Taylor-Aris dispersion in temperature gradient focusing.

Microfluidic temperature gradient focusing (TGF) uses an axial temperature gradient to induce a gradient in electrophoretic flux within a microchannel. When balanced with an opposing fluid flow, charged analytes simultaneously focus and separate according to their electrophoretic mobilities. We present a theoretical and experimental study of dispersion in TGF. We model the system using generalized dispersion analysis that yields a 1-D convection-diffusion equation that contains dispersion terms particular to TGF. We consider analytical solutions for the model under uniform temperature gradient conditions. Using a custom TGF experimental setup, we compare focusing measurements with the theoretical predictions. We find that the theory well represents the focusing behavior for flows within the Taylor-Aris dispersion regime.