Folded Nitinol Coil Sensor for Catheter Contact Force Detection
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Solution Overview
Problem
Current methods for verifying electrode contact with cardiac tissue during ablation procedures for arrhythmia treatment are inadequate, as they fail to accurately measure contact force and displacement, which can lead to inconsistent delivery of ablation energy and increased risk of complications.
Innovation Solution
A cardiac catheter equipped with a contact force sensor featuring a resilient member and electromagnetic coils that measure displacement of the distal tip relative to the proximal portion, allowing for precise detection of contact force and pressure exerted on the tissue, thereby enhancing the accuracy of electrode-tissue contact verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure transducer is used to measure contact pressure, then contact force verification is provided, but the measurement precision and reliability of electrode-tissue contact verification are insufficient
Solution Approach 1:
The patent replaces mechanical pressure transducers with an optical sensing system. A distal portion of the catheter includes a resilient member that deforms under contact force, and this deformation is measured optically using a light source and photodetector array, eliminating the need for mechanical pressure sensors and achieving more precise and reliable measurements.
Solution Approach 2:
The patent introduces an optical intermediary system consisting of a light source, resilient member, and photodetector array. The resilient member acts as a mediator that converts mechanical contact force into optical signal variations, allowing indirect but more accurate measurement of contact force without direct mechanical sensing.
2Measurement precision
If conventional contact sensing methods are used, then basic contact detection is possible, but accurate measurement of contact force and displacement cannot be achieved
Solution Approach 1:
The patent combines multiple functions into a single integrated optical sensing system. The distal portion of the catheter integrates the resilient member, light source, and photodetector array into one unified structure that simultaneously measures both contact force and displacement, eliminating the need for separate sensing systems.
Solution Approach 2:
The optical sensing system serves multiple functions: it measures contact force, measures displacement of the distal tip, and verifies electrode-tissue contact. This multi-functional approach achieves accurate measurements without requiring multiple separate devices, managing complexity through versatility.
3Reliability
If firm contact is made between electrode and tissue, then ablation energy delivery is effective, but excessive contact force can cause tissue damage and complications
Solution Approach 1:
The patent implements a feedback system where the optical sensor continuously monitors contact force and displacement in real-time. This information is fed back to the operator or control system, allowing adjustment of contact force to maintain optimal levels for effective ablation while preventing excessive force that could cause tissue damage.
Solution Approach 2:
The resilient member in the distal portion of the catheter acts as a mechanical cushion that limits maximum contact force. This passive safety mechanism prevents excessive force transmission to the tissue even if the operator applies too much pressure, providing beforehand protection against tissue damage.
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 provides reliable verification of electrode contact, ensuring consistent and controlled delivery of ablation energy, thereby improving the effectiveness and safety of arrhythmia treatment by creating precise non-conducting lesions in cardiac tissue.
Implementation Method 1
A resilient member couples the distal tip to the distal portion of the catheter and is configured to deform in response to pressure exerted on the distal tip when engaging tissue
Implementation Method 2
The relative position changes in response to deformation of the resilient member. The position sensor generates a signal indicative of the position of the distal tip responsively to a magnetic field produced by a magnetic field generator
Data Source
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AI summary
A contact force sensor is constructed using a spring in which a resilient member is interposed between two contacting elements. Extensions connected to the resilient member are in contact with the elements. A force applied to at least one of the elements causes a deformation of the spring that correlates with a displacement of the elements relative to one another.