Adjustable Capacitive Voltage Multiplier for Stable Stimulation Pulses
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Solution Overview
Problem
Existing implantable pulse generators (IPGs) for neurostimulation systems lack efficient mechanisms for real-time adjustment of capacitive voltage multipliers to optimize stimulation current pulses, leading to potential malfunctions due to varying battery voltages and tissue impedance.
Innovation Solution
An adjustable capacitive voltage multiplier (CVM) system with diagnostic circuitry and a control counter is integrated into the IPG, allowing for real-time adjustment of voltage output by disconnecting and reconnecting the CVM output node, maintaining an auxiliary voltage source, and reconfiguring the charge pump arrangement based on control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed capacitive voltage multiplier is used in the IPG, then the circuit design is simple, but the voltage output cannot be adjusted in real-time to compensate for battery voltage variations and tissue impedance changes
Solution Approach 1:
The patent implements a dynamic capacitive voltage multiplier that can adjust its output voltage in real-time during stimulation pulse delivery. The circuit transitions from a fixed configuration to a dynamically reconfigurable one, allowing the voltage multiplier to adapt to changing battery voltage and tissue impedance conditions while maintaining stable stimulation output.
Solution Approach 2:
The voltage multiplier circuit is divided into multiple selectable configurations or stages. By segmenting the capacitive multiplication process into discrete adjustable levels, the system can switch between different voltage output levels based on real-time conditions, providing adaptability without requiring a complete redesign of the entire circuit.
2Reliability
If the CVM voltage is adjusted in real-time during a stimulation pulse, then the voltage output stability is improved, but the control mechanism becomes more complex
Solution Approach 1:
The patent incorporates feedback mechanisms that monitor battery voltage and tissue impedance conditions during stimulation pulse delivery. This feedback information is used to automatically adjust the capacitive voltage multiplier output, ensuring stable voltage delivery without requiring complex manual control circuits. The system self-regulates based on real-time measurements.
Solution Approach 2:
The control circuit is designed to automatically manage the voltage adjustment process without external intervention. The system monitors its own operating conditions and self-adjusts the CVM output accordingly, reducing the burden on external control mechanisms and simplifying the overall control architecture while maintaining reliable voltage delivery.
3Adaptability or versatility
If an adjustable charge pump arrangement is implemented, then the voltage output can be optimized for different conditions, but the manufacturing complexity increases
Solution Approach 1:
The patent designs a universal charge pump arrangement that can serve multiple functions: it provides voltage multiplication, enables real-time adjustment, and adapts to different battery voltages and tissue impedance conditions. By creating a multi-functional circuit core, the system achieves voltage optimization capability without proportionally increasing manufacturing complexity, as the same basic circuit structure performs multiple roles.
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
The system ensures stable voltage delivery during stimulation, maintaining optimal electric field characteristics despite variations in battery voltage and tissue impedance, enhancing the effectiveness and reliability of neurostimulation therapy.
Implementation Method 1
a capacitive voltage multiplier (CVM) circuit having a charge pump arrangement configured to generate an adjustable target voltage at a CVM output node
Implementation Method 2
an electrochemical cell configured to provide a source of electrical energy
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
An implantable medical device (IMD) (102, 150) includes an adjustable capacitive voltage multiplier (CVM) (502) that is responsive to diagnostic circuitry (556, 554) configured to provide control signals within a single stimulation current pulse for adjusting the voltage output applied to an electrode of the IMD's lead system (508, 615). A control counter (504) is coupled to the diagnostic circuitry (556, 554) for incrementing or decrementing an N-bit counter output signal (503) operative to reconfigure a charge pump arrangement (714-1 to 714-3) of the CVM (502) so as to facilitate an adjusted voltage output.