Extensional opto-rheometry with biofluids and ultra-dilute polymer solutions

Haward, Simon J.; Sharma, Vivek; Odell, J. A.

doi:10.1039/c1sm05493g

Cited by 53 publications

(85 citation statements)

References 109 publications

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“…However, it has been shown using combined pressure drop and birefringence measurements for various fluids in stagnation point flow experiments that stress and birefringence can vary co-linearly over a surprisingly wide range of extension rates, such that a single-valued stress-optical coefficient can often be used in order to estimate ( ) E η ε , as described above. 8,36,54 As the concentration of HA in the solutions is increased to 0.3 wt %, the fluids become increasingly viscoelastic. The relaxation time ( λ ) and the polymer contribution to the viscosity Fig.…”

Section: B Ha Aqueous Solutionsmentioning

confidence: 99%

Instabilities in stagnation point flows of polymer solutions

Haward

McKinley

2013

Physics of Fluids

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A recently-developed microfluidic device, the optimized shape cross-slot extensional rheometer, or OSCER [S.J. Haward, M.S.N. Oliveira, M.A. Alves and G.H. McKinley, Phys. Rev. Lett. 109, 128301 (2012)], is used to investigate the stability of viscoelastic polymer solutions in an idealized planar stagnation point flow. Aqueous polymer solutions, consisting of poly(ethylene oxide) and of hyaluronic acid with various molecular weights and concentrations, are formulated in order to provide fluids with a wide range of rheological properties. Semi-dilute solutions of high molecular weight polymers provide highly viscoelastic fluids with long relaxation times, which achieve a high Weissenberg number (Wi) at flow rates for which the Reynolds number (Re) remains low; hence the elasticity number El = Wi/Re is high. Lower concentration solutions of moderate molecular weight polymers provide only weakly viscoelastic fluids in which inertia remains important and El is relatively low. Flow birefringence observations are used to visualize the nature of flow instabilities in the fluids as the volume flow rate through the OSCER device is steadily incremented. At low Wi and Re, all of the fluids display a steady, symmetric and uniform 'birefringent strand' of highly oriented polymer molecules aligned along the outflowing symmetry axis of the test geometry, indicating the stability of the flow field under such conditions. In fluids of El > 1, we observe steady elastic flow asymmetries beyond a critical Weissenberg number, Wi crit , that are similar in character to those already reported in standard cross-slot geometries [e.g. P.E. Arratia, C.C. Thomas, J. Diorio and J.P. Gollub, Phys. Rev. Lett. 96, 144502 (2006)]. However, in fluids with El < 1 we observe a sequence of timedependent inertio-elastic instabilities beyond a critical Reynolds number, Re crit , characterized by high frequency spatiotemporal oscillations of the birefringent strand. By plotting the critical limits of stability for the various fluids in the Wi-Re operating space, we are able to construct a stability diagram delineating the distinct steady symmetric, steady asymmetric and inertio-elastic flow regimes in this idealized planar elongational flow device.

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Section: B Ha Aqueous Solutionsmentioning

confidence: 99%

Instabilities in stagnation point flows of polymer solutions

Haward

McKinley

2013

Physics of Fluids

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“…The OSCER geometry operates on principles similar to traditional cross-slots (i.e., with opposed inlets and outlets to generate a free stagnation point) 17,20 but has an optimized shape that achieves a homogeneous strain rate along a significant portion of the inlet and outlet channel axes. 50,51 A 3D drawing and a photograph of the actual flow geometry are provided in Fig.…”

Section: A Extensional Flow Apparatusmentioning

confidence: 99%

“…19,20 Simulations of squeezing flows using a Finitely Extensible Non-linear Elastic (FENE) dumbbell-type model predict significant macromolecular stretching between the compressing plates for "fast squeezing"; i.e., when the timescale for the squeezing is much less than the relaxation time of the dumbbell or macromolecule. 21 If perfect slip is allowed at the solid surfaces of the plates, the squeezing flow generates a homogeneous biaxial extensional flow field with no contribution from shear.…”

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confidence: 99%

Extensional flow of hyaluronic acid solutions in an optimized microfluidic cross-slot device

et al. 2013

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We utilize a recently developed microfluidic device, the Optimized Shape Crossslot Extensional Rheometer (OSCER), to study the elongational flow behavior and rheological properties of hyaluronic acid (HA) solutions representative of the synovial fluid (SF) found in the knee joint. The OSCER geometry is a stagnation point device that imposes a planar extensional flow with a homogenous extension rate over a significant length of the inlet and outlet channel axes. Due to the compressive nature of the flow generated along the inlet channels, and the planar elongational flow along the outlet channels, the flow field in the OSCER device can also be considered as representative of the flow field that arises between compressing articular cartilage layers of the knee joints during running or jumping movements. Full-field birefringence microscopy measurements demonstrate a high degree of localized macromolecular orientation along streamlines passing close to the stagnation point of the OSCER device, while micro-particle image velocimetry is used to quantify the flow kinematics. The stress-optical rule is used to assess the local extensional viscosity in the elongating fluid elements as a function of the measured deformation rate. The large limiting values of the dimensionless Trouton ratio, Tr $ O(50), demonstrate that these fluids are highly extensional-thickening, providing a clear mechanism for the load-dampening properties of SF. The results also indicate the potential for utilizing the OSCER in screening of physiological SF samples, which will lead to improved understanding of, and therapies for, disease progression in arthritis sufferers. V C 2013 AIP Publishing LLC. [http://dx

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“…Many biological and chemical fluids possess non-Newtonian characteristics [43], where the former include blood [44][45][46], plasma [47], saliva [48,49], hyaluronic acid (HA) [50,51] and DNA solutions [52,53], etc. With high-concentration blood cells, blood exhibits viscoelastic and shear-thinning effects due mostly to the highly deformable and elastic properties of red blood cells (RBCs) as well as their reversible aggregations under shear strain [44][45][46].…”

Section: Non-newtonian Fluidsmentioning

confidence: 99%

Particle manipulations in non-Newtonian microfluidics: A review

Liu

et al. 2017

Journal of Colloid and Interface Science

234

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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Extensional opto-rheometry with biofluids and ultra-dilute polymer solutions

Cited by 53 publications

References 109 publications

Instabilities in stagnation point flows of polymer solutions

Instabilities in stagnation point flows of polymer solutions

Extensional flow of hyaluronic acid solutions in an optimized microfluidic cross-slot device

Particle manipulations in non-Newtonian microfluidics: A review

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