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Kaufmann BK, Rudolph M, Pechtl M, Wildenburg G, Hayden O, Clausen-Schaumann H, Sudhop S. mSLAb - An open-source masked stereolithography (mSLA) bioprinter. HARDWAREX 2024; 19:e00543. [PMID: 38988373 PMCID: PMC11234000 DOI: 10.1016/j.ohx.2024.e00543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 04/19/2024] [Accepted: 06/04/2024] [Indexed: 07/12/2024]
Abstract
3D bioprinting is a tissue engineering approach using additive manufacturing to fabricate tissue equivalents for regenerative medicine or medical drug testing. For this purpose, biomaterials that provide the essential microenvironment to support the viability of cells integrated directly or seeded after printing are processed into three-dimensional (3D) structures. Compared to extrusion-based 3D printing, which is most commonly used in bioprinting, stereolithography (SLA) offers a higher printing resolution and faster processing speeds with a wide range of cell-friendly materials such as gelatin- or collagen-based hydrogels and SLA is, therefore, well suited to generate 3D tissue constructs. While there have been numerous publications of conversions and upgrades for extrusion-based printers, this is not the case for state-of-the-art SLA technology in bioprinting. The high cost of proprietary printers severely limits teaching and research in SLA bioprinting. With mSLAb, we present a low-cost and open-source high-resolution 3D bioprinter based on masked SLA (mSLA). mSLAb is based on an entry-level (€350) desktop mSLA printer (Phrozen Sonic Mini 4 K), equipped with temperature control and humidification of the printing chamber to enable the processing of cell-friendly hydrogels. Additionally, the build platform was redesigned for easy sample handling and microscopic analysis of the printed constructs. All modifications were done with off-the-shelf hardware and in-house designed 3D printed components, printed with the same printer that was being modified. We validated the system by printing macroscopic porous scaffolds as well as hollow channels from gelatin-based hydrogels as representative structures needed in tissue engineering.
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Affiliation(s)
- Benedikt K Kaufmann
- Center for Applied Tissue Engineering and Regenerative Medicine, Munich University of Applied Sciences, 80335 Munich, Germany
- Center for NanoScience - CeNS, Ludwig Maximilian University of Munich, 80539 Munich, Germany
- Heinz-Nixdorf-Chair of Biomedical Electronics, School of Computation, Information and Technology & Munich Institute of Biomedical Engineering, Technical University of Munich, TranslaTUM, Einsteinstraße 25, 81675 Munich, Germany
| | - Matthias Rudolph
- Center for Applied Tissue Engineering and Regenerative Medicine, Munich University of Applied Sciences, 80335 Munich, Germany
- Center for NanoScience - CeNS, Ludwig Maximilian University of Munich, 80539 Munich, Germany
| | - Markus Pechtl
- Center for Applied Tissue Engineering and Regenerative Medicine, Munich University of Applied Sciences, 80335 Munich, Germany
| | - Geronimo Wildenburg
- Center for Applied Tissue Engineering and Regenerative Medicine, Munich University of Applied Sciences, 80335 Munich, Germany
| | - Oliver Hayden
- Heinz-Nixdorf-Chair of Biomedical Electronics, School of Computation, Information and Technology & Munich Institute of Biomedical Engineering, Technical University of Munich, TranslaTUM, Einsteinstraße 25, 81675 Munich, Germany
| | - Hauke Clausen-Schaumann
- Center for Applied Tissue Engineering and Regenerative Medicine, Munich University of Applied Sciences, 80335 Munich, Germany
- Center for NanoScience - CeNS, Ludwig Maximilian University of Munich, 80539 Munich, Germany
| | - Stefanie Sudhop
- Center for Applied Tissue Engineering and Regenerative Medicine, Munich University of Applied Sciences, 80335 Munich, Germany
- Center for NanoScience - CeNS, Ludwig Maximilian University of Munich, 80539 Munich, Germany
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2
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Rossi A, Pescara T, Gambelli AM, Gaggia F, Asthana A, Perrier Q, Basta G, Moretti M, Senin N, Rossi F, Orlando G, Calafiore R. Biomaterials for extrusion-based bioprinting and biomedical applications. Front Bioeng Biotechnol 2024; 12:1393641. [PMID: 38974655 PMCID: PMC11225062 DOI: 10.3389/fbioe.2024.1393641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 05/31/2024] [Indexed: 07/09/2024] Open
Abstract
Amongst the range of bioprinting technologies currently available, bioprinting by material extrusion is gaining increasing popularity due to accessibility, low cost, and the absence of energy sources, such as lasers, which may significantly damage the cells. New applications of extrusion-based bioprinting are systematically emerging in the biomedical field in relation to tissue and organ fabrication. Extrusion-based bioprinting presents a series of specific challenges in relation to achievable resolutions, accuracy and speed. Resolution and accuracy in particular are of paramount importance for the realization of microstructures (for example, vascularization) within tissues and organs. Another major theme of research is cell survival and functional preservation, as extruded bioinks have cells subjected to considerable shear stresses as they travel through the extrusion apparatus. Here, an overview of the main available extrusion-based printing technologies and related families of bioprinting materials (bioinks) is provided. The main challenges related to achieving resolution and accuracy whilst assuring cell viability and function are discussed in relation to specific application contexts in the field of tissue and organ fabrication.
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Affiliation(s)
- Arianna Rossi
- Smart Manufacturing Laboratory, Engineering Department, University of Perugia, Perugia, Italy
| | - Teresa Pescara
- Laboratory for Endocrine Cell Transplant and Biohybrid Organs, Department of Medicine and Surgery, University of Perugia, Perugia, Italy
| | - Alberto Maria Gambelli
- Department of Civil and Environmental Engineering, University of Perugia, Perugia, Italy
| | - Francesco Gaggia
- Laboratory for Endocrine Cell Transplant and Biohybrid Organs, Department of Medicine and Surgery, University of Perugia, Perugia, Italy
| | - Amish Asthana
- Wake Forest School of Medicine, Winston Salem, NC, United States
| | - Quentin Perrier
- Wake Forest School of Medicine, Winston Salem, NC, United States
| | - Giuseppe Basta
- Laboratory for Endocrine Cell Transplant and Biohybrid Organs, Department of Medicine and Surgery, University of Perugia, Perugia, Italy
| | - Michele Moretti
- Smart Manufacturing Laboratory, Engineering Department, University of Perugia, Perugia, Italy
| | - Nicola Senin
- Smart Manufacturing Laboratory, Engineering Department, University of Perugia, Perugia, Italy
| | - Federico Rossi
- Engineering Department, University of Perugia, Perugia, Italy
| | - Giuseppe Orlando
- Wake Forest School of Medicine, Winston Salem, NC, United States
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Oberloier S, Whisman NG, Pearce JM. Finding Ideal Parameters for Recycled Material Fused Particle Fabrication-Based 3D Printing Using an Open Source Software Implementation of Particle Swarm Optimization. 3D PRINTING AND ADDITIVE MANUFACTURING 2023; 10:1287-1300. [PMID: 38116208 PMCID: PMC10726196 DOI: 10.1089/3dp.2022.0012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
As additive manufacturing rapidly expands the number of materials including waste plastics and composites, there is an urgent need to reduce the experimental time needed to identify optimized printing parameters for novel materials. Computational intelligence (CI) in general and particle swarm optimization (PSO) algorithms in particular have been shown to accelerate finding optimal printing parameters. Unfortunately, the implementation of CI has been prohibitively complex for noncomputer scientists. To overcome these limitations, this article develops, tests, and validates PSO Experimenter, an easy-to-use open-source platform based around the PSO algorithm and applies it to optimizing recycled materials. Specifically, PSO Experimenter is used to find optimal printing parameters for a relatively unexplored potential distributed recycling and additive manufacturing (DRAM) material that is widely available: low-density polyethylene (LDPE). LDPE has been used to make filament, but in this study for the first time it was used in the open source fused particle fabrication/fused granular fabrication system. PSO Experimenter successfully identified functional printing parameters for this challenging-to-print waste plastic. The results indicate that PSO Experimenter can provide 97% reduction in research time for 3D printing parameter optimization. It is concluded that the PSO Experimenter is a user-friendly and effective free software for finding ideal parameters for the burgeoning challenge of DRAM as well as a wide range of other fields and processes.
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Affiliation(s)
- Shane Oberloier
- Department of Electrical and Computer Engineering, Michigan Technological University, Houghton, Michigan, USA
| | - Nicholas G. Whisman
- Department of Electrical and Computer Engineering, Michigan Technological University, Houghton, Michigan, USA
| | - Joshua M. Pearce
- Department of Electrical and Computer Engineering, Ivey School of Business, Western University, London, Canada
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Gomes Gama JF, Dias EA, Aguiar Coelho RMG, Chagas AM, Aguiar Coelho Nt J, Alves LA. Development and implementation of a significantly low-cost 3D bioprinter using recycled scrap material. Front Bioeng Biotechnol 2023; 11:1108396. [PMID: 37091338 PMCID: PMC10119389 DOI: 10.3389/fbioe.2023.1108396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Accepted: 03/15/2023] [Indexed: 04/25/2023] Open
Abstract
The field of 3D bioengineering proposes to effectively contribute to the manufacture of artificial multicellular organ/tissues and the understanding of complex cellular mechanisms. In this regard, 3D cell cultures comprise a promising bioengineering possibility for the alternative treatment of organ function loss, potentially improving patient life expectancies. Patients with end-stage disease, for example, could benefit from treatment until organ transplantation or even undergo organ function restoration. Currently, 3D bioprinters can produce tissues such as trachea cartilage or artificial skin. Most low-cost 3D bioprinters are built from fused deposition modeling 3D printer frames modified for the deposition of biologically compatible material, ranging between $13.000,00 and $300.000,00. Furthermore, the cost of consumables should also be considered as they, can range from $3,85 and $100.000,00 per gram, making biomaterials expensive, hindering bioprinting access. In this context, our report describes the first prototype of a significantly low-cost 3D bioprinter built from recycled scrap metal and off-the-shelf electronics. We demonstrate the functionalized process and methodology proof of concept and aim to test it in different biological tissue scaffolds in the future, using affordable materials and open-source methodologies, thus democratizing the state of the art of this technology.
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Affiliation(s)
- Jaciara Fernanda Gomes Gama
- Laboratory of Cellular Communication, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
| | - Evellyn Araujo Dias
- Laboratory of Cellular Communication, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
| | | | - André Maia Chagas
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
- TReND in Africa, Brighton, United Kingdom
- Biomedical Science Research and Training Center, Yobe State University, Damaturu, Nigeria
| | - José Aguiar Coelho Nt
- Laboratory of Cellular Communication, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
- National Institute of Industrial Property- INPI and Veiga de Almeida University, Rio de Janeiro, Brazil
| | - Luiz Anastacio Alves
- Laboratory of Cellular Communication, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
- *Correspondence: Luiz Anastacio Alves,
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Abstract
Open hardware solutions are increasingly being chosen by researchers as a strategy to improve access to technology for cutting-edge biology research. The use of DIY technology is already widespread, particularly in countries with limited access to science funding, and is catalyzing the development of open-source technologies. Beyond financial accessibility, open hardware can be transformational for the access of laboratories to equipment by reducing dependence on import logistics and enabling direct knowledge transfer. Central drivers to the adoption of appropriate open-source technologies in biology laboratories around the world are open sharing, digital fabrication, local production, the use of standard parts, and detailed documentation. This Essay examines the global spread of open hardware and discusses which kinds of open-source technologies are the most beneficial in scientific environments with economic and infrastructural constraints.
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Affiliation(s)
- Tobias Wenzel
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Macul, Región Metropolitana, Chile
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6
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Development of a high-performance open-source 3D bioprinter. Sci Rep 2022; 12:22652. [PMID: 36587043 PMCID: PMC9805454 DOI: 10.1038/s41598-022-26809-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 12/20/2022] [Indexed: 01/01/2023] Open
Abstract
The application of 3D printing to biological research has provided the tissue engineering community with a method for organizing cells and biological materials into complex 3D structures. While many commercial bioprinting platforms exist, they are expensive, ranging from $5000 to over $1,000,000. This high cost of entry prevents many labs from incorporating 3D bioprinting into their research. Due to the open-source nature of desktop plastic 3D printers, an alternative option has been to convert low-cost plastic printers into bioprinters. Several open-source modifications have been described, but there remains a need for a user-friendly, step-by-step guide for converting a thermoplastic printer into a bioprinter using components with validated performance. Here we convert a low-cost 3D printer, the FlashForge Finder, into a bioprinter using our Replistruder 4 syringe pump and the Duet3D Duet 2 WiFi for total cost of less than $900. We demonstrate that the accuracy of the bioprinter's travel is better than 35 µm in all three axes and quantify fidelity by printing square lattice collagen scaffolds with average errors less than 2%. We also show high fidelity reproduction of clinical-imaging data by printing a scaffold of a human ear using collagen bioink. Finally, to maximize accessibility and customizability, all components we have designed for the bioprinter conversion are provided as open-source 3D models, along with instructions for further modifying the bioprinter for additional use cases, resulting in a comprehensive guide for the bioprinting field.
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Maerz M, Treutwein M, Nabo J, Dobler B. Three-dimensional printers applied for the production of beam blocks in total body irradiation treatment. J Appl Clin Med Phys 2022; 23:e13592. [PMID: 35290701 PMCID: PMC9121048 DOI: 10.1002/acm2.13592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 01/20/2022] [Accepted: 03/01/2022] [Indexed: 12/02/2022] Open
Abstract
Purpose Total body irradiation (TBI) in extended source surface distance (SSD) is a common treatment technique before hematopoietic stem cell transplant. The lungs are organs at risk, which often are treated with a lower dose than the whole body. Methods This can be achieved by the application of blocks. Three‐dimensional (3D) printers are a modern tool to be used in the production process of these blocks. Results We demonstrate the applicability of a specific printer and printing material, describe the process, and evaluate the accuracy of the product. Conclusion The blocks and apertures were found to be applicable in clinical routine.
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Affiliation(s)
- Manuel Maerz
- Department of Radiotherapy, Regensburg University Medical Center, Regensburg, Germany
| | - Marius Treutwein
- Department of Radiotherapy, Regensburg University Medical Center, Regensburg, Germany
| | - Jan Nabo
- Department for Mathematics and Computer Science, Ostbayerische Technische Hochschule Regensburg, Regensburg, Germany
| | - Barbara Dobler
- Department of Radiotherapy, Regensburg University Medical Center, Regensburg, Germany
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Bajracharya S, Krige A, Matsakas L, Rova U, Christakopoulos P. Dual cathode configuration and headspace gas recirculation for enhancing microbial electrosynthesis using Sporomusa ovata. CHEMOSPHERE 2022; 287:132188. [PMID: 34543900 DOI: 10.1016/j.chemosphere.2021.132188] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 09/01/2021] [Accepted: 09/04/2021] [Indexed: 06/13/2023]
Abstract
High-rate production of acetate and other value-added products from the reduction of CO2 in microbial electrosynthesis (MES) using acetogens can be achieved with high reducing power where H2 appears as a key electron mediator. H2 evolution using metal cathodes can enhance the availability of H2 to support high-rate microbial reduction of CO2. Due to the low solubility of H2, the availability of H2 remains limited to the bacteria. In this study, we investigated the performances of Sporomusa ovata for CO2 reduction when dual cathodes were used together in an MES, one was regular carbon cathode, and the other was a titanium mesh that allows higher hydrogen evolution. The dual cathode configuration was investigated in two sets of MES, one set had the usual S. ovata inoculated graphite rod, and another set had a synthetic biofilm-imprinted carbon cloth. Additionally, the headspace gas in MES was recirculated to increase the H2 availability to the bacteria in suspension. High-rate CO2 reduction was observed at -0.9 V vs Ag/AgCl with dual cathode configuration as compared to single cathodes. High titers of acetate (up to ∼11 g/L) with maximum instantaneous rates of 0.68-0.7 g/L/d at -0.9 V vs Ag/AgCl were observed, which are higher than the production rates reported in the literatures for S. ovata using MES with surface modified cathodes. A high H2 availability supported the high-rate acetate production from CO2 with diminished electricity input.
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Affiliation(s)
- Suman Bajracharya
- Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, 971-87, Luleå, Sweden
| | - Adolf Krige
- Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, 971-87, Luleå, Sweden
| | - Leonidas Matsakas
- Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, 971-87, Luleå, Sweden
| | - Ulrika Rova
- Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, 971-87, Luleå, Sweden.
| | - Paul Christakopoulos
- Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, 971-87, Luleå, Sweden
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Engberg A, Stelzl C, Eriksson O, O'Callaghan P, Kreuger J. An open source extrusion bioprinter based on the E3D motion system and tool changer to enable FRESH and multimaterial bioprinting. Sci Rep 2021; 11:21547. [PMID: 34732783 PMCID: PMC8566469 DOI: 10.1038/s41598-021-00931-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 10/20/2021] [Indexed: 12/29/2022] Open
Abstract
Bioprinting is increasingly used to create complex tissue constructs for an array of research applications, and there are also increasing efforts to print tissues for transplantation. Bioprinting may also prove valuable in the context of drug screening for personalized medicine for treatment of diseases such as cancer. However, the rapidly expanding bioprinting research field is currently limited by access to bioprinters. To increase the availability of bioprinting technologies we present here an open source extrusion bioprinter based on the E3D motion system and tool changer to enable high-resolution multimaterial bioprinting. As proof of concept, the bioprinter is used to create collagen constructs using freeform reversible embedding of suspended hydrogels (FRESH) methodology, as well as multimaterial constructs composed of distinct sections of laminin and collagen. Data is presented demonstrating that the bioprinted constructs support growth of cells either seeded onto printed constructs or included in the bioink prior to bioprinting. This open source bioprinter is easily adapted for different bioprinting applications, and additional tools can be incorporated to increase the capabilities of the system.
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Affiliation(s)
- Adam Engberg
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Christina Stelzl
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Olle Eriksson
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Paul O'Callaghan
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Johan Kreuger
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.
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Koch F, Thaden O, Tröndle K, Zengerle R, Zimmermann S, Koltay P. Open-source hybrid 3D-bioprinter for simultaneous printing of thermoplastics and hydrogels. HARDWAREX 2021; 10:e00230. [PMID: 35607684 PMCID: PMC9123455 DOI: 10.1016/j.ohx.2021.e00230] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 09/03/2021] [Accepted: 09/07/2021] [Indexed: 05/04/2023]
Abstract
3D-bioprinting is a promising technology applicable in areas such as regenerative medicine or in vitro organ model development. Various 3D-bioprinting technologies and systems have been developed and are partly commercially available. Here, we present the construction and characterization of an open-source low-cost 3D-bioprinter that allows the alternated microextrusion of hydrogel and fused deposition modeling (FDM) of thermoplastic filaments. The presented 3D-bioprinter is based on a conventional Prusa i3 MK3 printer and features two independent printheads: the original FDM-head and a syringe-based microextrusion printhead for soft materials. Modifications were designed modularly to fit various syringe formats or heating elements to the device. The bioprinter is the first hybrid DIY 3D-bioprinter that allows switching between materials as often as required during a print run to produce complex multi-material constructs with arbitrary patterns in each layer. For validation of the printer, two designs suitable for relevant bioprinting applications were realized. First, a porous plastic construct filled with hydrogel was printed, serving as a mechanically stable bone replacement tissue model. Second, a plastic chamber, which might be used in organ-on-a-chip applications, was printed with an extruded silicone sealing that enables the liquid-tight attachment of glass slides to the top and bottom of the chamber.
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Affiliation(s)
- Fritz Koch
- Laboratory for MEMS Applications, IMTEK – Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, D-79110 Freiburg, Germany
| | - Ole Thaden
- Laboratory for MEMS Applications, IMTEK – Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, D-79110 Freiburg, Germany
| | - Kevin Tröndle
- Laboratory for MEMS Applications, IMTEK – Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, D-79110 Freiburg, Germany
| | - Roland Zengerle
- Laboratory for MEMS Applications, IMTEK – Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, D-79110 Freiburg, Germany
- Hahn-Schickard, Georges-Koehler-Allee 103, D-79110 Freiburg, Germany
| | - Stefan Zimmermann
- Laboratory for MEMS Applications, IMTEK – Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, D-79110 Freiburg, Germany
| | - Peter Koltay
- Laboratory for MEMS Applications, IMTEK – Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, D-79110 Freiburg, Germany
- Hahn-Schickard, Georges-Koehler-Allee 103, D-79110 Freiburg, Germany
- Freiburg Center for Interactive Materials and Bioinspired Technologies (FIT), Georges-Koehler-Allee 105, D-79110 Freiburg, Germany
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