Waveguide and Optical Motion Sensor Using Optical Power Modulation

• US 20080181556A1
• Filed: 11/21/2007
• Published: 07/31/2008
• Est. Priority Date: 01/31/2007
• Status: Active Grant

• Current Assignee: Tarilian Laser Technologies, Limited (Huma Therapeutics Ltd.)
• Original Assignee: Tarilian Laser Technologies, Limited (Huma Therapeutics Ltd.)
• Inventors: Pongratz, Troy, Borgos, Thomas A., Borgos, John A.
• Granted Patent: US 7,463,796 B2
• Time in Patent Office: Days
• US Class Current: 385/13
• CPC Class Codes: A61B 2562/0266 Optical strain gauges
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/0082 adapted for particular medical purposes
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/02108 from analysis of pulse wave characteristics
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/02225 using the oscillometric method
• CPC Class Codes: A61B 5/02233 Occluders specially adapted therefor tourniquets A61B17/132
• CPC Class Codes: G01D 5/35345 using Amplitude variations to detect the measured quantity

Abstract

An optical motion sensing device included a sensor frame defining an opening, a sensor pad disposed in the opening, an optical sensing system adapted to detect an amount of movement of the sensor pad in the sensor frame, and an output unit. The optical sensing system includes an optical waveguide, an optical source device, and an optical detector. The optical waveguide is positioned within the sensor frame such that the movement of the sensor pad results in the flexing or compressing of the optical waveguide. The optical source device supplies optical energy to the optical waveguide. The optical detector detects an amount of optical energy exiting the optical waveguide. The output unit is configured to receive a signal indicative of the amount of optical energy exiting the optical waveguide and to generate a measure of the amount of movement of the sensor pad from the received signal.

Claims

1. An optical motion sensing device comprising:

a sensor frame defining an opening;

a sensor pad disposed in the opening;

an optical sensing system adapted to detect an amount of movement of the sensor pad in the sensor frame, the optical sensing system comprising;

(a) an optical waveguide positioned within the sensor frame such that the movement of the sensor pad results in the flexing or compressing of the optical waveguide,

(b) an optical source device to supply optical energy to a first end of the optical waveguide, and

(c) an optical detector to detect an amount of optical energy exiting a second end of the optical waveguide; and

an output unit configured to receive a signal indicative of the amount of optical energy exiting the optical waveguide and to generate a measure of the amount of movement of the sensor pad from the received signal.

2. The optical motion sensing device of claim 1, further comprising a load spring attached to at least a portion of the sensor frame and also supporting the sensor pad, and configured to counter at least some of a pressure exerted against the sensor pad, and further adapted to allow a desirable displacement of the sensor pad at a maximum pressure.

3. The optical motion sensing device of claim 2, wherein the load spring is adapted to provide a maximum displacement of the sensor pad between 0.5 and 3 millimeters at a maximum pressure.

4. The localized motion sensing device of claim 1, wherein the optical waveguide comprises a siloxane elastomer.

5. The localized motion sensing device of claim 1, wherein the optical waveguide comprises an elastomer selected from the group consisting of polysiloxane, polyurethane, polybutadine rubber, and combinations thereof.

6. The localized motion sensing device of claim 1, wherein the optical waveguide comprises a numerical aperture of between 0.2 and 0.4.

7. The localized motion sensing device of claim 1, wherein the optical waveguide comprises a core and a cladding, the core having a refractive index between 1.43 and 1.50, the cladding having a refractive index between 1.39 and 1.48.

8. The localized motion sensing device of claim 7, wherein the core, the cladding, or both the core and the cladding have a Shore A hardness of between 25 and 75.

9. The localized motion sensing device of claim 1, further comprising a waveguide support structure comprising a non-compliant surface, the waveguide support supporting at least a portion of the optical waveguide.

10. The localized motion sensing device of claim 9, wherein the optical sensing system is further adapted for the movement of the sensor pad to cause a flexural deformation in an unsupported portion of the optical waveguide in response to an arterial pulse.

11. The localized motion sensing device of claim 1, further comprising a flexible and incompressible support surface that supports the optical waveguide over substantially all of its length.

12. The localized motion sensing device of claim 11, wherein the waveguide support surface is a flexible electronic circuit board, to which the waveguide is bonded with a flexible elastomer adhesive.

13. The localized motion sensing device of claim 11, wherein the optical source device and the optical detector are mounted on the surface of the waveguide support.

14. The localized motion sensing device of claim 11, further comprising a support return element which is configured within the support surface for the optical waveguide and adapted to oppose the flexing of the support surface.

15. The localized motion sensing device of claim 14, wherein the support return element is adapted to provide an increasing contact pressure between the sensor pad and the optical waveguide as the sensor pad moves from a rest position to a position of maximum displacement, with the optical waveguide adapted such that said increasing contact pressure causes a decreasing amount of light exiting the second end of the optical waveguide.

16. The localized motion sensing device of claim 1, wherein the compression and flexing of the optical waveguide when the sensor pad is at the position of maximum contact pressure causes a reduction of 20-80% in the total amount of light exiting the optical waveguide.

17. The localized motion sensing device of claim 16, wherein the compression and flexing of the optical waveguide at the position of maximum contact pressure causes a reduction of 50-70% in the total amount of light exiting the optical waveguide.

18. The localized motion sensing device of claim 1, wherein the optical detector is optically coupled to optical waveguide such that the optical detector receives substantially of the optical energy from the optical source that does not escape from the sides of the sides of the optical waveguide.

19. A method of detecting an amount of localized displacement, the method comprising:

transmitting optical energy into a first end of an optical waveguide, the optical waveguide positioned within a sensor frame including a sensor pad such that the downward displacement of the sensor pad results in the compression or flexing of the optical waveguide;

detecting, using an optical detector held by the sensor frame, an amount of optical energy exiting a second end of the optical waveguide and generating therefrom a signal indicative of optical energy received, the amount of optical energy exiting the second end of the optical waveguide being reduced in response to the downward displacement of the sensor pad; and

generating a measure of an amount of downward displacement of the sensor pad using the generated signal indicative of the optical energy exiting the second end of the optical waveguide

20. A compliant waveguide for detecting arterial pulses comprising:

a cladding having a flat surface and defining a lumen, the cladding comprising an elastomer having a Shore A hardness of between 25 and 75; and

a core disposed in the lumen, the core comprising an elastomer having a Shore A hardness of between 25 and 75 and a refractive index greater than the refractive index of the cladding.

21. The compliant waveguide of claim 20, wherein the optical waveguide comprises an elastomer selected from the group consisting of polysiloxane, polyurethane, polybutadine rubber, and combinations thereof.

22. The compliant waveguide of claim 20, wherein the cladding has a Shore A durometer of between 45 and 55 and the core has a Shore A hardness between 30 and 45.

23. The compliant waveguide of claim 20, wherein the waveguide is capable of guiding at least 10,000 modes.

24. The compliant waveguide of claim 23, wherein the waveguide is capable of guiding at least 50,000 modes.

25. The compliant waveguide of claim 23, wherein the core has a refractive index between 1.43 and 1.50 and the cladding has a refractive index between 1.39 and 1.48.

26. The compliant waveguide of claim 20, wherein the core has a radius of at least 45 micrometers.

27. The compliant waveguide of claim 20,

wherein the core comprises an elastomer selected from the group consisting of polysiloxane, polyurethane, polybutadine rubber, and combinations thereof, has a Shore A hardness between 30 and 45, has a refractive index between 1.45 and 1.47, and has a radius of between 150 and 200 micrometers;

wherein the cladding has a Shore A durometer of between 45 and 55 and has a refractive index between 1.39 and 1.41; and

wherein the waveguide has an NA of between 0.35 and 0.4.