Image segmentation of nanoscale Zernike phase contrast X-ray computed tomography images

Kumar, Arjun; Mandal, Pratiti; Zhang, Yongjie; Litster, Shawn

doi:10.1063/1.4919835

Cited by 21 publications

(25 citation statements)

References 28 publications

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“…However, imaging in Zernike phase contrast has the effect of producing dark and light ‘halo’ effects around the outside and inside of the fiber phase, respectively, which can be seen quite clearly in the xz orthoslices of the greyscale reconstructed data (Figures a) ,. Though this can be removed through the use of computer algorithms, it is not necessary in the case of the relatively small fibers imaged in this study, and in fact his serves to highlight the fiber phase and makes the mottled background less problematic for accurate segmentation.…”

Section: Methodsmentioning

confidence: 90%

X‐ray Nano Computed Tomography of Electrospun Fibrous Mats as Flow Battery Electrodes

et al. 2018

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Many electrochemical energy storage and conversion devices employ porous media as electrodes, gas diffusion layers or separators. Recently, electrospinning has received significant attention as a way to generate nano‐fibers of polymers with controlled morphology and properties that, once carbonised, can act as conductive and porous media for electrochemical energy devices. The recent advances in X‐ray computed tomography have led the technique to be widely used in the characterisation of energy technologies and porous media as it offers a uniquely non‐destructive insight into the 3D microstructure of materials. Here we present electrospun fibrous mats with uncontrolled, controlled and aligned morphology for use as redox flow battery electrodes and, for the first time, obtain ultra‐high resolution nano‐tomographic X‐ray imaging of the materials using a lab source. The virtual 3D volumes enable extraction of parameters that would not be possible via other characterisation routes.

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Section: Methodsmentioning

confidence: 90%

X‐ray Nano Computed Tomography of Electrospun Fibrous Mats as Flow Battery Electrodes

et al. 2018

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“…The tomographic data was reconstructed with Zeiss's filtered back projection software, resulting in the voxels of approximately 128 nm in a cylindrical volume with a 65 μm diameter and height. The phase contrast imaged was corrected from interface halos characteristic of phase contrast to volumetric images using the algorithm developed in Kumar et al, 78 which corrects phase contrast artifacts in the reconstructed data. Binary thresholding was applied to the 3D image to obtain the segmented structures of the fibers, binders, and PTFE.…”

mentioning

confidence: 99%

Micro-Scale Analysis of Liquid Water Breakthrough inside Gas Diffusion Layer for PEMFC Using X-ray Computed Tomography and Lattice Boltzmann Method

Satjaritanun

Weidner

Hirano

et al. 2017

J. Electrochem. Soc.

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The main objective of this work is to predict the breakthrough pressure of liquid water transport through the gas diffusion layer (GDL) and/or micro porous layer (MPL) used in polymer electrolyte membrane fuel cells. The integration of structural GDL and MPL with Lattice Boltzmann Method is primary focused. The numerical predictions are also compared with experimental data. The interaction between liquid phase and different surface treatments of solid structures controls the evolution of liquid water and the change of capillary pressure. The geometries of GDLs and MPLs were obtained by three dimensional reconstructed micro-structure images from both nanometer and micrometer-scaled high spatial resolution X-ray computed tomography (CT). The predictions of water breakthrough pressure agree with the data observed in the experiment. They also reveal that the breakthrough pressure and liquid water evolution inside the GDL samples are different when the wetting properties of GDL and/or MPL are changed. The detailed microporous property can be obtained using high spatial resolution image from nanometer-scaled X-ray CT, a.k.a. Nano X-ray CT. Meanwhile, images from micrometer-scaled X-ray CT, a.k.a. Micro X-ray CT, give proper field of view to cover complete vision of porous materials, including cracks in the MPL. The enhancement of the transport of liquid water and reactant gases in polymer electrolyte membrane fuel cells (PEMFCs) is a critical subject that has been greatly studied due to its critical importance to fuel cell performance at high current densities.1-3 The liquid transport and the concurrent two-phase flow in the gas diffusion layer (GDL) and micro porous layer (MPL) are the most widely studied. In general GDL materials for PEMFCs are made of carbon fiber based cloths and paper. These materials are typically porous to allow for the transport of reactant gases to the catalyst layer as well as transport of condensed water from the catalyst layer. To accelerate the removal of liquid water, GDLs are usually impregnated with non-wetting polymer such as polytetrafluoroethylene (PTFE) to create hydrophobic characteristics. Further, a thin MPL which consists of carbon powder and polymer binders is applied to the GDL side facing the catalyst layer in the membrane electrode assembly (MEA) to further increase cell performance and mechanical stability. The complex structural and chemical heterogeneity of the GDL and MPL make studying the transport of liquid water and obtaining the solution for mass transport losses substantially complicated. 4,5 Many researchers have studied the transport of liquid water through the GDL and MPL in order to develop an understanding of the resistance of reactant gas transport due to water accumulation.6-27 These included the observation of vapor condensation and liquid breakthrough in a GDL using an environmental scanning electron microscope (SEM).13,14 They proposed a treelike transport mechanism in which micro-droplets condensed from vapor agglomerate to form macro-droplets which even...

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“…Examples of reconstructed slices before and after phase artifact reduction are shown in Figure a–d. Recently, Kumar et al developed a full model of Zernike phase contrast for Fresnel zone plate X‐ray microscopes, allowing the Zernike artifacts to be removed by a similar deconvolution approach. However their model is complex to implement, and regularization for the deconvolution step requires eight user‐defined parameters to be optimized.…”

Section: Resultsmentioning

confidence: 99%

3D X-Ray Nanotomography of Cells Grown on Electrospun Scaffolds

2016

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Here, it is demonstrated that X-ray nanotomography with Zernike phase contrast can be used for 3D imaging of cells grown on electrospun polymer scaffolds. The scaffold fibers and cells are simultaneously imaged, enabling the influence of scaffold architecture on cell location and morphology to be studied. The high resolution enables subcellular details to be revealed. The X-ray imaging conditions were optimized to reduce scan times, making it feasible to scan multiple regions of interest in relatively large samples. An image processing procedure is presented which enables scaffold characteristics and cell location to be quantified. The procedure is demonstrated by comparing the ingrowth of cells after culture for 3 and 6 days.

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Image segmentation of nanoscale Zernike phase contrast X-ray computed tomography images

Cited by 21 publications

References 28 publications

X‐ray Nano Computed Tomography of Electrospun Fibrous Mats as Flow Battery Electrodes

X‐ray Nano Computed Tomography of Electrospun Fibrous Mats as Flow Battery Electrodes

Micro-Scale Analysis of Liquid Water Breakthrough inside Gas Diffusion Layer for PEMFC Using X-ray Computed Tomography and Lattice Boltzmann Method

3D X-Ray Nanotomography of Cells Grown on Electrospun Scaffolds

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