Moisture sensor

• US 5,036,704 A
• Filed: 03/23/1990
• Issued: 08/06/1991
• Est. Priority Date: 03/23/1990
• Status: Expired due to Fees

• Current Assignee: Gas Research Institute (GTI Energy)
• Original Assignee: Gas Research Institute (GTI Energy)
• Inventors: Zuercher, Joseph C., Pusatcioglu, Selami Y., Lewis, Edward G.
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): Roskos, Joseph W.
• Application Number:
  US07/498,306
• Time in Patent Office: 501 Days
• Field of Search: 73/336.5, 73/29.05, 338/34, 338/35
• US Class Current: 73/335.02
• CPC Class Codes: G01N 27/121 for determining moisture content, e.g. humidity, of the fluid moisture content of the tested material G01N27/048
• CPC Class Codes: G01N 27/126 comprising organic polymers
• CPC Class Codes: G01N 27/225 by using hygroscopic materials
• CPC Class Codes: G05D 22/02 characterised by the use of electric means

Abstract

A moisture sensor (100) is provided that utilizes a sulfonated fluorocarbon film (10) having a thickness of less than about one micron and capable of providing accurate measurements of humidity and extremely fast response to change in humidity. A preferred embodiment of an electrical system (150) is disclosed for use with sensor (100) and a sulfonated tetrafluoroethylene perfluoroether copolymer form of the film is especially preferred.

Claims

1. A moisture sensor comprising a sulfonated tetrafluorethylene perfluoroether copolymer film having a thickness of less than about one micron, at least one pair of spaced-apart electrical conductors disposed in electrical contacting engagement with the film, and means for supporting the film and the electrodes, said film operative to affect an electrical input signal of predetermined type received through the conductors thereby and to provide an electrical output signal therefrom that varies according to the moisture content thereof.

2. A moisture sensing system comprising, a moisture sensor, said sensor comprising a sulfonated fluorocarbon film having a thickness or less than about one micron, at least one pair of spaced-apart electrical conductors disposed in electrical contacting engagement with the film, means for supporting the film and the conductors, said film operative to affect an electrical current input signal of predetermined type received through the conductors thereby and to provide an electrical current output signal, that varies according to the moisture content thereof, means for providing the electrical current input signal and means for processing the electrical current output signal to a condition effective to provide preselected electrical characteristics desired, said processing means including:

means for converting the output current signal to an electrical voltage signal, means for filtering the voltage signal to as to only pass a voltage signal that is below a predetermined value, and means for amplifying the passed voltage signal to a desired level.

3. The sensor of claim 2 wherein the electrical input signal is an electrical current input signal, the unprocessed electrical output signal is an processed electrical current output signal and the processing means includes;

means for converting the output current signal to an electrical voltage signal, means for filtering the rectified voltage signal so as to only pass a voltage signal that is below a predetermined value, and means for amplifying the passed voltage signal to a desired level.

4. The system of claim 2 including means for displaying the amplified voltage signal.

5. The system of claim 2 wherein the electrical input signal is provided by an alternating electrical current sine wave oscillator at a predetermined frequency.

6. The system of claim 2 including means for compensating the filtered voltage signal for temperature.

7. The system of claim 2 to wherein the amplifier is a logarithmic amplifier.