Document Detail

Maximizing Flow Velocities in Redox-Magnetohydrodynamic Microfluidics Using the Transient Faradaic Current.
MedLine Citation:
PMID:  23057608     Owner:  NLM     Status:  Publisher    
There is a need for a microfluidic pumping technique that is simple to fabricate, yet robust, compatible with a variety of solvents, and easy to control fluid flow. Redox-magnetohydrodynamics (MHD) offers these advantages. However, the presence of high concentrations of redox species, important for inducing sufficient convection at low magnetic fields for hand-held devices, can limit the use of redox-MHD pumping for analytical applications. A new method for redox-MHD pumping is investigated that takes advantage of the large amplitude of the transient portion of the faradaic current response that occurs upon stepping the potential sufficiently past the standard electrode potential, E°, of the pumping redox species at an electrode. This approach increases velocity of the fluid for a given redox concentration. An electronic switch was implemented between the potentiostat and electrochemical cell to alternately turn on and off different electrodes along the length of the flow path to maximize this transient electronic current and as a result, the flow speed. Velocities were determined by tracking microbeads in a solution containing electroactive potassium ferrocyanide, potassium ferricyanide, and supporting electrolyte potassium chloride in the presence of a magnetic field. Fluid velocities with slight pulsation were obtained with the switch that were 70% faster than the smooth velocities without the switch. This indicates that redox species concentrations can be lowered by a similar amount to achieve a given speed, thereby diminishing interference of the redox species with detection of analyte in applications of redox-MHD microfluidics for chemical analysis.
Melissa C Weston; Christena K Nash; Jerry J Homesley; Ingrid Fritsch
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-12
Journal Detail:
Title:  Analytical chemistry     Volume:  -     ISSN:  1520-6882     ISO Abbreviation:  Anal. Chem.     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-12     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0370536     Medline TA:  Anal Chem     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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