A Polymer Cochlear Electrode Array

â Abstract. Contents. List of Figures. List of Tables. List of Abbreviations.





Chapter 1 Introduction. 1.1 Overview of Neural Prostheses and Cochlear Implant. 1.2 Review of Cochlear Electrode Array. 1.2.1 Conventional Cochlear Electrode Array. 1.2.2 Polymer-Based Cochlear Electrode Array. 1.3 Proposed Polymer Cochlear Electrode Array. 1.3.1 Electrode Array for Atraumatic Deep Insertion. 1.3.2 Electrode Array for Tripolar Stimulation. 1.4 Long-Term Reliability of Polymer-Based Neural Prostheses. 1.5 Objectives of the Dissertation.



Chapter 2 Materials and Methods. 2.1 Liquid Crystal Polymer (LCP). 2.1.1 Material Properties and Types of LCP. 2.1.2 MEMS Technologies compatible with LCP. 2.2 Cochlear Electrode Array for Atraumatic Deep Insertion. 2.2.1 Electrode Design. 2.2.2 Fabrication Process. 2.2.3 Experimental Setup and Protocol of In Vitroand In VivoEvaluation Tests. 2.2.3.1 Insertion and Extraction Force Measurements in Scala Tympani Model. 2.2.3.2 Human Temporal Bone Insertion Studies. 2.2.3.3 In VivoAnimal Study. 2.2.3.3.1 Acute Implantation and Electrically Evoked Auditory Brainstem Response (EABR) Recording. 2.2.3.3.2 Hearing Preservationand Histologic Evaluation. 2.3 Polymer Electrode Array for Tripolar Stimulation. 2.3.1 Modeling and Simulation of Polymer-Based Cochlear Electrode Array for Tripolar Stimulation. 2.3.1.1 Simulation Tool and Modeling. 2.3.1.2 Electrode Designs. 2.3.2 Fabrication Process. 2.3.3 In Vitro Measurements. 2.3.3.1 Test Board for Tripolar Stimulation. 2.3.3.2 Experimental Setup and Protocol. 2.4 Long-Term Reliability Analysis of LCP-Based Neural Implants. 2.4.1 Overview of the Long-Term Reliability. 2.4.1.1 Failure Mechanism. 2.4.1.2 Measurement Methods for Reliability Analysis. 2.4.2 Technical Strategiesto Improve Reliability of LCP-Based Implantable Device. 2.4.2.1 Mechanical Interlocking to Strengthen Metal-LCP Adhesion. 2.4.2.1.1 Fabrication Process using Dual Lithography and Electroplating. 2.4.2.1.2 In VitroPeel Testand Electrochemical Measurements. 2.4.2.1.3 In VitroAccelerated Soak Test. 2.4.2.1.4 Visual Inspection and Statistical Analysis. 2.4.2.2 Fabrication using LCP and Dielectric Materials. 2.4.2.2.1 Role of Dielectric Materials. 2.4.2.2.2 Proposed Fabrication Process. 2.4.2.2.3 Preliminary Study. 2.4.3 Experimental Comparison LCP-Based to Wire-Based Electrode Array.





Chapter 3 Results. 3.1 LCP-Based Cochlear Electrode Array for Atraumatic Deep Insertion. 3.1.1 Fabricated Electrode Array. 3.1.2 Insertion and Extraction Force Measurements. 3.1.3 Insertion Trauma in Human Temporal Bone Insertion Study. 3.1.4 Electrically Evoked Auditory Brainstem Response Recording. 3.1.5 Histological Change and Hearing Preservation. 3.2 Polymer Electrode Array for Tripolar Stimulation. 3.2.1 Simulation Results according to Electrode Site Design. 3.2.2 Fabricated Electrode Array. 3.2.3 In Vitro Measurements. 3.3 Long-Term Device Reliability. 3.3.1 LCP-Based Neural Electrode Array using Mechanical Interlocking at Metal-LCP Interface. 3.3.1.1 Fabricated Electrode Arrayand Metal-LCP Interface. 3.3.1.2 Adhesion Force and Electrochemical Measurements. 3.3.1.3 Accelerated Soak Test and Lifetime Estimation. 3.3.2 Fabrication Method using LCP and Dielectric Materials. 3.3.2.1 AdhesionStrength of Bonding between LCP and Dielectric Materials. 3.3.2.2 Lamination Result of the Proposed Fabrication Method. 3.3.3 Impedance Measurementsof LCP-Based and Wire-Based Electrode Array.







Chapter 4 Discussion. 4.1 LCP-Based Cochlear Electrode Array for Atraumatic Deep Insertion. 4.1.1 Comparison of the Current Proposed Electrode Array to the Previous Electrode Array. 4.1.2 Suggestion of Improvement in Electrode Design Related with Insertion Depth and Trauma. 4.1.3 Point to Improve in Fabrication Process. 4.1.4 In VivoImplantation. 4.2 Power Consumption and Stimulation Threshold of Tripolar Stimulation. 4.3 Technical Strategies to Improve Device Reliability. 4.3.1 Mechanical Interlocking at Metal-Polymer Interface. 4.3.2 Hybrid Device Based on Polymer and Dielectric Materials. 4.4 Review of Long-Term Reliability of LCP-Based Device.







Chapter 5 Conclusion.





References. Abstract in Korean.