Convective dispersion of particles in a segmented flow

Abstract

Convective dispersion of solutes is inherent to flow in channels because of the nonuniformity of the velocity profile. When diffusion is negligible, for large particles for

Encapsulation of Cells in a Collagen Matrix Surrounded by an Alginate Hydrogel Shell for 3D Cell Culture

“…To avoid drop coalescence in air and during the impact in the gelling bath, drops are electrically charged, thanks to an annular electrode, which allows drop–drop repulsion. For the manipulation of small volumes of core solutions below 1 mL, liquid samples are placed in a parallel circuit as previously described . This first allows a stable compound jet with a core solution without collagen and cells to form, and then, the solution or dispersion to be encapsulated is injected by switching the flow direction toward the line where the sample is loaded by pinching the electrovalves (Figure S1).…”

“…For the manipulation of small volumes of core solutions below 1 mL, liquid samples are placed in a parallel circuit as previously described. 29 This first allows a stable compound jet with a core solution without collagen and cells to form, and then, the solution or dispersion to be encapsulated is injected by switching the flow direction toward the line where the sample is loaded by pinching the electrovalves (Figure S1). To avoid dilution of the sample by the Taylor dispersion mechanism arising from the parabolic flow profile, 30 the sample is sandwiched between two bubbles having a length larger than the inner Teflon tube diameter, which is 0.8 mm 29 here (Figure S2).…”

Particulate suspension coating of capillary tubes

“…51 In particular, in addition to being non-uniform along a cross-section, the volume fraction is also not uniform along the length of the suspension plug. 53 A theoretical description of the distribution of particles at every location in the suspension plug is beyond the scope of the present study given the high complexity of the problem. Nevertheless, we can provide a qualitative explanation for the evolution of the film thickness during an experiment.…”

“…The flow of a suspension plug in a capillary tube presents a key difference with the dip coating: the shear-induced migration of the particles, [48][49][50] and a ''fountain-flow'' where particles are more concentrated at the front meniscus. 41,[51][52][53][54] Indeed, the flow of a plug in a cylindrical channel is a shear flow where the particles migrate from high shear stress to low shear stress region. 48 As a result the volume fraction of particles is not constant along a cross-section of the tube, but instead larger at the center and smaller near the outer wall.…”