Polymer Fiber Bending Sensor for Medical Instruments
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Solution Overview
Problem
Existing bending sensors for medical and endoscopic instruments face challenges in precision measurement, particularly at large deflection angles, due to the need for precise manufacturing and the use of multiple sensors to detect movements in different spatial directions, which also require additional space and can lead to erroneous measurement signals due to torsion.
Innovation Solution
A bending sensor with an elongate body of electrically insulating polymeric material containing substantially parallel and spaced electrically conductive polymeric fibers, where the spaces between the fibers are filled with insulating polymer material, allowing for flexible and uniform bending in multiple directions, and incorporating a braided hose for torsion prevention, enabling precise deflection measurement along X and Y axes without the need for multiple sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gaps are introduced between strands to enable bending measurement, then the sensor can detect deflection, but the sensor size increases and manufacturing precision requirements increase
Solution Approach 1:
The patent merges the measurement function into the continuous conductive polymer structure itself, eliminating the need for separate gaps or discrete contact points. The conductive polymer body continuously changes its electrical properties during bending, integrating the measurement mechanism into the structural material rather than adding separate components.
Solution Approach 2:
The patent utilizes changes in electrical resistance as a parameter that naturally occurs during bending of the conductive polymer body. By measuring the resistance change of the continuous conductive material, the system detects deflection without requiring physical gaps or additional measurement components, thus maintaining compact size while achieving measurement precision.
2Adaptability or versatility
If multiple bending sensors are used to detect movements in different spatial directions, then measurement coverage is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent makes a single conductive polymer body perform multiple measurement functions simultaneously. By strategically placing electrodes on the polymer body and measuring resistance changes between different electrode pairs, the system can detect bending in multiple directions using one sensor element, rather than requiring separate sensors for each spatial direction.
Solution Approach 2:
The patent transitions from measuring only one-dimensional bending to capturing three-dimensional deflection by utilizing the volumetric nature of the conductive polymer and measuring resistance changes between electrodes positioned at different locations and orientations on the polymer body, effectively adding measurement dimensions without adding separate sensor components.
3Measurement precision
If flat bending sensors are used for measuring bends, then measurement in one direction is enabled, but the sensor cannot be bent in the direction of its narrow longitudinal side and flexibility is reduced
Solution Approach 1:
The patent adopts a substantially cylindrical geometry for the conductive polymer body, which inherently allows bending in multiple directions around the circular cross-section. This curved, symmetric shape eliminates the directional limitations of flat sensors, enabling the sensor to accommodate bends from any direction while maintaining measurement precision through resistance changes in the conductive material.
4Ease of operation
If the sensor is made flexible for insertion into instruments, then usability in narrow spaces is improved, but torsion resistance is reduced leading to measurement errors
Solution Approach 1:
The patent employs a composite structure combining conductive polymer material with embedded electrodes and insulating layers. This composite construction provides both the flexibility needed for insertion into narrow instrument channels and sufficient torsional stability to maintain accurate measurements, as the composite structure resists unwanted twisting while allowing controlled bending.
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
The solution provides a compact, easy-to-manufacture bending sensor that accurately measures deflections in various directions, including large angles, while preventing torsion and reducing the need for additional sensors, thus enhancing precision and usability in tight spaces within medical and endoscopic instruments.
Implementation Method 1
fibers made of an electrically conductive polymer material embedded in the body... determine the position and deflection of flexible or bendable instruments... measured via a change in resistance
Data Source
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Figure 5~6
AI summary
The invention relates to a bending sensor (1) for measuring the deflection of a technical or medical instrument, comprising an elongated body (2) made of electrically insulating polymer material with a longitudinal axis (4) and fibers (5) made of an electrically conductive polymer material embedded in the body. The fibers (5) are arranged substantially parallel to the longitudinal axis and spaced apart from one another within the polymer body (2). A measuring unit (7) is provided, which is connected to the fibers (5) and is suitable for evaluating the change in the electrical resistance of the fibers (5) as a measure of the deflection of the body (2) from the longitudinal axis (4).