This thesis research aims at advancing our understanding of the coupled electric and hydrodynamic processes in the electrokinetic transport of particles in confined microfluidic devices and explores novel approaches for particles transport and manipulation in closed microfluidic chips. The first part of this thesis investigates the electrokinetic transport phenomena in open-ended microfluidic devices by employing both experimental and numerical approaches with the focus placed on the hydrodynamic and electric interactions among particles, fluid and the bounded domain boundaries. Fundamental study of wall effects on electrokinetic transport of microspheres in a rectangular microchannel is carried out. Both experimental results and numerical simulations suggest that the electrophoretic mobility of particles is obviously enhanced with reducing the particle-wall separation. In addition, a method for continuous concentration of particles in a confined microfluidic chamber is proposed and demonstrated. The second parts of this study focuses on exploring novel approaches for particle manipulation in closed microfluidic domains. A method for on-chip particle assembly in non-uniform electric field is demonstrated by using the combined effects of dielectrophoresis and dipole attractive force. Moreover, two novel electronic paper display technologies are developed and experimentally demonstrated by using polystyrene particles dispersed in DI water. Prototypes of the proposed electronic paper displays are fabricated. The proposed novel technologies can realize electronic paper displays with fast switching response, high resolution, superior optical transmittance and low manufacturing costs.