An electroplating-free and minimal noise polyimide microelectrode for recording auditory evoked potentials from the Epicranius

In this paper, we introduce an electrode for measuring auditory evoked potentials by employing the advantages of polyimide (PI), which is a well-known substrate material for producing flexible electrodes using MEMS technology. The PI multimicroelectrode array has four fingers that include 16 electrodes in order to achieve sufficient adhesion to the curved surface of the animal skull. For high-quality signal acquisition, we optimized the device to decrease crosstalk and improve contact impedance by adding ground channels and fabricating a raised electrode structure. In addition, implantation of the device was facilitated by the addition of an alignment site to ensure optimal positioning and enable signal measurement from the specific part of the cerebral cortex in charge of auditory sensing. After the implantation of the PI electrode on the skull surface, electrical signals were measured following stimulation at different stimulus frequencies (5 or 10 kHz). Unlike other techniques, administration of this PI electrode is less invasive, reducing patient recovery time dramatically in comparison with other electrocorticographic operations. Furthermore, as the exterior of the brain would not be exposed at any point, the chance of infection is minimized.