Rheological Analysis of Low Viscosity Hydrogels for 3D Bio-Printing Processes

Following the success of 3D printing with synthetic polymers like ABS, FLA, Nylon, etc., scientists and researchers have been putting efforts into fabricating bio-compatible materials. It has not only broadened the field of bioengineering and manufacturing but also regenerative medicine. Unlike the traditional 3D printing process, additive bio-manufacturing, also known as 3D bio-printing has a lot of challenges like cell survivability and proliferation, and the mechanical properties of the biomaterials which involve printability and the ability to hold its structural integrity. Proper design of experiments with extensive rheological investigation can help identify useful mechanical property ranges which are directly related to the geometric fidelity of 3D bio-printed scaffolds. Therefore, to investigate the printability of a low viscosity Alginate-Carboxymethyl Cellulose (CMC), multiple concentrations of the mixture were tested maintaining a 8% (w/v) solid content. A set of rheological tests such as the Steady Rate Sweep Test, Three Point Thixotropic Test (3ITT), and Amplitude test were performed. The outcome of those tests showed that the rheological properties can be controlled with the percentage of CMC in the mixtures. The fabricated filaments and scaffolds in the 5 combinations of CMC percentages were analyzed for flowability and shape fidelity. The rheological results and the printability and shape fidelity results were analyzed.