HIGH-SPEED RESPONSE/HIGH-SENSITIVITY DRYNESS/WETNESS RESPONSIVE SENSOR

• US 20170167995A1
• Filed: 07/21/2015
• Published: 06/15/2017
• Est. Priority Date: 07/23/2014
• Status: Active Application

• Current Assignee: National Institute for Materials Science
• Original Assignee: National Institute for Materials Science
• Inventors: KAWAKITA, Jin, SHINOHARA, Tadashi, CHIKYO, Toyohiro, NABATAME, Toshihide, OHI, Akihiko, OHKI, Tomoko
• Granted Patent: US 10,267,756 B2
• Time in Patent Office: Days
• CPC Class Codes: G01N 17/00 Investigating resistance of materials to the weather, to corrosion, or to light
• CPC Class Codes: G01N 17/04 Corrosion probes
• CPC Class Codes: G01N 27/045 Circuits measuring resistance per se G01R27/00, e.g. G01R27/22
• CPC Class Codes: G01N 27/048 for determining moisture content of the material
• 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 27/223 for determining moisture content, e.g. humidity rain detectors on vehicle windows B60S1/0825
• CPC Class Codes: G01N 27/4035 Combination of a single ion-sensing electrode and a single reference electrode G01N27/406 and G01N27/413 take precedence

Abstract

The present invention improves the sensitivity and the responsiveness of a dryness/wetness responsive sensor utilizing a galvanic current, allowing for downsizing of the dryness/wetness responsive sensor. Instead of the conventional structure in which an anode electrode and a cathode electrode are stacked with an intervening insulator, the present invention employs a structure in which both electrodes run in juxtaposition with each other on an insulating substrate in the form of, for example, a comb-shaped electrode as shown in the drawing. By utilizing a semiconductor manufacturing process or any other micro/nano-fabrication technology, an inter-electrode distance can be extremely shortened as compared with the conventional sensors, allowing enhancing the sensitivity per unit footprint of the electrodes. Accordingly, a decrease in the size of the dryness/wetness responsive sensor can be easily achieved.

Claims

1. A dryness/wetness responsive sensor comprising

a thin wire of a first metal, and

a thin wire of a second metal, the second metal being different from the first metal,

wherein the thin wire of the first metal and the thin wire of the second metal are disposed in juxtaposition with each other on an insulating substrate,

wherein a spacing between the first thin wire and the second thin wire is in a range of 5 nm or more and less than 20 μ

m, and

wherein existence of water across the thin wire of the first metal and the thin wire of the second metal causes an electromotive force thereacross that allows galvanic current to flow.

2. The dryness/wetness responsive sensor according to claim 1,

wherein a plurality of instances are provided for at least one of the thin wire of the first metal and the thin wire of the second metal, and

wherein the thin wire of the first metal and the thin wire of the second metal extend from mutually opposite sides toward the other sides so as to run in parallel.

3. The dryness/wetness responsive sensor according to claim 1, wherein the thin wire of the first metal and the thin wire of the second metal are arranged in a double spiral.

4. The dryness/wetness responsive sensor according to claim 1, wherein the insulating substrate is a silicon substrate with a silicon oxide film on its surface.

5. The dryness/wetness responsive sensor according to claim 1, wherein the first metal is selected from a group consisting of gold, platinum, silver, titanium, an alloy thereof, and carbon.

6. The dryness/wetness responsive sensor according to claim 1, wherein the second metal is selected from a group consisting of silver, copper, iron, zinc, nickel, cobalt, aluminum, tin, chromium, molybdenum, manganese, magnesium, and an alloy thereof.

7. The dryness/wetness responsive sensor according to claim 1, further comprising a meshed member covering an area in which the thin wire of the first metal and the thin wire of the second metal are disposed in juxtaposition with each other.

8. The dryness/wetness responsive sensor according to claim 1, further comprising an insulating protection film covering an area in which the thin wire of the first metal and the thin wire of the second metal are disposed in juxtaposition with each other,

wherein the insulating protection film has a groove-shaped opening that exposes at least a part of the thin wires.

9. The dryness/wetness responsive sensor according to claim 8, further comprising a groove-shape opening that exposes at least a part of a gap between the thin wire of the first metal and the thin wire of the second metal.

10. The dryness/wetness responsive sensor according to claim 1, comprising an opening portion passing through between front and rear sides of the insulating substrate by removing at least a part of a position of the insulating substrate corresponding to a gap between the thin wire of the first metal and the thin wire of the second metal.

11. A dryness/wetness responsive sensor assembly for remote installation comprising an attachment member with an attachment portion at one end for attachment to an object to which the dryness/wetness responsive sensor according to claim 1 is attached so as to allow the dryness/wetness responsive sensor to be remotely located.

12. A dryness/wetness responsive sensor system comprising a plurality of the dryness/wetness responsive sensors according to claim 1, wherein the dryness/wetness responsive sensor in the system in which a short circuit has occurred or which does not generate an output current is disconnected.

13. The dryness/wetness responsive sensor system according to claim 12, wherein the disconnection of the dryness/wetness responsive sensor is performed by electrically disconnecting the dryness/wetness responsive sensor or not using an output of the dryness/wetness responsive sensor.