https://ro.uow.edu.au/cgi/viewcontent.cgi?article=2017&context=eispapers1

Shear thickening fluids in protective applications: A review

Life at Low Reynolds Number

Microfluidic 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.

Particle manipulations in non-Newtonian microfluidics: A review.

Shear thickening fluid (STF) treated high performance fabrics have attracted much attention in the applications of body protection. In order to improve the contribution of STF treatments, we designed multi-phase STFs and investigated the stab resistance of fabrics impregnated with these novel fluids. Silica and polyethylene glycol (PEG) based STFs were synthesized with various particle size of silicon carbide (SiC) additives to constitute the multi-phase suspension systems. The influence of the additive particles on the thickening behavior of the STFs was analyzed via rheological testing. The stab resistance of the fabrics was investigated in a drop tower against spike and knife threats and therefore, the role of the STFs was discussed in detail. According to this study, multi-phase STFs realized further improvement in the stab resistance of fabrics with respect to single-phase STFs.

The stab resistance of fabrics impregnated with shear thickening fluids including various particle size of additives

Effect of pH on the gel properties and secondary structure of fish myosin

Afuega’l Pitu atroncau cheese, Blancu (B) and Roxu (R) varieties, were collected at 30 days of ripening from 9 farms (B1−B9 and R1−R9) to determine the biochemical and linear viscoelastic parameters, as well as the microstructure. B and R samples exhibited fused casein particles in the protein matrix with a high packing effect and different fat distribution. The lowest total solids content led to the lowest stress amplitude (σmax) and gel strength (G*). B samples exhibited higher values of strain amplitude (γmax) and σmax than R, but with a similar solid-like character (tanδ).

Microstructure, Rheology, and Composition of a Spanish Cheese

How does flow inside a microfluidic device behave when passing by a pressure tap? Will its natural state be disrupted by any means? We seek to answer these questions and assess the consequences (if any) of attaching pressure taps to microchannels. To do so, streakline photography was performed for flow patterns visualisation in the close proximity of different types of pressure taps, using ‘long’ exposure times. Both a Newtonian and a viscoelastic fluid were tested, in order to observe the interplay of inertio-elastic effects near the intake of the pressure taps. The microdevices were made out of PDMS and the main flow channel, to which the pressure taps were attached, had a cross-section of \(270\times 100\) \(\upmu \)m. Elastic effects were observed in the form of reduced streakline curvature near the taps intake and increased vortex formation.

Pressure Tap Influence on the Flow of Viscoelastic Fluids in a Microfluidic Channel

Corrigendum to “Influence of the starch content in the viscoelastic properties of surimi gels” [Journal of Food Engineering 84 (2008) 140–147]

This work studies the flow behavior and related pr essure losses of viscoelastic polymer solutions in microchannels with two different sequences of contr action/expansion, disposed in a symmetric and an asymmetric arrangement, respectively. These microfluidic devices are proposed as simplified microchann el analogues for the flow of Newtonian and viscoelasti c fluids through porous media. The results show tha t the symmetric configuration mimics the pressure gradient of these polymer solutions through a porous mediu m at low flow rates (below a critical Deborah number, De cr ), while the asymmetric arrangement gives the asymptotic limit at high De values (above Decr ) as a consequence of the intrinsic differences in the extensional rate profiles defined by each microgeom etry.

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Microchannels Analogues for the Study of Viscoelastic Fluid Flows Through Porous Media

Particle tracking applied to video passive microrheology is conventionally done through methods that are far from being automatic. Creating mechanisms that decode the image set properties and correctly detect the tracer beads, to find their trajectories, is fundamental to facilitate microrheology studies. In this work, the adequacy of two particle detection methods - a Radial Symmetry-based approach and Gaussian fitting - for microrheology setups is tested, both on a synthetic database and on real data. Results show that it is possible to automate the particle tracking process in this scope, while ensuring high detection accuracy and sub-pixel precision, crucial for an adequate characterization of microrheology studies.

Laura Campo-Deaño

Papers

Microstructure, Rheology, and Composition of a Spanish Cheese

Pressure Tap Influence on the Flow of Viscoelastic Fluids in a Microfluidic Channel

Corrigendum to “Influence of the starch content in the viscoelastic properties of surimi gels” [Journal of Food Engineering 84 (2008) 140–147]

Microchannels Analogues for the Study of Viscoelastic Fluid Flows Through Porous Media

Towards Automatic and Robust Particle Tracking in Microrheology Studies