Methods & Materials
Design description.
An Anycubic Kossel Linear Plus Delta 3D printer kit was selected for modification. Based on the criteria for bioprinting, both the hardware and software of the Delta printer was successfully modified to accommodate for tissue engineering purposes. The manufacture and assembly of the final delta bioprinter can be separated into three main parts; (1) the hardware modification of the 3D printer frame, (2) the replacement of the thermoplastic extruder for a cell-free hydrogel paste extruder, and (3) the software modifications for hydrogel paste extrusion. Majority of the added components were 3D printed – making it inexpensive and easily modified as necessary. A leadscrew driven hydrogel deposition concept is employed within the system and due to the modular nature of the extruder parts, the RRP system easily allows for adjustments regarding the use of different syringe diameters and volumes.
All 3D printed parts mentioned were printed using an ANYCUBIC Kossel Delta Linear Plus 3D printer following the same general printing parameters as listed: Layer height: 0.1 mm, Fill density: 100 %, Print speed: 80 mm/s, Printing temperature: 210 ̵̊C, 100 % Flow, No support structures unless necessary and No platform adhesion. Poly-L-lactic acid (PLA) was used as the printing material (1.75 mm diameter eSUN PLA+ 3D filament). No additional post-print processing was required. The 3D modelling software SketchupMake2017 (v.17.2.2555) was used to design all printed parts (unless otherwise specified) and the slicing software Cura (v.15.04.2) used to prepare the design files for further 3D printing.
Bioprinter Frame (Hardware) modifications
Enclosure: The printer was enclosed using both printed and non-printed parts (Fig 1a). The side frames and mid-sections (later referred to as bioprinter frames, windows, and doors) were designed and files sent for manufacture to a Perspex laser cutting service (M&D Creations, Makhanda, South Africa) using 3 mm thickness clear Perspex sheets. The 3D printed parts consist of three separate corners.
Board box: The Anycubic Tri-gorilla controller board was moved from under the build plate (as per printer design) to outside the system; shown in Fig 1b. Wiring was adjusted to accommodate for the new board position. A board box was designed, and 3D printed to accommodate for the new location of the board. Furthermore, a few changes were made to the electronic board such that the hotbed power input cables and fans were removed.
Bed platform : A new bed platform was designed, and 3D printed, to hold two 220 mm diameter glass plates of 2 mm thickness (Fig 1b). The bed platform with the glass in place was designed to cover most of the base of the printer with a few openings to allow for air flow to reduce any pressure build-up.