In this thesis I reviewed the literature in the fields of biomaterials and hydrogels, with a
focus on the natural polymers of alginate and different 3D bioprinting technologies such
as laser-assisted printing, inkjet printing, extrusion printing and stereolithography. In
addition to the choice of printing method, the choice of bio-ink and the optimisation of
printing parameters are also important. In the experimental section, I investigated
extrusion based bioprinting of calcium alginate and determined the optimum printing
parameter of flow, the mass flow rate of the 3D printer at default flow settings and
measured the viscosities of sodium alginate at different hydrogel compositions. I
determined the critical stresses required for gel flow by the Roberts-Barnes-Carew
viscosity correlation. The trend of increasing viscosity with increasing alginate
concentration by weight is true from 4 % to 6 % sodium alginate content, deviating at
7 %. Optimised flow rates and critical stresses increase with increasing sodium alginate
content. Deviations occurred at the 6 % gel. Reproducibility problems also arise quickly
in printing, due to inhomogeneity of hydrogels, inconsistency of extrusion or errors in
exacting measurements.
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