Factorial Design of Experiment Method to Characterize Bioprinting Process Parameters to Obtain the Targeted Scaffold Porosity

Abstract

Due to its inbuilt ability to release biocompatible materials encapsulating living cells in a predefined location, 3D bioprinting is a promising technique for regenerating patient-specific tissues and organs. Among various 3D bioprinting techniques, extrusion-based 3D bioprinting ensures a higher percentage of cell release, ensuring suitable external and internal scaffold architectures. Scaffold architecture is mainly defined by filament geometry and width. A systematic selection of a set of process parameters, such as nozzle diameter, print speed, print distance, extrusion pressure, and material viscosity, can control the filament geometry and width, eventually confirming the user-defined scaffold porosity. For example, carefully selecting two sets of process parameters can result in a similar filament width (FW). However, the lack of availability of sufficient analytical relationships between printing process parameters and FW creates a barrier to achieving defined scaffold architectures with available resources. In this article, the factorial design of experiment (DoE) method has been adopted to obtain a relationship among scaffold properties that is, FW with 3D printing process parameters. The FW was determined using an image processing technique and an analytical relationship was developed, including various process parameters to maintain defined FW variation for different hydrogels within an acceptable range to confirm the overall geometric fidelity of the scaffold. The validation experiment results showed that our analytical relationship obtained from the DoE effectively predicts the scaffold's architectural property. Furthermore, the proposed analytical relationships can help achieve defined scaffold architectures with available resources.