A flexible frame comprising an electrically conductive hollow cylindrical metallic tube having a plurality of cuts along the longitudinal axis to form a plurality of conductive wires. The wires are equally spaced apart circumferentially along the longitudinal axis of the tube by a gap to electrically isolate the wires. A first electrode is mounted around the circumference of the frame along the longitudinal axis and attached to a first wire of the plurality of wires. A second electrode is mounted around the circumference of the flexible frame along the longitudinal axis at a predetermined distance from the first electrode and attached to a second wire. A non-conductive thermoplastic layer may be secured to the outer surface of the flexible frame between the first and second electrodes to form an insulation layer between the first and second electrodes.
