Optical Pressure Sensor Guidewire Tolerance Design
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Solution Overview
Problem
Current medical devices for measuring blood pressure within blood vessels face challenges in accurately monitoring pressure due to potential contact between pressure sensors and the inner surface of the guidewire, leading to deformation and offset readings.
Innovation Solution
The design incorporates a pressure sensing guidewire with a distal cap and a fiber optic cable, where the tolerance between the fiber optic cable's outer surface and the distal lumen's inner surface limits radial movement of the optical pressure sensor, minimizing contact with the distal cap inner surface, and includes features like slotted tubes and coils to enhance flexibility and fluid access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical pressure sensor is positioned close to the distal cap inner surface for accurate pressure measurement, then measurement precision is improved, but the sensor may contact the inner surface causing deformation and reading offset
Solution Approach 1:
A fiber optic cable is introduced as an intermediary element between the optical pressure sensor and the distal cap inner surface. The cable's outer surface acts as a mediator that limits radial movement of the sensor, maintaining a controlled spacing (0.005-0.05 mm) that prevents direct contact while allowing accurate pressure measurement through fluid coupling.
2Stability of the object's composition
If the distal lumen inner diameter is reduced to minimize sensor movement, then sensor positioning stability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The invention specifies a particular tolerance range (0.005-0.05 mm) for the distal lumen inner diameter relative to the fiber optic cable outer diameter. This parameter optimization balances sensor stability with manufacturability, providing sufficient constraint without requiring excessively tight tolerances that would be difficult to achieve in production.
3Ease of operation
If the void space within the distal cap is maximized to accommodate the sensor, then sensor movement freedom is improved, but the sensor may contact the distal cap inner surface
Solution Approach 1:
The fiber optic cable serves as a structural intermediary that fills the void space while preventing sensor contact. The cable's presence provides both mechanical support and spatial constraint, allowing a larger void space for easy sensor assembly while simultaneously preventing the sensor from contacting the distal cap inner surface during operation.
Data Source
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AI summary
A medical device for measuring blood pressure includes a proximal shaft and a distal member including a slotted tube defining a distal lumen extending through the slotted tube, the distal lumen aligned with the proximal lumen and including a distal lumen inner surface. A distal cap is secured to the distal member, the distal cap including a distal cap inner surface defining a void space and an optical pressure sensor is disposed within the void space. A fiber optic cable is coupled to the optical pressure sensor and extends proximally through the distal lumen. A tolerance between an outer surface of the fiber optic cable and the inner surface of the distal lumen inner surface limits relative radial movement of the optical pressure sensor relative to the distal cap inner surface such that the optical pressure sensor is constrained from contacting the distal cap inner surface.