Authors:

Pratyush Shahir

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About Paper:

Global hearing loss impacts roughly 1.5 billion individuals today, and estimates suggest this figure could reach 2.5 billion within the next few decades [1]. Standard cochlear implants (Cls) use electrical currents that diffuse broadly across tissue, limiting the exactness of sound perception. While using light to stimulate nerves allows for far greater targeting accuracy, it requires a substantial power draw. We propose a solution that maximizes both battery life and focal accuracy: a hybrid opto-electrical cochlear implant (oeCl). This system leverages weak electrical currents to pre-condition the auditory nerves, fundamentally decreasing the light intensity needed to trigger a neural response. To investigate this concept, we engineered an implantable 42-channel device that combines electrical drivers with infrared neural stimulation (INS). We concurrently built a unique software algorithm, the opto-electrical frequency-modulated phase coding (oeFMPC) strategy. Unlike standard Cl programming, our method keeps pulse strengths strictly constant to prevent dangerous heat accumulation in tissue. Loudness is instead communicated through variations in the average speed of randomized, Poisson-like pulse sequences. Wide acoustic frequencies are routed to power-saving electrical nodes, whereas tight frequency ranges activate the highly accurate optical nodes. Initial animal testing confirmed the hardware's functionality, successfully producing compound action potentials in mice and guinea pigs via both stimulation methods. We also conducted human trials on 17 Cl recipients to test the algorithm's electrical mapping using HINT exams. Even with under an hour of exposure to our custom software, test subjects demonstrated rapid comprehension, with select individuals scoring above 80% and one achieving a perfect score of 100%. Average word recognition remained below their everyday, long-term Cl configurations, yet the immediate results strongly support the viability of this energy-conscious, high-fidelity neural prosthetic. Future clinical trials will evaluate the complete hybrid system to assess long-term user adaptation and overall improvements in spatial resolution.

Source:

Northwestern University

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Co-authors:

Pratyush Shahir