Document Detail

3D imaging of flow patterns in an internally-pumped microfluidic device: redox magnetohydrodynamics and electrochemically-generated density gradients.
MedLine Citation:
PMID:  23537496     Owner:  NLM     Status:  MEDLINE    
Redox magnetohydrodynamics (MHD) is a promising technique for developing new electrochemical-based microfluidic flow devices with unique capabilities, such as easily switching flow direction and adjusting flow speeds and flow patterns as well as avoiding bubble formation. However, a detailed description of all the forces involved and predicting flow patterns in confined geometries is lacking. In addition to redox-MHD, density gradients caused by the redox reactions also play important roles. Flow in these devices with small fluid volumes has mainly been characterized by following microbead motion by optical microscopy either by particle tracking velocimetry (PTV) or by processing the microbead images by particle image velocimetry (PIV) software. This approach has limitations in spatial resolution and dimensionality. Here we use fluorescence correlation spectroscopy (FCS) to quantitatively and accurately measure flow speeds and patterns in the ~5-50 μm/s range in redox-MHD-based microfluidic devices, from which 3D flow maps are obtained with a spatial resolution down to 2 μm. The 2 μm spatial resolution flow speeds map revealed detailed flow profiles during redox-MHD in which the velocity increases linearly from above the electrode and reaches a plateau across the center of the cell. By combining FCS and video-microscopy (with PTV and PIV processing approaches), we are able to quantify a vertical flow of ~10 μm/s above the electrodes as a result of density gradients caused by the redox reactions and follow convection flow patterns. Overall, combining FCS, PIV, and PTV analysis of redox-MHD is a powerful combination to more thoroughly characterize the underlying forces in these promising microfluidic devices.
Feng Gao; Adam Kreidermacher; Ingrid Fritsch; Colin D Heyes
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2013-04-18
Journal Detail:
Title:  Analytical chemistry     Volume:  85     ISSN:  1520-6882     ISO Abbreviation:  Anal. Chem.     Publication Date:  2013 May 
Date Detail:
Created Date:  2013-06-28     Completed Date:  2013-12-05     Revised Date:  2014-05-08    
Medline Journal Info:
Nlm Unique ID:  0370536     Medline TA:  Anal Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4414-22     Citation Subset:  IM    
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MeSH Terms
Electrochemical Techniques* / instrumentation
Microfluidic Analytical Techniques* / instrumentation
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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