# Development of a Micro-coil Based Cochlear Implant

> **NIH NIH R01** · MASSACHUSETTS GENERAL HOSPITAL · 2024 · $522,057

## Abstract

We have been evaluating magnetic stimulation from tiny, implantable coils (referred to as microcoils) for use in
a next-generation cochlear implant (CI). Existing CIs enable speech discrimination, but their effectiveness
decreases when background noise levels are high, and most users cannot appreciate music. While a number
of factors are thought to contribute to these limitations, it is generally agreed that complex auditory signals,
such as those arising from speech in the presence of background noise, or music, require more independent
spectral channels than are created by existing, electrode-based CIs. Increasing the number of channels has
proven challenging however, as the highly conductive solution surrounding implants (perilymph) expands the
spread of activation from each electrode so that fields from neighboring electrodes overlap and channels are
no longer independent. The spread of fields is worsened because the targets of stimulation (spiral ganglion
neurons) are within one of the bony cavities of the cochlea and thus higher stimulus levels are required for
activation which lead to increased current spread. Microcoils may be an attractive alternative to electrodes
because the physics governing the spread of induced fields (Maxwell’s equations) suggests narrower
confinement of activation. Further, the high permeability of biological tissues to magnetic fields allows
stimulation to pass readily through the bony wall, without the need for increased stimulation levels (and the
resulting spread of activation). Consistent with this, stimulation from micro-coils implanted in the cochleae of
both mice (Lee et al., 2022) and guinea pig (present proposal) results in narrow channels of activation in the
inferior colliculus, i.e., better approximating the normal physiological signal, and smaller than those from
electrodes. The ability to create narrow spectral channels suggests a larger number of independent channels
are possible with microcoils and thus the potential exists for improved rehabilitation of hearing. Our goal here is
to further evaluate the potential of microcoils for use in CIs. The Aims focus on (1) electrophysiological
evaluation of implanted microcoils, (2) evaluation of the interactions between neighboring channels on the
multi-coil array, (3) chronic testing of coil-based implants, and (4) development of a computer model to help
understand the mechanism(s) of activation. All physiological testing will take place in guinea pigs, a well-
established animal model for evaluation of CI performance; our team has previous experience with this animal
and new preliminary results validate the overall viability of our device and the approach. Our multi-disciplinary
team has strong expertise in microcoil design and development, magnetic stimulation, computer modeling,
cochlear implants and auditory physiology. Almost all of the team is located at Mass. General Hospital or next
door at Mass. Eye and Ear; the results presented here are the re...

## Key facts

- **NIH application ID:** 10828411
- **Project number:** 5R01DC019916-02
- **Recipient organization:** MASSACHUSETTS GENERAL HOSPITAL
- **Principal Investigator:** JULIE G Arenberg
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $522,057
- **Award type:** 5
- **Project period:** 2023-04-15 → 2028-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10828411

## Citation

> US National Institutes of Health, RePORTER application 10828411, Development of a Micro-coil Based Cochlear Implant (5R01DC019916-02). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10828411. Licensed CC0.

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