Document Detail

Fluorescence photobleaching to evaluate flow velocity and hydrodynamic dispersion in nanoslits.
MedLine Citation:
PMID:  22422108     Owner:  NLM     Status:  Publisher    
Velocity measurement is a key issue when studying flows below the micron scale, due to the lack of sensitivity of conventional detection techniques. We present an approach based on fluorescence photobleaching to evaluate flow velocity at the nanoscale by direct visualization. Solutions containing a fluorescent dye are injected into nanoslits. A photobleached line, created through laser beam illumination, moves through the channel due to the fluid flow. The velocity and effective diffusion coefficient are calculated from the temporal data of the line position and width respectively. The measurable velocity range is only limited by the diffusion rate of the fluorescent dye for low velocities and by the apparition of Taylor dispersion for high velocities. By controlling the pressure drop and measuring the velocity, we determine the fluid viscosity. The photobleached line spreads in time due to molecular diffusion and Taylor hydrodynamic dispersion. By taking into account the finite spatial and temporal extensions of the bleaching under flow, we determine the effective diffusion coefficient, which we find to be in good agreement with the expression of the two dimensional Taylor-Aris dispersion coefficient. Finally we analyze and discuss the role of the finite width of the rectangular slit on hydrodynamic dispersion.
Amandine Cuenca; Hugues Bodiguel
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-3-16
Journal Detail:
Title:  Lab on a chip     Volume:  -     ISSN:  1473-0189     ISO Abbreviation:  -     Publication Date:  2012 Mar 
Date Detail:
Created Date:  2012-3-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101128948     Medline TA:  Lab Chip     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Univ. de Bordeaux, CNRS, Rhodia, LOF UMR 5258, F-33600 Pessac cedex, France.
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