Fabrication and evaluation of an improved polymer-based cochlear electrode array for atraumatic insertion

Biomed Microdevices. 2015 Apr;17(2):32. doi: 10.1007/s10544-015-9941-1.

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.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cochlear Implantation / instrumentation
  • Cochlear Implantation / methods*
  • Cochlear Implants*
  • Electrodes
  • Equipment Design
  • Evoked Potentials, Auditory, Brain Stem
  • Female
  • Guinea Pigs
  • Humans
  • Microtechnology
  • Otologic Surgical Procedures / methods
  • Polymers
  • Prosthesis Design
  • Scala Tympani / anatomy & histology
  • Scala Tympani / physiology
  • Temporal Bone / surgery

Substances

  • Polymers
  • liquid crystal polymer