Various manufacturing innovations have been adopted to facilitate tissue engineering practices for better biomedical applications. Among them, maskless (including extrusion-, laser- and inkjet-based) three-dimensional (3D) cell bioprinting is a revolutionary advance for printing arbitrary cellular patterns as well as creating heterogeneous living constructs. Thus far, effective printing of cell-laden viscoelastic fluids and printing-induced injury to living cells still pose a significant challenge to ensuring the scale-up of robust bioprinting. Using laser bioprinting (laser-induced forward transfer) and inkjet bioprinting as two jet-based model printing systems, we have been studying the bioink jettability and printability as well as printing-induced cell injury problems, aiming to achieve robotic bioprinting. The jettability and printability of cell-laden viscoelastic bioinks are defined and characterized using material properties- and printing conditions-related non-dimensional numbers. The printing-induced cell injury and post-transfer cell viability are estimated based on the process-induced cell thermomechanical loading during the cell droplet formation and landing processes.
In this talk, the perspective of ongoing bioprinting research and various bioprinting technologies are first introduced. Then the jettability and printability of cell-laden viscoelastic bioinks are discussed using the dimensionless Ohnesorge and elasto-capillary numbers to capture the influence of material properties along with the Weber number to capture the influence of printing conditions. Furthermore, the modeling of laser-induced cellular droplet formation and landing processes is presented, and the relationship between the mechanical loading information and post-transfer cell injury/viability is established using an apoptosis signaling pathway-based modeling approach. Finally, this talk shares some thoughts regarding basic scientific challenges related to bioprinting.