Computational modelling of membrane gating in capsule translocation through microchannel with variable section

Abstract

As an effective physical method, cell squeezing technology based on microfluidics plays an increasingly promising role in intracellular delivery. To deepen our understanding of microfluidic chip design and optimization, it is essential to explore the underlying physics required in the generation of the appropriate tension for gating capsule membrane. In this investigation, an immersed finite element method (IFEM) has been adopted to simulate the interaction between capsule and fluid fields in microchannel with variable section. Having obtained the numerical results, the gating region on the membrane can be determined by the non-uniform tension distribution based on the critical gating membrane tension during the capsule translocates the microchannel. In addition, the gating integral, which is defined to measure the degree of gating, shows that the setting of driven pressure might be crucial for the design and optimization of the system. The numerical results demonstrate that the occurrence of secondary peak in deformed energy after the capsule passes through the confined microchannel under certain flow condition might be ascribed to the elastic recovery of the membrane. To investigate the effects of initial orientations, the translocation of an ellipsoid capsule through the channel has also been simulated numerically, which indicates that both flow shear force and compressive force due to the constrained solid wall have significant effects on membrane gating. Therefore, to improve the gating efficiency of capsule membrane, it is necessary to optimize various factors to achieve the balance among the compressive force, shear force and the translocation time.