Rapid and even spreading of complex fluids over a large area in porous substrates

Agrawal, Prashant; Kumar, Hemant; Kumar, Prasoon

doi:10.1063/5.0019939

Cited by 3 publications

(1 citation statement)

References 37 publications

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“…Paper has many advantages, such as a low cost, portability, compatibility with most biochemical reactions and high flexibility [1][2][3][4][5][6][7]; it can be combined with automation technologies to form programmable paper-based microfluidic devices for better control of fluidic sample transport, mixing and reaction, then to realize multiple biomarker detection, disease diagnosis, etc. [8][9][10][11][12][13][14][15]. Paper-based microfluidic devices have become a useful point-of-care testing (POCT) tool, however, there are some deficiencies, such as low sensitivity, poor reliability, and low reproducibility.…”

Section: Introductionmentioning

confidence: 99%

Imbibition of Newtonian Fluids in Paper-like Materials with the Infinitesimal Control Volume Method

Song

Huang

2021

Micromachines

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Paper-based microfluidic devices are widely used in point-of-care testing applications. Imbibition study of paper porous media is important for fluid controlling, and then significant to the applications of paper-based microfluidic devices. Here we propose an analytical approach based on the infinitesimal control volume method to study the imbibition of Newtonian fluids in commonly used paper-like materials. Three common paper shapes (rectangular paper strips, fan-shaped and circular paper sheets) are investigated with three modeling methods (corresponding to equivalent tiny pores with circle, square and regular triangle cross section respectively). A model is derived for liquid imbibition in rectangular paper strips, and the control equations for liquid imbibition in fan-shaped and circular paper sheets are also derived. The model is verified by imbibition experiments done using the mixed cellulose ester filter paper and pure water. The relation of imbibition distance and time is similar to that of the Lucas−Washburn (L−W) model. In addition, a new porosity measurement method based on the imbibition in circular paper sheets is proposed and verified. Finally, the flow rates are investigated. This study can provide guidance for the design of different shapes of paper, and for better applications of paper-based microfluidic devices.

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Section: Introductionmentioning

confidence: 99%

Imbibition of Newtonian Fluids in Paper-like Materials with the Infinitesimal Control Volume Method

Song

Huang

2021

Micromachines

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Capillary transfer: Numerical study of how topology affects the fluid flow rate into a planar microstructure with pseudopotential multiphase Lattice-Boltzmann method

Pham

2021

Physics of Fluids

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We investigate how topology impacts capillary action with the hope of aiding future thermal engineering decisions. Heat pipes and their two-dimensional variant, vapor chambers are essential components in electronics cooling. With thin-film evaporation as the driving force for such high-heat-flux movers, studies have been done to optimize the thermal performance of different designs. However, the fundamental problem of liquid transportation needs to be addressed exclusively: evaporation can only work as long as the new liquid is continuously being replaced. The device achieves this by the capillary process (or wicking) through the thermal ground (or wicks): a configuration of microstructures attached to the device's walls. Some planar topologies of the structure allow for consistent but slower mass feeding; others offer higher bandwidth but with local flow hindrance, creating a pulsating tendency; certain conditions would even block the capillary flow. Surveying the capillary performance of different two-dimensional designs of the thermal ground, we encounter a topological factor that correlates with this mass transfer rate. We incorporate in the factor the wick's width, its height, and the gap between one microstructure to another. An energy model is studied to explain the underlying influence of the structure topology, while Lattice-Boltzmann method is used to evaluate the capillary dynamics inside the thermal ground. With ultra-thin applications in mind, the paper looks at the length scales of micrometers with a wick height of 50 μm. Overall, we find that tightly packed structures pull the most liquid in the same amount of time; however, we find that two core constraints need to be met: sufficient clearance between structures and freedom of mobility.

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Dynamics of liquid flow through fabric porous media: Experimental, analytical, and numerical investigation

Patari,

Chowdhury,

Kumar

et al. 2023

Physics of Fluids

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Over the past few decades, there has been a significant increase in the use of paper-based microfluidic devices in various fields, including environmental monitoring, food safety analysis, and medical diagnostics. As a result, flow through paper-based substrates has gained much attention in the research community. Liquid flows through a paper substrate due to the inherent capillary suction pressure. In order to predict the flow through a paper substrate, we used macro- and microscopic methodologies to construct an analytical and numerical model. We have considered the effect of different factors, e.g., roughness, swelling, dynamic contact angle, and evaporation simultaneously to predict liquid wicking. A modified capillary radius technique is used to incorporate the effects of roughness and swelling into the numerical model, while a sink factor in Darcy's equation is used to model the evaporation. Experiments are performed to validate the developed models, and it is found that both models are in good agreement with the experiments, with a maximum error of 5%. The proposed analytical and numerical models can be used to forecast the capillary rise in a paper-based substrate, which has implications for paper-based microfluidic devices.

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Rapid and even spreading of complex fluids over a large area in porous substrates

Cited by 3 publications

References 37 publications

Imbibition of Newtonian Fluids in Paper-like Materials with the Infinitesimal Control Volume Method

Imbibition of Newtonian Fluids in Paper-like Materials with the Infinitesimal Control Volume Method

Capillary transfer: Numerical study of how topology affects the fluid flow rate into a planar microstructure with pseudopotential multiphase Lattice-Boltzmann method

Dynamics of liquid flow through fabric porous media: Experimental, analytical, and numerical investigation

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