Optimization of 3D printing parameters with sodium alginate hydrogel

In order to obtain biologically compatible objects with mechanical properties close to living tissues, 3D printing with biocompatible sodium alginate hydrogel at room temperature on the modified desktop 3D printer Up! Mini (manufactured by PP3DP, China) was carried out. The standard print head was replaced with a special syringe-extruder to allow the extrusion of a hydrogel, the details of which were made by 3D printing from ABS plastic. Of the parameters, the standard material feed and print head movement rates were changed. For accurate reproduction of object sizes using 3D printing from this hydrogel the next parameters were established: the optimal concentration of sodium alginate in extruded hydrogel (2.5 wt.%); the composition of the “support” gelatin suspension, which was fixed on the printing table of a 3D printer and served as volumetric support for hydrogel (10 g of calcium chloride CaCl2 and 13.5 g of gelatin per 500 ml of distilled water). The method of its preparation includes 1 minute mixing of components blend, dispersion at 9000 rpm on IKA ULTRA-TURRAX T 25 digital disperser, 4 hours settling at 4 °C, 3 minutes centrifuging at 5500 rpm, removal of the supernatant. The optimal movement speed of the print head during 3D printing and the speed of extrusion of the hydrogel during the formation of the external perimeter of the printing object are 9–11 and 5 mm/s, respectively, as well as the speed of material extrusion during the formation of the internal filling of the model is 0.83 mm/s.