Effects of viscoelasticity on droplet-based bioprinting

We computationally study effects of viscoelasticity of bio-inks on the cell viability during the deposition of cell-laden droplets on a substrate using a front tracking method. The inner droplet representing the cell and the encapsulating droplet are modeled as viscoelastic liquids, while the ambient fluid is Newtonian. Following Nooranidoost et al. [1], the viscoelasticity of the fluids is modeled using the FENE-CR model and is characterized by the Weissenberg number and the polymeric viscosity ratio. We demonstrate that these parameters significantly impact the cell viability and can be useful to control and improve droplet-based bioprinting systems. In particular, viscoelasticity of the encapsulating droplet fluid generally enhances the cell viability, favorable for bioprinting systems. A universal correlation is proposed to relate the cell viability and the viscoelasticity of the encapsulating droplet and is found to fit the computationally estimated values well. The effects of the cell viscoelasticity are also examined, and it is shown that the Newtonian cell models may significantly overpredict the cell viability.

[1] M. Nooranidoost, D. Izbassarov, and M. Muradoglu, Phys. Fluids 28, 123102 (2016)