Automatic diameter and orientation distribution determination of fibrous materials in micro X‐ray CT imaging data

Abstract

Fibrous nanomaterials such as electrospun materials have many uses ranging from tissue engineering to biosensors. High-resolution imaging is an important component in the characterization of these materials. Important parameters required to predict and study the properties of fibre rich materials include diameter and orientation distribution as well as fibre spacing. The orientations and the relative dimensions of the fibres can be measured via specially designed imaging software. Difficulties in this measurement process can arise if fibres are distributed in close proximity to each other in relation to the resolution of the imaging modality. For example, if some automation is required in the measurement process and, particularly, if the automated processes are not designed for situations where the fibres are in close proximity to each other. This work is therefore concerned with the development of automated measurement techniques to provide estimates of the diameters of fibres and also the orientation distribution. The software automatically detects special points in the fibrous materials where fibres can be considered to have some delineation from surrounding fibres. These sparse points are considered to be points at which estimates of the fibres' properties can be quantified. Aligned and randomly distributed electrospun poly(caprolactone) nanofibres were prepared. Imaging of these materials was performed with an X-ray Computer Tomography system with an image voxel size of 0.15 × 0.15 × 0.15 μm . Scanning Electron Microscopy images were also obtained. Fibre diameters estimated using images from both modalities using the developed techniques were found to be in agreement. Orientation distribution was summarized with multiscale entropy and found to be consistent with visual observation across different scales. LAY DESCRIPTION: Fibres are present in many types of materials which can include, for some materials, very small fibres e.g. a few nanometres in diameter. Very small fibres are present in collagen and elastin which are common tissues of many organs in many types of living things. The sizes of these very small fibres and how they are arranged are important information that can help in the understanding of the overall properties of these materials. Materials with very small fibres can also be synthesized using specialised techniques. The properties of these synthesized fibrous materials are also important to help in understanding how the materials will perform in various different applications. Applications are many and can range from tissue engineering to drug delivery. Some properties of these materials can be shown, visually, with the aid of 3D imaging techniques such as X-ray Computer Tomography (XCT) or in 2D, with Scanning Electron Microscopy (SEM) but at a higher magnification. The work described here is centred around the development of computer algorithms to automatically determine material properties from 3D XCT images. Tests are performed with material samples, where the fibres are aligned (in semi...

Volume orientation: a practical solution to analyse the orientation of fibres in composite materials

“…() with the aim of viewing human vasculature in radiographic images, enhancing objects similar to tubular shapes (vessels). Chiverton (Chiverton et al ., ) improved the method, making it suitable for an automatic determination of the diameter and orientation of electrospun fibres. Teßmann et al .…”

Volumetric Simulation of Nano-Fibres and 2D SEM and 3D XCT Imaging Processes

“…Previously, for our work in [2], Electrospun poly(caprolactone) (PCL) nanofibre samples were prepared. SEM images were obtained for gold-coated samples (sputter coater Q150R, Quorom Technologies) with a Zeiss EVO MA10 scanning electron microscope with electron back-scatter capability.…”

“…The two sources of imaging information can however be combined to provide more detailed understanding of sizes of fibres in 3D. This was the approach taken in our previous work in [2], where electrospun poly(caprolactone) PCL nano-fibre samples were prepared and then imaged with SEM and XCT modalities.…”

Evaluation of fiber orientation of AC and DC electrospun PLCL nanofibrous layers

“…The nature of both processes also indicates differences in the resulting morphologies of nanofiber layers, even in terms of fiber orientation controlled only by the rate of withdrawal of the base material. The orientation of fibres in DC electrospun materials with the special collectors using was studied several times for medical applications mainly [4][5][6][7][8]. The difference between the two technologies with changes in towing speed is described in this paper.…”