Microfabrication inside capillaries using multiphase laminar flow patterning

Science

Volumn 285, Issue 5424, 1999, Pages 83-85

  Kenis, Paul J A ^a   Ismagilov, Rustem F ^a   Whitesides, George M ^a  

^a HARVARD UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CAPILLARY FLOW; FABRICATION; LAMINAR FLOW; MULTIPHASE FLOW;

MICROFABRICATION; MULTIPHASE LAMINAR FLOW PATTERNING;

LITHOGRAPHY;

POLYMER;

CAPILLARY; FABRICATION; LAMINAR FLOW;

ARTICLE; CAPILLARY PRESSURE; CRYSTAL; LAMINAR FLOW; POLYMERIZATION; PRIORITY JOURNAL; SPECIES DIFFERENCE;

EID: 0033516506     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.285.5424.83     Document Type: Article

References (20)

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4. diff (s) the distance and time of diffusion, respectively [P. W. Atkins, Physical Chemistry (Freeman, New York. 1994)]. The broadening of the features fabricated by FLO cannot be calculated with that equation alone because the profile of pressure-driven flow is parabolic [J. P. Brody, P. Yager, R. E. Goldstein, R. H. Austin, Biophys. J. 71, 3430 (1995)]. The chemical reaction with the surface occurs in the stationary boundary layer; therefore the correct equation should account for lateral diffusion of the reagent within the layer, diffusional exchange with the moving liquid above the layer, and depletion of the reagent by the reaction. Preliminary experiments showed that broadening of an etched Au area increases roughly as the square root of the distance from the point where the separate flows join. The formula given above predicts a similar dependence, indicating that diffusional exchange between the boundary layer and the moving liquid dominates under our conditions.
5. diff (s) the distance and time of diffusion, respectively [P. W. Atkins, Physical Chemistry (Freeman, New York. 1994)]. The broadening of the features fabricated by FLO cannot be calculated with that equation alone because the profile of pressure-driven flow is parabolic [J. P. Brody, P. Yager, R. E. Goldstein, R. H. Austin, Biophys. J. 71, 3430 (1995)]. The chemical reaction with the surface occurs in the stationary boundary layer; therefore the correct equation should account for lateral diffusion of the reagent within the layer, diffusional exchange with the moving liquid above the layer, and depletion of the reagent by the reaction. Preliminary experiments showed that broadening of an etched Au area increases roughly as the square root of the distance from the point where the separate flows join. The formula given above predicts a similar dependence, indicating that diffusional exchange between the boundary layer and the moving liquid dominates under our conditions.
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7. We used pressure-driven flow generated with a syringe pump (Harvard Apparatus 22). Syringes were connected to the inlets of the microfluidic system by polyethylene tubing (Intramedic, inner diameter of 0.38 mm).
8. HE-300 solutions, Peacock Laboratories, 1901 South 54 Street, Philadelphia, PA 19143, USA. The counterion of the silver salt (X in the figures) is proprietary.
9. The roughness of the channel walls is typically 5 to 10 μm; the edge roughness of the etched or deposited structures is usually less than 1 μm.
10. Similarly, we deposited silver on one half of the inner surface of capillaries (PDMS, glass) by parallel laminar flow of water and an aqueous phase containing the premixed components of the electroless silver plating solution.
11. M. J. Cormier, D. M. Hercules, J. Lee, Eds., Chemiluminescence and Bioluminescence (Plenum, New York, 1973).
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19. The Ag wire extended into the middle inlet as a result of back flow during the first few seconds of the deposition process.
20. This work was financially supported by the Defense Advanced Research Projects Agency and NSF grant ECS-972940S. Materials Research Science and Engineering Center-shared facilities supported by the NSF under grant DMR-9400396 were used. P.J.A.K. acknowledges the Netherlands Organization for Scientific Research (NWO) for a postdoctoral fellowship. We acknowledge W. Huck and Y. Lu for their help with the atomic force microscopy and scanning electron microscopy experiments.