title: Fabrication and evaluation of an improved polymer-based cochlear electrode array for atraumatic insertion.
abstract: An atraumatic cochlear electrode array has become indispensable to high-performance cochlear implants such as electric acoustic stimulation (EAS), wherein the preservation of residual hearing is significant. For an atraumatic implantation, we propose and demonstrate a new improved design of a cochlear electrode array based on liquid crystal polymer (LCP), which can be fabricated by precise batch processes and a thermal lamination process, in contrast to conventional wire-based cochlear electrode arrays. Using a thin-film process of LCP-film-mounted silicon wafer and thermal press lamination, we devise a multi-layered structure with variable layers of LCP films to achieve a sufficient degree of basal rigidity and a flexible tip. A peripheral blind via and self-aligned silicone elastomer molding process can reduce the width of the array. Measuring the insertion and extraction forces in a human scala tympani model, we investigate five human temporal bone insertion trials and record electrically evoked auditory brainstem responses (EABR) acutely in a guinea pig model. The diameters of the finalized electrode arrays are 0.3 mm (tip) and 0.75 mm (base). The insertion force with a displacement of 8 mm from a round window and the maximum extraction force are 2.4 mN and 34.0 mN, respectively. The electrode arrays can be inserted from 360° to 630° without trauma at the basal turn. The EABR data confirm the efficacy of the array. A new design of LCP-based cochlear electrode array for atraumatic implantation is fabricated. Verification indicates that foretells the development of an atraumatic cochlear electrode array and clinical implant.
authors: Department of Electrical and Computer Engineering, Seoul National University, Bldg. 301 Room# 1006, Seoul National University, San 56-1, Shillim-dong, Gwanak-gu, Seoul, 151-742, South Korea.
authors: Tae Mok
authors: TM
authors: Gwon
authors: Kyou Sik
authors: KS
authors: Min
authors: Jin Ho
authors: JH
authors: Kim
authors: Seung Ha
authors: SH
authors: Oh
authors: Ho Sun
authors: HS
authors: Lee
authors: Min-Hyun
authors: MH
authors: Park
authors: Sung June
authors: SJ
authors: Kim
mesh_terms: D000818:Animals; D019929:Cochlear Implantation / Q000295:instrumentation / Q000379:methods*; D003054:Cochlear Implants; D004566:Electrodes; D004867:Equipment Design; D016057:Evoked Potentials, Auditory, Brain Stem; D005260:Female; D006168:Guinea Pigs; D006801:Humans; D055616:Microtechnology; D013506:Otologic Surgical Procedures / Q000379:methods; D011108:Polymers; D011474:Prosthesis Design; D012533:Scala Tympani / Q000033:anatomy & histology / Q000502:physiology; D013701:Temporal Bone / Q000601:surgery
chemical_list: D011108:Polymers; C422409:liquid crystal polymer