Single-cell trapping utilizing negative dielectrophoretic quadrupole and microwell electrodes

The handling of individual cells, which has attracted increasing attention, is a key technique in cell engineering such as gene introduction, drug injection, and cloning technology. Alternating current (AC) electrokinetics has shown great potential for microfluidic functions such as pumping, mixing, and concentrating particles. The non-uniform electric field gives rise to Joule heating and dielectrophoresis (DEP). The motion of particles suspended in the medium can be influenced directly, by means of dielectrophoretic effects, and indirectly, via fluid flow through a viscous drag force that affects the particles. Thus alternating current electrothermal effect (ACET) induced flow and DEP force can be combined to manipulate and trap single particles and cells. This study presents a microfluidic device which is capable of specifically guiding and capturing single particles and cells by ACET fluid flow and the negative dielectrophoretic (nDEP) trap, respectively. The experiment was operated at high frequencies (5-12 MHz) and in a culture medium whose high conductivity (σ = 1.25 S/m) is of interest to biochemical analysis and environmental monitoring, which are both prone to producing ACET and nDEP. Manipulation of particle motion using ACET-induced fluid flow to the target trap is modeled numerically and is in good agreement with the experimental results.