Looped Fiber-Optic Sensor for Micro-Movement Detection
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Solution Overview
Problem
Current vital sign monitoring technologies, including optical fiber sensors, face challenges in sensitivity, accuracy, and cost, with existing sensors being intrusive, inaccurate, and prone to electromagnetic interference, and lacking the ability to detect subtle movements effectively.
Innovation Solution
A looped structure formed of continuous multi-mode optical fiber with partially overlapping and laterally offset loops, coupled with a light source and receiver, and accompanied by signal processing components, is used to detect micro-movements and vital signs, increasing sensor sensitivity and coverage while minimizing light loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a macro-bending fiber sensor is integrated into a belt to measure respiratory rate, then the device becomes portable and wearable, but the sensor experiences significant light loss due to macroscopic deviations in the fiber's axis, resulting in low sensitivity
Solution Approach 1:
The fiber is divided into multiple small loops instead of a single continuous macro-bending section. Each loop creates a controlled micro-bending zone that maintains sensitivity while distributing the bending effects throughout the sensor structure, preventing excessive light loss in any single location
Solution Approach 2:
The sensor uses looped configurations with specific curvature radii that optimize the bending effect for detecting micro-movements. The curved loop structure creates consistent micro-bending that enhances sensitivity to physiological movements while maintaining portability and wearability
2Measurement precision
If optical phase interferometry is used to monitor vital signs, then measurement precision is improved, but the device requires expensive phase modulators and coherent optical sources, increasing device complexity and cost
Solution Approach 1:
The invention replaces expensive coherent optical sources and phase modulators with simpler, less costly optical components. By using intensity-modulated light sources and detection schemes that measure light intensity changes rather than phase changes, the system achieves adequate measurement precision at a fraction of the cost of interferometric systems
Solution Approach 2:
The complex optical phase modulation mechanism is replaced with a simpler mechanical-like bending mechanism where physical deformation of the fiber loops directly modulates light intensity. This substitution eliminates the need for expensive phase modulators while maintaining the ability to detect vital signs through physiological-induced micro-movements
3Ease of operation
If conventional vital sign trackers are used, then ease of operation is improved with simple wearable devices, but accuracy is compromised and they are prone to electromagnetic interference
Solution Approach 1:
Electrical and electronic sensing mechanisms are replaced with optical fiber-based sensing. The optical fiber sensor detects physiological movements through light intensity changes caused by micro-bending, eliminating susceptibility to electromagnetic interference while maintaining wearability and portability
Solution Approach 2:
The sensor integrates optical fiber with flexible wearable materials to create a composite structure that combines the sensitivity and EMI resistance of optical fibers with the flexibility and comfort of wearable textiles. This composite approach enables accurate vital sign monitoring in a wearable form factor
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 enables accurate detection of heart rate, ballistocardiogram signals, and shifts in body weight, improving sensor sensitivity and reducing wear and artifacts, while being cost-effective and resistant to electromagnetic interference.
Implementation Method 1
The receiver is configured to sense changes in an intensity of light traveling through the looped structure
Data Source
AI summary
A sensor for detecting micro-movements is provided herein. In various embodiments, the sensor includes a looped structure formed of a continuous multi-mode optical fiber arranged into a plurality of loops disposed substantially in a plane. Each loop within the looped structure is partially overlapping yet laterally offset from neighboring loops. The sensor further includes a light source coupled to a first end of the looped structure, a receiver coupled to a second end of the looped structure, and one or more control and processing modules. Related methods of manufacture and use are also disclosed.