Microfluidic Flows of Viscoelastic Fluids

Sousa, P.C.; Afonso, A.M.; Oliveira, Mónica; Alves, M.A.; Pinho, F.T.

doi:10.1002/9783527639748.ch6

Cited by 14 publications

(14 citation statements)

References 160 publications

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“…The most-often used ones in academic research include polyvinylpyrrolidone (PVP), polyethylene oxide (PEO) and polyacrylamide (PAA) solutions, which are all biocompatible and have been extensively used in microfluidic devices [57,58]. They are prepared in water or any aqueous buffer solution (for a further enhanced biocompatibility), whose viscosity can be tuned by being mixed with glycerol (or other chemicals) at different (weight or volume) ratios.…”

Section: Non-newtonian Fluidsmentioning

confidence: 99%

Particle manipulations in non-Newtonian microfluidics: A review

Liu

et al. 2017

Journal of Colloid and Interface Science

235

192

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a b s t r a c tMicrofluidic devices have been widely used since 1990s for diverse manipulations of particles (a general term of beads, cells, vesicles, drops, etc.) in a variety of applications. Compared to the active manipulation via an externally imposed force field, the passive manipulation of particles exploits the flow-induced intrinsic lift and/or drag to control particle motion with several advantages. Along this direction, inertial microfluidics has received tremendous interest in the past decade due to its capability to handle a large volume of samples at a high throughput. This inertial lift-based approach in Newtonian fluids, however, becomes ineffective and even fails for small particles and/or at low flow rates. Recent studies have demonstrated the potential of elastic lift in non-Newtonian fluids for manipulating particles with a much smaller size and over a much wider range of flow rates. The aim of this article is to provide an overview of the various passive manipulations, including focusing, separation, washing and stretching, of particles that have thus far been demonstrated in non-Newtonian microfluidics.

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Section: Non-newtonian Fluidsmentioning

confidence: 99%

Particle manipulations in non-Newtonian microfluidics: A review

Liu

et al. 2017

Journal of Colloid and Interface Science

235

192

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“…A great number of industrial and scientific fields require applications that can provide meaningful and accurate information on the mechanical properties of the fluids employed in their daily processes, which are often characterised by a complex microstructure. Microfluidic devices bring about a number of features that makes them a very attractive choice as a platform for monitoring the fluid behaviour and their mechanical properties (Oliveira et al 2012a). Most importantly, the characteristic small-length scales which microfluidic devices operate (1-1000 μm ) provide high surface-tovolume ratios, thus enhancing some mechanical properties of the fluids and/or samples of interest, compared to macroscale flows.…”

Section: Introductionmentioning

confidence: 99%

Optimised multi-stream microfluidic designs for controlled extensional deformation

Zografos

Haward

Oliveira

2019

Microfluid Nanofluid

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In this study, we optimise two types of multi-stream configurations (a T-junction and a flow-focusing design) to generate a homogeneous extensional flow within a well-defined region. The former is used to generate a stagnation point flow allowing molecules to accumulate significant strain, which has been found very useful for performing elongational studies. The latter relies on the presence of opposing lateral streams to shape a main stream and generate a strong region of extension in which the shearing effects of fluid-wall interactions are reduced near the region of interest. The optimisations are performed in two (2D) and three dimensions (3D) under creeping flow conditions for Newtonian fluid flow. It is demonstrated that in contrast with the classical-shaped geometries, the optimised designs are able to generate a well-defined region of homogeneous extension. The operational limits of the obtained 3D optimised configurations are investigated in terms of Weissenberg number for both constant viscosity and shear-thinning viscoelastic fluids. Additionally, for the 3D optimised flow-focusing device, the operational limits are investigated in terms of increasing Reynolds number and for a range of velocity ratios between the opposing lateral streams and the main stream. For all obtained 3D optimised multi-stream configurations, we perform the experimental validation considering a Newtonian fluid flow. Our results show good agreement with the numerical study, reproducing the desired kinematics for which the designs are optimised.

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“…Therefore, understanding the rheological behavior of viscoelastic fluids is of both fundamental and practical importance. 9 Formation of Newtonian droplets in another Newtonian medium (NN system) has been extensively studied both experimentally [10][11][12][13][14] and numerically. [15][16][17] However, effects of viscoelasticity on droplet formation have received less attention.…”

Section: Introductionmentioning

confidence: 99%

Droplet formation in a flow focusing configuration: Effects of viscoelasticity

2016

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We numerically investigate the effects of bulk fluid viscoelasticity on droplet formation and dynamics in an axisymmetric flow focusing configuration. Viscoelasticity is modeled using the finitely extensible nonlinear elastic-Chilcott-Rallison (FENE-CR) model. Extensive simulations are performed to examine droplet formation and breakup dynamics for a wide range of parameters including flow rate ratio, Weissenberg number, polymeric viscosity ratio, and extensibility parameter. It is found that these parameters have a significant influence on the droplet size and size distribution (dispersity). Three different regimes are observed in the sequence of squeezing, dripping, and jetting modes as the flow rate ratio is increased. It is also found that the viscoelasticity has a similar effect as decreasing flow rate ratio and acts to delay transition from squeezing to dripping and from dripping to jetting regimes. The strain-rate hardening occurs at a critical Weissenberg number resulting in an abrupt increase in droplet size and this effect is more pronounced as the polymeric viscosity ratio is increased.

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Microfluidic Flows of Viscoelastic Fluids

Cited by 14 publications

References 160 publications

Particle manipulations in non-Newtonian microfluidics: A review

Particle manipulations in non-Newtonian microfluidics: A review

Optimised multi-stream microfluidic designs for controlled extensional deformation

Droplet formation in a flow focusing configuration: Effects of viscoelasticity

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