Fiber-optic sensors and methods for monitoring micro-movements
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.
1. A sensor for detecting micro-movements, the sensor comprising:
one looped structure or a plurality of looped structures, where each looped structure formed of a continuous multi-mode optical fiber arranged into a plurality of parallel equally-sized loops disposed substantially in a plane, wherein each loop within the looped structure is partially overlapping yet laterally offset from neighboring loops; where the laterally offset distance between each parallel neighboring loop and arranging the looped structure fiber segment in the looped structure is between 1 mm and 10 mm whereby the looped structure causes the optical fiber to cover significantly more of a surface;
a light source coupled to a first end of the looped structure and configured to send light into the loop structure; and
a receiver coupled to a second end of the looped structure, the receiver configured to sense changes in an intensity of light traveling through the looped structure.
2. The sensor of claim 1 , wherein the continuous multi-mode optical fiber comprises a core diameter that is greater than 49% of a total diameter of the continuous multi-mode optical fiber.
3. The sensor of claim 1 , wherein each of the loops are in a form shaped like a square, other rectangle, or other parallelogram, wherein the formed shape has rounded corners.
4. The sensor of claim 1 , wherein each of the loops forms a circle or other ellipse.
5. The sensor of claim 1 , wherein each of the loops forms a matching irregular shape.
6. The sensor of claim 1 , wherein the continuous multi-mode optical fiber is formed of glass, plastic, or other suitable material.
7. The sensor of claim 1 , wherein the distance between each parallel fiber segment is between 2 mm and 5 mm.
8. The sensor of claim 7 , wherein the plurality of looped structures is formed of a single continuous multi-mode optical fiber such that each of the looped structures is directly connected to the other looped structures in the sensor.
9. The sensor of claim 7 , wherein the plurality of looped structures comprises a plurality of multi-mode optical fibers, each of the multi-mode optical fibers forming a separate looped structure.
10. The sensor of claim 7 , wherein the plurality of looped structures are positioned adjacent to each other on a plane.
11. The sensor of claim 7 , wherein the plurality of looped structures partially or fully overlay each other.
12. The sensor of claim 1 , further comprising a mesh structure, wherein the mesh structure is a single layer of mesh disposed above or below the optical fiber looped structure; or the mesh structure is formed of two layers of mesh which sandwich the optical fiber looped structure therebetween.
13. A method of manufacturing a looped structure, the of claim 1 , the method comprising:
providing an axle having a plurality of coupling elements coupled thereto;
rotating the axle and the coupling elements;
wrapping a continuous multi-mode optical fiber as a coil around the rotating axle, wherein the multi-mode optical fiber becomes engaged with the coupling elements on the axle; and
displacing the multi-mode optical fiber from the axle by disengaging the plurality of coupling elements from the axle; using a wedge, rod, or other tool to push the coiled multi-mode optical fiber from the axle in a manner that will allow the coiled fiber to fall into a flat looped structure on a flat surface; wherein the looped structure is formed of the continuous multi-mode optical fiber neighboring loop and arranging the looped structure into a plurality of equally-sized loops disposed substantially in a plane, each loop within the looped structure is partially overlapping yet laterally offset from neighboring loops by a distance between 1 mm and 10 mm.
14. The method of claim 13 , wherein the multi-mode optical fiber is wrapped around the rotating axle by moving an arm axially with respect to the axle from a first position to a second position parallel to the axle, the arm being configured to dispense the multi-mode optical fiber on the axle.
15. The method of claim 13 , wherein the plurality of coupling elements are equally or substantially equally spaced laterally on the axle; the plurality of coupling elements comprise one or more of tape, glue, resin, other adhesive compound, hooks, latches, or other physical coupling elements.
16. The method of claim 13 , wherein the axle includes one or more grooves running along a length of the axle surface in an axial direction; the tool inserted into the groove is wedged under the coiled multi-mode optical fiber and used to push the coiled fiber from the axle.
17. A method of detecting a physiological parameter, the method comprising:
positioning a sensor for detecting micro-movements under a patient, the sensor for detecting micro-movements comprising:
one looped structure or a plurality of looped structures, where each looped structure formed of a continuous multi-mode optical fiber arranged into a plurality of parallel equally-sized loops disposed substantially in a plane, wherein each loop within the looped structure is partially overlapping, yet laterally offset from, neighboring loops; where the laterally offset distance between each parallel neighboring loop fiber segment in the looped structure is between 1 mm and 10 mm the looped configuration causes the optical fiber to cover significantly more of a surface;
a light source coupled to a first end of the looped structure and configured to send light into the loop structure; and
a receiver coupled to a second end of the looped structure;
detecting, by the receiver, a change in an intensity of light traveling through the looped structure, wherein the change in light intensity corresponds to fiber deformation caused by one or more micro-movements of the human body; and
determining a physiological parameter from the change in light intensity.
18. The method of claim 17 , wherein the physiological parameter comprises one or more of: a ballistocardiogram waveform, a heartbeat, breathing, body weight, body weight distribution on a surface or a shift in body weight or posture change.