| Microelectrode devices have proven their usefulness in several scientific fields such as material characterization and electrokinetics. Interdigitated microelectrode (IDE) devices are used in this work to estimate the dielectric and geometric properties of dielectric films and also to study the electrokinetics of submicron dielectric particles. This dissertation is broadly divided into two segments: the dielectric film characterization and AC electrokinetics.; In the first segment, a novel method, which is proposed to estimate the dielectric and geometric properties of dielectric films using IDE devices, is validated by several experiments. In this novel method, the properties of the film are deduced from the capacitance and resistance responses of an IDE device when the dielectric film is placed on top of it. Although the measured quantities contain significant noisy elements, the dielectric permittivity of the film is estimated from them. The thickness of the dielectric film can also be estimated by first predicting the capacitances of a known film of various thicknesses, and by later comparing the predicted and measured capacitances. The method is validated by several experiments. This study finds an excellent agreement between the estimated and measured properties in all the experiments, when certain conditions are obeyed.; In the second segment of this dissertation, a novel simulation model is developed to study the electrokinetic behavior of submicron dielectric particles in a dilute suspension. The nonuniform electric fields generated by the IDE device exert electrokinetic forces that govern the motion of particles. When the particles are suspended in an ionic medium, besides exerting forces on the particles, the electric fields set the medium in motion due to electroosmosis. Also, the electrical double layer, formed at the electrode and particle interfaces in ionic media, strongly influences the potential in the bulk medium, thereby affecting the forces on the particles and medium. Taking into account these forces and affects, a simulation model is developed to study the motion of particles of various sizes at various electrical excitations. Experiments with 600nm latex particles and an IDE device are conducted to test the simulation model. A qualitative comparison of simulated and experimental results show very good agreement. |
