Numerical design of microfluidic-microelectric hybrid chip for the separation of biological cells.

A miniature microfluidic-microelectric hybrid chip is numerically designed for separation of biological cells, where the characteristic length of the chip is close to the cell radius. A mathematical model is developed to characterize the motion and deformation of a biological cell in the hydrodynamic and nonuniform electric coupled fields, in which the mechanical and dielectric behaviors of the cell are taken into consideration. Subsequently, the model is validated by comparing with the experimental results published previously. By taking a red blood cell (RBC) as the sample of biological cell, the chip structure is numerically designed from the viewpoints of the electrode width, fluid flow velocity, and electric potential, respectively. Using the designed microfluidic-microelectric hybrid chip, the effects of the shape and initial position of the RBC on the separation ability are then analyzed. After that, the separation of the RBCs with the different permittivities or conductivities using the designed chip is simulated, and the deformation behaviors of the RBCs are discussed as well. At the high frequency, the permittivities of the RBCs play a dominant role in the separation of the RBCs, which causes the RBCs moving toward or away from the electrode array. However, the conductivity of the RBC plays a significant role at the low frequency. With suitable suspending fluid therefore, the separation of cells with different permittivities or conductivities can be achieved using the microfluidic-microelectric hybrid chip designed by the present work.