Molecular Transport and Fluidic Manipulation in Three Dimensional Integrated Nanofluidic Networks - Nanofluidics: Nanoscience and Nanotechnology - page 75

Figure 4.4 Pre-concentration in a hybrid microfluidic/nanofluidic system. (a) When a small trans-nanopore

potential, E n , is applied, ion concentrations in the microchannel are unaffected. (b) At higher
values of E n diffusion limits ion transport across an ion-depletion region. (c) Over time a
breakdown in local electroneutrality results, creating a space-charge region above the
nanochannels. (d) Application of a second potential along the microchannel, E t , induces
electroosmotic flow of the 2 nd kind, rapidly accumulating counterions against the space-charge
region. Adapted from Wang, Y.C., A.L. Stevens, and J. Han, Million-fold preconcentration of
proteins and peptides by nanofluidic filter. Anal Chem, 2005, 77 , 4293 and reproduced with
permission.