Moisture sensor based on evanescent wave light scattering by porous sol-gel silica coating
First Claim
1. A method for preparing an optical fiber for use as a transducer in a moisture sensor, comprising the steps of:
- (a) polishing the two ends of an optical fiber;
(b) applying a heat source to a portion of said optical fiber in order to remove the cladding layer of said portion;
(c) soaking said portion of said optical fiber in a first solution in order to wash off any organic material possibly sticking on the surface of said portion of said optical fiber;
(d) soaking said portion of said optical fiber in a second solution until the surface hydroxyl groups of said portion are activated; and
(e) coating at least said portion of said optical fiber with a porous sol-gel silica solution.
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Abstract
An optical fiber moisture sensor that can be used to sense moisture present in gas phase in a wide range of concentrations is provided, as well techniques for making the same. The present invention includes a method that utilizes the light scattering phenomenon which occurs in a porous sol-gel silica by coating an optical fiber core with such silica. Thus, a porous sol-gel silica polymer coated on an optical fiber core forms the transducer of an optical fiber moisture sensor according to an embodiment. The resulting optical fiber sensor of the present invention can be used in various applications, including to sense moisture content in indoor/outdoor air, soil, concrete, and low/high temperature gas streams.
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Citations
20 Claims
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1. A method for preparing an optical fiber for use as a transducer in a moisture sensor, comprising the steps of:
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(a) polishing the two ends of an optical fiber; (b) applying a heat source to a portion of said optical fiber in order to remove the cladding layer of said portion; (c) soaking said portion of said optical fiber in a first solution in order to wash off any organic material possibly sticking on the surface of said portion of said optical fiber; (d) soaking said portion of said optical fiber in a second solution until the surface hydroxyl groups of said portion are activated; and (e) coating at least said portion of said optical fiber with a porous sol-gel silica solution. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification