Skip to main content
2024 BMES Annual Meeting Main banner
Icon Legend
This session is not in your schedule.
This session is in your schedule. Click again to remove it.

Biomaterials

Biomaterials - Poster Session E

Poster B10 - Testing the Variation of 3D Printer Settings to Optimize Print Shape and Quality on Sharp Turns Using Bioinks

Saturday, October 26, 2024
10:00 AM - 11:00 AM EST
Location: Exhibit Hall E, F & G

Introduction:  Bioprinting is a new research topic and has many variables that still need to be optimized. Understanding how to optimize the settings on a 3D printer and use bioinks can expand the scope of projects, geometries, and achievable applications. In previous research studies, a ring shape was used since it is simpler and more tolerant to errors in print geometry error (Schwab, et al., 2020). The typical extrusion velocities for extrusion based bioprinting (Emmermacher, et al., 2020), were used to determine an equivalent flow rate (0.4964 mL/min ) for use with the modified Prusa 3D MK3 printer used in this study. The main goal of this research study is to optimize the 3D printer settings, in a geometry with sharp turns, thin wall, and straight features, to expand the library of attainable print geometries. In this research study, the information learned will be used to create and adapt existing bioprinting protocols to be used for various printing parameters and geometries.

Materials and

Methods:  A Prusa 3D MK3 was modified by replacing the original hot extrusion ends with new components, to extrude from a 3 mL syringe with an 18-gauge blunt needle tip. The G code was written manually and the Pronterface interface was used to communicate with the Prusa.

To investigate how the different printer settings handle sharp turns, a single wall structure with a length of 20 mm and a height of 10 mm was implemented. 3D structures were printed with a 4% sodium alginate hydrogel bioink into a support medium slurry consisting of 1% agar with a 11mM calcium chloride crosslinker. The sodium alginate mixture was placed inside the 3 mL syringe and then printed into a well of a 6-well plate filled with the support medium. 27 trials were printed to test extrusion rates of 0.216, 0.432, and 0.649 uL/mm, printing speeds of 500, 1000, 1500 mm/min, and pausing periods after each layer of 0, 1, and 2 seconds. Each trial was allowed a post-print settling time of 2 hours to fully crosslink before being extracted. A sheet of paper with a printed outline of the desired shape was used to find the shape error for the print. The Windows Paint software was used to calculate shape errors (height and length) in pixels relative to the printed outline.

Results, Conclusions, and Discussions: By comparing the desired length and height of the print to the actual dimensions, conclusions can be drawn about how various printer settings affect the shape of the print. There was a noticeable difference in the heights of the lines within cells C1, C4 and C7 which were all extruded at a rate of 0.216 uL/mm, the lowest extrusion rate setting tested. Cells C3 and C6 have the lowest height error and the highest extrusion rate setting of 0.649 uL/mm. Therefore, it can be concluded that there is a relationship between a smaller height error and a larger extrusion rate as well as larger length errors and the lowest extrusion rate setting. These results can be visualized in Table 1.

After analyzing the data gathered from how the pausing periods affected the prints, there is a larger length error in the prints with a longer pause. The prints with a pausing period of 0 seconds have on average the lowest length errors. For the prints with a pausing period of 1 second, exhibited the lowest height error. Meanwhile, a pausing period of 2 seconds caused the largest height error.

When analyzing the effect, the feed rate had on the print shape, it can be determined that a higher feed rate results in lower height and length errors. This relationship can be shown Table 1.

Overall, the data gathered can conclude that the optimal settings for this print geometry is a higher extrusion rate and a higher feed rate, in combination with a pausing period of 1 second. In this study, T18 would be mathematically the best print in terms of length and height error.
The numerical values collected from this study can be used to help optimize the 3D printer settings for bioinks by knowing the relationship between extrusion rates, feed rates, and pausing periods. Future research could use these printer settings on more complex geometries in order to understand the relationship between shape and printer settings.

Acknowledgements (Optional):