Adjustable Compliance Voltage Source for Implantable Neural Stimulation
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Solution Overview
Problem
Current implantable medical devices using current output for neural stimulation face challenges in battery longevity due to varying tissue/electrode interface impedance, which requires a compliance voltage that can impact device performance.
Innovation Solution
A system with a power supply and circuitry to detect tissue/electrode impedance, featuring a current output pulse generator with an adjustable compliance voltage source that can adjust its amplitude based on detected impedance, ensuring optimal voltage delivery for neural stimulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current output device is used to provide superior neural recruitment characteristics, then neural stimulation performance is improved, but battery longevity deteriorates due to varying compliance voltage requirements caused by tissue/electrode interface impedance variation
Solution Approach 1:
The patent implements a dynamic compliance voltage adjustment mechanism where the compliance voltage is no longer fixed but varies based on real-time tissue/electrode interface impedance measurements. The system continuously monitors impedance and adjusts the compliance voltage level accordingly, allowing the current output device to maintain optimal neural recruitment characteristics while adapting to changing tissue conditions, thereby reducing unnecessary power consumption and extending battery longevity
Solution Approach 2:
The system changes the operational parameters of the compliance voltage source by adjusting its output voltage level based on detected impedance values. When impedance is low, the compliance voltage is reduced; when impedance is high, the compliance voltage is increased only to the extent necessary. This parameter adaptation allows the device to maintain effective current delivery for neural stimulation while minimizing energy consumption across varying tissue conditions
2Power
If compliance voltage is increased to accommodate high tissue/electrode interface impedance, then current delivery capability is maintained, but energy consumption increases reducing battery longevity
Solution Approach 1:
The compliance voltage source dynamically adjusts its output parameter (voltage level) based on the detected tissue/electrode interface impedance. Instead of maintaining a high fixed compliance voltage that would ensure current delivery in all conditions but consume excessive energy, the system adjusts the voltage parameter to match the actual impedance requirements, thereby maintaining current delivery capability only when necessary and reducing energy consumption during normal operation
Solution Approach 2:
The system transitions from a static compliance voltage configuration to a dynamic one where the voltage level is continuously adjusted in response to impedance changes. This dynamic adaptation ensures that the compliance voltage is elevated above the minimum required level only transiently when impedance spikes occur, rather than maintaining an unnecessarily high voltage level continuously, thus preserving both current delivery capability and energy efficiency
Data Source
AI summary
A system for providing stimulation current in implantable medical devices is provided. One aspect of this disclosure relates to an apparatus including a power supply terminal adapted to be connected to a power supply. The apparatus embodiment also includes circuitry connected to the power supply terminal and adapted to detect a parameter dependent on tissue/electrode impedance. The apparatus embodiment further includes a current output pulse generator adapted to deliver electrical therapy. The current generator includes an adjustable compliance voltage source connected to the power supply terminal. The compliance voltage source has a programmable amplitude and is adapted to provide different potentials for different tissue/electrode interface impedances. According to various embodiments, the apparatus embodiment also includes at least one stimulating electrode, and the current generator is adapted to deliver electrical therapy using the electrode. Other aspects and embodiments are provided herein.