequently, for the flows of fluid A, a symmetric profile is observed in the region between the PDMS wall and the glass wall in a low flow rate, but the velocity profile slightly becomes asymmetric with increasing flow rate: the velocity near the PDMS wall is larger than that near the glass wall. For the flows of fluid B, a slightly asymmetric profile is observed even in the low flow rate and a largely asymmetric one in the large flow rate. The PDMS wall significantly affects the velocity profile in the flow of polymer solution through a PDMS microchannel.

Measurements of flow distribution in a thin resin layer during ultraviolet nanoimprint lithography by means of digital holographic particle-tracking velocimetry

“…As a result, the average velocity near to the hydrophobic lower substrate was faster than that near to the hydrophilic upper substrate. A similar phenomenon has been observed in microchannels [11,12]. The range of UV resin layer thickness that the particles existed at the first frame and the last frame was also decreased from about 16.0 lm to 14.5 lm while the NIL press process.…”

Entry Flows of Polymer Solutions through a Planar Contraction in a Microchannel

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