Particle Focusing in the Poiseuille Flow of Colloidal Dispersion

We recently reported the lateral migration and focusing of non-colloidal particles, suspended in the nanoparticle colloidal dispersion, by its normal stress differences in microchannel flow at Brownian-motion-dominant low Péclet number conditions [1]. In this presentation, we will demonstrate the key experimental results of the normal stress difference-driven particle focusing in the colloidal dispersion [1]. We will also show that the experimental results are in consistency with the existing theories on the colloidal rheology [2] and the lateral particle migration [3] in viscoelastic fluid [1]. In addition, it will be demonstrated that the second normal stress difference in the colloidal dispersion generates the secondary flow in non-circular channel and the recently observed viscoelastic properties of blood plasma [4] can be elucidated by the colloidal dynamics of the blood plasma-constituting protein molecules [1]. Finally, we will present the characterization of the viscoelasticity of micelle solution based on the microfluidic methods applied to the colloidal dispersion. \textbf{References} [1] Kim \textit{et al}., \textit{Sci. Adv. }5, eaav4819 (2019). [2] J. F. Brady and M. Vicic, \textit{J. Rheol.} 39, 545--566 (1995). [3] P. Brunn, \textit{J. Non-Newt. Fluid Mech.} 7, 271--288 (1980). [4] M. Brust \textit{et al., Phys. Rev. Lett.} 110, 078305 (2013).