Session: 02-15-01: BioManufacturing and Biomaterials

Paper Number: 66750

Start Time: Friday, 03:45 PM

66750 - Shape Fidelity Study in Extrusion-Based Bio 3d Printing With Highly Viscous Bioink 

Bio 3D printing process utilizes additive manufacturing technique to fabricate living tissues or constructs with customized geometries in a layer by layer deposition way. The 3D bioprinting techniques can be generally categorized into various types such as inkjet, extrusion, and laser printing depending on process characteristics. The extrusion based bioprinter is advantageous because it is able to print the high density cell-laden biomaterials with different viscosities. Due to the biocompatible characteristics, hydrolgel has been widely used as a sacrificial material for cell-laden tissue in extrusion based bioprinting. The bioink is pushed by pneumatic pressure and extrudes from printing nozzle to form printing filament. The tissue geometry is fabricated following the computer-designed path with layer-by-layer style. During the printing process, the pneumatic pressure and other printing parameters such as nozzle diameter and printing speed sensitively affect the filament shape (width, thickness, and profile), which further influences the geometrical accuracy of tissue or construct and also cells viability. However, due to bioink’s fluidity and filament’s small size, experimental study of filament shape and printability is challenging and very limited. In this work, a three dimensional COMSOL modeling approach based on computational fluid dynamics theory is used to investigate the effect of printing parameters on hydrogel (START, CELLINK LLC) filament shape. This is the first time to predict printing ink geometry using high quality 3D modelling and 809, 911 meshes are mapped through the entire model. Laminar two-phase flow and level set modules are coupled in COMSOL to simulate the entire printing process. The filament width, thickness, and cross-section profile are discussed under five different substrate moving speed between 600 mm/min, 900 mm/min, 1200 mm/min, 1500 mm/min 1800 mm/min. In addition, experimental observation of the filament width was carried out on a commercial bio 3D bioprinter (CELLINK LLC). Image J (developed by National Institutes of Health, US) and in-house program are used for experimental results processing and measuring the width of these filament specimens. The measured filament widths were used to validate the simulation results, and prove the accuracy of modeling prediction approach. Then the model is safe to predict the thickness and side profile of printed filament. The rheological property of bioink and velocity field/shear rate are investigated to understand the printing process. The study results of printing process including experimental investigation and numerical modelling will work as significant reference data to improve printability, resolution, printing throughput and cell viability with appropriate and optimized printing parameter.

Presenting Author: Ran Zhou Purdue University Northwest

Authors:

Ran Zhou Purdue University Northwest
Wei Li University of Texas at Dallas
Benquan Li University of Texas at Dallas