Optical Fiber Shape Sensor Constraint for Twist Error Reduction
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Solution Overview
Problem
Existing shape sensing optical fibers in medical instruments suffer from measurement errors due to twisting, temperature variations, and axial loading, compromising the accuracy and precision of navigational assist systems.
Innovation Solution
The use of mechanical elements such as splines and adhesives to constrain the movement of optical fibers within medical instruments, coupled with optical fiber shape sensors, to minimize the effect of twist and improve positional and shape assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical fiber shape sensors are used in medical instruments, then shape and position sensing capability is provided, but measurement accuracy deteriorates due to twisting, temperature variations, and axial loading
Solution Approach 1:
A twist-resistant feature acts as an intermediary element between the optical fiber shape sensor and the instrument body. This feature mechanically couples to the sensor while resisting twisting forces, thereby mediating the transmission of shape information while blocking the transmission of harmful twist-induced measurement errors
Solution Approach 2:
The harmful twisting effect is extracted and isolated from the measurement system. The twist-resistant feature separates the optical fiber sensor from the twisting motions of the instrument, allowing the sensor to measure only the intended shape parameters without contamination from rotational movements
2Measurement precision
If the optical fiber is constrained to prevent twisting, then measurement accuracy improves, but device complexity increases due to additional mechanical elements
Solution Approach 1:
The twist-resistant feature serves multiple functions simultaneously: it mechanically constrains the optical fiber to prevent twisting, provides structural support within the instrument, and maintains the relative positioning of sensor components. This multi-functionality reduces the need for separate dedicated constraint mechanisms
Solution Approach 2:
The twist-resistant feature utilizes flexible structural elements that can accommodate the bending and deformation required for minimally invasive navigation while maintaining resistance to twisting. These flexible structures provide constraint without requiring rigid, complex mechanical assemblies
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
Enhances the accuracy and precision of shape and position sensing in medical instruments by reducing errors introduced by twisting, thereby improving the intuitiveness and efficiency of minimally invasive procedures.
Implementation Method 1
shape sensing optical fibers
Implementation Method 2
shape measuring optical fibers capable of propagating desired detection light applied from the light source
Data Source
Figure 1
Figure 2
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AI summary
An apparatus comprises an instrument including an elongated shaft. The apparatus also comprises a first shape sensor including an elongated optical fiber extending within the elongated shaft at a first radial distance from the neutral axis. The apparatus also comprises a twist resistant feature configured to reduce twisting of the elongated optical fiber relative to the elongated shaft while permitting axial translation of the elongated optical fiber within the elongated shaft.