Artificial Cochlear Implants For The Hearing Impaired Sherry

Artificial Cochlear Implants For The Hearing Impaired Sherry Johnson April 14 th, 2020

Purpose The following topics will be covered: ● What Artificial Cochlear Implants do ● How the devices operate ● Materials ● How well the Implants work ● Future of Cochlear Implants https: //medcureindia. com/treatments/head-neck-surgery/cochlear-implant-surgery

History of Cochlear Implants: https: //www. ncbi. nlm. nih. gov/pmc/ articles/PMC 2782849/

How the Ear Works ● Outer Ear: ○ Canal ○ Drum ● Inner Ear: ○ Cochlea ○ Auditory Nerve ● Middle Ear: ○ Malleus ○ Incus ○ Stapes https: //www. zmescience. com/science/biology/skull-hearing-ear-directly-27062014/

What are Artificial Cochlear Implants? ● ● Cochlea: transmits sound waves into nerve signals ○ 200, 000 nerves ○ Size of a pea ○ Unable to heal Help mitigate sensorineural hearing loss ○ Nerve deftness ○ Serious hearing loss to complete hearing loss ○ Bypass damaged ear https: //www. webmd. com/cold-and-flu/ear-infection/picture-of-the-ear#1

How Cochlear Implants Work 1. Sounds Picked up by Microphone 2. Signal Coded to electron pulses 3. Pulse sent to coil 4. Pulse goes from coil - skin - receiver 5. Implant send pattern to cochlea 6. Auditory nerve senses patten and sends to brain 7. Brain recognizes sound https: //www. ncbi. nlm. nih. gov/pmc/articles/PMC 2782849/figure/F 5/

Components ● External: ○ Microphone ○ Processor ○ Transmitter ● Internal: ○ Receiver ○ Electrode Array https: //www. lustwithlife. com/tag/cochlear-implant/

Microphone ● Sends sound signal to processor ● Broad range of frequency ○ Typically 800 -2000 Hz ● Designed to pick up lower frequencies ● Can improve function with directional microphones ○ Helps in noisy environments

Signal Processor ● Digitizes signal ● Filters into signal bands ○ ● Typically 12 -22 bands Extracts envelope and modulates amplitude https: //physicstoday. scitation. org/doi/10. 1063/PT. 3. 3661

Transmitter ● Radio Frequency signal ● Signal moves to implanted receiver ● A direct wire would be superior ○ Risk of infection too high https: //ecs. utdallas. edu/loizou/cimplants/tutorial. htm

Electrode Array ● Collects signal from receiver ● Sends impulses to auditory nerve ● Needs flexibility and mechanical stability ● Total length: 100 mm ● Array Diameter: 05 -0. 8 mm https: //blog. medel. com/close-up-with-cochlear-implant-electrode-arrays/

Inside the Electron Array ● Silicone Casing ● One sound channel/wire ● Small Wires ○ 90% platinum ○ 10% iridium Both Figures: https: //blog. medel. com/close-up-with-cochlear-implant-electrode-arrays/

Materials ● Silicone: ○ Good biostability ■ ○ High flexibility and stability Embeds wire ● Platinum: ○ Used as electrode contact ○ Wires between receiver and electrode contacts ■ platinum/iridium 90/10 ● Titanium/Ceramics: ○ Casing for implanted electronics

Sound Quality ● Not the same as a hearing aid ● Described as ● ○ Muffled ○ Similar to “out of tune radio” ○ Robotic Without context sound can be difficult to understand ● Speech recognition is possible https: //www. researchgate. net/publication/225375933_Music_Perception_Ability_of_Korean_ Adult_Cochlear_Implant_Listeners/figures? lo=1

Advantages and Disadvantages Advantages Disadvantages Hearing immediately recovered after ● High cost 40, 000 -100, 000$ surgery ● Any natural hearing will be lost ● Speech Recognition ● External components may be damaged ● Recognize variation of sounds ● External Components can be damaged ● Increased independence ● Increased risk of infection ● Components can be upgraded ●

Plans for the Future ● Fully implantable devices ○ Reduced power consumption ○ Smaller ● Teflon ○ Can be used to better function of electron array ● Electron Conducting polymers ○ Improved mechanical properties ○ Increased electrode contacts ● Silicon Electrodes ○ Optimize coupling between nerve and electrode ○ Possibly cost effective https: //www. researchgate. net/publication/282244112_Wireless_charing_pillow_for_a_fully_implantable _hearing_aid_Design_of_a_circular_array_coil_based_on_finite_element_analysis_for_reducing_mag netic_weak_zones/figures

Summary ● Intended for people with serious to complete hearing loss ● Not the same as a hearing aid ● Directly stimulates auditory nerve with electrodes ● Research being conducted to fully implant the device

References [1] “Cochlear Implant Surgery: The Artificial Hearing Aid, ” medcureindia. [Online]. Available: https: //medcureindia. com/treatments/head-neck-surgery/cochlear-implant-surgery. [Accessed: 04 -Apr-2020]. [2] Fan-Gang Zeng, S. Rebscher, W. Harrison, Xiaoan Sun, and Haihong Feng, “Cochlear Implants: System Design, Integration, and Evaluation, ” IEEE Reviews in Biomedical Engineering, vol. 1, pp. 115– 142, 2008 [Online]. Available: https: //www. ncbi. nlm. nih. gov/pmc/articles/PMC 2782849/. [Accessed: 01 -Nov-2019] [3]H. -G. Lim, J. H. Kim, D. H. Shin, S. T. Woo, K. W. Seong, J. H. Lee, M. N. Kim, Q. Wei, and J. -H. Cho, “Wireless charging pillow for a fully implantable hearing aid: Design of a circular array coil based on finite element analysis for reducing magnetic weak zones, ” Bio-Medical Materials and Engineering, vol. 26, no. s 1, 2015. [4] M. Hoffman, “Picture of the Ear, ” Web. MD, 09 -Jul-2009. [Online]. Available: https: //www. webmd. com/cold-and-flu/ear-infection/picture-of-the-ear#1. [Accessed: 04 -Apr-2020] [5] M. Svirsky, “Cochlear implants and electronic hearing, ” Physics Today, vol. 70, no. 8, pp. 52– 58, Aug. 2017. [6] NIDCD Information Clearinghouse, “Cochlear Implants, ” NIDCD, 15 -Jun-2018. [Online]. Available: https: //www. nidcd. nih. gov/health/cochlear-implants. [Accessed: 04 -Apr-2020]

Key Points 1. Sound travels into the ear, contacts the eardrum, and creates mechanical vibrations. These vibrations create waves in the cochlea that are detected by tiny hairs and transmitted through nerves as sound. 2. Cochlear implants use electrodes to directly stimulate the nerve cells in the cochlea. 3. Five main components: Microphone, signal processor, transmitter, receiver, and electrode array 4. Materials used include: Silicone, Platinum, Titanium, and Ceramics because they don't react with the body when implanted 5. The future of cochlear implants is moving towards fully implantable devices.