title: Computer simulation and theory of the diffusion- and flow-induced concentration dispersion in microfluidic devices and HPLC systems based on rectangular microchannels.
abstract: The dynamics of formation of solute peaks in microfluidic systems are investigated by computer simulation. A finite-element numerical procedure is applied to analyze the diffusion- and flow-controlled concentration dispersion in a 40 microm-high rectangular flow-through channel. Two-dimensional concentration profiles are shown for channels with cross sections of large aspect ratio. The final shapes of the peaks are formed during a very short time period, ranging from a few milliseconds to about 1s for low and high flow velocities, respectively. The observed standard half-width sigma of the peaks is found to strictly follow a linear function of t(1/2) over the whole time range. The extrapolated long-term peak characteristics are in perfect agreement with theoretical predictions. For comparison, theoretical results on the concentration dispersion for solute peaks in open-channel liquid-chromatography (HPLC) are re-examined and applied.
authors.affiliation: SAMLAB, Institute of Microtechnology, University of Neuchâtel, CH-2000 Neuchâtel, Switzerland. werner.morf@unine.ch
authors.forename: Werner E
authors.initials: WE
authors.lastname: Morf
authors.forename: Peter D
authors.initials: PD
authors.lastname: van der Wal
authors.forename: Nicolaas F
authors.initials: NF
authors.lastname: de Rooij