Efficiency of size-dependent particle separation by pinched flow fractionation

Pinched flow fractionation is shown to be an efficient and selective way to quickly separate particles by size in a very polydisperse semi-concentrated suspension. In an effort to optimize the method, we discuss the quantitative influence of the pinching intensity in the balance between the requirements of selectivity and minimal dilution.Comment: 5 pages, 3 figures, accepted in Microfluidics and Nanofluidic

Interaction et diffusion hydrodynamiques dans une suspension de vésicules et globules rouges

Blood is a complex suspension of deformable particles, red blood cells, which exhibits a sophisticated dynamics when flowing in the microvasculature. Most of these complex phenomena, non-linear rheology, structuration of the suspension, heterogeneities of the hematocrit distribution, are directly connected to the rich microscopic dynamics of individual red blood cells, and their hydrodynamics interactions. We investigate a few aspects of the dynamics of red blood cells and giant vesicles - a simple model for RBCs. A study on the dynamics of very deflated vesicles, with shapes similar to those of red blood cells, shows that these objects which haven't received a lot of attention so far can exhibit richer than expected dynamics. We then mainly focus on the still unexplored problem of hydrodynamic interactions between vesicles or red blood cells and their consequences at the scale of the suspension. An experimental study of the interaction of two identical vesicles in shear flow shows that there is a net repulsion between the cells that leads to an increase of the distance between vesicles in a suspension. Scaling arguments are proposed for this interaction and a comparison with numerical results is performed and a quantitative estimation of a shear induced diffusion coefficient obtained by averaging the results for pair interactions is found. Finally, we investigate the diffusion of a cloud of red blood cells in Poiseuille flow in order to directly determine diffusion coefficients. The experiment shows that the cloud widens when traveling along the channel with a power law behaviour indicating sub-diffusion. This effect is confirmed by a theoretical analysis of a few limit cases.Blood is a complex suspension of deformable particles, red blood cells, which exhibits a sophisticated dynamics when flowing in the microvasculature. Most of these complex phenomena, non-linear rheology, structuration of the suspension, heterogeneities of the hematocrit distribution, are directly connected to the rich microscopic dynamics of individual red blood cells, and their hydrodynamics interactions. We investigate a few aspects of the dynamics of red blood cells and giant vesicles - a simple model for RBCs. A study on the dynamics of very deflated vesicles, with shapes similar to those of red blood cells, shows that these objects which haven't received a lot of attention so far can exhibit richer than expected dynamics. We then mainly focus on the still unexplored problem of hydrodynamic interactions between vesicles or red blood cells and their consequences at the scale of the suspension. An experimental study of the interaction of two identical vesicles in shear flow shows that there is a net repulsion between the cells that leads to an increase of the distance between vesicles in a suspension. Scaling arguments are proposed for this interaction and a comparison with numerical results is performed and a quantitative estimation of a shear induced diffusion coefficient obtained by averaging the results for pair interactions is found. Finally, we investigate the diffusion of a cloud of red blood cells in Poiseuille flow in order to directly determine diffusion coefficients. The experiment shows that the cloud widens when traveling along the channel with a power law behaviour indicating sub-diffusion. This effect is confirmed by a theoretical analysis of a few limit cases

Pairwise hydrodynamic interactions and diffusion in a vesicle suspension

The hydrodynamic interaction of two deformable vesicles in shear flow induces a net displacement, in most cases an increase of their distance in the transverse direction. The statistical average of these interactions leads to shear-induced diffusion in the suspension, both at the level of individual particles which experience a random walk made of successive interactions, and at the level of suspension where a non-linear down-gradient diffusion takes place, an important ingredient in the structuring of suspension flows. We make an experimental and computational study of the interaction of a pair of lipid vesicles in shear flow by varying physical parameters, and investigate the decay of the net lateral displacement with the distance between the streamlines on which the vesicles are initially located. This decay and its dependency upon vesicle properties can be accounted for by a simple model based on the well established law for the lateral drift of a vesicle in the vicinity of a wall. In the semi-dilute regime, a determination of self-diffusion coefficients is presented

High-throughput triggered merging of surfactant-stabilized droplet pairs using traveling surface acoustic waves

We present an acoustofluidic device for fluorescently triggered merging of surfactant-stabilized picoliter droplet pairs at high throughput. Droplets that exceed a preset fluorescence threshold level are selectively merged by a traveling surface acoustic wave (T-SAW) pulse. We characterize the operation of our device by analyzing the merging efficiency as a function of acoustic pulse position, duration, and acoustic pressure amplitude. We probe droplet merging at different droplet rates and find that efficient merging occurs above a critical acoustic power level. Our results indicate that the efficiency of acoustically induced merging of surfactant stabilized droplets is correlated with acoustic streaming velocity. Finally, we discuss how both time-averaged and instantaneous acoustic pressure fields can affect the integrity of surfactant layers. Our technique, by allowing the merging of up to 105 droplets per hour, shows great potential for integration into microfluidic systems for high-throughput and high-content screening applications

Hydrodynamic interactions and diffusion in vesicle and red blood cell suspensions

Blood is a complex suspension of deformable particles, red blood cells, which exhibits a sophisticated dynamics when flowing in the microvasculature. Most of these complex phenomena, non-linear rheology, structuration of the suspension, heterogeneities of the hematocrit distribution, are directly connected to the rich microscopic dynamics of individual red blood cells, and their hydrodynamics interactions. We investigate a few aspects of the dynamics of red blood cells and giant vesicles - a simple model for RBCs. A study on the dynamics of very deflated vesicles, with shapes similar to those of red blood cells, shows that these objects which haven't received a lot of attention so far can exhibit richer than expected dynamics. We then mainly focus on the still unexplored problem of hydrodynamic interactions between vesicles or red blood cells and their consequences at the scale of the suspension. An experimental study of the interaction of two identical vesicles in shear flow shows that there is a net repulsion between the cells that leads to an increase of the distance between vesicles in a suspension. Scaling arguments are proposed for this interaction and a comparison with numerical results is performed and a quantitative estimation of a shear induced diffusion coefficient obtained by averaging the results for pair interactions is found. Finally, we investigate the diffusion of a cloud of red blood cells in Poiseuille flow in order to directly determine diffusion coefficients. The experiment shows that the cloud widens when traveling along the channel with a power law behaviour indicating sub-diffusion. This effect is confirmed by a theoretical analysis of a few limit cases.Blood is a complex suspension of deformable particles, red blood cells, which exhibits a sophisticated dynamics when flowing in the microvasculature. Most of these complex phenomena, non-linear rheology, structuration of the suspension, heterogeneities of the hematocrit distribution, are directly connected to the rich microscopic dynamics of individual red blood cells, and their hydrodynamics interactions. We investigate a few aspects of the dynamics of red blood cells and giant vesicles - a simple model for RBCs. A study on the dynamics of very deflated vesicles, with shapes similar to those of red blood cells, shows that these objects which haven't received a lot of attention so far can exhibit richer than expected dynamics. We then mainly focus on the still unexplored problem of hydrodynamic interactions between vesicles or red blood cells and their consequences at the scale of the suspension. An experimental study of the interaction of two identical vesicles in shear flow shows that there is a net repulsion between the cells that leads to an increase of the distance between vesicles in a suspension. Scaling arguments are proposed for this interaction and a comparison with numerical results is performed and a quantitative estimation of a shear induced diffusion coefficient obtained by averaging the results for pair interactions is found. Finally, we investigate the diffusion of a cloud of red blood cells in Poiseuille flow in order to directly determine diffusion coefficients. The experiment shows that the cloud widens when traveling along the channel with a power law behaviour indicating sub-diffusion. This effect is confirmed by a theoretical analysis of a few limit cases

Interaction et diffusion hydrodynamiques dans une suspension de vésicules et globules rouges

Blood is a complex suspension of deformable particles, red blood cells, which exhibits a sophisticated dynamics when flowing in the microvasculature. Most of these complex phenomena, non-linear rheology, structuration of the suspension, heterogeneities of the hematocrit distribution, are directly connected to the rich microscopic dynamics of individual red blood cells, and their hydrodynamics interactions. We investigate a few aspects of the dynamics of red blood cells and giant vesicles - a simple model for RBCs. A study on the dynamics of very deflated vesicles, with shapes similar to those of red blood cells, shows that these objects which haven't received a lot of attention so far can exhibit richer than expected dynamics. We then mainly focus on the still unexplored problem of hydrodynamic interactions between vesicles or red blood cells and their consequences at the scale of the suspension. An experimental study of the interaction of two identical vesicles in shear flow shows that there is a net repulsion between the cells that leads to an increase of the distance between vesicles in a suspension. Scaling arguments are proposed for this interaction and a comparison with numerical results is performed and a quantitative estimation of a shear induced diffusion coefficient obtained by averaging the results for pair interactions is found. Finally, we investigate the diffusion of a cloud of red blood cells in Poiseuille flow in order to directly determine diffusion coefficients. The experiment shows that the cloud widens when traveling along the channel with a power law behaviour indicating sub-diffusion. This effect is confirmed by a theoretical analysis of a few limit cases.Blood is a complex suspension of deformable particles, red blood cells, which exhibits a sophisticated dynamics when flowing in the microvasculature. Most of these complex phenomena, non-linear rheology, structuration of the suspension, heterogeneities of the hematocrit distribution, are directly connected to the rich microscopic dynamics of individual red blood cells, and their hydrodynamics interactions. We investigate a few aspects of the dynamics of red blood cells and giant vesicles - a simple model for RBCs. A study on the dynamics of very deflated vesicles, with shapes similar to those of red blood cells, shows that these objects which haven't received a lot of attention so far can exhibit richer than expected dynamics. We then mainly focus on the still unexplored problem of hydrodynamic interactions between vesicles or red blood cells and their consequences at the scale of the suspension. An experimental study of the interaction of two identical vesicles in shear flow shows that there is a net repulsion between the cells that leads to an increase of the distance between vesicles in a suspension. Scaling arguments are proposed for this interaction and a comparison with numerical results is performed and a quantitative estimation of a shear induced diffusion coefficient obtained by averaging the results for pair interactions is found. Finally, we investigate the diffusion of a cloud of red blood cells in Poiseuille flow in order to directly determine diffusion coefficients. The experiment shows that the cloud widens when traveling along the channel with a power law behaviour indicating sub-diffusion. This effect is confirmed by a theoretical analysis of a few limit cases

Interaction et diffusion hydrodynamiques dans une suspension de vésicules et globules rouges

Blood is a complex suspension of deformable particles, red blood cells, which exhibits a sophisticated dynamics when flowing in the microvasculature. Most of these complex phenomena, non-linear rheology, structuration of the suspension, heterogeneities of the hematocrit distribution, are directly connected to the rich microscopic dynamics of individual red blood cells, and their hydrodynamics interactions. We investigate a few aspects of the dynamics of red blood cells and giant vesicles - a simple model for RBCs. A study on the dynamics of very deflated vesicles, with shapes similar to those of red blood cells, shows that these objects which haven't received a lot of attention so far can exhibit richer than expected dynamics. We then mainly focus on the still unexplored problem of hydrodynamic interactions between vesicles or red blood cells and their consequences at the scale of the suspension. An experimental study of the interaction of two identical vesicles in shear flow shows that there is a net repulsion between the cells that leads to an increase of the distance between vesicles in a suspension. Scaling arguments are proposed for this interaction and a comparison with numerical results is performed and a quantitative estimation of a shear induced diffusion coefficient obtained by averaging the results for pair interactions is found. Finally, we investigate the diffusion of a cloud of red blood cells in Poiseuille flow in order to directly determine diffusion coefficients. The experiment shows that the cloud widens when traveling along the channel with a power law behaviour indicating sub-diffusion. This effect is confirmed by a theoretical analysis of a few limit cases.Blood is a complex suspension of deformable particles, red blood cells, which exhibits a sophisticated dynamics when flowing in the microvasculature. Most of these complex phenomena, non-linear rheology, structuration of the suspension, heterogeneities of the hematocrit distribution, are directly connected to the rich microscopic dynamics of individual red blood cells, and their hydrodynamics interactions. We investigate a few aspects of the dynamics of red blood cells and giant vesicles - a simple model for RBCs. A study on the dynamics of very deflated vesicles, with shapes similar to those of red blood cells, shows that these objects which haven't received a lot of attention so far can exhibit richer than expected dynamics. We then mainly focus on the still unexplored problem of hydrodynamic interactions between vesicles or red blood cells and their consequences at the scale of the suspension. An experimental study of the interaction of two identical vesicles in shear flow shows that there is a net repulsion between the cells that leads to an increase of the distance between vesicles in a suspension. Scaling arguments are proposed for this interaction and a comparison with numerical results is performed and a quantitative estimation of a shear induced diffusion coefficient obtained by averaging the results for pair interactions is found. Finally, we investigate the diffusion of a cloud of red blood cells in Poiseuille flow in order to directly determine diffusion coefficients. The experiment shows that the cloud widens when traveling along the channel with a power law behaviour indicating sub-diffusion. This effect is confirmed by a theoretical analysis of a few limit cases.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Lift and Down-Gradient Shear-Induced Diffusion in Red Blood Cell Suspensions

info:eu-repo/semantics/publishe