Perpendicular-Grid Strain Gauge for Compact Catheter Pressure Sensing
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Solution Overview
Problem
Existing strain gauges for cardiac radiofrequency ablation catheters are limited by their large size, susceptibility to temperature changes, and inability to be fitted in the axial direction, which affects their precision and applicability.
Innovation Solution
A strain gauge design with at least two sensitive grids arranged perpendicularly and sharing a common grounding interface, reducing the number of grounding interfaces and allowing for a smaller size and improved temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional copper-nickel alloy strain gauges with large grid filament area are used, then the sensitivity coefficient can reach 2.0, but the strain gauges are significantly affected by external temperature and require tight temperature control
Solution Approach 1:
The patent uses a composite material structure combining aluminum alloy substrate with nickel-chromium sensitive grid. The aluminum alloy substrate provides thermal expansion characteristics that compensate for the temperature sensitivity of the nickel-chromium grid, creating a composite structure that reduces temperature error while maintaining high sensitivity coefficient
Solution Approach 2:
The patent changes the material parameters by selecting aluminum alloy with specific thermal expansion coefficient and combining it with nickel-chromium alloy having different thermal properties. This parameter optimization allows the strain gauge to maintain stable performance across temperature variations while preserving measurement precision
2Reliability
If existing strain gauges with large size are used, then they provide stable performance, but they cannot be fitted with the ablation catheter in the axial direction
Solution Approach 1:
The patent segments the strain gauge structure into a thin substrate layer with integrated sensitive grid patterns. This segmentation allows the strain gauge to be flattened and conform to the axial direction of the catheter while maintaining the functional integrity and stable performance of the measurement system
Solution Approach 2:
The patent transitions from a traditional planar strain gauge layout to a three-dimensional conformal structure that can wrap around or align with the axial direction of the catheter. This dimensional change enables the strain gauge to fit the catheter geometry while preserving measurement stability
3Ease of manufacture
If traditional strain gauges with multiple separate grounding interfaces are used, then each grid can be independently connected, but the number of grounding interfaces increases the wiring space and device complexity
Solution Approach 1:
The patent merges multiple grounding interfaces into a single common grounding interface that serves all sensitive grids. This consolidation reduces the number of wiring connections and simplifies the overall device structure while maintaining the ability to independently connect each grid through the shared grounding point
Solution Approach 2:
The single grounding interface is designed with universal functionality to serve multiple sensitive grids simultaneously. This multi-functional grounding structure eliminates the need for separate grounding connections for each grid, reducing wiring space and device complexity while preserving electrical connection integrity
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 facilitates easier installation on interventional medical catheters, reduces the size of the catheter, enhances measurement accuracy, and improves the success rate of interventions by minimizing temperature drift and wiring space.
Implementation Method 1
When stretched, the sensitive grid becomes narrower or longer, and the resistance becomes larger. When compressed, the sensitive grid becomes thicker or shorter, and the resistance becomes smaller.
Implementation Method 2
strain gauges are generally provided thereon to measure the contact force between distal end of the catheter and the tissue or vessel wall
Data Source
AI summary
A strain gauge (10, 40, 50), a pressure sensor (20, 60), and an interventional medical catheter. The strain gauge (10, 40, 50) comprises a substrate (11) and at least two sensitive gages (1, 2) provided on the substrate (11), the at least two sensitive gages (1, 2) being arranged along two mutually perpendicular directions and sharing one ground port (3). The pressure sensor (20, 60) comprises an elastic body (21, 61) and the strain gauge (10, 40, 50) provided on the elastic body (21, 61). The interventional medical catheter comprises a catheter distal end and the pressure sensor (20, 60) provided at the catheter distal end. The present application not only saves the trace space for mounting and using the strain gauge (10, 40, 50) on the interventional medical catheter, facilitating the successful mounting and use of the strain gauge (10, 40, 50) on the interventional medical catheter, improving the adaptability of the strain gauge (10, 40, 50), but also reduces the size of the strain gauge (10, 40, 50), thereby shortening the length of the elastic body (21, 61) of the pressure sensor (20, 60) and reducing the size of the interventional medical catheter.