A great interest has been attracted to the development of nanoscale biosensor. Electrical detection provides a label-free and direct real-time method. Here, we have demonstrated a new model of nanoscale bioswitch based on the electrical detection of the cleavage of chemical bonds linking the nanowire across a pair of electrodes. Carbon nanofibers are manipulated dielectrophoretically to form bridges across microelectrode junction, and anchored through a biomolecular interaction. Once in place, chemically-induced cleavage of a recognition site along the bond linking the nanowires to the electrode surface allows the nanowire to be easily removed by a flow of fluid, and this removal can be detected in real time using an AC voltage and a lock-in amplifier. This form of sensing is in inherently digital in nature, as the removal of a single nanowire produces a sudden decrease in the current between electrodes. Our results suggest that it could be a general method for digital chemical and/or biosensing using nanowires.