Authors: A. Kumar, A. Acrivos, B. Khusid and C.D. James
Affilation: New Jersey Institute of Technology, United States
Pages: 614 - 616
Keywords: dielectrophoresis, phase-quadrature sinusoidal signal, high-gradient strong electric field, particle aggregation
Conventional and traveling-wave dielectrophoresis in suspensions are proven techniques for the manipulation, separation, and characterization of suspended particles with potential applications ranging from biological warfare agent detection to healthcare industry. In contrast to previous studies, our work focuses on the field-driven particle aggregation in suspensions subjected to a spatially non-uniform AC field. We report the design of a device and an electric circuit capable of generating a high-gradient strong electric field by applying a phase-quadrature sinusoidal signal with voltage amplitude up to 200V(peak-to-peak) at frequencies as high as 250kHz. Experiments are conducted on suspensions of 4-micrometer polystyrene particles dispersed in deionized water. The accumulation of the particles in certain regions of the device caused by the conventional and/or traveling-wave dielectrophoresis is accompanied by the growth of the electrical and hydrodynamic interactions between them. When the interparticle interactions exceed their thermal randomizing motion, the electrically and hydrodynamically induced aggregation of the particles will occur (often referred to as an electro-rheological effect), resulting in the formation of well defined large-scale structures. The combination of conventional and traveling-wave dielectrophoresis accompanied by the field-driven particle aggregation in a single micro-device suggests a technique for consecutive 2-D manipulation and separation of suspended particles.