omation mbers - Society for Laboratory Automation and Screening

4:30 pm Tuesday, February 3 Microfluidics Room A4
Rajiv Bharadwaj
Stanford University
Building 500, Chemical Engineering,
Stanford, California 94305
rajivb@stanford.edu
A Generalized Dispersion Theory Model for Field Amplified Sample Stacking
70
Co-Author(s)
Juan G. Santiago
We will present an analytical model for concentration enhancement using field amplified sample stacking (FASS).
This transient model is based on generalized dispersion theory and accounts for convective-diffusive transport
of chemical species and electromigration. We model the FASS process as a one-dimensional electromigration
and dispersion of two background electrolyte ions and one sample ion across an initial concentration gradient.
Regular perturbation methods are used to solve for the concentration fields. The model has been validated
using experiments performed in a microchannel system. We use an acidified poly(ethylene oxide) (PEO) coating
to minimize dispersion due to EOF. Also, we use CCD-based full-field, quantitative, epi-fluorescence imaging to
experimentally measure the unsteady concentration fields and validate the model.
8:00 am Wednesday, February 4 Microfluidics – Separations Room A4
Johan Vanderhoeven
Free University of Brussels
Pleinlaan 2
Brussels, 1050 Belgium
Johan.Vanderhoeven@vub.ac.be
Co-Author(s)
David Clicq, Kris Pappaert,
Sarah Vankrunkelsven, Gino Baron,
Gert Desmet
On the Use of Nano-Channel Flows for the Enhancemant of Micro-Analytical Separations
We will report on the use of 1D nano-channel flows for the enhancement of a wide range of different microanalytical
separation techniques (liquid chromatography, DNA hybridization, protein binding kinetics measurement
and the size separation and classification of particles and cells). To exploit the advantages (increased mass
transfer rates and reduced solvent consumption and sample dilution) of miniaturised separation systems at their
most extreme limit, we replaced the traditionally employed pressure-gradient and voltage-gradient flow driving
techniques by a so-called shear-force driven method, enabling to establish high velocity flows through channels
as thin as 50 nanometer, by simply mechanically moving the bottom part of the channel wall past the (stationary)
upper part of the channel wall. With this novel flow driving principle, a wide variety of different fluid substances,
ranging from small molecules, and going over proteins and large DNA coils to micron-sized particles, could be
transported through silicon and fused silica etched nano-channels at velocities up to 5 cm/s. Examples of nanochannel
separation applications such as ultra-rapid liquid chromatography separations of a 4-component coumarin
dye mixture, enhanced DNA micro-array analysis, as well as a new separation method for the size separation of
cells and nano-particles will be shown and discussed.