Finite element simulation of a cell entering a pipette: Effects of large deformation and frictional contact

The process of single cells entering a confined channel under pressure is widely seen in cell mechanics experiments (e.g., micropipette aspiration) and biological process (e.g., tumor cell migration in capillaries). Finite element method that models the cell as a continuum solid has been extensively used to study this process. However, most previous modeling studies suffered from limitations including inaccurate pressure and frictional boundary conditions, therefore making it challenging to simulate the complete entry process involving large deformation of the cell. Here we present a simulation approach that can continuously update the boundary condition according to the contact status as the cell enters the channel, thus enabling more accurate description of the pressure and frictional conditions. Using a quasi-linear viscoelastic solid model for the cell, we show that the detailed pressure boundary condition and interface friction coefficients can significantly affect the cell entry process.