Hydrogel electrode – a new approach to realize an atraumatic electrode
The use of a hydrogel causes a curvilinear movement of the electrode shaft. The aim is to protect the sensitive biological structures as much as possible during implantation in order to preserve residual hearing that is often still present. The newly developed hydrogel compartment is inserted into a silicon-based CI shaft. When the electrode is inserted, the hydrogel swells through the perilymph fluid and induces the so-called intrinsic bimorph bending effect. In order to meet the demand for life-long durability, the hydrogel is mixed into the outer part of the silicone mantle and thus firmly anchored to the silicone. The difficulty here is to combine the hydrophobic material silicone with the hydrophilic material hydrogel. The hydrogel is therefore introduced into the silicone prepolymer in the form of a dry powder. Advanced grinding techniques have made it possible to achieve micro-particle fractions of hydrogel powders that allow both water absorption and homogeneity of curvature to be controlled.
As the development is very promising, the hydrogel electrode will be realized in cooperation with the cochlear implant manufacturer Advanced Bionics.