Cochlear implants (CI), which are standard in the care of profoundly deaf and hearing impaired patients, can fail even after years of good function due to corrosion reactions of the platinum electrodes. As a result, speech understanding deteriorates and the dissolved platinum can have a cytotoxic effect on the cells. Early detection of toxic processes (e.g. release of platinum ions) could prevent negative cell reactions and thus damage in the target organ as well as implant failure.The aim of subproject A05 is to increase the reliability of CIs. Their functionality as electrical implants is also to be used as a sensor for diagnostic purposes. In this way, the influences of, for example, the CI stimulation strategy, the material properties of the electrode and possible inflammation processes on the degradation process can be investigated.
The degradation processes will be evaluated as a function of the microstructure, the degree of impurities and the surface roughness of the platinum using electrochemical measurement methods such as cyclic voltammetry and impedance spectroscopy. The degree of cell toxicity is investigated in cell culture experiments using the “patch clamp technique” under various conditions. Furthermore, in order to detect pathological changes in the perilymph as a result of degradation processes, additional gold electrodes are integrated as sensors, which are provided with special coatings. These are able to intercept the platinum, which is noticeable in a change in impedance. In the future, a therapeutic implant should detect inflammation and critical degradation processes at an early stage and independently adjust the electrical stimulation strategy of the CI by reacting in time.