Fluoropolymer humidity sensors

• US 5,045,828 A
• Filed: 07/27/1989
• Issued: 09/03/1991
• Est. Priority Date: 07/27/1989
• Status: Expired due to Fees

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: McGovern, Robert T., Kulwicki, Bernard M., Conlan, Thomas C.
• Primary Examiner(s): Lateef, Marvin M.
• Application Number:
  US07/386,335
• Time in Patent Office: 768 Days
• Field of Search: 338/34, 338/35, 428/421, 73/29.01, 73/29.02, 73/335, 73/336, 73/336.5, 73/337, 73/73, 204/280, 204/412, 204/415, 204/430, 55/158
• US Class Current: 338/35
• 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: Y10T 428/3154 Of fluorinated addition polymer from unsaturated monomers

Abstract

A humidity sensor composed of interdigitated electrodes and a material therebetween which is composed of perfluorosulfonic acid substituted poly (tetrafluoroethylene) copolymer wherein H+ sites have undergone ion exchange with at least one of NH4+ and Li+, Na+, Ag+ and Mg+.

Claims

1. A humidity sensor comprising:

(a) a substrate having an electrically insulative surface,

(b) a pair of spaced electrodes on said surface; and

(c) a film having a thickness of approximately 5 microns or less on said surface interconnecting said electrodes, said film comprising;

the reaction product of polytetrafluorethylene with ionogenic grouping appended thereto and an aqueous solution of a compound taken from the class consisting of lithium compounds, ammonium compounds, sodium compounds, silver compounds, magnesium compounds and combinations thereof.

2. The humidity sensor of claim 1 wherein said lithium compounds are taken from the class consisting of lithium chloride, lithium hydroxide, lithium acetate and lithium citrate.

3. The humidity sensor of claim 1 wherein said ammonium compounds are taken from the class consisting of ammonium chloride, ammonium hydroxide, ammonium acetate and ammonium citrate.

4. The humidity sensor of claim 2 wherein said ammonium compounds are taken from the class consisting of ammonium chloride, ammonium hydroxide, ammonium acetate and ammonium citrate.

5. A humidity sensor comprising:

(a) a substrate having an electrically insulative surface,

(b) a pair of spaced electrodes on said surface; and

(c) a film on said surface interconnecting said electrodes, said film comprising;

the reaction product of polytetrafluoroethylene with ionogenic grouping appended thereto and an aqueous solution of an ammonium compound taken from the class consisting of ammonium chloride, ammonium hydroxide, ammonium acetate and ammonium citrate and a lithium compound taken from the class consisting of lithium chloride, lithium hydroxide, lithium acetate and lithium citrate.