MICROARRAY FOR SINGLE-PARTICLE TRAP WITH ADDRESSABLE CONTROL BASED ON NEGATIVE DIELECTROPHORESIS

Abstract

Biological sample analysis is a costly and time-consuming process. In the world of rising health-care cost, the drive towards a more cost-effective solution calls for a point-of-care device that performs accurate analyses of small samples. To achieve this goal, today¿s bulky laboratory instruments need to be scaled down and integrated on a single microchip of only a few square centimeters or millimeters in size. However, it is the challenge to trap single particles and to sort them. Several novel micro-devices for particle sorting and trapping are presented based on dielectrophoresis (DEP). The devices use the phenomenon of dielectrophoresis-the force on polarizable bodies in a non-uniform electric field-to generate potential energy wells. In previous works, researchers have presented lots of micro-devices based on dielectrophoresis. However, most of them are 2D structure. This report investigates a 3D structure. The sorting device is presented first. By using the Comsol software to design an improved grid electrode structure, this 3D electrode structure is arranged in a trapezoidal fashion to enhance the electric field and sorting efficiency. Fabrication process for the electrodes uses lithography to achieve the required geometries. The trapping device is introduced next. The trap consists of three layers, well layer, two electrode layers. Besides photolithography for the formation of ITO electrode and the well array, the fabrication for middle electrodes of these traps involved lift-off process. At last, a multifunctional microarray is presented. This design has the advantage of simple fabrication, single particle trapping and sorting with addressable control.Top-bottom electrodes structure is used in this design. Due to the small jags on the electrodes, a virtual electrical cage can be formed to trap particles. Experiments were performed with beads and cells to verify the design of these micro-devices. This multi-functional and simple design has the potential to be commercialized. All of the knowledge can be very useful in designing and operating a dielectrophoretic barrier or filter to sort and select particles entering the microfluidic devices for further analysis.