Microcatheter Pressure Sensor Mounting to Minimize Bending Strain
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Solution Overview
Problem
Conventional pressure sensors on microcatheters are prone to distortion due to bending stresses, leading to incorrect pressure readings when measuring Fractional Flow Reserve (FFR) across vessel lesions, and there is a need for a catheter design that allows the use of conventional guidewires instead of FFR guidewires and minimizes catheter profile and stress on the sensor.
Innovation Solution
The catheter design features an elongate shaft with separate lumens for a guidewire and a pressure sensor wire, with a deformable member or intermediate member with a hinge that reduces stress and strain on the pressure sensor by maintaining it in a straight configuration relative to bending, or a pressure sensor suspended above the shaft wall to prevent contact and stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure sensor is mounted on the distal end of a microcatheter, then pressure measurements can be obtained, but the sensor experiences bending stresses that cause distortion and incorrect readings
Solution Approach 1:
A deformable member is introduced as an intermediary element between the pressure sensor and the microcatheter shaft. This deformable member acts as a mediator that isolates the sensor from bending stresses while still allowing it to measure pressure accurately. The deformable member deforms with the catheter bending while protecting the sensor from direct mechanical stress.
Solution Approach 2:
The deformable member is constructed from flexible materials that can accommodate bending movements. This flexible structure allows the sensor assembly to move with the catheter while the flexible material absorbs and dissipates bending stresses before they reach the pressure sensor, preventing distortion.
2Productivity
If the catheter profile is reduced to minimize blood flow disruption, then blood flow is better maintained, but the catheter becomes more flexible and increases bending stresses on the sensor
Solution Approach 1:
The deformable member serves as a protective intermediary that allows the catheter to have a thin, flexible profile for minimal blood flow disruption while simultaneously shielding the pressure sensor from the increased bending stresses that result from this flexibility.
Solution Approach 2:
The deformable member provides beforehand cushioning by being positioned between the sensor and the catheter shaft, absorbing and cushioning against bending stresses before they can reach and distort the pressure sensor, even when the catheter is highly flexible.
3Measurement precision
If a deformable member is added to reduce stress on the sensor, then sensor distortion is reduced, but the catheter structure becomes more complex
Solution Approach 1:
The deformable member is implemented as a thin-walled flexible structure that provides effective stress isolation while adding minimal structural complexity. The thin-walled design allows it to be integrated into the existing catheter architecture without requiring major structural modifications.
Solution Approach 2:
The deformable member utilizes changes in material parameters (flexibility, durometer) to achieve stress isolation. By selecting materials with specific flexibility characteristics, the design achieves effective sensor protection while keeping the structural complexity low and the member easily integrable into the catheter.
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 minimizes distortion of the pressure sensor, enabling accurate FFR measurements and allowing the use of conventional guidewires, while reducing the catheter profile to minimize disruption of blood flow and bending stresses.
Implementation Method 1
The deformable member has adhesive properties and is disposed between the pressure sensor and the catheter. The deformable member reduces the amount of stress and strain transferred to the pressure sensor
Data Source
AI summary
A catheter, such as a fractional flow reserve catheter, includes an elongate shaft having a proximal end optionally coupled to a handle or luer fitting and a distal end having a distal opening. A pressure sensing wire extends to the distal portion of the elongate shaft to be coupled to a pressure sensor mounted on the distal end for measuring a pressure of a fluid within lumen of vessel. The pressure sensor wire is disposed within a pocket formed adjacent to the pressure sensor thereby minimizing the profile of the catheter. Bending or flexing stress or strain experienced by a pressure sensor mounted to a fractional flow reserve catheter when tracking the catheter through the vasculature creates a distortion of the sensor resulting in an incorrect pressure reading or bend error. In order to isolate the sensor from bending or flexing stress and strain, the sensor is mounted so that the sensor is spaced apart from the elongate shaft of the catheter.