Dimensionless evaluation of cell deformability with high resolution positioning in a microchannel

This chapter covers dimensionless evaluation for the stiffness-based deformability of a cell using a high-resolution vision system and a microchannel. In conventional approaches, the transit time of a cell through a microchannel is often utilized for the evaluation of cell deformability. However, such time includes both the information of cell stiffness and viscosity. In this work, we eliminate the effect from cell viscosity, and focus on the cell stiffness only. We find that the velocity of a cell varies when enters a channel, and eventually reaches to equilibrium where the velocity becomes constant. The constant velocity is defined as the equilibrium velocity of the cell, and it is utilized to define the observability of stiffness based deformability. The necessary and sufficient numbers of sensing points for evaluating stiffness-based deformability are discussed. Through the dimensional analysis on the microchannel system, three dimensionless parameters determining stiffness-based deformability are derived, and a new index is introduced based on these parameters. The experimental study is conducted on the red blood cells from a healthy subject and a diabetic patient. With the proposed index, we showed that the experimental data can be nicely arranged.