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Microfluidic device for robust generation of two-component liquid-in-air slugs with individually controlled composition.

Liu K, Chen YC, Tseng HR, Shen CK, van Dam RM - Microfluid Nanofluidics (2010)

Bottom Line: The use of microvalves in this approach enables robust operation with different liquids, and also enables one to work with extremely small samples, even down to a few slug volumes.The latter is important for applications involving precious reagents such as optimizing the reaction conditions for radiolabeling biological molecules as tracers for positron emission tomography.ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10404-010-0617-0) contains supplementary material, which is available to authorized users.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular & Medical Pharmacology, Crump Institute for Molecular Imaging, California NanoSystems Institute, David Geffen School of Medicine, University of California, Los Angeles, 570 Westwood Plaza, Los Angeles, CA 90095 USA.

ABSTRACT
Using liquid slugs as microreactors and microvessels enable precise control over the conditions of their contents on short-time scales for a wide variety of applications. Particularly for screening applications, there is a need for control of slug parameters such as size and composition. We describe a new microfluidic approach for creating slugs in air, each comprising a size and composition that can be selected individually for each slug. Two-component slugs are formed by first metering the desired volume of each reagent, merging the two volumes into an end-to-end slug, and propelling the slug to induce mixing. Volume control is achieved by a novel mechanism: two closed chambers on the chip are initially filled with air, and a valve in each is briefly opened to admit one of the reagents. The pressure of each reagent can be individually selected and determines the amount of air compression, and thus the amount of liquid that is admitted into each chamber. We describe the theory of operation, characterize the slug generation chip, and demonstrate the creation of slugs of different compositions. The use of microvalves in this approach enables robust operation with different liquids, and also enables one to work with extremely small samples, even down to a few slug volumes. The latter is important for applications involving precious reagents such as optimizing the reaction conditions for radiolabeling biological molecules as tracers for positron emission tomography. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10404-010-0617-0) contains supplementary material, which is available to authorized users.

No MeSH data available.


a Photographs of slug generator after completion of the filling step for different combinations of filling pressures Pfill,A (liquid A in left chamber) and Pfill,B (liquid B in right chamber). b Generation of two-component slugs with different compositions. Inlet A was kept at a constant pressure, Pfill,A = 140 kPag, and inlet B was varied over a range of pressures, Pfill,B. Pcarrier was 60 kPag, Pinitial was 0 kPag (vented), and tfill was 100 ms. The fraction of chambers A and B that are filled in each case are shown, along with a dotted line representing the theoretical ideal gas model with modification for PDMS expansion. The volume ratio of the two components in each resulting slug, A/B, is shown on the secondary y-axis
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Fig5: a Photographs of slug generator after completion of the filling step for different combinations of filling pressures Pfill,A (liquid A in left chamber) and Pfill,B (liquid B in right chamber). b Generation of two-component slugs with different compositions. Inlet A was kept at a constant pressure, Pfill,A = 140 kPag, and inlet B was varied over a range of pressures, Pfill,B. Pcarrier was 60 kPag, Pinitial was 0 kPag (vented), and tfill was 100 ms. The fraction of chambers A and B that are filled in each case are shown, along with a dotted line representing the theoretical ideal gas model with modification for PDMS expansion. The volume ratio of the two components in each resulting slug, A/B, is shown on the secondary y-axis

Mentions: This model, plotted in Figs. 4 and 5 (dotted lines), has one fitted parameter, k, and shows good agreement with the data when k = 0.00065 kPag−1. The dependence on, and sensitivity to, the material and geometrical properties should be investigated in more detail to ensure operational parameters remain constant from chip to chip. As a preliminary test, we performed experiments with several different chips of varying ages and observed only about 1% discrepancy in chamber filling fractions (data not shown).Fig. 5


Microfluidic device for robust generation of two-component liquid-in-air slugs with individually controlled composition.

Liu K, Chen YC, Tseng HR, Shen CK, van Dam RM - Microfluid Nanofluidics (2010)

a Photographs of slug generator after completion of the filling step for different combinations of filling pressures Pfill,A (liquid A in left chamber) and Pfill,B (liquid B in right chamber). b Generation of two-component slugs with different compositions. Inlet A was kept at a constant pressure, Pfill,A = 140 kPag, and inlet B was varied over a range of pressures, Pfill,B. Pcarrier was 60 kPag, Pinitial was 0 kPag (vented), and tfill was 100 ms. The fraction of chambers A and B that are filled in each case are shown, along with a dotted line representing the theoretical ideal gas model with modification for PDMS expansion. The volume ratio of the two components in each resulting slug, A/B, is shown on the secondary y-axis
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2944379&req=5

Fig5: a Photographs of slug generator after completion of the filling step for different combinations of filling pressures Pfill,A (liquid A in left chamber) and Pfill,B (liquid B in right chamber). b Generation of two-component slugs with different compositions. Inlet A was kept at a constant pressure, Pfill,A = 140 kPag, and inlet B was varied over a range of pressures, Pfill,B. Pcarrier was 60 kPag, Pinitial was 0 kPag (vented), and tfill was 100 ms. The fraction of chambers A and B that are filled in each case are shown, along with a dotted line representing the theoretical ideal gas model with modification for PDMS expansion. The volume ratio of the two components in each resulting slug, A/B, is shown on the secondary y-axis
Mentions: This model, plotted in Figs. 4 and 5 (dotted lines), has one fitted parameter, k, and shows good agreement with the data when k = 0.00065 kPag−1. The dependence on, and sensitivity to, the material and geometrical properties should be investigated in more detail to ensure operational parameters remain constant from chip to chip. As a preliminary test, we performed experiments with several different chips of varying ages and observed only about 1% discrepancy in chamber filling fractions (data not shown).Fig. 5

Bottom Line: The use of microvalves in this approach enables robust operation with different liquids, and also enables one to work with extremely small samples, even down to a few slug volumes.The latter is important for applications involving precious reagents such as optimizing the reaction conditions for radiolabeling biological molecules as tracers for positron emission tomography.ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10404-010-0617-0) contains supplementary material, which is available to authorized users.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular & Medical Pharmacology, Crump Institute for Molecular Imaging, California NanoSystems Institute, David Geffen School of Medicine, University of California, Los Angeles, 570 Westwood Plaza, Los Angeles, CA 90095 USA.

ABSTRACT
Using liquid slugs as microreactors and microvessels enable precise control over the conditions of their contents on short-time scales for a wide variety of applications. Particularly for screening applications, there is a need for control of slug parameters such as size and composition. We describe a new microfluidic approach for creating slugs in air, each comprising a size and composition that can be selected individually for each slug. Two-component slugs are formed by first metering the desired volume of each reagent, merging the two volumes into an end-to-end slug, and propelling the slug to induce mixing. Volume control is achieved by a novel mechanism: two closed chambers on the chip are initially filled with air, and a valve in each is briefly opened to admit one of the reagents. The pressure of each reagent can be individually selected and determines the amount of air compression, and thus the amount of liquid that is admitted into each chamber. We describe the theory of operation, characterize the slug generation chip, and demonstrate the creation of slugs of different compositions. The use of microvalves in this approach enables robust operation with different liquids, and also enables one to work with extremely small samples, even down to a few slug volumes. The latter is important for applications involving precious reagents such as optimizing the reaction conditions for radiolabeling biological molecules as tracers for positron emission tomography. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10404-010-0617-0) contains supplementary material, which is available to authorized users.

No MeSH data available.