Fiber-Optic Force Sensor with Stiffening Means for Uniaxial Response
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Solution Overview
Problem
Existing fiber optic force sensors, particularly those used in catheters, face challenges in achieving optimal sensitivity in the z-direction without compromising stability and requiring additional sensors for temperature compensation, leading to increased complexity and cost.
Innovation Solution
A force sensor design featuring an FBG fiber with a predominantly uniaxial response behavior, utilizing stiffening means to suppress lateral forces and bending moments, allowing for sensitive axial force measurement while omitting temperature sensors by optimizing the sensor holder's structure to enhance sensitivity in the z-direction and maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional sensor areas are added to achieve temperature compensation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the temperature sensing function from the mechanical force sensing function by using a separate, dedicated temperature sensor. This allows the FBG fiber to focus solely on force measurement while temperature is measured independently, eliminating the need for complex multi-area sensor designs that would be required to achieve temperature compensation through mechanical sensor arrangements.
Solution Approach 2:
The sensor holder structure serves multiple functions: it provides mechanical support for the FBG fiber, enables axial force transmission, and facilitates temperature sensing through its thermal coupling with the distal section. This multi-functional design eliminates the need for separate temperature compensation sensors while maintaining measurement precision.
2Measurement precision
If the sensor is made more sensitive to axial forces, then measurement precision is improved, but stability deteriorates
Solution Approach 1:
The sensor holder is designed with localized flexibility in the axial direction while maintaining rigidity in lateral directions. This is achieved through the specific geometric configuration that allows controlled deformation along the force application axis while restraining movements in other directions, thereby achieving high axial sensitivity without compromising overall stability.
Solution Approach 2:
The sensor holder employs an asymmetric geometric configuration where the structural properties differ along different axes. The holder is designed to be more compliant in the axial direction (z-axis) where force measurement is needed, while being stiffer in lateral directions (x and y axes) to maintain stability and suppress unwanted movements.
3Measurement precision
If stiffening means are added to suppress lateral forces, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The stiffening function is merged into the sensor holder structure itself rather than being implemented as separate components. The holder's geometric configuration inherently provides the necessary lateral stiffness through its shape and material distribution, eliminating the need for additional stiffening elements while achieving the desired uniaxial response behavior.
Solution Approach 2:
The sensor holder utilizes a shell structure with controlled flexibility characteristics. The holder is designed to be flexible in the axial direction to allow force transmission while the shell geometry provides inherent lateral stiffness. This approach achieves uniaxial sensitivity without requiring complex mechanical stiffening components.
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 simplifies signal processing, reduces system complexity and cost, and achieves improved sensitivity to mechanical loads while minimizing temperature influence, enabling effective force measurement without the need for additional temperature compensation.
Implementation Method 1
The invention relates to a fiber optic force sensor comprising an FBG fiber held in a sensor holder with at least one force sensor area... utilizing the principle of the so-called FBG (fiber Bragg grating) sensor
Implementation Method 2
stiffening means for suppressing laterally acting forces and bending moments... designed and arranged to enhance sensitivity in the z-direction and maintain stability
Data Source
Figure 1~2
Figure 3A~4B
Figure 5A~6
AI summary
Fiber optic force sensor comprising an FBG fiber with a force sensor area to which stiffening means for suppressing or decoupling laterally acting forces and bending moments are assigned such that the force sensor has a predominantly uniaxial response behavior for detecting only the magnitude of a force acting axially in the fiber direction.