Implantable Stimulator Level-Dependent Excitation Field Control
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Solution Overview
Problem
Existing implantable stimulators, such as cochlear implants, face performance deterioration due to broad excitation fields generated by monopolar stimulation, which is not optimally focused across different stimulation levels, leading to suboptimal hearing restoration in sensorineural hearing loss cases.
Innovation Solution
The implementation of a system with at least one stimulating electrode and additional compensating electrodes that dynamically adjust the compensating current as a function of the stimulation current amplitude, allowing for level-dependent focusing or broadening of excitation fields to improve performance and minimize side lobes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If monopolar stimulation is used to deliver current to the stimulation site, then the stimulation can be applied with a simple electrode configuration, but the excitation fields become broad which deteriorates stimulator performance
Solution Approach 1:
The patent divides the single monopolar electrode configuration into multiple segmented electrodes (first stimulating electrode, second stimulating electrode, and return electrode). This segmentation allows independent control of current delivery to different regions, enabling focused stimulation patterns that improve spatial selectivity and stimulator performance while maintaining reasonable system complexity.
Solution Approach 2:
The patent implements local quality by applying different stimulation parameters (current amplitude, pulse width, frequency) to different electrode segments based on local requirements. The controller adjusts stimulation characteristics for each electrode pair independently, creating localized excitation fields that target specific neural populations without affecting adjacent regions, thereby improving performance reliability.
2Manufacturing precision
If fixed compensating current is applied to narrow excitation fields, then spatial focus can be improved, but the solution is not optimal across all stimulation levels
Solution Approach 1:
The patent implements dynamics by making the compensating current adaptive rather than fixed. The controller dynamically adjusts the amplitude and timing of compensating current delivered through the return electrode based on real-time feedback from the stimulation site and the current stimulation level. This dynamic adjustment optimizes spatial focus precision across the full range of stimulation intensities, from threshold to maximum levels.
Solution Approach 2:
The patent incorporates feedback mechanisms where the controller monitors stimulation parameters and tissue response, then adjusts compensating current accordingly. This feedback loop enables the system to maintain optimal excitation field narrowing across varying stimulation levels, adapting to changes in tissue impedance, neural excitability, and stimulation requirements.
3Measurement precision
If excitation fields are narrowed at all stimulation levels, then spatial precision is improved, but side lobe effects increase at higher stimulation levels
Solution Approach 1:
The patent applies parameter changes by dynamically modifying stimulation parameters (current amplitude, pulse duration, electrode selection) based on the stimulation level. At lower stimulation levels, the system uses focused electrode configurations with higher current density to achieve spatial precision. At higher stimulation levels, the system adjusts parameters to broaden the effective stimulation field slightly, reducing side lobe effects while maintaining adequate spatial precision through coordinated multi-electrode activation.
Data Source
AI summary
An exemplary method includes an implantable stimulator simultaneously applying stimulation current to a stimulation site within a patient via at least one stimulating electrode and compensating current via one or more additional electrodes of opposite polarity as the at least one stimulating electrode and dynamically adjusting the simultaneously applied compensating current as a function of a stimulation level of the stimulation current by increasing a stimulation level of the compensating current if the stimulation level of the stimulation current decreases and decreasing the stimulation level of the compensating current if the stimulation level of the stimulation current increases. Corresponding methods and systems are also disclosed.