Wireless Force Sensor for Cardiac Catheter Tip Contact

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Solution Overview

Problem

Existing catheter systems for treating cardiac arrhythmias face challenges in precisely controlling the contact force between the ablation catheter tip and myocardial tissue, leading to either excessive ablation or reduced efficacy due to the complexity and cost of deformable body designs and electrical connection issues in force measurement systems.

Innovation Solution

A wireless force sensor system integrated into the catheter shaft, utilizing direct-write electronic printing to create strain-sensitive elements that deform in response to force, transmitting force data wirelessly to a communication subsystem for real-time feedback and control of ablation therapy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If deformable body designs with sensors are used to measure force, then force measurement capability is achieved, but device complexity and cost increase

Engineering Contradiction:
Improveforce measurement capabilityVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical deformable body designs with magnetic field-based sensing. Magnets embedded in the catheter tip interact with a sensor array on the shaft, using magnetic field detection instead of mechanical deformation to measure contact force. This substitution of mechanical systems with electromagnetic fields reduces device complexity while maintaining measurement capability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces magnetic fields as an intermediary between the catheter tip and the sensing system. Rather than directly measuring mechanical deformation, the system uses magnets to create a magnetic field that serves as a mediator, allowing force measurement through field interaction without direct mechanical coupling. This intermediary approach simplifies the overall system architecture.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If deformable body designs with sensors are used to measure force, then force measurement capability is achieved, but cost increases

Engineering Contradiction:
Improveforce measurement capabilityVSAvoidcost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive mechanical deformable body designs with a magnetic field-based sensing system. By using magnets and magnetic sensors instead of complex mechanical structures, the manufacturing cost is reduced while maintaining force measurement capability. The magnetic field approach uses simpler, more cost-effective components.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The magnetic field sensing system serves multiple functions: it measures contact force, provides spatial positioning information, and enables wireless communication capabilities. This multi-functionality reduces the need for separate systems, thereby lowering overall manufacturing cost while maintaining measurement precision.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Loss of information

If electrical connections are used to transmit sensor signals, then signal transmission is achieved, but signal noise increases

Engineering Contradiction:
Improvesignal transmissionVSAvoidsignal noise
Core Design Contradiction:
Loss of informationVSObject-affected harmful factors

Solution Approach 1:

The patent replaces electrical wire-based signal transmission with wireless electromagnetic communication. The magnetic sensor array wirelessly transmits force measurement data and spatial information to external systems, eliminating the need for electrical connections along the catheter shaft. This substitution removes the source of electrical noise and interference that plagues wired systems.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses electromagnetic fields as an intermediary for signal transmission instead of electrical wires. The magnetic field serves as a clean mediator that can carry information without the electrical noise, ground loops, and interference issues inherent in wired electrical connections. This field-based communication approach significantly reduces signal noise.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 wireless force sensor system enhances the precision and consistency of ablation therapies by providing real-time force feedback, reducing the risk of excessive ablation and improving the conformity of lesion lines, while simplifying the catheter assembly and reducing signal noise.

Implementation Method 1

The strain sensitive element deforms in response to a force translated from the catheter tip to the strain sensitive element. The deformation of the strain sensitive element changes at least one electrical characteristic of the strain sensitive element, and the change in the electrical characteristic is indicative of the force exerted on the catheter tip.

Methodology Applied
Scientific EffectStrain sensitivity: Piezoresistive Effect

Implementation Method 2

The wireless communication circuitry is configured to wirelessly transmit an electronic signal that conveys the force exerted on the catheter tip.

Methodology Applied
Scientific EffectWireless transmission: Electromagnetic Induction

Data Source

PatentEP3821794B1Wireless force sensor
Publication Date: 2023.02.15 ST JUDE MEDICAL INT HLDG SARL
  • EP3821794B1 patent drawingFigure 1
  • EP3821794B1 patent drawingFigure 2A~2B
  • EP3821794B1 patent drawingFigure 3

AI summary

Aspects of the instant disclosure relate to an electrophysiological catheter system for performing diagnostics and therapies within a cardiac muscle; more specifically, to a wireless force sensor, mounted to an external surface of a catheter shaft, that detects force exerted on a catheter tip and wirelessly transmits a signal indicative of the sensed force to a wireless transceiver in proximity thereto.