Neural Stimulation Electrode Array Current Density Control
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Solution Overview
Problem
Existing methods for determining neural stimulation thresholds and applying electrical stimulation to the brain face challenges due to limited output capacity of implantable pulse generators, making it difficult to achieve desired subthreshold stimulation levels, especially when stimulating large areas or deep within the cortex.
Innovation Solution
The method involves determining and adjusting current density by selectively activating subsets of electrodes within an electrode array, allowing for higher current density in specific areas without exceeding the maximum output of the pulse generator, and using multiplexing techniques to distribute the signal effectively across the cortex.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If electrical current is applied to a large area of the cortex using multiple electrodes simultaneously, then the intended therapeutic effect is improved, but the current level required exceeds the maximum output of the implantable pulse generator
Solution Approach 1:
The electrode array is divided into multiple independently controllable electrode groups or contacts. Instead of activating all electrodes simultaneously with high current, the system selectively activates subsets of electrodes in different time periods, allowing each electrode to receive higher current density while maintaining overall coverage of the target cortical area.
Solution Approach 2:
The pulse generator applies electrical current to different electrode subsets in a periodic or sequential manner across different time periods. This time-multiplexed approach allows the same physical infrastructure to deliver higher peak currents to individual electrodes while averaging to a manageable total power output from the pulse generator.
2Reliability
If the output capacity of the implantable pulse generator is increased to achieve desired subthreshold stimulation levels, then the stimulation effectiveness is improved, but the device complexity and power consumption increase
Solution Approach 1:
Instead of requiring the pulse generator to output high current to all electrodes simultaneously, the system concentrates current locally at selected electrodes during specific time periods. This allows subthreshold stimulation to be achieved at target locations with moderate overall power output, avoiding the need for a high-capacity (and thus more complex and power-consuming) pulse generator.
Solution Approach 2:
The system dynamically adjusts which electrodes are active and at what current levels during different time periods. This dynamic control allows the same pulse generator with fixed moderate output capacity to achieve variable stimulation patterns that would otherwise require a more powerful device, thereby maintaining stimulation effectiveness without increasing device complexity.
3Volume of stationary object
If electrical current is applied to stimulate deep cortical regions, then the therapeutic coverage is improved, but the current density required exceeds the output limitation of the pulse generator
Solution Approach 1:
The electrode array is configured with multiple contacts at different positions and depths. By selectively activating specific electrode contacts that are positioned to target deep cortical regions, the system can achieve deep stimulation coverage without requiring excessive current density from the pulse generator, as the current is concentrated at strategically positioned electrodes rather than distributed across all electrodes.
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 precise determination of neural stimulation thresholds and effective delivery of subthreshold or suprathreshold stimulation, overcoming the limitations of implantable pulse generators and enhancing therapeutic efficacy by increasing current density in targeted areas.
Implementation Method 1
applying a first electrical current to the cortex via the first electrode(s)... applying a second electrical current to the cortex via the second electrode(s)
Data Source
AI summary
Methods for providing electrical stimulation therapy to a cortex of a patient via a plurality of electrodes proximate to the cortex and a pulse generator implanted in the patient. One embodiment of a method in accordance with the invention comprises determining whether the current applied via the plurality of electrodes results in a sufficient current density in the cortex. The current density, for example, may need to be high enough to induce a response in the patient for determining the activation threshold of the specific stimulation site, or the current density may need to be high enough to perform a specific therapy. If the current density is not sufficient, the method continues by selecting a subset of the plurality of electrodes, and applying electrical current to the cortex via the subset of the electrodes. For example, if the current density is not sufficient when the current is applied to the full plurality of electrodes at approximately the maximum output of the pulse generator, then the current level from the pulse generator can be applied to only a subset of the electrodes to effectively increase the current density in the cortex at the active electrodes.