Document Detail


Rails and anchors: guiding and trapping droplet microreactors in two dimensions.
MedLine Citation:
PMID:  21060946     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
This paper presents a method to control the motion of nanolitre drops in a wide and thin microchannel, by etching fine patterns into the channel's top surface. Such control is possible for drops that are squeezed by the channel roof, by allowing them to reduce their surface energy as they enter into a local depression. The resulting gain in surface energy pulls a drop into the groove such that localized holes can be used as anchors for holding drops, while linear patterns can be used as rails to guide them along complex trajectories. An anchored drop can remain stationary indefinitely, as long as the driving flow rate is below a critical value which depends on the hole and drop sizes. By micro-fabricating holes into a grid pattern, drops can be arrayed and held in the observation field of a microscope against the mean carrier flow. Their contents can then be modulated by gas exchange with the flowing carrier oil. We demonstrate in particular how the pH or the oxygen levels within the drops can be controlled spatially and temporally, either by exposing rows of drops to two streams of oil at different gas concentrations or by periodically switching oil inputs to vary the gas concentration of drops as a function of time. Oxygen control is used to selectively deoxygenate droplets that encapsulate red blood cells from patients suffering from sickle cell disease, in order to study the polymerization of intracellular hemoglobin. Cycles of oxygenation and deoxygenation of anchored droplets induce depolymerization and polymerization of the hemoglobin, thus providing a method to simulate the cycling that takes place in physiological flows.
Authors:
Paul Abbyad; Rémi Dangla; Antigoni Alexandrou; Charles N Baroud
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Publication Detail:
Type:  Journal Article     Date:  2010-11-09
Journal Detail:
Title:  Lab on a chip     Volume:  11     ISSN:  1473-0189     ISO Abbreviation:  Lab Chip     Publication Date:  2011 Mar 
Date Detail:
Created Date:  2011-02-17     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101128948     Medline TA:  Lab Chip     Country:  England    
Other Details:
Languages:  eng     Pagination:  813-21     Citation Subset:  IM    
Affiliation:
Laboratoire d'Hydrodynamique (LadHyX) and Department of Mechanics, Ecole Polytechnique, CNRS, 91128, Palaiseau, France. baroud@ladhyx.polytechnique.fr.
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