Evaluating 3D-printed bioseparation structures using multi-length scale tomography.

Current research in bioseparation often requires detailed structural analysis of 3D-printed materials. While 3D printing enables complex geometries, the internal structure and porosity remain poorly understood at multiple scales. Prior studies have demonstrated the potential of X-ray tomography for imaging such materials but have not fully explored its application across a range of resolutions. The ability to assess printing fidelity and internal porosity is essential for optimizing bioseparation performance. However, no prior work had resolved how these structures behave across both macro and nano scales. This gap motivated the use of multi-length scale tomography to evaluate 3D-printed gyroids. The study aimed to bridge the knowledge between design and fabrication outcomes. Understanding the relationship between design parameters and printed results is critical for improving bioseparation technologies. This research contributes by offering a comprehensive imaging approach for 3D-printed structures.

The goal of this research was to evaluate the structural fidelity and internal porosity of 3D-printed gyroids used for bioseparation. The specific problem addressed was the lack of detailed characterization across multiple length scales. The motivation stemmed from the need to understand how design parameters translate into physical properties. By using X-ray tomography at varying resolutions, the study aimed to visualize and analyze the printed structures. The researchers sought to assess printing accuracy and internal void distribution. They also wanted to determine how these factors influence potential bioseparation performance. The study focused on methacrylate-based prints with different feature sizes. This approach enabled a detailed comparison between design and actual printed structures.

X-ray computed tomography was used to image 3D-printed gyroids at multiple resolutions. The method involved scanning samples with two X-ray scanners to achieve pixel sizes from 5 µm to 16 nm. The samples were printed with feature sizes of 500 µm, 300 µm, and 200 µm. The material phase of each sample was found to have a porous substructure. Digital representations of the samples were created for geometric analysis. Flow simulations were conducted using segmented subvolumes of the material. Avizo XLAB software was used to calculate diffusivity values. The study combined imaging, segmentation, and simulation to evaluate structural properties.

The study found that the 3D-printed gyroids maintained structural fidelity across all feature sizes. At the gyroid scale, imaged samples were visually compared to the original designs. A 500 µm feature was overlaid with its design to identify printed layers. Internal subvolumes were segmented into material and void phases. An average porosity of 45% was measured, which matched the expected design range. The tortuosity factor was found to be 2.52. A voidage network map revealed an average pore size of 793 nm. Using Avizo XLAB, the simulated material diffusivity was 2.17 × 10^-11 m²s^-1 ± 0.16 × 10^-11 m²s^-1.

The authors concluded that multi-length scale tomography is a viable method for evaluating 3D-printed bioseparation structures. The study demonstrated that the printed gyroids retained their design fidelity across various feature sizes. The porous substructure was consistent across all samples, indicating reliable printing. The average porosity of 45% was within the expected design range. The tortuosity factor of 2.52 suggests the material's potential for bioseparation. The voidage network map provided insights into pore size and connectivity. The simulated diffusivity values indicated the material's performance under flow conditions. These findings support the use of X-ray tomography for characterizing 3D-printed structures in bioseparation.