Dual Optical Fibre Probe for Temperature-Compensated Force Sensing
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Solution Overview
Problem
Optical sensing systems for measuring changes in properties within narrow regions, such as blood vessels or pipes, face challenges in accurately correcting for differential temperature changes, especially when the probe is very narrow, leading to unreliable measurements.
Innovation Solution
An optical sensing apparatus comprising first and second optical fibre portions arranged to experience a change in force with a transversal component, resulting in differential and common mode changes in optical properties, allowing for the separation of force and temperature effects, with the fibres oriented in close proximity to minimize temperature differences and facilitate narrow design applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a single optical fibre is used for sensing, then the device size is reduced, but the ability to distinguish between temperature and force effects is lost
Solution Approach 1:
The single optical fibre is segmented into two distinct portions (first and second portions) with different sensing orientations. Each portion responds differently to temperature and force applications, enabling differential measurement that distinguishes between these two effects while maintaining a compact probe structure.
Solution Approach 2:
The two fibre portions are oriented asymmetrically relative to the force application direction. The first fibre portion is oriented such that it experiences different strain responses compared to the second fibre portion when force is applied, creating asymmetric sensitivity patterns that enable mathematical separation of temperature and force contributions.
2Measurement precision
If multiple optical fibres are used for differential measurement, then temperature compensation is improved, but the device complexity increases
Solution Approach 1:
Two optical fibre portions are merged into a single integrated probe structure, sharing common housing, mounting, and optical coupling infrastructure. This combining approach achieves differential temperature-compensated measurement capability while minimizing the increase in overall device complexity compared to using completely separate sensing systems.
3Adaptability or versatility
If the probe is made very narrow for accessing narrow body lumens, then the adaptability to narrow spaces is improved, but the reliability of temperature correction is reduced
Solution Approach 1:
The sensing element is segmented into two functionally distinct fibre portions within the narrow probe. This segmentation enables differential measurement capability that reliably distinguishes temperature effects from force effects, even when the overall probe diameter is constrained for access to narrow body lumens.
Solution Approach 2:
Asymmetric orientation of the two fibre portions within the narrow probe creates different thermal and mechanical response characteristics. This asymmetry, combined with differential measurement, provides reliable temperature correction capability despite the constrained probe geometry required for accessing narrow body lumens.
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
Enables accurate measurement of changes in properties like pressure and temperature within narrow spaces by distinguishing between differential and common mode changes, reducing the impact of temperature variations on force measurements and allowing for precise analysis in constrictive environments.
Implementation Method 1
The optical devices may comprise an optical fibre Bragg grating, which has an optical response that depends on a strain of the Bragg grating. The strain on the Bragg grating can be applied by a 'squeezing' force in the vicinity of the Bragg grating and the resultant change in strain shifts a wavelength of an optical response to a different wavelength range.
Implementation Method 2
it is often not possible, or it is inconvenient and unreliable to correct a measurement of a change in a property, such as a pressure, for differential temperature change
Data Source
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AI summary
The present disclosure provides an optical sensing apparatus for measuring a change in a first property. The optical sensing apparatus comprises first and second optical fibre portions and a sensing region for exposing both the first and second optical fibre portions to a change in an applied force. The force is, or is related to, the first property and has a component that is transversal to the optical fibre portions. The apparatus further comprises a holder for holding the first and second optical fibre portions in the sensing region. The first and second optical fibre portions are arranged relative to each other such that the change in the force results in a first change of an optical property of the first optical fibre portion and in a second change of the optical property of the second optical fibre portion and wherein the first change differs from the second change.