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International Journal of Bioprinting Affordable temperature-controlled bioprinter

Keywords: Do-it-yourself bioprinter; GelMA; Open-source; Bioprinting; Temperature-controlled printhead;
Temperature-dependent rheology.

1. Introduction bioprinter is equipped with a cooling/heating jacket
integrated into the printhead and is ideally suited for
Bioprinters show great promise in tissue engineering and use with printing inks whose viscosities strongly rely on
regenerative medicine [1-5] . At present, a wide spectrum temperature. By precisely controlling the temperature
of bioprinters is available from several companies [2,6,7] . during extrusion, we demonstrate considerable control
Commercial bioprinters currently support relevant of the rheological properties of the inks/bioinks and
research and developmental efforts [7-10] . Nevertheless, therefore their printability. We also provide a protocol
bioprinting is still far from being a mature or widespread that will allow the reader to reproduce this open-source
technology in bioengineering laboratories [9,11,12] .
device, and we include detailed information on both the
Indisputably, one of the most prominent limitations for hardware development and the bioprinting process. Lastly,
the development of bioprinting in these fields is the present we demonstrate that our bioprinter is capable of printing
cost of commercial bioprinters, particularly for researchers GelMA-based and Pluronic-based inks with high fidelity
in academic [2,13] and educational settings [10,14] . State-of-the- and resolution, as well as cell-laden bioinks that show
art commercial bioprinters have a market value between adequate cell viability after extrusion.
20,000 and 1,000,000 USD [15,16] . An additional problem,
frequently mentioned by users, is the lack of flexibility and 2. Materials and methods
ease of customization of the available devices . A significant 2.1. 3D printer
[17]
fraction of the bioprinting community still perceives
commercial bioprinters as equipment that is difficult to The modification process and method explained in this
modify or adapt for use in new or specific applications. work are based on the Anet A8 3D (Anet 3D Printer,
The relatively high cost of the commercial equipment and France) printer, but they will also work on other similar
the perception of insufficient flexibility have therefore 3D printers (e.g., Prusa i3 clones), with minor changes.
motivated the development of a good number of low-cost 2.2. 3D printer modifications
do-it-yourself (DiY) or open-source bioprinters [13,18-22] . After successful assembly of the 3D printer, which can be
The bioinks available for bioprinting add other technical accomplished in less than 8 h, several modifications were
limitations that further restrict the more extensive use of made to convert it to a bioprinter. Each modification was
currently available bioprinters [1,17,23,24] . One of the more implemented to increase the resolution and quality of
serious of these limitations is the restricted resolution subsequent (bio)prints. Most of the modifications were taken
imposed by the rheology of the bioinks [17,25-27] . For instance, directly from open-source designs found on Thingiverse ®[32]
gelatin methacryloyl (GelMA), one of the most widely and are described in the following sections. As a note to the
[28]
[17]
used inks in bioprinting and tissue engineering reader, the open-source standard tessellation language STL
applications, has rheological properties that depend files are also available in the Supplementary File.
strongly on temperature [29,30] . Specifically, GelMA must be We improved the mechanical robustness of the 3D printer
kept cool during extrusion to ensure sufficient viscosity for to increase its resolution. We did this by 3D-printing several
bioprinting, as its effective viscosity significantly increases parts using polylactic acid (PLA), or a similar 3D printer
at a temperature range of 15°C to 5°C compared to room filament, and then incorporating them onto the printer
temperature conditions [25,29,31] . A consistent viscosity is frame. The first modification consisted of adding T-corner
crucial for GelMA printability; therefore, manipulation supports to minimize vibrations from wobbling of the upper
of the rheology, and thus the resolution, of GelMA-based frames of the printer (Figure S1A and B). We then added
inks/bioinks by controlling the extrusion temperature is a belt-tensioner mechanisms to the X- and Y-axes (Figure
promising approach. Unfortunately, only a limited number S1C and D) to increase the resolution; these belt-tensioners
of bioprinters can control the bioink temperature in the could be adjusted as needed, thereby minimizing vibrations.
range of 5°C–15°C, and these devices again tend to be cost Finally, large braces were added to the front and rear frames
[2]
prohibitive .
on the underside of the (bio)printer to eliminate small
In the present study, we describe the transformation of vibrations that could lead to (bio)printing offsets (Figure
a commercially available 3D printer ($200–300 USD) into a S1E and F). Figure S1 also shows a visual representation of
fully functional 3D bioprinter capable of bioink temperature the location of the 3D-printed modifications/additions in
control in the range of 5°C–35°C. This extrusion-based relation to the original printer frame.

Volume 9 Issue 6 (2023) 97 https://doi.org/10.36922/ijb.0244