Odo One was a special computer program created by Doctor Julian Bashir and Constable Odo in 2369. The program was designed to drive away the energy field that had merged with the conscious personalities of the humanoids on board Deep Space 9.
The program generated a signal that interfered with the natural resonance frequencies of the field. When Odo executed the program in cargo bay 4, an ionic interference signal locked on to the resonance frequencies and drove the field out of the brains of those affected. (DS9: "Dramatis Personae")