81 research outputs found
3D Porous biomaterials Through Microfluidics: a New Route for Tailored PolyHIPEs Future investigator of Tissue engineering
No full textWall fluidization in two acts: from stiff to soft roughness
No full textFluidization of soft glassy materials (SGMs) in microfluidic channels is affected by the wall roughness in the form of microtexturing. When SGMs flow across microgrooves, their constituents are likely trapped within the grooves’ gap, and the way they are released locally modifies the fluidization close to the walls. By leveraging a suitable combination of experiments and numerical simulations on concentrated emulsions (a model SGM), we quantitatively report the existence of two physically different scenarios. When the gap is large compared to the droplets in the emulsion, the droplets hit the solid obstacles and easily escape scrambling with their neighbors. Conversely, as the gap spacing is reduced, droplets get trapped inside, creating a ‘‘soft roughness’’ layer, i.e. a complementary series of deformable posts from which overlying droplets are in turn released. In both cases, the induced fluidization scales with the grooves’ density, although with a reduced prefactor for narrow gaps, accounting for the softness of the roughness. Both scenarios are also well distinguished via the statistics of the droplets displace- ment field close to the walls, with large deviations induced by the surface roughness, depending on its stiffness
Fluidization and wall slip of soft glassy materials by controlled surface roughness
No full textWe present a comprehensive study of concentrated emulsions flowing in microfluidic channels, one wall of which is patterned with micron-size equally spaced grooves oriented perpendicularly to the flow direction. We find a scaling law describing the roughness-induced fluidization as a function of the density of the grooves, thus fluidization can be predicted and quantitatively regulated. This suggests common scenarios for droplet trapping and release, potentially applicable for other jammed systems as well. Numerical simulations confirm these views and provide a direct link between fluidization and the spatial distribution of plastic rearrangements
Reliability of engineering methods of assessment the critical buckling load of steel beams
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Axisymmetric polydimethysiloxane microchannels for in vitro hemodynamic studies
No full textThe current microdevices used for biomedical research are often manufactured using microelectromechanical systems (MEMS) technology. Although it is possible to fabricate precise and reproducible rectangular microchannels using soft lithography techniques, this kind of geometry may not reflect the actual physiology of the microcirculation. Here, we present a simple method to fabricate circular polydimethysiloxane (PDMS) microchannels aiming to mimic an in vivo microvascular environment and suitable for state-of-the-art microscale flow visualization techniques, such as confocal µPIV/PTV. By using a confocal µPTV system individual red blood cells (RBCs) were successfully tracked trough a 75 µm circular PDMS microchannel. The results show that RBC lateral dispersion increases with the volume fraction of RBCs in the solution, i.e. with the hematocrit
Designing and interpretation of digital assays: Concentration of target in the sample and in the source of sample
No full textAbstractWe explain how to design classic digital assays, comprising identical partitions, in order to obtain the required precision of the estimate within a defined range of concentrations. The design, including the number and volume of partitions, depends significantly on whether the assay is to assess the concentration of the target analyte in the sample or in the source of the sample (e.g. a patient body) with a given precision. We also show how to translate the result referring to the concentration in the sample into the concentration in the source of the sample, including the significant change in the breath of the confidence intervals
Controlled droplet microfluidic systems for multistep chemical and biological assays
No full textDroplet microfluidics is a relatively new and rapidly evolving field of science focused on studying the hydrodynamics and properties of biphasic flows at the microscale, and on the development of systems for practical applications in chemistry, biology and materials science.</p
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