Capillary pumps with constant flow rate

Wijngaart, Wouter van der

doi:10.1007/s10404-014-1365-3

Cited by 6 publications

(7 citation statements)

References 5 publications

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“…For this specific shape, the twodimensional model (Ref. 27; see also ESI) predicts an elliptic liquid The region of uniform width ‫ݓ‬ and length ݈ represents a generalized initial load, and ߚ denotes the opening angle of the expansion. In the hyperbolic section, the 2D model 29 predicts an elliptical liquid front (red curve) whereas the 1D model considered here involves a flat front (blue line).…”

Section: Resultsmentioning

confidence: 99%

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Rational design of capillary-driven flows for paper-based microfluidics

2015

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The design of paper-based assays that integrate passive pumping requires a precise programming of the fluid transport, which has to be encoded in the geometrical shape of the substrate. This requirement becomes critical in multiple-step processes, where fluid handling must be accurate and reproducible for each operation. The present work theoretically investigates the capillary imbibition in paper-like substrates to better understand fluid transport in terms of the macroscopic geometry of the flow domain. A fluid dynamic model was derived for homogeneous porous substrates with arbitrary cross-sectional shapes, which allows one to determine the cross-sectional profile required for a prescribed fluid velocity or mass transport rate. An extension of the model to slit microchannels is also demonstrated. Calculations were validated by experiments with prototypes fabricated in our lab. The proposed method constitutes a valuable tool for the rational design of paper-based assays.

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Section: Resultsmentioning

confidence: 99%

“…Solving eqn (10) certainly helps to rationalize several engineering problems in paper-based microfluidics. For instance, the design of capillary pumps that provide a constant flow rate, which is largely explored at present; 15,18,27 this particular case will be discussed later.…”

Section: Inverse Calculationmentioning

confidence: 99%

Rational design of capillary-driven flows for paper-based microfluidics

2015

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“…They further demonstrated that this micropump can pump fluid of varying viscosity and density with a constant speed ( Figure 5 (d)) [103,104]. In an another study, researchers have suggested the use of a converging tube to increase the capillary flow velocity [105]. Such systems can be investigated for the blood flow studies where the hematocrit significantly affects the viscosity of blood and thereby the capillary flow velocity.…”

Section: Design Modification To Facilitate Capillary Pumping Of High mentioning

confidence: 99%

Challenges and opportunities in blood flow through porous substrate: A design and interface perspective of dried blood spot

Kumar

Agrawal

Chatterjee

2019

Journal of Pharmaceutical and Biomedical Analysis

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Highlights  Comparative analysis of current blood microsampling devices is reviewed.  Intrinsic and extrinsic factors affecting blood flow in porous materials are presented.  Current advances in the design and development of micro devices and materials for development of blood microsamplers are presented.  Major clinical and preclinical applications of dried blood spot created by a blood microsampler device are discussed.

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“…In capillary devices with constant cross-sections, this leads to the well-known Washburn behavior, which is characterized by a flow rate that depends on the square root of time 19–21 . Constant capillary flow can be obtained by introducing a large upstream liquid resistance that dominates the viscous losses in the capillary device 22,23 . Sample viscosity-independent capillary pumping can be obtained by introducing a downstream fluidic resistance for the displaced air that dominates the viscous losses in the capillary system 1 .…”

Section: Introductionmentioning

confidence: 99%

Capillary pumping independent of the liquid surface energy and viscosity

2018

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Capillary pumping is an attractive means of liquid actuation because it is a passive mechanism, i.e., it does not rely on an external energy supply during operation. The capillary flow rate generally depends on the liquid sample viscosity and surface energy. This poses a problem for capillary-driven systems that rely on a predictable flow rate and for which the sample viscosity or surface energy are not precisely known. Here, we introduce the capillary pumping of sample liquids with a flow rate that is constant in time and independent of the sample viscosity and sample surface energy. These features are enabled by a design in which a well-characterized pump liquid is capillarily imbibed into the downstream section of the pump and thereby pulls the unknown sample liquid into the upstream pump section. The downstream pump geometry is designed to exert a Laplace pressure and fluidic resistance that are substantially larger than those exerted by the upstream pump geometry on the sample liquid. Hence, the influence of the unknown sample liquid on the flow rate is negligible. We experimentally tested pumps of the new design with a variety of sample liquids, including water, different samples of whole blood, different samples of urine, isopropanol, mineral oil, and glycerol. The capillary filling speeds of these liquids vary by more than a factor 1000 when imbibed to a standard constant cross-section glass capillary. In our new pump design, 20 filling tests involving these liquid samples with vastly different properties resulted in a constant volumetric flow rate in the range of 20.96-24.76 μL/min. We expect this novel capillary design to have immediate applications in lab-on-a-chip systems and diagnostic devices.

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Capillary pumps with constant flow rate

Cited by 6 publications

References 5 publications

Rational design of capillary-driven flows for paper-based microfluidics

Rational design of capillary-driven flows for paper-based microfluidics

Challenges and opportunities in blood flow through porous substrate: A design and interface perspective of dried blood spot

Capillary pumping independent of the liquid surface energy and viscosity

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