No large-scale demixing due to differences in diffusivity in a model for confluent tissues

Phase-separation, or demixing, is an important behavior seen in biological materials, contributing to compartmentalization within cells as well as cell sorting and patterning. In confluent tissues, where there are no gaps between cells, micro-demixing due to shape differences between cells has been observed. In particulate matter, differences in size, shape and persistent motion have all been shown to cause large-scale demixing. More recently, a two-species particle-based model where each species had a different fixed diffusivity was also shown to completely demix via nucleation and coarsening. In this study, we ask whether a similar demixing via diffusivity persists in a confluent model for biological tissue. Using a Voronoi Model with two cell types that differ only in their translational noise, we analyze the dynamics using correlation functions and segregation metrics. We find no evidence of demixing in this model, in stark contrast to particulate systems. We also will discuss preliminary results on particle-based mixtures with different diffusivities at very high densities, to better understand how changing cell-cell interactions affect the mechanism for diffusion-based demixing.