Bragg Grating Pressure Sensor with Transverse Force Actuation
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Solution Overview
Problem
Current pressure sensing technologies, such as multi-bore catheters and piezoelectric devices, are uncomfortable for patients and costly, while optical pressure measurement devices using fibre Bragg gratings face challenges in sensitivity and design complexity, particularly in in-vivo applications.
Innovation Solution
An apparatus comprising a light guide with a Bragg grating and a moveable wall portion that applies a transversal force to the Bragg grating, allowing for sensitive pressure detection through changes in tensile strain, which is compact and suitable for various environments, including in-vivo use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If piezoelectric or electro-mechanical devices are used for pressure measurement, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces piezoelectric or electro-mechanical pressure sensing devices with an optical sensing system using a fibre optic cable and Bragg grating. This substitution eliminates the need for complex electrical components, wires, and power sources within the catheter, thereby reducing device complexity while maintaining pressure measurement precision through optical wavelength detection.
Solution Approach 2:
The patent uses a Bragg grating that creates an optical response (wavelength reflection) as a copy or representation of the pressure applied to the fibre optic cable. This optical copy allows pressure measurement without direct mechanical or electrical contact, simplifying the device structure while preserving measurement accuracy.
2Measurement precision
If piezoelectric or electro-mechanical devices are used for pressure measurement, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent replaces expensive piezoelectric or electro-mechanical pressure sensors with a fibre optic-based Bragg grating system. This substitution reduces manufacturing costs by eliminating complex electrical components, multiple wires, and associated assembly processes, while maintaining measurement precision through optical wavelength detection.
Solution Approach 2:
The fibre optic cable with Bragg grating can be implemented as a disposable or single-use component, reducing the need for expensive, complex, and difficult-to-manufacture reusable piezoelectric devices. This approach lowers overall system cost while maintaining measurement precision for each use.
3Device complexity
If fibre Bragg grating optical devices are used for pressure measurement, then device complexity is reduced, but sensitivity decreases
Solution Approach 1:
The patent applies a transverse force to the fibre optic cable at the location of the Bragg grating, causing the cable to expand or contract in a dimension perpendicular to its length. This dimensional change creates tensile strain on the Bragg grating, which produces a measurable shift in optical wavelength. This approach enhances sensitivity by converting pressure-induced transverse deformation into axial strain on the grating, while keeping the device structure simple.
4Measurement precision
If multi-bore catheter is used for pressure measurement, then measurement precision is improved, but ease of operation worsens due to patient discomfort
Solution Approach 1:
The patent replaces the multi-bore catheter design with a single fibre optic cable containing a Bragg grating. This substitution eliminates the need for multiple fluid-filled bores and water flow systems, significantly reducing catheter diameter and improving patient comfort during insertion and use, while maintaining pressure measurement precision through optical sensing.
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 apparatus provides a comfortable and cost-effective means to detect pressure changes with high sensitivity, enabling accurate diagnostics and distributed pressure sensing, while minimizing discomfort and complexity.
Implementation Method 1
a Bragg grating incorporated into the light guide... a change in strain of the Bragg grating causes a change in an optical response of the Bragg grating to light that is in use guided to the Bragg grating
Data Source
AI summary
The present invention provides an apparatus for pressure sensing. The apparatus comprises a light guide, a Bragg grating incorporated into the light guide and a moveable wall portion. The moveable wall portion has opposite first and second sides and is being positioned so that a change in pressure at one of the sides relative to a pressure at the other side will move the moveable wall portion. The moveable wall portion is coupled to the Bragg grating so that the movement of the moveable wall portion causes a force on a side of the Bragg grating. The force has a component that is transversal to the Bragg grating and effects a change in strain of the Bragg grating and thereby a change in an optical period of the Bragg grating.