Micro-CT is used in the analysis of filter media to study specific properties such as wet strength, porosity, particle retention, volumetric flow rate, compatibility, efficiency, and capacity. Applications such as the filtration of air, fuel, chemicals, and beverages utilize various types of filter media, typically composed of natural or synthetic fibers such as cellulose, polypropylene, and polyethylene. Filter properties depend on the 3D fiber network and interconnected pores, and micro-CT is an excellent tool for the non-destructive visualization and quantitative analysis of filter media.

3D imaging and analysis of fibrous filter sheets using X-ray microtomography and image analysis
Micro-CT is widely used to study the porosity of cellular and fibrous material. These include food products, cancellous bone, paper, textile fabrics, and membranes.”In this study micro-CT is used for the 3D visualisation and analysis of fibrous filter sheets with a thickness ranging from 40 to 90 μm made from different fibre materials and produced using different processes. Fibres with different densities are visible in micro-CT images as gradients of grey levels or intensities.” This study presented a methodology to determine the thickness of thin fibrous filters and obtain quantitative information on porosity, pore size distribution, and pore interconnectedness.
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Microcomputed tomography–based characterization of advanced materials: a review
This article discusses the use of micro-CT for materials science research. Among other applications, micro-CT is used in the design and improvement of efficient filters. Since the microstructure of materials helps determine their mechanical and physical attributes and behavior, imaging the inner structure and characteristics is important. 3D imaging can reveal the volume, shape, spatial and size distribution, and connectivity of pores, cracks, and so on. The article gives the example of viewing local changes in porosity through the whole thickness of a fibrous filter and “capturing the structure-dependent behavior of deposits: these do not leave the filter, rather they gradually move to the deeper regions. It was also possible to study the effects of microstructure on aerosol deposition in high efficiency particulate air (HEPA) filters, assess liquid distribution in the filter during liquid aerosol filtration, and uncover the effects of filtration velocity on clogging. Water filtration membranes are also accessible for micro-CT analysis.”
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Analysis of the behavior of deposits in fibrous filters during non-steady state filtration using X-ray computed tomography
This paper explains the non-steady state aerosol particle filtration in fibrous filters and the use of micro-CT analysis to study the process. Fibrous filters are widely used for removing particles from fluids. “Due to the development of new technologies, increasing environmental pollution, and greater emphasis placed on the protection of human health and the environment,” the requirements for gas purification systems are increasingly becoming more strict. This study examines the behavior of deposits in a filter during filtration, observing whether they travel inside the filter structure, stay in place, or completely leave the filter.
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3D imaging and analysis of fibrous filter sheets using X-ray microtomography and image analysis
This study analyzes filter material that is used in many applications such as filtration of air, fuel, chemicals, and beverages. “In this study micro-CT is used for the 3D visualisation and analysis of fibrous filter sheets with a thickness ranging from 40 to 90 μm made from different fibre materials and produced using different processes. Fibres with different densities are visible in micro-CT images as gradients of grey levels or intensities, and can be straightforwardly segmented using thresholding. Image analysis is used to quantify the pore morphology.” This study demonstrates how micro-CT was used to determine the true thickness of thin fibrous filters, as well as how quantitative information on porosity, pore size distribution, and pore interconnectedness was obtained from the scans.
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X-ray Microscopic Examination of Filter Media
X-ray Microscopic Inspection of a Multistage HEPA Filter
A Water Filter and the Watershed Model