(236f) Numerical Study On Droplet Formation and Cell Encapsulation Process In a T-Junction

Droplets are widely used as reaction vessels for the chemical manipulation of cells. A critical step in this process is the cell encapsulation, which is typically performed in a T-junction of a microchannel. Two immiscible liquids enter the channel in two perpendicular directions and form droplets, and at the same time cells are encapsulated into the droplets. The droplet formation and cell encapsulation process involves multiphase flow problems and coupled membrane-fluid mechanics problems. In this study, the cell encapsulation into a droplet at a microchannel T-junction is investigated using numerical simulations. The two-phase flow with droplet formation is simulated using the lattice Boltzmann method (LBM), a robust and efficient numerical approach for simulating complex fluid systems. In order to simulate the cell encapsulation as well as the cell deformation inside the droplet, the standard LBM has been combined with the immersed boundary method (IBM). Numerical studies on the shape, size, generating frequency, and formation mechanism of droplets under various operation conditions are carried out on both 2D and 3D cases. This paper also studies the deformation of the cell under the shear-stress and pressure that act on the cell membrane by the flow field during the dynamic process of droplet formation and cell encapsulation, as well as the interactions between cell membrane and flow field in the droplet, which are critical to the success of the cell encapsulation process. The current numerical results are compared to the experimental and numerical results in literature for validation and for the study of 3D effects in the droplet formation process. This study provides useful knowledge on the fundamental mechanism of droplet formation and cell encapsulation process in microchannels.