Rapid reconstruction of 3D structure of fibrous media

TL;DR

This paper introduces a quick, cost-effective method for reconstructing 3D fibrous porous media structures, specifically gas diffusion layers in fuel cells, using focus stacking and open-source software, achieving about 1% accuracy in under 10 minutes.

Contribution

The authors present a novel, simple approach for 3D reconstruction of fibrous media using focus stacking with standard microscopes and open-source tools, enabling rapid and accurate modeling.

Findings

Reconstruction accuracy is approximately 1% for ~100 μm depth.

The method can reproduce 3D structures up to 50-100 μm deep.

Deepest channels in GDL can reach 100-160 μm depth.

Abstract

Characterization of transport properties of porous media is increasingly relying on computational methods that require reconstruction of the media structure. We present a simple method of constructing the 3D surface of fibrous porous media - the gas diffusion layer (GDL) used as the porous electrode in PEM fuel cells. The method is based on extending the depth-of-field on the whole attainable thickness of the GDL. A series of images of the GDL sample is recorded by the sequential movement of the sample with respect to the microscope focus. Different layers of the surface of the sample appear in focus in the different images in the series. The indexed series of the in-focus portions of the sample surface is combined into one sharp 2D image and interpolated into the 3D surface representing the surface of an original GDL sample. The method uses a conventional upright stage microscope that is operated manually, the inexpensive Helicon Focus software, and the open source MeshLab software. The accuracy of the reconstruction of the image features was found to be ~ 1% for probing depth of ~ 100 um with the corresponding image acquisition time being ~ 10 min. Applying this method we found that: i) this technique is able to reproduce 3D-projection of the GDL structure for a depth of ~ 50-100 um, ii) the depth of the deepest channel in the GDL can be as much as ~ 100-160 um, for GDL samples with a thickness ~ 200 um.