Effect of channel geometry on solute dispersion in pressure-driven microfluidic systems

Abstract

Pressure-driven transport of fluid and solute samples is often desirable in microfluidic devices, particularly where sufficient electroosmotic flow rates cannot be realized or the use of an electric field is restricted. Unfortunately, this mode of actuation also leads to hydrodynamic dispersion due to the inherent fluid shear in the system. While such dispersivity is known to scale with the square of the Peclet number based on the narrower dimension of the conduit (often the channel depth), the proportionality constant can vary significantly depending on its actual cross section. In this article, we review previous studies to understand the effect of commonly microfabricated channel cross sections on the Taylor-Aris dispersion of solute slugs in simple pressure-driven flow systems. We also analyze some recently proposed optimum designs which can reduce the contribution to this band broadening arising from the presence of the channel sidewalls. Finally, new simulation results have been presented in the last section of this paper which describe solutal spreading due to bowing of microchannels that can occur from stresses developed during their fabrication or operation under high-pressure conditions.

System-Theoretic Analysis and Least-Squares Design of Microfluidic Channels for Flow-Induced Molecular Communication

“…It is a linear partial differential equation defined as (23) where is the diffusion constant adjusted based on the crosssection parameters of the microfluidic channel due to the Taylor dispersion [30]. The convection-diffusion equation relates to the change of concentration in time on the left hand side, i.e., , to convection and diffusion terms on the right hand side.…”

“…Propagation delay for traveling time of peak concentration level to a distance is found via setting as (30) which yields (31) The dominance of convection over diffusion is determined by the dimensionless Peclet number (Pe) which is defined as . For a large value of Pe, the molecular transport is said to be dominated by the convection, and for small Pe values, the transport is dominated by the diffusion.…”

Choosing the Optimal Gel Morphology in Electrophoresis Separation by a Differential Evolution Approach (Dea)

“…Under experimentally relevant electric fields, the results show the field and size dependences of mobility and diffusivity with maximum difference on the order of 10%. Dutta et al (Dutta et al, 2006) reviewed the effect of dispersion due to fluid shear in pressure-driven transport of fluid and solute on the channel geometry in microfluidic devices. They analyzed dispersion in rectangular, elliptical, trapezoidal, and isotropically etched designs and proposed optimum cross-sectional designs which have been shown to reduce the dispersion arising from the presence of channel walls.…”

Laminar dispersion at high Péclet numbers in finite-length channels: Effects of the near-wall velocity profile and connection with the generalized Leveque problem

“…It still provides a source of interest within the fluid dynamic community, especially in connection to microfluidic applications. [3][4][5] The first analysis of this problem is due to Taylor,6 and has been subsequently elaborated in an elegant way by Aris 7 using moment analysis, in what is currently referred to as the Taylor-Aris laminar dispersion theory.…”

“…5,28,29 Zhao and Bau 29 analyze the influence of cross flows, whereas Dutta and Leighton 28 consider the coupling of a pressure-driven flow in an electrokinetically driven microchannel for reducing dispersion in polymerase chain reaction and DNA-hybridization is considered in Refs. 32 and 33, while Leconte et al 34 study the occurrence of Taylor regimes in the evolution of autocatalytic reaction fronts.…”