This paper reports an on-chip micro- flow cytometer that focuses cells to the center region of a microchannel by a negative dielectrophoretic force generated by ac fringing fields from microelectrodes. This design eliminates the sheath flow that makes the conventional cytometer sophisticated and difficult to operate. The micro- cytometer has a circular microfluidic channel that is fabricated by isotropic etching of soda lime glass wafers and a subsequent wafer bonding process. Electrode arrays are patterned inside the circular channel to facilitate dielectrophoretic particle focusing. We have demonstrated that the device can focus micro-beads into the center of the channel, and are integrating optical components with the micro- cytometer to realize a handheld device with integrated fluorescence detection, and will test the micro- cytometer for blood cell profiling and tumor cell detection.Copyright © 2003 by ASME