Characterization of a macro porous polymer membrane at micron-scale by Confocal-Laser-Scanning Microscopy and 3D image analysis

Ley, Adrian; Altschuh, Patrick; Thom, Volkmar; Selzer, Michael; Nestler, Britta; Vana, Philipp

doi:10.1016/j.memsci.2018.07.062

Cited by 21 publications

(11 citation statements)

References 23 publications

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“…The stack of 8-bit (256 intensity levels) grayscale images is filtered by a Gaussian 3D filter with a sigma of three voxels. Following this, a binarization algorithm is applied, in which the threshold is adjusted to obtain the experimentally measured porosity as described in [ 27 ]. For both processing steps, the image processing software ImageJ v1.51J8 [ 46 ] is used.…”

Section: Materials and Methodsmentioning

confidence: 99%

“…Geometry-based approaches to determine an effective pore radius require a detailed representation of the pore space, which can be obtained by scanning electron microscopy (SEM), transmission electron microscopy (TEM), confocal laser scanning microscopy, or X-ray computer tomography (CT) measurements [ 27 ], among others. Alternatively, digital representations can be approached by algorithmically generating both simplified and complex capillary pore spaces [ 28 , 29 ].…”

Section: Introductionmentioning

confidence: 99%

“…For the derivation, high-resolution X-ray computer tomography experiments were conducted, and 3D representations of the two membranes were obtained. In our previous work [ 27 ], a characterization tool was presented, which allows extracting both the pore and the ligament radius distributions of porous microstructures as the basic geometric properties.…”

Section: Introductionmentioning

confidence: 99%

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Wicking in Porous Polymeric Membranes: Determination of an Effective Capillary Radius to Predict the Flow Behavior in Lateral Flow Assays

et al. 2022

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The working principle of lateral flow assays, such as the widely used COVID-19 rapid tests, is based on the capillary-driven liquid transport of a sample fluid to a test line using porous polymeric membranes as the conductive medium. In order to predict this wicking process by simplified analytical models, it is essential to determine an effective capillary radius for the highly porous and open-pored membranes. In this work, a parametric study is performed with selected simplified structures, representing the complex microstructure of the membrane. For this, a phase-field approach with a special wetting boundary condition to describe the meniscus formation and the corresponding mean surface curvature for each structure setup is used. As a main result, an analytical correlation between geometric structure parameters and an effective capillary radius, based on a correction factor, are obtained. The resulting correlation is verified by applying image analysis methods on reconstructed computer tomography scans of two different porous polymeric membranes and thus determining the geometric structure parameters. Subsequently, a macroscale flow model that includes the correlated effective pore size and geometrical capillary radius is applied, and the results are compared with wicking experiments. Based on the derived correction function, it is shown that the analytical prediction of the wicking process in highly porous polymeric membranes is possible without the fitting of experimental wicking data. Furthermore, it can be seen that the estimated effective pore radius of the two membranes is 8 to 10 times higher than their geometric mean pore radii.

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Section: Materials and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Wicking in Porous Polymeric Membranes: Determination of an Effective Capillary Radius to Predict the Flow Behavior in Lateral Flow Assays

et al. 2022

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“…The obtained images were reconstructed into small cubes for further investigation of their properties and flow pathways. This reconstruction of porous structures based on imaging techniques has recently been established in the fields of geophysics [32], fuel cells [33], and symmetric flat sheet membranes [34]; however, not for polymeric multibore membranes.…”

Section: Introductionmentioning

confidence: 99%

How does porosity heterogeneity affect the transport properties of multibore filtration membranes?

Wypysek,

Rall,

Neef

et al. 2022

Preprint

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The prediction of pressure and flow distributions inside porous membranes is important if the geometry deviates from singlebore tubular geometries. This task remains challenging, especially when considering local porosity variations caused by lumenand shell-side membrane skins and macro-and micro-void structures, all of them present in multibore membranes.This study analyzes pure water forward and reverse permeation and backwashing phenomena for a polymeric multibore membrane with spatially-varying porosity and permeability properties using computational fluid dynamics simulations. The heterogeneity of porosity distribution is experimentally characterized by scanning electron microscopy scans and reconstructed cuboids of X-ray micro-computed tomography scans. The reconstructed cuboids are used to determine porosity, pore size distribution, and intrinsic permeability in the membrane's porous structure in all spatial directions. These position-dependent properties are then applied to porous media flow simulations of the whole membrane domain with different properties for separation layer, support structure, and outside skin layer. Various cases mimicking the pure water permeation, fouling, and backwashing behavior of the membrane are simulated and compared to previously obtained MRI measurements.This work reveals (a) anisotropic permeability values and isoporosity in all directions and (b) differing contributions of each lumen channel to the total membrane performance, depending on the membrane-skin's properties. This study encourages to pertain the quest of understanding the interaction of spatially distributed membrane properties and the overall membrane module performance of multibore membranes.

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“…Optical investigation of membrane structures can be achieved by angle‐resolved [ 14 ] or polarization‐resolved [ 15 ] light scattering, by 3D optical reconstruction based on low coherence interferometry [ 16 ] or optical coherence tomography, [ 17 ] and by direct observation through confocal microscopy. [ 18 ]…”

Section: Introductionmentioning

confidence: 99%

Fabrication and Optical Modeling of Micro‐Porous Membranes Index‐Matched with Water for On‐Line Sensing Applications

Lanfranco

Giavazzi

Bellini

et al. 2020

Macro Materials & Eng

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Membranes made of perfluorinated materials having a refractive index close to that of water enable straightforward detection of water solutes at the interface, hence providing a novel sensing tool for fluidic systems. Here it is reported the production by non‐solvent induced phase separation and characterization of microporous membranes made of Hyflon AD, an amorphous copolymer of tetrafluoroethylene. Their optical turbidity when soaked in liquids having different refractive indices is studied and the data are interpreted with an optical model linking scattered light and structural features of the membrane. The average polymer and pore chord lengths obtained in this way scale with the filtering pore size measured by capillary flow porometry. Then, the optical response of the membranes when soaked in aqueous surfactant solutions is investigated and the effects of the molecular adsorption on the internal membrane surface is successfully interpreted by an extension of the model. Overall, the results show that index‐matched membranes can be designed and produced to provide a simple optical detection of the composition of the soaking liquid or to monitor the initial stage of membrane fouling.

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Characterization of a macro porous polymer membrane at micron-scale by Confocal-Laser-Scanning Microscopy and 3D image analysis

Cited by 21 publications

References 23 publications

Wicking in Porous Polymeric Membranes: Determination of an Effective Capillary Radius to Predict the Flow Behavior in Lateral Flow Assays

Wicking in Porous Polymeric Membranes: Determination of an Effective Capillary Radius to Predict the Flow Behavior in Lateral Flow Assays

How does porosity heterogeneity affect the transport properties of multibore filtration membranes?

Fabrication and Optical Modeling of Micro‐Porous Membranes Index‐Matched with Water for On‐Line Sensing Applications

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