Computer simulation and theory of the diffusion- and flow-induced concentration dispersion in microfluidic devices and HPLC systems based on rectangular microchannels Original Research Article

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 μm-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 1 s for low and high flow velocities, respectively. The observed standard half-width σ of the peaks is found to strictly follow a linear function of t1/2 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.