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Experimental and theoretical scaling laws for transverse diffusive broadening in two-phase laminar flows in microchannels

Ismagilov, Rustem F. and Stroock, Abraham D. and Kenis, Paul J. A. and Whitesides, George and Stone, Howard A. (2000) Experimental and theoretical scaling laws for transverse diffusive broadening in two-phase laminar flows in microchannels. Applied Physics Letters, 76 (17). pp. 2376-2378. ISSN 0003-6951. doi:10.1063/1.126351.

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This letter quantifies both experimentally and theoretically the diffusion of low-molecular-weight species across the interface between two aqueous solutions in pressure-driven laminar flow in microchannels at high Peclet numbers. Confocal fluorescent microscopy was used to visualize a fluorescent product formed by reaction between chemical species carried separately by the two solutions. At steady state, the width of the reaction-diffusion zone at the interface adjacent to the wall of the channel and transverse to the direction of flow scales as the one-third power of both the axial distance down the channel (from the point where the two streams join) and the average velocity of the flow, instead of the more familiar one- half power scaling which was measured in the middle of the channel. A quantitative description of reaction-diffusion processes near the walls of the channel, such as described in this letter, is required for the rational use of laminar flows for performing spatially resolved surface chemistry and biology inside microchannels and for understanding three-dimensional features of mass transport in shearing flows near surfaces.

Item Type:Article
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Ismagilov, Rustem F.0000-0002-3680-4399
Whitesides, George0000-0001-9451-2442
Additional Information:© 2000 American Institute of Physics. (Received 29 October 1999; accepted 24 February 2000) This work was supported by DARPA, NSF ECS-9729405 [for one of the authors (G.M.W.)]; by DARPA Army Research Office DAAG55-97-1-0114 [for one of the authors (H.A.S.)], and by the NSF MRSEC DMR-9809363 [for two of the authors (G.M.W. and H.A.S.)]. One of the authors (A.D.S.) was supported by NIH Molecular Biophysical Training Grant No. 5T32GM08313-10. The authors acknowledge Shuichi Takayama for helpful suggestions.
Funding AgencyGrant Number
Army Research OfficeDAAG55-97-1-0114
Subject Keywords:mass-transfer, two-phase flow, chemically reactive flow, laminar flow, channel flow, flow visualisation, fluorescence, optical microscopy, scaling phenomena, chemical interdiffusion, reaction-diffusion systems
Issue or Number:17
Classification Code:PACS: 47.55.Kf Particle-laden flows 47.70.Fw Chemically reactive flows 47.60.-i Flow phenomena in quasi-one-dimensional systems 47.15.-x Laminar flows 47.80.-v Instrumentation and measurement methods in fluid dynamics 07.60.Pb Conventional optical microsc
Record Number:CaltechAUTHORS:20130821-160720579
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:40804
Deposited By: Whitney Barlow
Deposited On:23 Aug 2013 21:51
Last Modified:10 Nov 2021 00:08

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