This dissertation describes the scientific life cycle of a new essential part of a biomedical implant: a cochlear implant electrode. Cochlear implants are semi-implantable prostheses that have been developed for patients with profound to severe sensory hearing loss. The electrode of a cochlear implant is inserted into the cochlea (inner ear) and forms the interface between the auditory nerves and electronics. The electrode consists of a silicone carrier with very small metal (Platinum) contacts that are linked by very fine (33mum) wires to an implanted electronic micro-chip. The electrical current, which flows between the intra-cochlear metal contacts, activates the sensory nerves in a certain order so that the patient can regain hearing. The performance and quality of hearing are dependent on different elements and will determine the final result of the individual patient.; An important group of determining factors are the technological parameters of the very cochlear implant, the interface between the electronics and the remaining nerve fibres of the cochlea. The more the interface between the nerves and electronics can be refined, the more the information can be transferred in a refined way. The electrode is called the bottleneck of the cochlear implant when we take into account that the commercially available systems today have 20 metal contacts for about 30,000 nerve fibres. A new electrode was developed in this dissertation with 48 electrode contacts to improve the transfer of information. This dissertation describes the study, design and production of the new electrode and concludes with the first clinical experiments. The dissertation is divided in four main parts.; The first part describes the background and history of cochlear implants and then goes further into detail on the basic principles of the cochlea. We describe the concept of this electrode, where we wanted to obtain a deep insertion in the cochlea (till two turns), with as many Platinum contacts as possible present in the silicone carrier. Position and orientation of the contacts should also enable a more efficient stimulation of the nerve fibres.; The second part of this dissertation describes the research and development steps. New tooling and work methods had to be developed. Micro-mechanical studies were initiated to improve the electrode for optimal insertion depth and to test patient safety.; The third part describes the first clinical trial with this new concept of electrode in a patient group of nine subjects. The fourth part offers general conclusions based on the performed research and explores future research possibilities derived from this dissertation.
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