A cochlear implant electrode includes an implantable electrode array made of resilient material with a center longitudinal axis and an outer surface. Electrode contacts are distributed on the outer surface of the electrode array along the longitudinal axis for applying electrical stimulation signals to adjacent neural tissue. At least one biocompatible hydrogel layer is fixed to the electrode array solely by mechanical connection and adapted to swell from contact with perilymph fluid within a cochlea without separating away from the outer surface of the electrode array.
