Continuous DLP printing of cell-laden hydrogels
Biography:Jun Yin received the Ph.D. degree in mechanical engineering of Clemson University in 2011. From 2011 to 2013, he was a post-doctoral scholar with the School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA. Since 2014, he has been a Professor with the School of Mechanical Engineering, Zhejiang University. His main research interests are focused on 3D bioprinting, including the design and modeling of biofabrication processes, synthesis and application of biomaterials, and biomechanics during bioprinting.
Abstract： In conventional digital light process (DLP) printing, the higher printing resolution generally leads to a low printing efficiency, while the multiple prolonged UV light exposure affects the activity of cells encapsulated in the hydrogel-based bioinks. In this study, an analytical model based on differential analysis is developed to theoretically obtain the relationship between exposure time and the cured thickness of a single layer. Based on this model, the analytical Jacobs working curve can be described as depending only on three physical properties of photocurable materials: solid absorbance, liquid absorbance, and gelation time. This model can be used to obtain the working curve of soft photocurable materials, especially for the cell-laden hydrogel-based bioinks.
Based on the precise curing condition controlling, a pre-curing DLP printing method was developed, where the photocurable solution is initially pre-cured and kept at the pre-gelled state, and then the curing of each layer start from this state. Both printing efficiency and printing resolution can be improved by pre-curing DLP printing, since the printing time is not affected by the number of slices and the step effect was also eliminated. This high-fidelity and high-efficiency DLP method can significantly improve the activity of cells in the process of making biological tissue engineering scaffolds and is more conducive to the growth of cells in the scaffold.