Cochlear Implant Optical Pulse Encoding for Spatially Selective Stimulation
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Solution Overview
Problem
Current cochlear implant systems face limitations in spatial selectivity due to stimulation current dispersion in tissues, and optical stimulation offers potential better selectivity but faces challenges in power requirements and safety for chronic use.
Innovation Solution
The system generates optical stimulation signals by transforming input sound signals into band pass signals, half-wave rectifying signal components, determining positive signal slopes, and producing constant-rate optical stimulation pulses amplitude modulated based on envelope components for delivery to optical stimulation contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrical stimulation is used in cochlear implants, then auditory nerve tissue can be stimulated, but spatial selectivity is limited due to stimulation current dispersion in tissues
Solution Approach 1:
The patent replaces electrical stimulation with optical stimulation using laser light to mechanically displace cochlear tissue (basilar membrane or organ of Corti). This substitution eliminates current dispersion issues inherent in electrical stimulation while achieving the desired mechanical effect on auditory neural tissue through localized optical energy delivery
2Measurement precision
If optical stimulation is used to improve spatial selectivity, then better selectivity is achieved, but power requirements and safety concerns increase for chronic use
Solution Approach 1:
The patent employs periodic pulsed laser stimulation rather than continuous optical energy delivery. By delivering brief, periodic pulses synchronized with the mechanical resonance frequency of the cochlear structures, the system achieves effective stimulation with reduced average power consumption, making chronic use more feasible
Solution Approach 2:
The patent utilizes the photoacoustic effect where optical energy is absorbed and converted to mechanical vibration through thermal expansion and phase change in the cochlear fluid or tissue. This phase transition mechanism enables efficient energy transfer from optical to mechanical domain with minimal power requirements
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables efficient optical stimulation of auditory neural tissue with improved spatial selectivity and potentially reduced power consumption, while ensuring safety through controlled pulse duration and amplitude modulation.
Implementation Method 1
system for multichannel opto-mechanical stimulation
Data Source
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AI summary
A signal processing arrangement generates optical stimulation signals to optical stimulation contacts in an implanted cochlear implant array. An input sound signal is transformed into band pass signals that each represent an associated band of audio frequencies, with each band pass signal includes an envelope component characterizing loudness of the band pass signal, and a fine structure component characterizing temporal details of the band pass signal. One or more of the signal components of each band pass signal is half wave rectified to remove negative phase signals. Signal slope is determined that corresponds to rate of change of the rectified one or more signal components. Then constant-rate optical stimulation pulses are generated for one or more given band signals only when the rectified one or more signal components has a positive signal slope.