Compared with conventional cochlear electrode arrays, which are hand assembled and wire-based, polymer-based implants have several advantages. They are very precise, and their fabrication is inexpensive because of the use of thin-film processes. In the present study, a cochlear electrode array based on a high-performance liquid crystal polymer material is devised. Furthermore, the device is encapsulated in silicone elastomer.
The fabrication steps introduced here include thin-film processes with liquid crystal polymer (LCP) films and customized self-aligning molding processes for the electrode array. To assess the feasibility of the proposed electrode array, the charge storage capacitance and impedance were measured using a potentiostat. Vertical and horizontal deflection forces were measured using a customized fixture and a force sensor. Insertion and extraction forces were also measured using a transparent human cochlear plastic model, and five cases involving human temporal insertion trials were undertaken to assess the level of safety during the insertion process.
The charge storage capacity and impedance at 1 kHz were 33.26 mC/cm2 and 1.02 kΩ, respectively. Likewise, the vertical force and horizontal force of the electrode array were 3.15 g and 1.07 g. The insertion force into a transparent plastic cochlear model with displacement of 8 mm from a round window was 8.2 mN, and the maximum extraction force was 110.4 mN. Two cases of human temporal bone insertion showed no observable trauma, whereas 3 cases showed a rupture of the basilar membrane.
An LCP-based intracochlear electrode array was fabricated, and its electrical and mechanical properties were found to be suitable for clinical use.
*School of Electrical Engineering and Computer Science, †Department of Otorhinolaryngology–Head and Neck Surgery, Seoul National University College of Medicine, ‡Sensory Organ Research Institute, Seoul National University Biomedical Research Institute, Seoul, Republic of Korea §Department of Otorhinolaryngology, Boramae Medical Center, SMG-SNU, Seoul, Korea
Address correspondence and reprint requests to Sung June Kim, Ph.D., School of Electrical Engineering and Computer Science, Bldg. 301 Room 1006, Seoul National University, San 56-1, Shillim-dong, Gwanak-gu, Seoul, 151-742, Korea; E-mail: email@example.com
This work was supported in part by the Ministry of Knowledge Economy of Korea under Grant 10033657; in part by the Pioneer Research Center Program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology (NRF-2009-0082961); in part by the Public Welfare and Safety research program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology (NRF-2010-0020851).
The authors disclose no conflicts of interest.