Colloid particle transport in a microcapillary: NMR study of particle and suspending fluid dynamics

Abstract

HIGHLIGHTSNMR 'active' colloidal particles at 22 vol% flowed through a μ-capillary Simultaneous measurement of particle and suspending fluid phase dynamics Dynamics of suspending fluid contains particle structure information Shear induced migration within μ-capillaries Results provide experimental data for further investigation and model verification Microcapillary Colloids NMR Hydrodynamic dispersion Particle dynamics ABSTRACT Precise manipulation of the hydrodynamic interaction between particles is particularly important for operation of microfluidic devices. Shear-induced migration gives rise to dynamical patterns within the flow that have been observed in a range of systems. In this work NMR 'active' colloidal particles (a¼1.25 mm) at volume fraction of 22% in an aqueous phase are flowed through a m-capillary (R¼126 mm) and the transport dynamics of the particle and suspending fluid phases are studied using dynamic NMR techniques. Simultaneous interrogation of shear rheology of the suspending fluid and particle phases of colloidal suspensions is presented. The dynamic behavior of the suspending fluid is shown to carry within it information about the structure of the colloidal particle ensembles on the time scales in-vestigated (Δ¼25 ms-250 ms) providing rich experimental data for further investigation and model verification. The importance of determining the particle concentration profile within μ-capillaries is explicitly demonstrated as shear induced migration causes significant concentration gradients to occur at strong flow conditions (i.e. Pe p ¼270).

Dynamic Clustering and Scaling Behavior of Active Particles under Confinement

“…Magnetically controlled active particles, such as those made of iron oxide, have shown great promise in drug delivery as well as in the removal of blockages from blood vessels within the body [ 37 , 38 , 39 ]. In applications where active particles are abundantly present, such as in microfluidics devices or the human body, systems can be considered confined fluid systems [ 40 ]. However, depending on factors like driving force and particle density, active particles within the body may exhibit tendencies to aggregate and cluster together, which could raise potential risks yet to be investigated in biomedical applications [ 21 , 41 ].…”

Dynamic Clustering and Scaling Behavior of Active Particles under Confinement

“…Magnetically-controlled active particles, such as those made of iron oxide, have shown great promise in drug delivery as well as the removal of blockages from blood vessels within the body [37][38][39]. In applications where active particles are abundantly present, such as in microfluidics devices or the human body, the system can be considered confined fluid systems [40]. However, depending on factors like driving force and particle density, active particles within the body may exhibit tendencies to aggregate and cluster together, which could raise potential risks yet to be investigated in biomedical applications [21,41].…”