Taylor dispersion of a solute in a microfluidic channel

The dispersion of a solute, traveling in a laminar-flow microfluidic channe l, along the major axis of the channel is described by Taylor dispersion. I t is shown that although diffusion of solute along the major axis is often neglected in constructing a governing transport equation, axial dispersion due to the laminar flow profile influences the distribution of solute in th e channel. An expression for the effective Taylor dispersion coefficient du e to the laminar velocity profile is derived and verified by comparing the predicted dispersion to results from a three-dimensional finite-element rep resentation of the fluid dynamics and solute transport. Since the dispersio n coefficient can be several orders of magnitude greater than the molecular diffusion coefficient, axial dispersion in microfluidic channels should no t be casually neglected. (C) 2001 American Institute of Physics.