Selectable Magnetic Pulse Shaping for Low-Energy Nerve Stimulation

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Solution Overview

Problem

Current inductive magnetic stimulation devices face challenges with high energy consumption, rapid coil overheating, and inflexibility in adapting pulse time profiles to different nerve cell types, leading to inefficient stimulation and limited application areas.

Innovation Solution

A device that generates freely selectable magnetic pulses using a modular multilevel converter to optimize the time course of current pulses, reducing energy requirements and enabling adaptable pulse shapes tailored to specific nerve or muscle cells, with power electronics capable of controlling coil current and voltage for efficient stimulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional inductive magnetic stimulation devices use short, strong current pulses to generate magnetic fields for nerve stimulation, then stimulation effect is achieved, but field energy consumption and coil current are excessively high

Engineering Contradiction:
Improvestimulation effectVSAvoidfield energy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by making the pulse shape adaptive rather than fixed. The control unit dynamically adjusts the time profile of current pulses based on stored pulse shapes, allowing optimization of energy efficiency while maintaining stimulation effectiveness. This resolves the contradiction by enabling the system to adapt pulse characteristics to minimize energy consumption while achieving reliable nerve stimulation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes physical parameters by storing multiple pulse shapes with different time profiles and selecting optimal ones for specific nerve cell types. By varying the temporal characteristics of current pulses (parameter changes), the system achieves effective stimulation with reduced field energy consumption, resolving the contradiction between stimulation reliability and energy efficiency.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If conventional devices use fixed pulse shapes generated by resonant oscillating circuits, then device complexity is reduced, but adaptability to different nerve cell types is limited

Engineering Contradiction:
Improvecircuit structureVSAvoidpulse shape adaptability
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent segments the pulse generation function by storing multiple pre-defined pulse shapes in memory, each optimized for different nerve cell types. Instead of using a single resonant circuit configuration, the system divides the solution into discrete, selectable pulse profiles. This segmentation allows adaptability to different cell types while keeping the hardware architecture relatively simple.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses copying by storing digital representations (copies) of optimal pulse shapes in memory. Rather than implementing complex hardware circuits for each pulse type, the system creates and stores copies of optimized waveforms, then retrieves and applies the appropriate copy based on the target nerve cell type. This approach achieves high adaptability with minimal additional hardware complexity.

Inventive Principle:
Principle #26Copying

3Temperature

If high current pulses are used for magnetic stimulation, then sufficient field strength is generated, but coil overheating occurs rapidly

Engineering Contradiction:
Improvecoil temperatureVSAvoidcurrent pulse strength
Core Design Contradiction:
TemperatureVSPower

Solution Approach 1:

The patent applies preliminary action by pre-calculating and storing optimized pulse shapes that minimize energy loss and heat generation. Before actual stimulation, the control unit selects the appropriate pre-optimized pulse profile from memory, ensuring that the current pulses are shaped to achieve necessary field strength with minimal power consumption and heat generation, preventing coil overheating.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent converts the harmful effect of energy loss into benefit by optimizing pulse shapes to minimize resistive heating in the coil. The stored pulse profiles are designed to deliver necessary stimulation power while reducing the portion of energy that would be wasted as heat. This transforms the energy efficiency problem into an opportunity to reduce coil temperature and enable safer, more sustainable operation.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

4Ease of manufacture

If simple monophasic square-wave pulses with DC component are used, then electrical stimulation is simple, but inductive magnetic stimulation is inefficient

Engineering Contradiction:
Improvepulse generation simplicityVSAvoidinduction efficiency
Core Design Contradiction:
Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent applies dynamics by transitioning from static, simple square-wave pulses to dynamic, optimized pulse shapes. The control unit dynamically selects and generates pulse profiles from stored patterns that are specifically optimized for inductive magnetic stimulation efficiency. This dynamic approach improves induction efficiency while maintaining ease of implementation through digital control and pre-stored waveforms.

Inventive Principle:
Principle #15Dynamics

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 reduces the field energy and coil current needed for stimulation, allowing for repetitive use at higher rates, minimizing heat losses, and enabling flexible pulse shaping for optimal nerve or muscle cell stimulation with reduced noise and acoustic artifacts, making the device more suitable for various applications, including repetitive and mobile use.

Implementation Method 1

A time-varying magnetic field generates an induced electric field. The time-varying magnetic field can be generated by a coil through which a time-varying current flows.

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The time-dependent magnetic fields are generated via short current pulses with a duration of typically 50 - 400 microseconds.

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2523726B1Magnetic stimulation having a freely selectable pulse shape
Publication Date: 2022.02.16 TECHNISCHE UNIVERSITAT MUNCHEN
  • EP2523726B1 patent drawingFigure 1~2
  • EP2523726B1 patent drawingFigure 3~4
  • EP2523726B1 patent drawingFigure 5~6

AI summary

The invention relates to a device and method for generating brief, strong current pulses in a coil, for generating magnetic field pulses, which in accordance with the electromagnetic induction principle cause stimulation currents in the body tissue that trigger an action potential of the nerve and/or muscle cells, wherein the coil can be positioned close to the body tissue to be stimulated, so that the magnetic field thereof permeates the body tissue, and wherein the device comprises a current generating unit, which can generate a freely selectable temporal course of the current through the coil during the current pulse. The invention further relates to a method for determining an optimized temporal course of a brief, strong current pulse through the coil, wherein the temporal course of the current pulse is calculated using a method that numerically simulates the electrical behavior of the nerve and/or muscle cells and of the coil and optimizes the course of the current pulse with respect to at least one parameter, or which optimizes the temporal course of the current pulse with respect to at least one parameter and, based thereon, determines essential characteristic variables of the nerve and/or muscle cells by stimulating the nerve and/or muscle cells with predefined current pulses.