Stimulation Delivery Circuit Impedance Model
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Solution Overview
Problem
Biphasic current stimulation devices face challenges in delivering sufficient charge to excitable tissue due to varying electrode impedance, leading to high power consumption and reduced battery life, as they often require higher voltages to cater for occasional high impedance situations, resulting in inefficient energy use.
Innovation Solution
A device with a stimulation delivery circuit that monitors voltage or current and generates an impedance model to adjust pulse width or charge quantum, allowing for voltage-controlled stimulation based on measured impedance, thereby optimizing charge delivery and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If higher voltage is provided to cater for high impedance situations, then sufficient charge delivery is ensured, but power consumption increases significantly
Solution Approach 1:
The patent implements dynamic voltage adjustment by switching from constant voltage mode to constant current mode based on real-time impedance detection. The system continuously monitors the voltage required to deliver the programmed current and dynamically changes operating modes to optimize power consumption while ensuring charge delivery compliance.
Solution Approach 2:
The system employs feedback mechanisms by monitoring the actual voltage required to deliver the programmed stimulation current. This feedback information is used to determine whether to operate in constant voltage or constant current mode, creating a closed-loop control system that adapts to changing electrode-tissue interface conditions.
2Reliability
If constant current stimulation is used, then charge delivery is unaffected by impedance changes, but voltage requirements become excessively high
Solution Approach 1:
The system dynamically switches between constant voltage and constant current stimulation modes based on real-time impedance measurements. When impedance is within acceptable ranges, constant voltage mode is used to reduce power consumption. When impedance increases, the system transitions to constant current mode to ensure charge delivery consistency, thus adapting to changing conditions optimally.
Solution Approach 2:
The patent changes the control parameter from fixed constant current to variable current under constant voltage, based on impedance conditions. By modifying the stimulation parameter (current vs. voltage control) according to the electrode-tissue interface state, the system achieves both energy efficiency and reliable charge delivery.
3Reliability
If maximum voltage level is always provided, then charge delivery compliance is maintained, but battery life is reduced due to unnecessary power consumption
Solution Approach 1:
The system applies partial action by delivering only the voltage necessary to achieve charge delivery compliance rather than always using maximum voltage. By detecting when lower voltage levels are sufficient for adequate stimulation, the system reduces power consumption and extends battery life while maintaining therapeutic effectiveness.
Solution Approach 2:
The patent implements dynamic voltage level adjustment based on real-time impedance monitoring. The system transitions from static maximum voltage provision to dynamic voltage adjustment, switching between constant voltage and constant current modes as needed, thereby optimizing the balance between charge delivery compliance and battery life.
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 ensures consistent stimulation outcomes while reducing power consumption and extending battery life by adapting to varying electrode impedance, achieving efficient charge delivery with lower average supply voltage.
Implementation Method 1
Biphasic current stimulation is widely used in electrical stimulation of neurons and other electrically excitable tissue
Implementation Method 2
a monitoring component to monitor voltage supplied in at least one current-driven charge pulse via the stimulation delivery circuit
Data Source
AI summary
Embodiments relate to a device for controlling delivery of stimulation signals, comprising: a stimulation delivery circuit; a monitoring component to monitor voltage supplied in at least one current-driven charge pulse via the stimulation delivery circuit; and a stimulation control component to control voltage supplied in at least one subsequent charge pulse based on the charge of the at least one charge pulse delivered by the stimulation delivery circuit. The device may further comprise a model generation component to generate an impedance model of stimulation electrodes in the stimulation delivery circuit, wherein the stimulation control component is configured to control the stimulation delivery circuit to deliver charge according to the impedance model.