2D Optical Waveguide Pressure Sensor Array
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current pressure sensing methods using optical fibers lack full 2-D position resolution and are not unobtrusive, as they require physical connections and can be influenced by electromagnetic fields.
Innovation Solution
A 2-D optical waveguide pressure sensor array with crossing waveguides and rigid rings to enhance bending, allowing for pressure measurement without physical connections and electromagnetic interference, using Plastic Optical Fiber (POF) for robustness and scalability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical fibers are used for pressure sensing, then wireless position sensing is achieved, but full 2-D position resolution cannot be obtained
Solution Approach 1:
The optical sensing system is segmented into multiple independent optical waveguides arranged in a grid pattern, where each waveguide intersection point represents a discrete sensing location. This segmentation allows the system to resolve pressure positions in both x and y dimensions by identifying which specific waveguide intersections experience pressure-induced coupling, thereby achieving full 2-D position resolution rather than losing position information along the fiber length.
Solution Approach 2:
The invention transitions from one-dimensional fiber-based sensing to two-dimensional waveguide array sensing by introducing a grid arrangement of optical waveguides. Pressure applied at any location on the surface couples light between specific pairs of waveguides (one from each orthogonal direction), enabling 2-D position resolution through the combination of two orthogonal measurement dimensions.
2Measurement precision
If physical connections are made to objects for sensing, then measurement capability is improved, but the sensing becomes obtrusive and hampers movement
Solution Approach 1:
The invention replaces traditional mechanical/wire-based sensing systems with an optical sensing system. By using optical waveguides that detect pressure through light coupling changes rather than electrical connections, the system achieves accurate pressure sensing without requiring physical attachments to the monitored objects, thereby maintaining unobtrusiveness and freedom of movement.
3Device complexity
If traditional optical fiber sensing is used, then simplicity is maintained, but electromagnetic field interference affects measurements
Solution Approach 1:
The invention substitutes electrical field-based detection with optical field-based detection. By measuring pressure through changes in light propagation characteristics (intensity, coupling efficiency) rather than electrical signals, the system becomes immune to electromagnetic field interference from sources such as Wi-Fi systems, power lines, and medical equipment, while maintaining relative system simplicity.
4Measurement precision
If waveguide bending is increased to enhance pressure sensitivity, then pressure detection capability improves, but light loss increases
Solution Approach 1:
The invention introduces a third waveguide as an intermediary to capture the light that would otherwise be lost due to bending at waveguide intersections. The crossing waveguide acts as a mediator that collects evanescent field light from the bending waveguides and guides it to the detector, thereby preserving light energy while maintaining the enhanced pressure sensitivity provided by the bending geometry.
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 unobtrusive, high-resolution 2-D pressure sensing without electromagnetic interference, suitable for monitoring sleep behavior and fall detection, with low cost and thin design for easy integration under mattresses or carpets.
Implementation Method 1
Bending optical waveguide can introduce losses because of light that escapes. The light that escapes can be captured in a crossing waveguide. So bending crossing optical waveguides, when pressure or force is exerted, can result in optical coupling between the two crossing waveguides
Implementation Method 2
bending crossing optical waveguides, when pressure or force is exerted, can result in optical coupling between the two crossing waveguides, which is roughly proportional to this exerted pressure or force
Data Source
Figure 1
Figure 2~3B
Figure 4~5
AI summary
Pressure sensing having 2-D resolution is provided by an array of optical waveguides having wave-guide intersections (e.g., intersecting rows and columns). Pressure induced cross-coupling between intersecting wave-guides is enhanced by including mechanical structures at each intersection that enhance local waveguide bending. For example, such structures can be rigid rings around the wave-guide intersections.