title: A polymer-based multichannel cochlear electrode array.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  The charge storage capacity and impedance at 1 kHz were 33.26 mC/cm 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.
  
  
  CONCLUSIONS
  An LCP-based intracochlear electrode array was fabricated, and its electrical and mechanical properties were found to be suitable for clinical use.
authors.affiliation: *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.
authors.forename: Kyou Sik
authors.initials: KS
authors.lastname: Min
authors.forename: Seung Ha
authors.initials: SH
authors.lastname: Oh
authors.forename: Min-Hyun
authors.initials: MH
authors.lastname: Park
authors.forename: Joonsoo
authors.initials: J
authors.lastname: Jeong
authors.forename: Sung June
authors.initials: SJ
authors.lastname: Kim
mesh_terms: D003051:Cochlea / Q000601:surgery; D019929:Cochlear Implantation / Q000295:instrumentation*; D003054:Cochlear Implants; D006801:Humans; D011108:Polymers; D011474:Prosthesis Design
chemical_list: D011108:Polymers