Pressure sensor positioning in an electrokinetic microrheometer device: simulations of shear-thinning liquid flows

Craven, Thomas J.; Rees, Julia M.; Zimmerman, William B.

doi:10.1007/s10404-010-0573-8

Cited by 17 publications

(11 citation statements)

References 23 publications

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“…The channel geometry can be slit shaped [11,27,38,49,53,75,84,88], square [42,70] or a combination of a rectangular and a cylindrical shape [22]. The flow in the channels is either generated under a constant flow rate [22,42,75,84] or a constant pressure [27,53]. The pressure drop over the m-VROC measures viscosity from the pressure drop of a test liquid as it flows through a rectangular slit-a well known scientific application (K. Walters, Rheometry, Chapman and Hall, London, 1975).…”

Section: Microfluidicsmentioning

confidence: 99%

“…As the test liquid is pumped to flow through the flow channel (slit) of the chip, pressure is measured at increasing distances from the inlet. channel is measured by local pressure sensors in the channel walls [22,75], inline with the channel [27,42] or with pressure sensors in microcavities linked to the channel [11,49,70,88]. If the flow rate is not directly set, in some devices the flow rate is also monitored e.g.…”

Section: Microfluidicsmentioning

confidence: 99%

“…The limits of the microfluidic devices for microrheological measurements depends on their design. For channel heights typically on the order of 10 −100 µm [11,22,38,42,70,75] shear rates up to 10 4 −10 6 s −1 are achieved [42,49,70]. The measurable stress is restricted by either the measurement range of the pressure sensors or by the bonding strength of the device for which upper pressure limits on the order of 10 6 Pa are reported [11].…”

Section: Microfluidicsmentioning

confidence: 99%

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The dark side of microrheology: Non-optical techniques

Vleminckx

Clasen

2014

Current Opinion in Colloid & Interface Science

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Microrheology probes the mesoscale between bulk rheology, which provides an integral sample response, and nanorheology, which refers to a local response at a molecular confinement level. The term 'microrheology' is often used to refer to optical particle tracking methods that measure a local response of a sample. In contrast to this, non-optical microrheology techniques generally allow two different effects to be studied: actual confinement effects on the rheology and boundary effects such as slip. Investigating the mesoscale range has additional advantages such as the possibility to perform measurements with small sample volumes and at high shear rates. This review bundles the wide array of non-optical techniques into five categories: adaptations to a conventional rotational rheometer, sliding plate rheometry on a micrometer scale, microfluidics, piezo vibrators and radial channel flows. The concept of each set of techniques is described, together with their operational window and examples of recent studies.

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Section: Microfluidicsmentioning

confidence: 99%

Section: Microfluidicsmentioning

confidence: 99%

Section: Microfluidicsmentioning

confidence: 99%

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The dark side of microrheology: Non-optical techniques

Vleminckx

Clasen

2014

Current Opinion in Colloid & Interface Science

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“…An overview of development in microfluidic rheometry up to 2009 was given by Pipe and McKinley (2009). More recent work in this field was done, for example, by Zimmerman and co-workers: Bandalusena et al (2010) and Craven et al (2010).…”

Section: Introductionmentioning

confidence: 99%

Hele-Shaw rheometry

Drost¹,

Westerweel²

2013

Journal of Rheology

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SynopsisIn this paper, we describe a novel approach to determine the flow behavior index of a power-law fluid by means of a microfluidic device. The concept of this method is based on a mathematical analysis by Aronsson and Janfalk [Eur. J. Appl. Math. 3, 343-366 (1992)] of Hele-Shaw flow of power-law liquids. We implement this approach by driving a non-Newtonian fluid through a glass microfluidic chip with a 100:1 contraction. The flow in this chip satisfies the Hele-Shaw flow conditions in most of the device. Two conjugate p-Laplace equations describe the pressure and stream function in such flows. These equations depend on the flow behavior index, n. Therefore, by fitting the p-Laplace equation to the velocity field obtained from a micro particle image velocimetry measurement of the flow, the flow behavior index of the fluid in the chip can be determined. Because in practice, fluids rarely show perfectly inelastic power-law behavior, conditions under which the assumption of inelastic flow is valid were derived by analyzing Hele-Shaw flow of an Oldroyd-B fluid. The concept was tested using three different classes of model fluids, a Newtonian fluid, an inelastic power-law fluid, and a Boger fluid. In all three cases, satisfactory results were obtained, with values of n deviating at most 4% from values measured using conventional rheometry. The method presented here is expected to be potentially useful in online quality control in, for example, polymer or food processing. V C 2013 The Society of Rheology. [http://dx

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“…14 Schematic illustration of rough micro channel with complex-wavy surface [82]. The electro-osmotic driven Carreau non-Newtonian fluid in a T junction was simulated by Craven, et al[83]. The simulation was conducted via the finite element method.…”

mentioning

confidence: 99%

Non-newtonian fluids and droplets in microchannels

Huang¹

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With the development of microfluidics, electro-osmotic (EO) driven flow has gained intense research interest as a result of its unique flow profile and the corresponding benefits in its application in the transportation of sensitive samples. Challenges occur when the EO driven mechanism encounters complex rheology and vital questions such as "Can the zeta potential still be assumed to be constant when dealing with fluids with complex rheology?", "Does the shear thinning effect enhances electroosmotic driven flow?" need to be answered. Experiments were conducted via using current monitoring and microscopy fluorescent methods, and a analytical model was developed by coupling a generalized Smoluchowski approach with the power-law constitutive model. The zeta potential was calculated. The shear thinning effect is also addressed via experimental data and theoretical calculations. The mathematical model for the two immiscible layers of electro-osmotic driven flow in the parallel microchannel was proposed. One layer is a conducting non-Newtonian power-law fluid driven by electro-osmotic force. The other layer is a nonconducting Newtonian layer driven by interface shear. The effects of Debye-Hueckel parameter xhi, interfacial zeta potential If/ I , the Newtonian viscosity 1'2' the non-Newtonian fluid consistency coefficient m & flow behavior index n were discussed. The complex flow behavior, namely fluid consistent coefficient and flow behavior index, play important roles in the velocity distributions. The shear thinning effect is also analyzed. The results show that the shear thinning fluid is not only ideal for direct electro-osmotic driving but also for hybrid driving. A flow-focusing geometry in a microfluidic device was studied for the formation of uniform droplets and we qualitatively illustrated aspects of controlling the droplet I

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Pressure sensor positioning in an electrokinetic microrheometer device: simulations of shear-thinning liquid flows

Cited by 17 publications

References 23 publications

The dark side of microrheology: Non-optical techniques

The dark side of microrheology: Non-optical techniques

Hele-Shaw rheometry

Non-newtonian fluids and droplets in microchannels

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