Particle-wall interactions in micro/nanochannels

The objective of the present paper is to review the fundamental theory of the motion of a collection of colloidal particles near solid walls and to compare theoretical computations with the experiments conducted by Kazoe and Yoda1 for electroosmotic flow. Under-standing the near-wall transport of suspended particles is also relevant to a number of microfluidic applications where a two-or three-dimensional array of colloidal particles is assembled on a solid substrate. We first discuss methods of describing the motion of single colloidal particles and subsequently show an approach to describe the motion and distribu-tion of a collection of particles (a mass transfer approach) where the particles are considered to be the third species in an electrolyte mixture. The parameter range of interest in the experiments is identified and the results for the particle velocity are compared with the results of a single-particle electrophoresis study. The particle distribution is obtained using the aforementioned mass transfer approach and the results for both the velocity and the particle distribution compare well with the experimental results. Surprisingly, the pres-ence of the walls has little or no effect on the particle velocity. Therefore, a review of the principles and fundamentals of DLVO and non-DLVO surface forces is addressed. A future objective of this work is to develop a unified theory of the motion of a distribution of colloidal particles near charged walls for electroosmotic flow.