Emulsion inks for 3D printing porous materials

Event Abstract Back to Event Emulsion inks for 3D printing porous materials Nicholas A. Sears1, Michael E. Whitely1, Prachi S. Dhavalikar1 and Elizabeth M. Cosgriff-Hernandez1 1 Texas A&M University, Biomedical Engineering, United States Introduction: 3D printing techniques have been adapted to print novel polymers and biological gels into complex tissue engineering scaffolds. Here, we report a new method of creating high porosity foams with complex shapes by using open source, solid freeform fabrication (SFF) technology and emulsion inks developed in our lab. High internal phase emulsions (HIPE) prepared from hydrophobic photopolymers exhibit shear thinning behavior that permits extrusion, and a high zero-shear viscosity sufficient for shape retention after deposition. Each layer is actively polymerized with a UV Cure-on-Dispense (CoD) technique. In this study, the effects of emulsion viscosity and cure rate on print fidelity were studied. Materials and Methods: HIPEs were fabricated using a FlackTek Speedmixer DAC 150 FVZ-K according to a protocol adapted from Moglia et al[1]. Poly(propylene glycol) dimethacrylate (PPGDMA, 560 Da), was used as the main HIPE macromer and diurethane dimethacrylate (DUDMA, 471 Da), was used to increase the viscosity of the emulsion. Shapes were designed in Solidworks and exported into the STL file format. Printer G-code was created with Slic3r v1.2.6. Infill (50%, 70%), layer height (0.2 mm), extrusion width (0.6 mm), and a print speed of 10 mm/s were crucial for the formation of accurate, cohesive constructs. Objects were printed on a modified HYREL 3D printer utilizing Arduino Mega+RAMPS v1.4 electronics. An emulsifiable extruder (EMO-25) by HYREL with a 22 gauge dispensing tip were used to deposit the HIPE material. Four, 3 watt UV LEDs mounted to the extruder cure HIPE material as it is dispensed. Cylinders were printed to evaluate the ability to create high fidelity constructs and single lines of extruded material were examined with SEM to evaluate shape retention after extrusion. Results and Discussion: Uncured HIPEs exhibited low viscosity at typical printing shear rates, (10 Pa*s at 50 1/s), allowing for precise dispensing. Increasing the viscous component, DUDMA, increased the viscosity of the macromer phase, resulting in increased emulsion zero-shear viscosity, (up to 3500 Pa*s at 0.01 1/s) while retaining shear-thinning characteristics, Figure 1 (A). Increased viscosity decreased printed line slumping and improved print fidelity (B). Cure-on-dispense printing increased print fidelity relative to post-print curing, but increasing photoinitiator to 5% showed a smaller decrease in line spreading and increase in shape retention (C). HIPEs with sufficient viscosity produced tall, complex scaffolds with an internal lattice structure and hierarchical porosity, Figure 2. Conclusion: These findings indicate that the viscosity of emulsion inks and cure rate play important roles in print fidelity. Overall, the demonstrated ability to print porous materials using emulsion inks and CoD technology advance current additive manufacturing efforts to generate custom porous materials for tissue engineering and drug delivery applications. References:[1] Moglia, R.S., et al., Injectable polyHIPEs as high-porosity bone grafts. Biomacromolecules, 2011. 12(10): p. 3621-3628. Keywords: biomaterial, Bioprinting, Rapid prototyping, 3D scaffold Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: New Frontier Oral Topic: Three-dimensional fabrication Citation: Sears NA, Whitely ME, Dhavalikar PS and Cosgriff-Hernandez EM (2016). Emulsion inks for 3D printing porous materials. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.02721 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Mar 2016; Published Online: 30 Mar 2016. Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Nicholas A Sears Michael E Whitely Prachi S Dhavalikar Elizabeth M Cosgriff-Hernandez Google Nicholas A Sears Michael E Whitely Prachi S Dhavalikar Elizabeth M Cosgriff-Hernandez Google Scholar Nicholas A Sears Michael E Whitely Prachi S Dhavalikar Elizabeth M Cosgriff-Hernandez PubMed Nicholas A Sears Michael E Whitely Prachi S Dhavalikar Elizabeth M Cosgriff-Hernandez Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.