Instrumented Catheter with Embedded Strain Gauge for Shape Sensing
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Solution Overview
Problem
Current minimally invasive surgical devices lack effective force and shape sensing capabilities, often due to costly and complex technologies that occupy valuable space within the catheter lumen, limiting the amount of information available during procedures.
Innovation Solution
An instrumented minimally invasive surgical device featuring a deformable segment with a strain gauge having a conductive trace that changes conductivity based on deformation, allowing for precise measurement of force and shape through a controller that processes resistance changes, enabling detailed feedback on catheter shape and external forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex and expensive sensing technologies are used for force and shape sensing, then measurement precision is improved, but device complexity increases and lumen space is reduced
Solution Approach 1:
The patent replaces complex mechanical sensing technologies with strain gauges that utilize electrical resistance changes to measure deformation. The strain gauge includes a conductive trace whose resistance varies with catheter deformation, providing force and shape sensing capabilities through electrical measurements rather than mechanical sensors, thereby reducing device complexity while maintaining measurement precision
Solution Approach 2:
The patent changes the measurement parameter from mechanical sensor output to electrical resistance variation. The conductive trace's resistance changes in response to strain, and this resistance change is measured to determine catheter deformation and applied forces, providing an alternative parameter-based sensing approach that simplifies the overall system
2Measurement precision
If complex and expensive sensing technologies are used for force and shape sensing, then measurement precision is improved, but the lumen space available for surgical instruments is reduced
Solution Approach 1:
The patent replaces bulky mechanical sensing components with a thin conductive trace that can be integrated into the catheter wall structure. This electrical sensing approach occupies minimal space within the catheter lumen while providing comprehensive force and shape measurement capabilities, preserving lumen space for surgical instruments
Solution Approach 2:
The strain gauge is implemented as a thin conductive trace that can be embedded in or bonded to the catheter wall. This thin-film approach minimizes the space required for sensing components while maintaining the flexibility and functionality of the catheter structure, ensuring adequate lumen space remains available
3Measurement precision
If relatively large sensing components are used, then measurement precision is improved, but the quantity of information available is limited due to space constraints
Solution Approach 1:
The patent segments the sensing capability into multiple strain gauges distributed at different locations along the catheter. Each strain gauge provides localized deformation information, and by combining measurements from multiple segments, comprehensive shape and force information throughout the catheter length is obtained, increasing the quantity of available information
Solution Approach 2:
The thin conductive trace allows for the integration of multiple sensing elements along the catheter length without excessive space consumption. This enables distributed sensing that captures detailed shape and force information at multiple locations, thereby increasing the quantity of information available while maintaining measurement precision
4Measurement precision
If traditional force sensing technologies are used, then force magnitude and direction are measured, but detailed force information is not available
Solution Approach 1:
The patent uses multiple strain gauges positioned at different locations and orientations along the catheter. Each gauge measures strain in its specific direction, and by combining these segmented measurements, detailed force vector information including magnitude, direction, and distribution along the catheter is reconstructed, providing comprehensive force details beyond what a single sensor could provide
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 solution provides a cost-effective means to gather extensive information about the device's shape and forces applied, maintaining a large lumen space while using mechanically simple and precise SMA-based actuators, enhancing surgical precision and procedure outcomes.
Implementation Method 1
a strain gauge, the strain gauge including a conductive trace provided in the elongated tube between the inner and outer surfaces in the deformable segment, wherein a conductance of the conductive trace depends on a deformation of the deformable segment
Data Source
AI summary
An instrumented minimally invasive surgical device (10), comprising an elongated tube (12) defining an inner surface (18) delimiting a lumen (20) and an opposed outer surface (22), the elongated tube (12) including a deformable segment; and a strain gauge (25), the strain gauge (25) including a conductive trace (26) provided in the elongated tube (12) between the inner and outer surfaces (18 and 22) in the deformable segment, wherein a conductance of the conductive trace (26) depends on a deformation of the deformable segment.