We have fabricated a microfluidic device based on a novel geometrical arrangement of lateral metal electrodes and a patterned insulator. We have used the concept of insulator-based "electrodeless" dielectrophoresis to achieve focusing and continuous separation of dielectric particles flowing down a channel. The novelty consists of generating several electric fields in the structure which allow getting multiple opposite dielectrophoresis with a controllable position of equilibrium. Two and three dielectrophoretic forces were used for accurately focusing a stream of beads and yeasts respectively at different positions across the channel by simply adjusting potentials and frequencies of applied signals. The same combination of opposite forces is also extended to an application of continuous separation of particles with different dielectric properties.