an improved bionic ear, cochlear implants, new

Paddy Boyle, Paddy French, Johan Frijns,

Wouter Serdijn, Jeroen Briaire

An Improved Bionic Ear, Cochlear

Implants, new developments

based on bioelectronics

Overview

• Introduction

• The healthy cochlea

• The cochlear implant

• New generation devices

• Summary

Advanced Bionics

• Founded in 1991 by Al Mann

• Request from UCSF – Robert Schindler MD

• Located in southern California

• First implants in Europe in 1993

• Formally part of Boston Scientific

• Now part of Sonova

• Around 800 staff

• 80 in Europe

• European Research Center Hannover

Brain

Cochlea

AdvancedBionics.com

The Cochlea • Basic anatomy

• Around 2.5 turns in the human

• Some 10 mm across

• Coiled to save space rather than for function

• Basal turn separated from the others

• Three dimensional structure

• Elevation significant for higher turns

• Non-uniform change from turn to turn

• 25 to 40 mm length between individuals

Cochlear Function

• Transduction of mechanical to neural

activity

• Tonotopic organization high to low

frequency from base to apex

• Compressive non-linearity of basilar

membrane: 120 dB dynamic range

• Motile outer hair cells (OHC) provide

active tuning mechanism

• Inner hair cells (IHC) do transduction

Cross-section through cochlea

Nauwelaers T, with permission

8

Frequency response

Working of a Healthy ear.

Movement of hair cells inside the

cochlea leads to sense of

hearing.

Anatomy of human ear.

Electrode Array in Position

Cochlear Implant

12

Hearing Instrument

Input-Output function

Input Sound Pressure Level dB SPL

Ou

tpu

t S

ou

nd

Pre

ssu

re L

ev

el

dB

SP

L

Expansion

Linear

Compressed

Clipped

25 40 100

50

65

95

Goals of compression

• Restore normal loudness growth

function

• Maximize audibility of low intensity

sounds

• Avoid discomfort from higher

intensity sounds

Materials Applications

Metal

Titanium Case; Encapsulation

Platinum Electrode

Iridium Electrode

Zirconium Case

Gold Coil; Encaspulation

Non-metal

Ceramic Case; Feedthroughs

Glass Feedthroughs

Silicone rubber Carrier; Encapsulation

Parylene Insulation coating

Teflon Insulation coating

Biocompatibility and Biocompatible

materials.

FDA approved materials used in Cochlear

Implant’s [1]

[1] Cochlear implants: System Design, Integration &

Evaluation, Fan-Gang Zeng, Stephen Rebscher, IEEE Rev

Biomed Eng. January 2008, 115 – 142.

Definition:

“ The ability of the material to perform with an appropriate

host response in a specific application”

Factors considered under Biocompatibility:

• Material properties.

• Host response.

• Material functionality.

• Corrosion, Fatigue, Fracture, Adsorption,

Absorption, Degradation.

• Byproducts generated due to degradation.

• Ability to achieve hermetic isolation.

17

Wannaya Ngamkham

Supervisor : Dr. Ir. W. A. Serdijn

Low power read out

electronics & integration

Electrode design, fabrication

& biological interface

Nishant Lawand

Supervisors : Prof. Dr. P J. French

Prof. Dr. ir. J H M. Frijns

Dr. J. J. Briaire

Complete System

level Optimizations

Ghazaleh Nazarian

Supervisor: Dr. G. N. Gaydadjiev

Framework of Smac-it project.

System

In CI’s, the software frame work running on the speech processor is

composed of: Profiler, Graphical-User-Interface, Compiler, Assembler

and other sub-modules

Electronics

Wavepackages

Microfabricated completely Flexible

Device

“Flexi-Stiff”

Conclusions

• Cochlear implants have restored hearing to many 1000’s of people around the world.

• Present day implants restore hearing but have limited

sound quality due to limited numbers of electrodes

and they miss the lower frequencies.

• Improved electronics, software and implant

technology will lead to a new generation of cochlear

implants with greater sound quality.