A sensor array apparatus for monitoring medical signals includes a first flexible substrate defining a central focal point and a second flexible substrate associated with the central focal point. A plurality of medical electrodes are disposed on the periphery of the first flexible substrate and a reference electrode is disposed on the second flexible substrate. A connector is in electrical communication with the medical electrodes and the reference electrode and adapted to connect to an electronic system. Bio-electric information is monitored between one of the medical electrodes and the reference electrode.