(81h) Hydrodynamic Mobility of Particles, Vesicles and Cancer Cells in a Square Microchannel

Understanding the transport of deformable particles such as vesicles and cells in moderately or tightly confined conduits is of interest in microfluidic technologies ranging from particle sorting to biomedical diagnostics. A key parameter of interest in these studies is the hydrodynamic mobility of the deformable particle, β, which is defined as the ratio of the particle velocity to the surrounding fluid velocity. Here, we report experimental measurements of hydrodynamic mobility of particles, vesicles and tumor cells at low Reynolds number, under conditions of moderate geometric confinement in a square microchannel. For rigid and elastic particles, we find that the mobility as a function of particle confinement agrees well with the theoretical result of Hetsroni, Haber and Wacholder (J. of Fluid Mech., 41, 1970) for cylindrical conduits under Stokes flow, with the modification that the mean velocity is that of a square microchannel. With respect to vesicles, we find that they move faster than the particles probably due to their lower reduced volume and mobile interface. For cancer cells, we observe that their mobility lies between those of particles and vesicles. We will also discuss aspects such as the role of particle off-centeredness and nonspherical shape on hydrodynamic mobility.