Antifouling iridium oxide as a reference electrode for electrochemical sensing on cochlear implants

Implantable sensors would significantly improve patient care. For instance, by combining them with prosthetic devices like cochlear implants (CI) they could monitor implant-induced inflammation. Although multiple sensing methods have been demonstrated, two major problems are holding back the clinical translation of implantable electrochemical sensors. Firstly, the absence of miniaturized reference electrodes, stable over long periods, and, secondly, the biofouling inherently occurring in vivo. In this contribution, we discuss the implementation and validation of miniaturized iridium oxide reference electrodes on CI-like electrode arrays, with antifouling surface coatings. These electrodes are employed for the detection of hydrogen peroxide, an inflammatory marker, with a detection limit of 6.9 mu M in artificial perilymph.