A cell-based biosensor comprising of integrated dielectrophoretic electrodes for cell positioning, ion-sensitive field-effect-transistors (ISFETs), and pseudo-reference electrode has been fabricated using nMOS silicon technology. The fabrication process is described and sensor properties and performances are demonstrated. The ISFETs have shown good operating characteristics as pH sensors. Bacteria cells have been successfully positioned on the active area of the ISFET by integrated dielectrophoretic microelectrodes. Bacterial metabolism detection over a few hours has been made possible by monitoring pH variations after adding glucose. This microsystem will be used for bacteriological applications and for food analysis in particular. As future applications of this system we consider: (i) on-line monitoring of the ability of various types of bacteria to metabolize sugars and (ii) on-line measurements of pH variations under different conditions.