Charge Balancing Circuit for Functional Electrical Stimulation

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Solution Overview

Problem

Existing charge balancing systems for functional electrical stimulation of biological tissue face challenges with high power consumption, complexity, and response time, which can lead to tissue and electrode damage due to residual charge accumulation.

Innovation Solution

A charge balancing circuit with an amplifier and compensation stage, utilizing transistors to generate an output current that drives the electrode voltage within a safety range, reducing the need for external components and minimizing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing charge balancing systems are used, then charge accumulation is addressed, but power consumption increases and response time slows

Engineering Contradiction:

Improvecharge balancing effectivenessVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The charge balancing circuit uses the existing electrode voltage signal itself to control the compensation transistor, creating a self-regulating system that eliminates the need for external control circuits and reduces power consumption while maintaining effective charge balancing

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent extracts only the essential charge balancing function by using a simple transistor-based compensation circuit that selectively activates only when charge accumulation occurs, removing unnecessary circuitry that would increase power consumption in existing systems

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If existing charge balancing systems are used, then charge accumulation is addressed, but system complexity increases

Engineering Contradiction:

Improvecharge balancing effectivenessVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts only the essential charge balancing function by using a simple transistor-based compensation circuit, removing complex control logic, sensors, and external components that are present in existing systems while maintaining effective charge balancing

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The charge balancing circuit uses the existing electrode voltage signal itself to control the compensation transistor, creating a self-regulating system that eliminates the need for external control circuits, microcontrollers, or additional sensing elements, thereby significantly reducing system complexity

Inventive Principle:

Principle #25Self-service

3Reliability

If existing charge balancing systems are used, then charge accumulation is addressed, but response time increases

Engineering Contradiction:

Improvecharge balancing effectivenessVSAvoidresponse time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The compensation transistor operates in continuous real-time response to electrode voltage changes, providing uninterrupted charge balancing action that quickly counteracts charge accumulation without the delays inherent in sampled or periodically-controlled existing systems

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The charge balancing circuit uses the existing electrode voltage signal itself to immediately control the compensation transistor, creating a self-regulating system with minimal signal processing delay that achieves rapid response to charge accumulation events

Inventive Principle:

Principle #25Self-service

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 solution effectively reduces power consumption, complexity, and response time, ensuring the electrode voltage remains within a safe range, thereby preventing tissue and electrode damage.

Implementation Method 1

an amplifier coupled to the electrode terminal and adapted to amplify and invert the electrode voltage for generating an intermediate voltage

Methodology Applied

Scientific EffectVoltage amplification and inversion:

Implementation Method 2

The compensation stage is adapted to generate an output current if the electrode voltage lies outside a specified safety range and to generate the output current depending on the intermediate voltage

Methodology Applied

Scientific EffectVoltage-controlled current generation:

Data Source

PatentUS10166399B2Charge balancing circuit, stimulator circuit and method for charge balancing

Publication Date: 2019.01.01 ALBERT LUDWIGS UNIV FREIBURG

AI summary

A charge balancing circuit is adapted to be connected to an electrode and to a stimulation source. The charge balancing circuit has an electrode terminal for receiving an electrode voltage, an amplifier coupled to the electrode terminal and adapted to amplify and invert the electrode voltage for generating an intermediate voltage and a compensation stage. The compensation stage is adapted to generate an output current if the electrode voltage lies outside a specified safety range and to generate the output current depending on the intermediate voltage. The compensation stage is further adapted to supply the output current to the electrode terminal for driving the electrode voltage towards and/or into the safety range.