Force Sensor for Electrophysiology Catheter
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Solution Overview
Problem
Conventional electrophysiology catheters face limitations in accurately measuring contact forces at the distal end due to interference from external magnetic fields and lack of accuracy in non-axial load measurement, making them unsuitable for precise surgical interventions.
Innovation Solution
The electrophysiology catheter incorporates an elastic tube with strategically arranged strain gauges over solid portions, rather than overlapping them with hollow portions, allowing for more accurate contact force measurement by minimizing signal interference and enhancing deformability, while also measuring axial and lateral components of force and contact angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic position sensors are used to sense contact strength, then contact force measurement is enabled, but measurement precision deteriorates due to interference from external magnetic fields
Solution Approach 1:
The patent replaces magnetic position sensors with a strain gauge-based force sensor that uses electrical resistance changes to measure contact force. The strain gauge is bonded to the catheter shaft, and when the catheter bends or deforms under contact force, the strain gauge's resistance changes, providing a magnetic-field-independent measurement of contact strength.
Solution Approach 2:
The patent introduces an elastic tube with hollow portions as an intermediary structure between the catheter shaft and the strain gauge. This elastic tube transfers the mechanical deformation from the catheter to the strain gauge while isolating the strain gauge from direct magnetic field interference, enabling accurate force measurement without magnetic sensitivity.
2Adaptability or versatility
If magnetic fields are used for three-dimensional magnetic positioning, then positioning capability is improved, but measurement precision deteriorates due to interference with force sensor readings
Solution Approach 1:
The patent replaces magnetic field-based force sensing with a strain gauge-based electrical measurement system. This substitution allows the catheter to maintain three-dimensional magnetic positioning capabilities while using a separate, non-magnetic strain gauge system for force measurement, eliminating the interference between these two functions.
3Measurement precision
If force-sensitive materials are used for axial load measurement, then axial force sensing is improved, but measurement precision deteriorates in non-axial load measurement
Solution Approach 1:
The patent segments the force measurement capability by placing multiple strain gauges at different orientations and positions on the catheter shaft. This segmentation allows the system to measure not only axial forces but also lateral forces and bending moments by combining readings from multiple strain gauge elements oriented in different directions.
Solution Approach 2:
The patent creates a universal force sensing system where the strain gauge configuration can measure multiple types of loads (axial, lateral, bending) with a single integrated sensor assembly. The hollow portion structure and strategically placed strain gauges enable the same device to accurately measure various force vectors regardless of their direction.
4Measurement precision
If fiber-optic systems are used for sensing contact forces, then measurement capability is improved, but device complexity increases due to packaging and external signal requirements
Solution Approach 1:
The patent uses conventional, inexpensive strain gauge technology instead of complex fiber-optic systems. The strain gauge can be easily bonded to the catheter shaft using standard adhesive techniques, eliminating the need for complex fiber-optic packaging and external signal processing devices, thereby simplifying the overall system while maintaining force measurement capability.
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 design improves the accuracy and sensitivity of contact force measurement, reduces bulkiness, and provides immunity to temperature variations, making it cost-effective and suitable for precise surgical applications.
Implementation Method 1
the strain gauge disposed external to the hollow portion
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An electrophysiology catheter (100) includes a catheter distal portion (110) on which a force sensor (200) is arranged. The force sensor (200) includes an elastic tube (210) and strain gauges (220). The elastic tube (210) has a hollow portion in its wall, and the strain gauges (220) are disposed external to the hollow portion. Compared to the design with the strain gauges (220) overlapping the hollow portion, arranging them over solid portions of the elastic tube (210) allows the strain gauges (220) to collect more accurate electrical signals while suffering from less interference. This can result in a significant improvement in contact force measurement accuracy of the catheter distal portion (110).