Inertio-elastic flow instabilities in a 90° bent microchannel. Issue 34 (17th August 2017)

• Record Type: Journal Article
• Authors: Kim, Junghee; Hong, Sun Ok; Shim, Tae Soup; Kim, Ju Min
• Is Part Of: Soft matter. Volume 13:Issue 34(2017)
• Page Start: 5656
• Page End: 5664
• Publication Date: 2017-08-17
• Subjects: Soft condensed matter -- Periodicals; 530.413
• DOI: 10.1039/c7sm01355h
• Languages: English
• ISSNs: 1744-683X

Abstract

Abstract : We report the novel inertio-elastic flow instability in dilute polymer solutions for a microchannel having a 90° bent geometry. Abstract : Biological samples having viscoelastic properties are frequently tested using microfluidic devices. In addition, viscoelastic fluids such as polymer solutions have been used as a suspending medium to spatially focus particles in microchannels. The occurrence of flow instability even at low Reynolds number is a unique property of viscoelastic fluids. In this study, we report the instability in viscoelastic flow for a channel having a 90° bent geometry, which is a characteristic of many microfluidic devices. Interestingly, we observed that the flow instability in aqueous poly(ethylene oxide) (PEO) solution occurs when the concentration of PEO is as low as 50 ppm. We systematically investigated the effects of the polymer concentration, flow rate, and elasticity number on the flow instability. The results show that the flow is stabilized in shear-thinning fluids, whereas the flow instability is amplified when both elastic and inertial effects are pronounced. We believe that this study is useful to design microfluidic devices such as cell-deformability measurement devices based on viscoelastic particle focusing.