Medical Device Contact Force Sensing Tip Using Electromagnetic Induction

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Solution Overview

Problem

Conventional medical devices face challenges in accurately measuring contact force between the device and tissue, which is crucial for effective diagnosis and treatment, particularly in procedures like electrophysiological mapping and ablation, due to complexity and high costs associated with multiple conductors and intricate force sensing mechanisms.

Innovation Solution

A medical device with an elongate tubular shaft featuring a flexible member and an electromagnetic coil system, where an electrically passive element, such as ferrite or unpoled magnetic material, is used to induce changes in the coil's electrical characteristics upon contact with tissue, allowing for contact force measurement without the need for multiple conductors, thus reducing complexity and cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional force sensing mechanisms with multiple conductors are used, then contact force measurement capability is achieved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improvecontact force measurement capabilityVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces conventional mechanical force sensing mechanisms with electromagnetic sensing. An electromagnetic coil and magnet assembly detects contact force through changes in electrical characteristics (inductance, resonant frequency) caused by mechanical deformation of the shaft, eliminating the need for multiple conductors and complex mechanical force sensors.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an electromagnetic field as an intermediary between the mechanical contact force and the measurement system. The electromagnetic coil and magnet convert mechanical deformation into electrical signal changes, serving as a mediator that simplifies the measurement mechanism while maintaining measurement capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If conventional force sensing mechanisms with multiple conductors are used, then contact force measurement capability is achieved, but manufacturing cost increases

Engineering Contradiction:

Improvecontact force measurement capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive mechanical force sensing mechanisms with a simpler electromagnetic sensing system. The electromagnetic coil and magnet assembly requires fewer components and conductors, reducing manufacturing complexity and cost while maintaining contact force measurement capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If multiple conductors are used for force sensing, then contact force measurement is enabled, but valuable space within the device is consumed

Engineering Contradiction:

Improvecontact force measurementVSAvoidspace within device

Core Design Contradiction:

Measurement precisionVSVolume of moving object

Solution Approach 1:

The patent substitutes electromagnetic sensing for mechanical sensing with multiple conductors. The electromagnetic coil and magnet assembly occupies less space within the catheter shaft while providing equivalent or superior measurement capability, freeing up valuable space for other catheter components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution enables accurate measurement of contact force magnitude and orientation in three-dimensional space, enhancing diagnostic and treatment precision while reducing device complexity and manufacturing costs by eliminating unnecessary conductors and preserving valuable space within the device.

Implementation Method 1

an electromagnetic coil disposed within the shaft and an electrically passive element disposed within the shaft. The electrically passive element comprises a material effecting an electrical characteristic of the electromagnetic coil

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The electrically passive element comprises a material effecting an electrical characteristic of the electromagnetic coil and may comprise a ferrite or unpoled magnetic material

Methodology Applied

Scientific EffectMagnetic permeability: Ferromagnetism

Data Source

PatentUS11051877B2Medical device with contact force sensing tip

Publication Date: 2021.07.06 ST JUDE MEDICAL CARDILOGY DIV INC

AI summary

Medical devices for diagnosis or treatment of tissue in a body. Representative devices include an elongate shaft having a proximal portion and a distal portion configured for movement relative to the proximal portion. A flexible member having a predetermined stiffness is disposed between the proximal and distal portions. One or more coils and an electrically passive element are disposed within the shaft with either the coils or element configured for movement with the distal portion. The element comprises a material effecting an electrical characteristic of the coils. Movement of the distal portion in response to its contact with the tissue and relative movement of the coils and element causes a change in the electrical characteristic in at least one of the coils indicative of at least a contact force magnitude between the distal portion and the tissue. Several embodiments allow determination of both force magnitude and force vector direction.