Coated fiber optic sensor for the detection of substances
First Claim
1. A method for detecting the presence or absence of a particular substance in an environment, the method comprising the steps of:
- providing a fiber optic guide having at least at some point along its length between a first end and a second end a coating that has an index of refraction greater than the index of refraction of the fiber optic guide, the coating having a composition such that it at least partially degrades in the presence of a substance to be detected such that the amount of coating on the fiber optic guide decreases;
transmitting light through the first end of the fiber optic guide;
detecting light from the second end of the fiber optic guide, the step of detecting light including the step of detecting an increase in the intensity of light at the second end when the presence of the substance to be detected is brought into contact with the fiber optic guide.
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Accused Products
Abstract
The present invention provides methods and apparatus for inexpensively and accurately sensing with the use of a fiber optic guide the presence or absence of a particular substance ("analyte"). The preferred embodiment of the sensor of the present invention comprises a light source, a photodetector, and a loop shaped plastic fiber that is exposed to the environment and that acts as a sensing element. In the preferred embodiment, the fiber optic guide comprises a core and a cladding, either of which are coated with a coating that is selected to at least partially degrade in the presence of the analyte. The coating is selected to have an index of refraction below that of the core but sufficiently large to allow at least some light to escape from the core even in the absence of the analyte. A decrease in the amount of light is detected when the analyte is present. Alternatively, the coating is selected to have an index of refraction just above or greater than the core, causing an increase in the amount of light that is detected when the analyte is present.
68 Citations
19 Claims
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1. A method for detecting the presence or absence of a particular substance in an environment, the method comprising the steps of:
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providing a fiber optic guide having at least at some point along its length between a first end and a second end a coating that has an index of refraction greater than the index of refraction of the fiber optic guide, the coating having a composition such that it at least partially degrades in the presence of a substance to be detected such that the amount of coating on the fiber optic guide decreases; transmitting light through the first end of the fiber optic guide; detecting light from the second end of the fiber optic guide, the step of detecting light including the step of detecting an increase in the intensity of light at the second end when the presence of the substance to be detected is brought into contact with the fiber optic guide. - View Dependent Claims (2, 3, 4, 5)
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6. A method for detecting the presence or absence of a particular substance in an environment, the method comprising the steps of:
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providing a fiber optic guide having at least at some point along its length between a first end and a second end a coating that has an index of refraction different than the index of refraction of a portion of the environment, the coating having a composition such that it degrades more in the absence of a substance to be detected than in the presence of the substance to be detected; transmitting light through the first end of the fiber optic guide; detecting light from the second end of the fiber optic guide, the step of detecting light including the step of detecting an intensity of light at the second end, the intensity detected being different if the substance to be detected is not brought into contact with the coating compared to the intensity detected if the substance to be detected is brought into contact with the coating. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. A method for detecting the presence or absence of a particular substance in an environment, the method comprising the steps of:
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providing a fiber optic guide having at least at some point along its length between a first end and a second end a coating that has an index of refraction less than the fiber optic guide, the coating having a composition such that it at least partially degrades in the presence of a substance to be detected such that the amount of coating on the fiber optic guide decreases; transmitting light through the first end of the fiber optic guide, at least some of the light passing through the coating and into the environment when the substance to be detected is not present in the environment; detecting light from a second end of the fiber optic guide, the step of detecting light including the step of detecting a decrease in the intensity of light at the second end when the substance to be detected is introduced into the environment. - View Dependent Claims (14)
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15. A method for detecting the presence or absence of a particular substance in an environment, the method comprising the steps of:
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providing a fiber optic guide having at least at some point along its length between a first end and a second end a coating comprising a first material, the coating being covered with a selectively permeable material such that the flux of the first material through the covering depends on whether a substance to be detected is brought into contact with the coating; transmitting light through the first end of the fiber optic guide; detecting light from the second end of the fiber optic guide, the step of detecting light including the step of detecting an intensity of light at the second end, the intensity detected being different if the substance to be detected is not brought into contact with the coating compared to the intensity detected if the substance to be detected is brought into contact with the coating. - View Dependent Claims (16, 17, 18, 19)
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Specification