Mixing Analysis of High Viscous Hydrogels for Bioprinting

3D bioprinting is a promising additive manufacturing technique that use several kinds of material. However, sometimes it is needed to work with material proportions that generate high viscous hydrogels, and its mixing becomes difficult. Although some well-known techniques are commonly used to work with large volumes, it is still missing a specific methods and equipment to stir volumes under 100 mL. Specifically, in 3D bioprinting around 50mL (a Falcon tube) can be an ideal volume to perform a couple of days of experiments, optimizing the performance without compromise the quality of the hydrogel. For this reason, a comparative study was developed to perform a mechanical stirring mixture of two died hydrogels, Gellan Gun (yellow) and Konjac Glucomannan (blue). The experiments were performed with two impeller shapes. One of them, it is a standard triangular impeller and, the other one, it is a scraper 3D printed impeller shape that was manufactured in polycarbonate. Both, a quantitative and qualitative measures were performed. First, the mixing time at three different rotation speeds was evaluated. Second, a fuzzy scoring was obtained from two experts about the quality of the hydrogel mixture. Specifically, grumes, bubbles and homogeneity of the samples were scored. In general, mixing time is highly reduced when the 3D printed scraper shape was used. Further, lower rotation speeds are needed in comparison with the triangle shape. Additionally, better homogeneity and less grumes and bubbles are obtained with the scraper shape. In conclusion, the new scraper shape impeller provides better hydrogel mixture.