Nested Optical Fiber Shape Sensing Accuracy
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Solution Overview
Problem
The accuracy of shape sensing in flexible tools, such as catheters, is compromised by the need for a small optical fiber diameter to accommodate a large central working channel, limiting the precision of navigation through narrow passages, and the space used by control lines for imaging devices is not efficiently utilized during insertion.
Innovation Solution
Incorporating a larger diameter optical fiber that can be inserted within the tool body's channel to enhance accuracy, which can then be removed and replaced by other instruments, allowing the smaller fiber to provide continuous shape sensing with corrections derived from the larger fiber's readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a smaller diameter optical fiber is used in the catheter wall, then the central working channel size is increased, but the shape sensing accuracy deteriorates
Solution Approach 1:
The patent embeds a second, larger diameter optical fiber within the lumen of the first optical fiber that runs through the catheter wall. This nesting arrangement allows the smaller fiber to maintain shape sensing accuracy while the larger fiber provides enhanced measurement capability when inserted into the central working channel.
Solution Approach 2:
The smaller diameter optical fiber is pre-installed within the catheter wall during manufacturing, establishing a baseline shape sensing capability. The larger diameter optical fiber is then inserted into the central working channel when needed to augment accuracy for critical measurements.
2Measurement precision
If a larger diameter optical fiber is used for shape sensing, then the shape sensing accuracy is improved, but the central working channel size is reduced
Solution Approach 1:
The second, larger diameter optical fiber is nested within the lumen of the first optical fiber, allowing it to be transported through the catheter structure without permanently occupying space in the central working channel. The larger fiber is only deployed when insertion into the central channel is possible.
Solution Approach 2:
The system dynamically switches between using the smaller embedded fiber for continuous monitoring and the larger inserted fiber for high-precision measurements. The larger fiber can be inserted and removed as needed based on operational requirements.
3Ease of operation
If control lines for optical imaging devices are used during insertion, then imaging capability is provided, but space utilization is inefficient
Solution Approach 1:
The central working channel is designed to serve multiple functions: it accommodates control lines for optical imaging devices during insertion and navigation, and later accepts the larger diameter optical fiber for enhanced shape sensing. This multi-functionality maximizes space utilization throughout the procedure.
Solution Approach 2:
The control lines are used temporarily during the insertion and navigation phase, then discarded or retracted. The larger diameter optical fiber is then inserted into the same channel for the measurement phase, recovering the space for its intended high-precision function.
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 configuration increases the accuracy of shape sensing by a factor of 5-6 and allows for the use of larger instruments post-insertion, optimizing space utilization and maintaining precise measurements without substantial movement of the catheter.
Implementation Method 1
the first optical fiber and the second optical fiber are each configured to sense a shape of the flexible portion of the tool body
Data Source
AI summary
Where a flexible tool includes a tool body with a flexible portion, a distal end and a first optical fiber within the flexible portion, shape sensing can be achieved with increased accuracy by inserting or otherwise including a second optical fiber within the flexible portion. The increased accuracy can be achieved when the second optical fiber has a diameter larger than that of the first optical fiber. Once the shape of the flexible tool has been determined using at least the second optical fiber, the first optical fiber can be used for subsequent shape sensing. This may be particularly applicable where the tool includes an instrument such as an optical imaging device inserted in a channel of the tool, where not all of the width of the channel is occupied by functional components behind the operable end of the instrument.