Two-dimensional model of imbibition into paper-based networks using Richards’ equation

Pérez-Cruz, Ángel; Stiharu, Ion; Domínguez-González, Aurelio

doi:10.1007/s10404-017-1937-0

Cited by 42 publications

(30 citation statements)

References 35 publications

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“…where is the imbibition index by which the width of the transition zone is controlled and more discussion regarding can be found in Ref (Perez-Cruz, et al, 2017). Note that here the format of Brooks-Corey relations is used for describing the liquid front, and is indirectly related to the intrinsic material properties.…”

Section: Liquid Front Trackingmentioning

confidence: 99%

Modelling Imbibition Processes in Heterogeneous Porous Media

2018

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Imbibition is a commonly encountered multiphase problem in various fields, and exact prediction of imbibition processes is a key issue for better understanding capillary flow in heterogeneous porous media. In this work, a numerical framework for describing imbibition processes in porous media with material heterogeneity is proposed to track the moving wetting front with the help of a partially saturated region at the front vicinity. A new interface treatment, named the interface integral method, is developed here, combined with which the proposed numerical model provides a complete framework for imbibition problems. After validation of the current model with existing experimental results of one-dimensional imbibition, simulations on a series of two-dimensional cases are analysed with the presences of multiple porous phases. The simulations presented here not only demonstrate the suitability of the numerical framework on complex domains but also present its feasibility and potential for further engineering applications involving imbibition in heterogeneous media.

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Section: Liquid Front Trackingmentioning

confidence: 99%

Modelling Imbibition Processes in Heterogeneous Porous Media

2018

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“…A two-dimensional imbibition model of paper networks for various geometries is proposed by solving the nonlinear Richard's equation for unsaturated porous media. 90 A hydrophobic top cover is also implemented. 91 There are some studies on the effect of channel boundaries on the imbibition speed, which is not present in the Washburn equation.…”

Section: Theoretical and Computational Approachesmentioning

confidence: 99%

A review on wax printed microfluidic paper-based devices for international health

2017

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Paper-based microfluidics has attracted attention for the last ten years due to its advantages such as low sample volume requirement, ease of use, portability, high sensitivity, and no necessity to well-equipped laboratory equipment and well-trained manpower. These characteristics have made paper platforms a promising alternative for a variety of applications such as clinical diagnosis and quantitative analysis of chemical and biological substances. Among the wide range of fabrication methods for microfluidic paper-based analytical devices (PADs), the wax printing method is suitable for high throughput production and requires only a commercial printer and a heating source to fabricate complex two or three-dimensional structures for multipurpose systems. PADs can be used by anyone for diagnosis and analysis; therefore, wax printed PADs are promising especially in resource limited environments where people cannot get sensitive and fast diagnosis of their serious health problems and where food, water, and related products are not able to be screened for toxic elements. This review paper is focused on the applications of paper-based microfluidic devices fabricated by the wax printing technique and used for international health. Besides presenting the current limitations and advantages, the future directions of this technology including the commercial aspects are discussed. As a conclusion, the wax printing technology continues to overcome the current limitations and to be one of the promising fabrication techniques. In the near future, with the increase of the current interest of the industrial companies on the paper-based technology, the wax-printed paper-based platforms are expected to take place especially in the healthcare industry.

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“…To better understand flow patterns in such an assembly, we present a Richards equation model of wicking flow in this stacked assembly. Richards equation 7 accounts for partial saturation in paper membranes and our group 8,9 and others 10,11 have previously established its use in modelling flow in paper microfluidic devices. We demonstrate the multiplexing feature of BF-μPAD by simultaneously testing four analytes thiocyanate 12 , protein 3 , glucose 4,13 , and nitrite 14,15 in a 2cm x 2cm assembly.…”

Section: Introductionmentioning

confidence: 99%

Barrier-Free Microfluidic Paper Analytical Devices for Multiplex Colorimetric Detection of Analytes

Chauhan¹,

Toley²

2021

Preprint

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<p>In recent years, microfluidic paper analytical devices (μPADs) have been extensively utilized to conduct multiplex colorimetric assays. Despite their simple and user-friendly operation, the need for patterning paper with wax or other physical barriers to create flow channels makes large scale manufacturing cumbersome. Moreover, convection of rehydrated reagents in the test zones leads to non-uniform colorimetric signals, which makes quantification challenging. To overcome these challenges, we present a new device design called barrier-free μPAD (BF-μPAD) that consists of a stack of two paper membranes having different wicking rates – the top layer acting as a fluid distributing layer and the bottom layer containing reagents for colorimetric detection. Multiple analytes can be detected using this assembly without the need to pattern either layer with wax or other barriers. In one embodiment, a device is capable of delivering the sample fluid to 20 distinct dried reagent spots stored on an 8cm x 2cm membrane in as few as 30 seconds. The multiplexing feature of BF-μPAD is demonstrated for colorimetric detection of salivary thiocyanate, protein, glucose, and nitrite. Most importantly, the device improves the limit of detection of colorimetric assays performed on conventional μPADs by more than 3.5x. To understand fluid imbibition in the paper assembly, the device geometry is modelled in COMSOL Multiphysics using Richards equation; the results obtained provide insights into the non-intuitive flow pattern producing perfectly uniform signals in the barrier-free assembly.<b></b></p>

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Two-dimensional model of imbibition into paper-based networks using Richards’ equation

Cited by 42 publications

References 35 publications

Modelling Imbibition Processes in Heterogeneous Porous Media

Modelling Imbibition Processes in Heterogeneous Porous Media

A review on wax printed microfluidic paper-based devices for international health

Barrier-Free Microfluidic Paper Analytical Devices for Multiplex Colorimetric Detection of Analytes

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