A cochlear implant electrode includes an implantable array carrier made of flexible material with electrode contacts distributed on its outer surface along a longitudinal axis. Electrode wires are embedded within the array carrier, each electrode wire having a terminal end electrically connected to a corresponding electrode contact for applying electrical stimulation signals carried by the electrode wires to adjacent neural tissue within the cochlea. Each electrode wire has an inner non-crystal conductive material surrounded by a flexible outer seal. The flexible material of the array carrier is configured to be reactive with the non-crystal conductive material of the electrode wires so that if a break occurs in the outer seal of an electrode wire that allows contact between the flexible material and the non-crystal conductive material, then a local leakage seal will form at the break that resists migration of the non-crystal conductive material to the outer surface of the array carrier.