CNT bundle-based thin intracochlear electrode array
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Objective: It is known that the insertion of the intracochlear electrode is critical procedure because the damage around cochlear structures can deteriorate hearing restoration. To reduce the trauma during the electrode insertion surgery, we developed a thin and flexible intracochlear electrode array constructed with carbon nanotube (CNT) bundles. Methods: Each CNT bundle was used for an individual electrode channel after coated with parylene C for insulation. By encapsulating eight CNT bundles with silicone elastomer, an 8-channel intracochlear electrode array was fabricated. The mechanical and electrochemical characteristics were assessed to evaluate the flexibility and feasibility of the electrode as a stimulation electrode. The functionality of the electrode was confirmed by electrically evoked auditory brainstem responses (eABR) recorded from a rat. Results: The proposed electrode has a thickness of 135 μm at the apex and 395 μm at the base. It was demonstrated that the CNT bundle-based electrodes require 6-fold the lower insertion force than metal wire-based electrodes. The electrode impedance and the cathodic charge storage capacitance (CSCc) were 2.70 kΩ ∠-20.4° at 1 kHz and − 708 mC/cm2, respectively. The eABR waves III and V were observed when stimulation current is greater than 50 μA. Conclusion: A thin and flexible CNT bundle-based intracochlear electrode array was successfully developed. The feasibility of the proposed electrode was shown in terms of mechanical and electrochemical characteristics. A proposed CNT bundle-based intracochlear electrode may reduce the risk of trauma during electrode insertion surgery.
KeywordsCarbon nanotube fiber Intracochlear electrode array Neural interface Soft neural microelectrodes
This work was supported in part by the CABMC grant funded by the Defense Acquisition Program Administration (UD170030ID) of Korea, in part by Business for Startup growth and technological development (TIPS Program) funded by Korea Small and Medium Business Administration in 2017 under Grants No. S2442573, in part by the Institute of Information & communications Technology Planning & Evaluation (IITP) grant funded by the Korea government (MSIT) (2017-0-00432, Development of non-invasive integrated BCI SW platform to control home appliances and external devices by user’s thought via AR/VR interface), in part by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI17C1648), and in part by the National Research Foundation (NRF) of Korea (NRF-2017R1A2B4006604), MEST as GFP (CISS-2012M3A6A054204).
We also thank Dr. Taek Dong Chung at Department of Chemistry, Seoul National University, for his generous comments on electrochemical properties of electrode materials. Also, we thank Shinyong Shim at Department of Electrical and Computer Engineering, Seoul National University, for offering a custom-made pulse generator.
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