In this paper a Lab-On-Chip device using negative dielectrophoresis has been proposed for the focusing of particles at the center of the micro-channel. A 3D computational model was presented to simulate the focusing process. In particular, the model will solve for bioparticle movement and Joule heating. In the experimental study, the mixture of viable and nonviable yeast cells was used to demonstrate the focusing effect of the designed microfluidic device. The fabricated chip performs a desired focusing result for the conditions with the electric fields frequency of 1MHz, the medium conductivity of and the applied voltage , which validities the proposed 3D computational model. This Lab-On-Chip device provides a simple and effective mean of particle focusing.