SBIR-STTR Award

Sensorineural hearing loss (SNHL) affects 30 million people in the United States, and over 275 million people worldwide, leading to a significantly lowered quality of life and a large economic burden. For those with severe to profound SNHL, a cochlear implant is currently the only available route for restoring `adequate' functionality. Only 310,000 implants had been done worldwide till 2012, and about 50,000 devices are being sold annually. This large discrepancy between those that can benefit and those that actually get the implant is driven partly by their cost, availability and the lack of trained surgeons and facilities. However, there are critical limitations in the current devices which contribute significantly to very low adoption: (a) The external microphone does not localize sound from the auricle and ear canal, introducing unnatural cues; (b) The cumbersome, highly visible unit attached to the skull outside the mastoid bone, connected by a cable to the sound processor and rechargeable battery placed behind the ears, makes the disability very obvious, and creates an unacceptable social stigma for many patients, causing them to refuse this option; (c) The device must be taken off during showering or swimming (although a few water-resistant versions are now available), and during sleeping, increasing the likelihood of damage, misplacement, or the ability to communicate in these situations. (d) Having an external magnet can lead to skin breakdown and implant extrusion (e) The large footprint and placement leaves open the risk for device migration requiring revision surgery. A fully-internal cochlear implant (FICI), would address this large unmet medical need. The lack of a self-contained power supply is a key roadblock preventing realization of all FICIs. Based upon our extensive experience with fabricating lithium ion battery (LIB) electrodes, and our synthesis of several novel solid polymer electrolytes specifically targeted for LIBs, we hypothesize that an all-solid LIB with a LiFePO4 cathode, a Li5Ti4O12 anode and a lithium salt doped (poly) ethylene oxide solid electrolyte, will meet all of the electrochemical, safety and footprint requirements for this application. At Audiance, Inc. we have the engineering, electrochemical and medical expertize, as well as the facilities to fabricate this battery, characterize its performance and iterate on processing strategies and component loadings until it meets or exceeds all of the metrics required for a FICI. The all-solid LIB will remove one of the most critical roadblocks for the development of a FICI, and thus open up an option for many patients around the world with severe to profound SNHL. The battery design strategy could also be used for other implants that have similar stringent performance metrics.

Public Health Relevance Statement:
Narrative Severe to profound sensorineural hearing loss affects millions of people worldwide, leading to a significantly lowered quality of life and a large economic burden. While current cochlear implants are a very successful prosthetic for this population, it has limitations, and a fully internal cochlear implant (FICI) that provides the most natural aural cues and complete invisibility is an important option. In this work, we will develop a battery that meets the performance criteria, the footprint and the durability required for this implant, thus removing one of the most critical roadblocks in the path towards a FICI.

Project Terms:
Address; Adoption; Affect; Anatomy; Anodes; Auditory; base; Benchmarking; Biological Response Modifier Therapy; bone; Bypass; Cathodes; Charge; Child; Cochlear Implants; commercialization; cost; cranium; Cues; deep brain stimulator; design; Development; Devices; disability; Disease; Ear; Economic Burden; Electrodes; Electrolytes; Engineering; Epilepsy; Ethylene Oxide; experience; External auditory canal; external ear auricle; Eye; FDA approved; Hearing Aids; Hour; Implant; innovation; Institutes; Ions; Lead; Liquid substance; Lithium; Location; Massachusetts; Mastoid process; Medical; microphone; middle ear; migration; Nerve; novel; Operative Surgical Procedures; Output; Parkinson Disease; Patients; Performance; Phase; Polymers; Population; Power Sources; prevent; Prosthesis; prototype; Quality of life; Research; Resistance; Risk; Route; Safety; Sensorineural Hearing Loss; signal processing; Skin; Sleep; Small Business Innovation Research Grant; social stigma; Sodium Chloride; Solid; sound; Surgeon; Swimming; System; Technology; Temperature; Testing; Training; United States; voltage; Water; Work

Severe to profound sensorineural hearing loss (SNHL), caused by disease, aging, ototoxicity,head trauma and heredity, affects about 60 million worldwide, and is expected to reach around100 million by 2050. This disability leads to a significantly lowered quality of life and a largeeconomic burden, estimated to be around $750 billion worldwide, coming from health sectorcosts, educational support, and loss of workplace productivity. For this population, amplificationwith even the most sophisticated hearing aids is usually ineffective, and restorative biologicaltherapies are years away. A cochlear implant is currently the only available route for restoring"˜adequate' functionality. Only 600,000 implants have been done worldwide till 2019, and about50,000 devices are being sold annually. This large discrepancy between those that can benefitand those that actually get the implant is driven partly by their cost, availability and the lack oftrained surgeons and facilities. However, there are several limitations in the current devices thatcontribute to very low adoption: (a) The highly visible unit attached to the skull outside themastoid bone, connected by a cable to the sound processor and rechargeable battery placedbehind the ears, makes the disability very obvious, and creates an unacceptable social stigmafor many patients, causing them to refuse this option; (b) Sound filtering by the auricle andauditory canal is bypassed because of the external microphone, introducing unnatural cues; (c)The device typically must be taken off during showering or swimming (although a few water-resistant versions are now available), and during sleeping, increasing the likelihood of damage,misplacement, or the ability to hear in these situations; (d) Having an external magnet thatcouples and aligns the internal and external components can lead to skin breakdown andimplant extrusion; (e) The large footprint and placement leaves open the risk for devicemigration requiring revision surgery. A fully internal cochlear implant (FICI), that does not haveany behind the ear components, would address this large unmet medical need.There are no FICIs currently approved by the FDA. The lack of a self-contained power supply isa key roadblock preventing realization of all FICIs. Through innovations in circuit design andsignal processing, collaborating groups at Massachusetts Eye and Ear and MassachusettsInstitute of Technology have developed, tested and patented a low power (1 mW) system-on-a-chip (SoC) for a FICI, a critical advance. Current rechargeable batteries have organic liquidelectrolytes making them unsafe for this application. With SBIR Phase I funding, Audiance, Inc.has shown proof of concept of an all-solid single-stack cell that is the building block for a batterythat meets the electrochemical, safety and footprint requirements for a FICI. The focus of thisSBIR Phase II project is to build a multi-stack wirelessly rechargeable battery and integrate itwith a battery management system that senses the state of health of the battery and controlsthe charge profile to provide timely charging and maximum battery life. The all-solid LIB willremove a critical roadblock for the development of a FICI, and thus open up an opportunity tohelp millions of patients around the world with severe to profound SNHL. The learning from thedesign and fabrication of this battery will allow Audiance to customize batteries for a range ofother active implantable medical devices.

Public Health Relevance Statement:
PROJECT NARRATIVE Severe to profound sensorineural hearing loss affects millions of people worldwide, leading to a significantly lowered quality of life and a large economic burden. While current cochlear implants are a very successful prosthetic for this population, it has limitations, and a fully internal cochlear implant (FICI) that provides the most natural aural cues, complete invisibility and ability to hear at all times, is an important option. In this work, we will develop a battery that meets the performance criteria, the footprint and the durability required for this implant, and integrate it with a battery management system that surveys the state of health and wirelessly recharges the battery, removing one of the most critical roadblocks in the path towards a viable FICI.

Project Terms: