Variable capacitance sensors and methods of making the same

• US 9,018,060 B2
• Filed: 06/02/2011
• Issued: 04/28/2015
• Est. Priority Date: 06/15/2010
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Gryska, Stefan H., Palazzotto, Michael C.
• Primary Examiner(s): Sarkar, Asok K
• Application Number:
  US13/703,545
• Publication Number:
  US 20130088244A1
• Time in Patent Office: 1,426 Days
• Field of Search: 257/E21.351, 438/171, 438/190, 438/210, 438/239, 438/244, 438/250, 438/381, 438/393
• US Class Current: 438/250
• CPC Class Codes: G01N 27/223 for determining moisture content, e.g. humidity rain detectors on vehicle windows B60S1/0825
• CPC Class Codes: G01N 27/226 Construction of measuring vessels; Electrodes therefor
• CPC Class Codes: G01R 27/2605 Measuring capacitance capacitive sensors G01D5/24

Abstract

A variable capacitance sensor includes a first conductive electrode comprising electrically interconnected first conductive sheets; a second conductive electrode comprising electrically interconnected second conductive sheets, wherein the first conductive sheets are at least partially interleaved with the second conductive sheets, and wherein the second conductive electrode is electrically insulated from the first conductive electrode; and microporous dielectric material at least partially disposed between and contacting the first conductive sheets and the second conductive sheets. A method of making a variable capacitance sensor by replacing ceramic in a ceramic capacitor with a microporous material is also disclosed.

Claims

1. A variable capacitance sensor comprising:

a first conductive electrode comprising electrically interconnected first conductive sheets;

a second conductive electrode comprising electrically interconnected second conductive sheets, wherein the first conductive sheets are at least partially interleaved with the second conductive sheets, and wherein the second conductive electrode is electrically insulated from the first conductive electrode;

a ceramic material at least partially disposed between and contacting the first conductive sheets and the second conductive sheets; and

microporous dielectric material at least partially disposed between and contacting the first conductive sheets and the second conductive sheets.

2. The variable capacitance sensor of claim 1, wherein the microporous dielectric material comprises a polymer of intrinsic microporosity.

3. The variable capacitance sensor of claim 1, further comprising an encapsulant layer covering a portion of the first and second conductive electrodes.

4. A method of making a variable capacitance sensor, the method comprising steps:

a) providing a ceramic capacitor comprising;

a first conductive electrode comprising electrically interconnected first conductive sheets;

a second conductive electrode comprising electrically interconnected second conductive sheets, wherein the first conductive sheets are at least partially interleaved with the second conductive sheets, and wherein the second conductive electrode is electrically insulated from the first conductive electrode; and

ceramic material at least partially disposed between and contacting the first conductive sheets and the second conductive sheets; and

b) replacing at least a portion of the ceramic material with a microporous dielectric material, wherein the microporous dielectric material is at least partially disposed between and contacts the first conductive sheets and the second conductive sheets.

5. The method of claim 4, wherein step b) comprises:

etching away at least a portion of the ceramic material; and

applying the microporous dielectric material to replace at least a portion of the ceramic material removed by etching.

6. The method of claim 4, wherein substantially all of the ceramic material is replaced with the microporous dielectric material.

7. The method of claim 6, wherein step b) comprises:

etching away substantially all of the ceramic material; and

applying the microporous dielectric material to replace of the ceramic material removed by etching.

8. The method of claim 4, wherein the microporous dielectric material comprises a polymer of intrinsic microporosity.