Fiber optic moisture sensor

• US 5,440,927 A
• Filed: 02/25/1994
• Issued: 08/15/1995
• Est. Priority Date: 07/16/1992
• Status: Expired due to Fees

• Current Assignee: Rutgers University
• Original Assignee: Rutgers University
• Inventors: Pedersen, Henrik, Chu, Ling
• Primary Examiner(s): Raevis, Robert
• Assistant Examiner(s): Brock, Michael J.
• Application Number:
  US08/201,820
• Time in Patent Office: 536 Days
• Field of Search: 73/335.01, 73/29.05, 73/29.01, 250/361 R, 250/362, 250/363.01, 250/365, 250/458.1, 250/461.1, 250/573, 250/372, 422/88, 422/91
• US Class Current: 73/335.01
• CPC Class Codes: G01N 2021/6432 Quenching
• CPC Class Codes: G01N 2021/6434 Optrodes
• CPC Class Codes: G01N 2021/7786 Fluorescence
• CPC Class Codes: G01N 21/643 non-biological material
• CPC Class Codes: G01N 21/81 Indicating humidity

Abstract

This invention provides for a fiber optic moisture sensor. The sensor is comprised of a housing and a support positioned within the housing. The support is coated with a film. A first and second light guides are positioned within the housing and communicate illumination to and from the film. A reflective surface is positioned within the housing facing the film. The film comprises an optically transparent polymer and a salt complex of a metal ion and an organic compound. The salt complex is capable of absorbing moisture and emits a fluorescence signal when excited by light at the appropriate wavelength. The fluorescence signal can be quenched when the salt complex absorbs moisture. An apparatus incorporating the sensor and a method of making the sensor are also provided.

Claims

1. A method for the measurement of the level of moisture in a gaseous phase utilizing an optical sensor, said sensor comprising a film of a polymer, said polymer having embedded therein a predetermined amount of a salt complex of a metal ion and an organic compound, wherein said salt complex emits fluorescence within a determined wavelength range, said polymer optically transparent in said wavelength range, and wherein said salt complex absorbs the moisture in said gaseous phase, the fluorescence emission being sensitive to quenching by said moisture, said method comprising the steps of:

contacting said optically transparent polymer with said gaseous phase;

introducing excitation light into the distal end of a first optical fiber and communicating said excitation light to said polymer through the proximal end of said first optical fiber to induce said fluorescence emission;

collecting said fluorescence emission into the proximal end of a second optical fiber;

detecting said fluorescence emission through the distal end of said second optical fiber;

measuring the quenching of said fluorescence emission; and

determining the level of moisture in said gaseous phase.