In Situ Characterization of Melt–Electrowritten Scaffolds in 3D Using Optical Coherence Tomography

Recent developments in melt electrowriting (MEW), a high‐resolution additive manufacturing technology, have led to increases in scaffold complexity. However, MEW scaffolds are currently characterized ex situ, which causes time–consuming iterations of characterization and fabrication that limit scaffold throughput and more widespread use of the technology. For the first time, an in situ method to characterize the 3D microstructure of MEW scaffolds using optical coherence tomography (OCT) is described. Calculations of microstructural features are performed on OCT data using a custom algorithm, demonstrating close correspondence with scanning electron microscopy (SEM). For example, OCT calculations of fiber diameter and scaffold thickness are within an average of 0.31 and 1.79 μm, respectively, of corresponding SEM–derived calculations. Additionally, the 3D capabilities of OCT enable the nondestructive characterization of scaffolds with depth–varying microstructures, overcoming some main limitations of SEM. Finally, in situ characterization is achieved by integrating the OCT scanner within an MEW printer, enabling the scaffold microstructure to be evaluated and optimized during manufacture. This new capability represents an important step toward achieving an efficient fabrication–characterization cycle with the guaranteed scaffold quality and reproducibility required to validate the manufacturing process. In this work, the 3D microstructure of melt‐electrowritten (MEW) scaffolds with depth–varying features is characterized in situ using optical coherence tomography (OCT). Calculations of features including fiber diameter are validated to accuracies within 0.31 μm of scanning electron microscopy (SEM)‐derived measurements. This new methodology can enable efficient in–process characterization to ensure scaffold quality and reproducibility for clinical applications.