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Issue 23, 2009
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Passive microfluidic pumping using coupled capillary/evaporation effects

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Controlled pumping of fluids through microfluidic networks is a critical unit operation ubiquitous to lab-on-a-chip applications. Although there have been a number of studies involving the creation of passive flows within lab-on-a-chip devices, none has shown the ability to create temporally stable flows for periods longer than several minutes. Here a passive pumping approach is presented in which a large pressure differential arising from a small, curved meniscus situated along the bottom corners of an outlet reservoir serves to drive fluid through a microfluidic network. The system quickly reaches steady-state and is able to provide precise volumetric flow rates for periods lasting over an hour. A two-step mathematical model provides accurate predictions of fluid and mass transport dynamics in these devices, as validated by particle tracking in laboratory systems. Precise flow rates spanning an order of magnitude are accomplished via control of the microchannel and outlet reservoir dimensions. This flow mechanism has the potential to be applied to many micro-total analytical system devices that utilize pressure-driven flow; as an illustrative example, the pumping technique is applied for the passive generation of temporally stable chemical gradients.

Graphical abstract: Passive microfluidic pumping using coupled capillary/evaporation effects

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Publication details

The article was received on 23 Jun 2009, accepted on 25 Aug 2009 and first published on 05 Oct 2009

Article type: Paper
DOI: 10.1039/B912213C
Citation: Lab Chip, 2009,9, 3422-3429
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    Passive microfluidic pumping using coupled capillary/evaporation effects

    N. S. Lynn and D. S. Dandy, Lab Chip, 2009, 9, 3422
    DOI: 10.1039/B912213C

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