Decaying Current Pulse Control for Implantable Stimulation
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Solution Overview
Problem
Medical electrical stimulation devices face challenges in maintaining reliable current regulation during electrical stimulation therapy due to fluctuations in supply voltage and load capacitance, which can lead to loss of regulation and increased complexity in implantable medical devices.
Innovation Solution
A method and device for generating electrical stimulation pulses using a current regulator that controls the pulse current level to decrease during the pulse width, ensuring the sum of the pulse voltage level and headroom voltage does not exceed the supply voltage level, achieved through a capacitor module that selectively adjusts capacitance and a controller that manages the current level based on supply and load voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant current level is maintained during the pulse width, then therapeutic effectiveness is improved, but the sum of pulse voltage level and headroom voltage exceeds supply voltage level causing loss of regulation
Solution Approach 1:
The current regulator dynamically adjusts the pulse current level during the pulse width based on real-time supply voltage and load conditions. The controller continuously monitors the supply voltage level and modifies the current level to maintain reliable regulation throughout the pulse duration, transitioning from a static constant current approach to a dynamic adaptive current control system.
2Reliability
If higher average current is delivered to improve therapy effectiveness, then therapeutic effectiveness is improved, but device size and cost increase
Solution Approach 1:
The system employs periodic pulse delivery with variable current levels within each pulse cycle. By delivering higher current at the beginning of the pulse and reducing current toward the end, the system achieves higher average current delivery over time without requiring the continuous high current capability that would necessitate larger power supplies and capacitors.
3Reliability
If higher initial supply voltage is used to maintain regulation throughout pulse width, then current regulation reliability is improved, but battery life is reduced
Solution Approach 1:
The system changes the current level parameter dynamically during the pulse width based on the discharge characteristics of the supply capacitor. As the supply voltage naturally decreases during the pulse, the controller adjusts the current level to compensate, maintaining regulation without requiring an excessively high initial supply voltage that would deplete the battery faster.
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 allows for reliable current regulation, enabling higher average current delivery with reduced initial supply voltage requirements, potentially extending battery life and reducing device size and cost while maintaining therapeutic effectiveness.
Implementation Method 1
a capacitor module that selectively adjusts capacitance
Data Source
AI summary
This disclosure describes generation of electrical stimulation pulses for electrical stimulation therapy. The stimulation pulses have a pulse current level and pulse width, and may be generated by a current regulator. The pulse voltage level may be a voltage level delivered by the current regulator while maintaining regulation of the pulse current level. During delivery of a pulse, a supply voltage level may decrease due to discharging of a supply capacitance, and the pulse voltage level may increase due to charging of a load capacitance. The pulse current level may be controlled to decrease during the pulse width such that a sum of the pulse voltage level and a headroom voltage of the current regulator does not exceed the supply voltage level. In some examples, the pulse may include sub-pulses with different sub-pulse current levels, where an earlier sub-pulse has a higher pulse current level than a later sub-pulse.