Development of double-sided multi-channel microelectrodes for a vestibular prosthesis

Vestibular prostheses aim at substituting lost vestibular function by stimulating the vestibulocochlear nerve. For this purpose, suitable microelectrode structures have to be developed, making high demands on fabrication technology. Flexible, polyimide-based systems can be used for this purpose, however in order to insert such electrodes in the semicircular canals in the ear, adequate stiffness of the structures is required. Moreover, to increase selectivity of the electrodes and to reduce size, it is desirable to arrange electrode contacts on both sides of the polyimide foil. In the following, two approaches to create such electrode systems are presented and compared. While monolithic technology using a double-sided photolithography process is the preferred method to create very thin and flexible electrodes, thicker and stiffer electrodes can be produced by precisely gluing together two single-sided electrodes. This sandwich technology allows a faster and more reliable production of vestibular microelectrodes.