Cell transport and suspension in high conductivity electrothermal flow with negative dielectrophoresis by immersed boundary-lattice Boltzmann method

•Cell manipulation is achieved by DEP force and ACET flow in physiological solution.•A single cell is suspended at an equilibrium position under ACEK.•Double cells are under periodic motion under ACEK with cell-cell interactions.•The DEP force is significant for anchoring the cell and stabilizing its transport. The cell transport and suspension using AC electrokinetics is essential for cell patterning and other biomedical applications in microfluidics. To avoid the undue cellular stress and irreversible damage to cells caused by low conductivity media, direct manipulations of cells in physiological solution of high electrical conductivity without dilution becomes significant. The driving mechanism of alternating current electrothermal (ACET) flow makes it attractive for pumping the physiological conductivity solution and transporting cells through the electrohydrodynamic (EHD) force. In addition, negative dielectrophoresis (nDEP) force is induced on a cell when its electrical conductivity is lower than that of solution media. In this paper, the effectiveness of ACET flow and negative DEP force in high conductivity solution is novelly used simultaneously to achieve a successful long-range cell transport and suspension in the microfluidic chamber. An immersed boundary-lattice Boltzmann method (IB-LBM) is developed to investigate the cell transport and suspension mechanism with respect to AC voltage magnitude, electrical conductivities of cell and solution, cell initial position, and cell size. It is found that a sufficient DEP force is indispensable for stabilizing the cell transport process and anchoring cells by overcoming the cell-cell interaction. Based on this, the design of a lab-on-a-chip device to generate a large DEP force is essential for future research to realize an efficient AC electrokinetic-based cell transport and suspension in physiological fluids.