A microfluidic device comprising one or more fluidic microchannels and one or more arrays of cell assay units is disclosed. Each cell assay unit in turn comprises at one bipolar electrode, micropocket, reaction chamber, and leak channel. In some embodiments, the cell assay unit further comprises two or more split BPEs inside the reaction chamber. The disclosed microfluidic device can be used to separate cells, especially rare cells, from its biological matrix and then analyze the isolated cell inside the reaction chamber. The disclosed device can isolate and analyze cells in a high-throughput fashion and without any modification or labelling to the cells. Cells isolated using the disclosed devices does not lose their vitality.