1
|
Reid A, Windmill J. Impact of Beam Shape on Print Accuracy in Digital Light Processing Additive Manufacture. 3D PRINTING AND ADDITIVE MANUFACTURING 2024; 11:517-528. [PMID: 38689905 PMCID: PMC11057548 DOI: 10.1089/3dp.2022.0193] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
Photopolymerization-based additive manufacturing requires selectively exposing a feedstock resin to ultraviolet (UV) light, which in digital light processing is achieved either using a digital micromirror device or a digital mask. The minimum tolerances and resolution for a multilayer process are separate for resolution through the Z-axis, looking through the thickness of a printed part, and resolution in the XY-axes, in the plane of the printed layer. The former depends wholly on the rate of attenuation of the incident UV light through the material relative to the mechanical motion of the build layer, while the latter is determined by a two-dimensional pattern of irradiance on the resin formed by the digital micromirror device or the digital mask. The size or the spacing of elements or pixels of this digital mask is frequently given by manufacturers as the "resolution" of the device, however, in practice the achievable resolution is first determined by the beam distribution from each pixel. The beam distribution is, as standard, modeled as a two-parameter Gaussian distribution but the key parameters of peak intensity and standard deviation of the beam are hidden to the user and difficult to measure directly. The ability of models based on the Gaussian distribution to correctly predict the polymerization of printed features in the microscale is also typically poor. In this study, we demonstrate an alternative model of beam distribution based on a heavy-tailed Lorentzian model, which is able to more accurately predict small build areas for both positive and negative features. We show a simple calibration method to derive the key space parameters of the beam distribution from measurements of a single-layer printed model. We propose that the standard Gaussian model is insufficient to accurately predict a print outcome as it neglects higher-order terms, such as beam skew and kurtosis, and in particular failing to account for the relatively heavy tails of the beam distribution. Our results demonstrate how the amendments to the beam distribution can avoid errors in microchannel formation, and better estimates of the true XY-axes resolution of the printer. The results can be used as the basis for voxel-based models of print solidification that allow software prediction of the photopolymerization process.
Collapse
Affiliation(s)
- Andrew Reid
- Center for Ultrasonic Engineering, University of Strathclyde, Glasgow, United Kingdom
| | - James Windmill
- Center for Ultrasonic Engineering, University of Strathclyde, Glasgow, United Kingdom
| |
Collapse
|
2
|
Levato R, Lim KS, Li W, Asua AU, Peña LB, Wang M, Falandt M, Bernal PN, Gawlitta D, Zhang YS, Woodfield TBF, Malda J. High-resolution lithographic biofabrication of hydrogels with complex microchannels from low-temperature-soluble gelatin bioresins. Mater Today Bio 2021; 12:100162. [PMID: 34870141 PMCID: PMC8626672 DOI: 10.1016/j.mtbio.2021.100162] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 11/18/2021] [Accepted: 11/18/2021] [Indexed: 12/20/2022] Open
Abstract
Biofabrication via light-based 3D printing offers superior resolution and ability to generate free-form architectures, compared to conventional extrusion technologies. While extensive efforts in the design of new hydrogel bioinks lead to major advances in extrusion methods, the accessibility of lithographic bioprinting is still hampered by a limited choice of cell-friendly resins. Herein, we report the development of a novel set of photoresponsive bioresins derived from ichthyic-origin gelatin, designed to print high-resolution hydrogel constructs with embedded convoluted networks of vessel-mimetic channels. Unlike mammalian gelatins, these materials display thermal stability as pre-hydrogel solutions at room temperature, ideal for bioprinting on any easily-accessible lithographic printer. Norbornene- and methacryloyl-modification of the gelatin backbone, combined with a ruthenium-based visible light photoinitiator and new coccine as a cytocompatible photoabsorber, allowed to print structures resolving single-pixel features (∼50 μm) with high shape fidelity, even when using low stiffness gels, ideal for cell encapsulation (1-2 kPa). Moreover, aqueous two-phase emulsion bioresins allowed to modulate the permeability of the printed hydrogel bulk. Bioprinted mesenchymal stromal cells displayed high functionality over a month of culture, and underwent multi-lineage differentiation while colonizing the bioresin bulk with tissue-specific neo-deposited extracellular matrix. Importantly, printed hydrogels embedding complex channels with perfusable lumen (diameter <200 μm) were obtained, replicating anatomical 3D networks with out-of-plane branches (i.e. brain vessels) that cannot otherwise be reproduced by extrusion bioprinting. This versatile bioresin platform opens new avenues for the widespread adoption of lithographic biofabrication, and for bioprinting complex channel-laden constructs with envisioned applications in regenerative medicine and hydrogel-based organ-on-a-chip devices.
Collapse
Affiliation(s)
- Riccardo Levato
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, the Netherlands
- Department of Orthopaedics, University Medical Center Utrecht, the Netherlands
| | - Khoon S Lim
- Christchurch Regenerative Medicine and Tissue Engineering (CReaTE) Group, Department of Orthopaedic Surgery and Musculoskeletal Medicine, University of Otago Christchurch, Christchurch, the Netherlands
| | - Wanlu Li
- Division of Engineering in Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Cambridge, USA
| | - Ane Urigoitia Asua
- Department of Orthopaedics, University Medical Center Utrecht, the Netherlands
| | - Laura Blanco Peña
- Department of Orthopaedics, University Medical Center Utrecht, the Netherlands
| | - Mian Wang
- Division of Engineering in Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Cambridge, USA
| | - Marc Falandt
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, the Netherlands
| | | | - Debby Gawlitta
- Department of Oral and Maxillofacial Surgery & Special Dental Care, University Medical Center Utrecht, the Netherlands
| | - Yu Shrike Zhang
- Division of Engineering in Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Cambridge, USA
| | - Tim B F Woodfield
- Christchurch Regenerative Medicine and Tissue Engineering (CReaTE) Group, Department of Orthopaedic Surgery and Musculoskeletal Medicine, University of Otago Christchurch, Christchurch, the Netherlands
| | - Jos Malda
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, the Netherlands
- Department of Orthopaedics, University Medical Center Utrecht, the Netherlands
| |
Collapse
|
3
|
Wang Y, Cui H, Wang Y, Xu C, Esworthy TJ, Hann SY, Boehm M, Shen YL, Mei D, Zhang LG. 4D Printed Cardiac Construct with Aligned Myofibers and Adjustable Curvature for Myocardial Regeneration. ACS APPLIED MATERIALS & INTERFACES 2021; 13:12746-12758. [PMID: 33405502 PMCID: PMC9554838 DOI: 10.1021/acsami.0c17610] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
As an innovative additive manufacturing process, 4D printing can be utilized to generate predesigned, self-assembly structures which can actuate time-dependent, and dynamic shape-changes. Compared to other manufacturing techniques used for tissue engineering purposes, 4D printing has the advantage of being able to fabricate reprogrammable dynamic tissue constructs that can promote uniform cellular growth and distribution. For this study, a digital light processing (DLP)-based printing technique was developed to fabricate 4D near-infrared (NIR) light-sensitive cardiac constructs with highly aligned microstructure and adjustable curvature. As the curvature of the heart is varied across its surface, the 4D cardiac constructs can change their shape on-demand to mimic and recreate the curved topology of myocardial tissue for seamless integration. To mimic the aligned structure of the human myocardium and to achieve the 4D shape change, a NIR light-sensitive 4D ink material, consisting of a shape memory polymer and graphene, was created to fabricate microgroove arrays with different widths. The results of our study illustrate that our innovative NIR-responsive 4D constructs exhibit the capacity to actuate a dynamic and remotely controllable spatiotemporal transformation. Furthermore, the optimal microgroove width was discovered via culturing human induced pluripotent stem cell-derived cardiomyocytes and mesenchymal stem cells onto the constructs' surface and analyzing both their cellular morphology and alignment. The cell proliferation profiles and differentiation of tricultured human-induced pluripotent stem cell-derived cardiomyocytes, mesenchymal stem cells, and endothelial cells, on the printed constructs, were also studied using a Cell Counting Kit-8 and immunostaining. Our results demonstrate a uniform distribution of aligned cells and excellent myocardial maturation on our 4D curved cardiac constructs. This study not only provides an efficient method for manufacturing curved tissue architectures with uniform cell distributions, but also extends the potential applications of 4D printing for tissue regeneration.
Collapse
Affiliation(s)
| | | | | | | | | | | | - Manfred Boehm
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | | | | | | |
Collapse
|