Neurostimulator Current Steering via Shared Control Signals
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Solution Overview
Problem
Current neuromodulation systems face challenges in delivering precise electrical stimuli due to the large size and spacing of electrode arrays, which limits spatial control over neural tissue stimulation, and current steering approaches complicate clinical fitting and ongoing control by increasing the number of control parameters.
Innovation Solution
An implantable neurostimulator with a plurality of current sources, where each source is defined by a shared current control signal and a unique signal, allowing for effective current steering and precise control of stimulation intensity, with a shared signal used for adjustments during posture changes and unique signals providing fine spatial resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current steering is used to deliver stimuli to locations between physical electrodes, then spatial control precision is improved, but device complexity increases due to multiple duplications of current sources and control circuitry
Solution Approach 1:
The patent combines multiple current sources into a single shared current source that can simultaneously drive multiple electrodes through a current steering network. This merging approach allows virtual electrode formation between physical electrodes while avoiding the complexity of duplicating entire current source circuits for each electrode pair.
Solution Approach 2:
The patent introduces a current steering network as an intermediary component between the single current source and multiple electrodes. This network enables precise control of current distribution to create virtual stimulation locations without requiring separate current sources for each electrode, thus reducing overall device complexity while maintaining spatial precision.
2Measurement precision
If multiple duplications of current sources are used for current steering, then spatial control is improved, but ease of operation deteriorates due to significant increase in control parameters
Solution Approach 1:
By merging multiple current sources into one shared source with a current steering network, the patent reduces the number of independent control parameters from multiple separate current source amplitudes to a single current magnitude control, while spatial control is maintained through the steering network's switch configuration.
Solution Approach 2:
The patent employs dynamic switching through a current steering network that can reconfigure connections based on desired stimulation location. This dynamic reconfiguration allows the system to adapt to different spatial requirements without requiring separate control parameters for each electrode, simplifying operation while maintaining precision.
3Measurement precision
If current steering with multiple control parameters is implemented, then spatial resolution is improved, but ease of operation worsens due to complexity in clinical fitting and ongoing control
Solution Approach 1:
The current steering network serves as an intermediary that translates a single control parameter into multiple electrode activation patterns with different spatial resolutions. This intermediary layer enables high spatial resolution without requiring the clinician or patient to manage multiple independent control parameters, thereby maintaining ease of operation.
Solution Approach 2:
The patent segments the control function into two parts: a high-level single parameter control for overall stimulation intensity and a lower-level current steering network for spatial distribution. This segmentation allows complex spatial control to be achieved through a simple interface, maintaining ease of operation while providing fine spatial resolution.
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 solution enables precise control over stimulation intensity and location, simplifying clinical fitting and ongoing control, while maintaining a minimal feedback loop speed and supporting higher stimulation rates, by using a shared current control signal for net stimulation adjustments and unique signals for fine spatial resolution.
Implementation Method 1
An electrical pulse applied to the neural tissue by an electrode causes the depolarisation of neurons, which generates propagating action potentials
Data Source
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AI summary
An implantable neurostimulator has an implantable electrode array comprising a plurality of stimulus electrodes. Each stimulus electrode is configured to deliver electrical stimuli to neural tissue. An implantable control module is configured to produce the electrical stimuli delivered by the stimulus electrodes, and is configured to effect current steering. The control module has a plurality of related current sources, each current source configured to deliver a respective stimulus current which is defined in a first part by a shared current control signal which is shared by each of the related current sources, and which is defined in a second part by a respective unique current control signal which is not shared by all of the related current sources.