Capacitive gas sensor

Patent metadata

Field	Value
Publication number	US-11287395-B2
Application number	US-201716331701-A
Country	US
Kind code	B2
Filing date	Sep 8, 2017
Priority date	Sep 9, 2016
Publication date	Mar 29, 2022
Grant date	Mar 29, 2022

Abstract

A capacitive gas sensor in which a second electrode layer made of a nano-carbon material entangled to be three-dimensionally reticulated and a gas-sensitive film are not separated from each other. A capacitive gas sensor includes a substrate; a first electrode layer formed on the substrate; a gas-sensitive film formed on the first electrode layer and having air permeability; and a second electrode layer formed on the gas-sensitive film to be opposed to the first electrode layer and made of a nano-carbon material entangled to be three-dimensionally reticulated. The capacitive gas sensor also includes a reinforcing resin layer having air permeability and disposed at least on the second electrode layer.

First claim

The invention claimed is:

1. A capacitive gas sensor comprising:
a substrate;
a first electrode layer formed on the substrate;
a gas-sensitive film formed on the first electrode layer and having air permeability, the gas-sensitive film varying in capacitance according to a change in humidity and having hydrophilic properties;
a second electrode layer formed on the gas-sensitive film to be opposed to the first electrode layer and made of a nano-carbon material entangled to be three-dimensionally reticulated; and
a reinforcing resin layer having air-permeability, made of a same material as the gas-sensitive film, varying in capacitance according to a change in humidity and having hydrophilic properties, and disposed at least on the second electrode layer,
wherein the material of the reinforcing resin layer gets into voids in the nano-carbon material of the second electrode layer that is entangled to be three-dimensionally reticulated, and a part of the reinforcing resin layer directly contacts the gas-sensitive film; and
wherein both the gas-sensitive film and the reinforcing resin layer are made of fluorinated polyimide.

2. The capacitive gas sensor according to claim 1 , wherein the reinforcing resin layer is present only on the second electrode layer.

3. The capacitive gas sensor according to claim 1 , wherein:
the second electrode layer is sized such that a part of the gas-sensitive film extends out around the second electrode layer; and
the reinforcing resin layer having air permeability covers the second electrode layer and at least a part of the gas-sensitive film that extends out of the second electrode layer.

4. The capacitive gas sensor according to claim 1 , wherein:
the reinforcing resin layer is 2 μm or less in thickness.

5. The capacitive gas sensor according to claim 1 , wherein the nano-carbon material is composed of one or more sorts selected from SWCNT, MWCNT, DWCNT, and graphene.

6. The capacitive gas sensor according to claim 1 , wherein:
at least one first electrode portion is formed on the substrate to connect to the first electrode layer and at least one second electrode portion is formed on the substrate to connect to the second electrode layer;
the gas-sensitive film is formed on the substrate to cover the first electrode layer and to expose the at least one first electrode portion and the at least one second electrode portion; and
the second electrode layer, the at least one second electrode portion, and the gas-sensitive film are electrically connected to each other via an electrically conductive through-hole portion.

7. The capacitive gas sensor according to claim 1 , wherein:
a pair of electrode portions are formed on the substrate such that the pair of electrode portions are overlaid respectively on both ends of the second electrode layer for electrical connection; and
the reinforcing resin layer is shaped and sized to cover the both ends of the second electrode layer and a part of the pair of electrode portions.

8. The capacitive gas sensor according to claim 2 ,
wherein the nano-carbon material is composed of one or more sorts selected from SWCNT, MWCNT, DWCNT, and graphene.

9. A capacitive gas sensor comprising:
a substrate;
a first electrode layer formed on the substrate;
a gas-sensitive film formed on the first electrode layer and having air permeability, the gas-sensitive film varying in capacitance according to a change in humidity and having hydrophilic properties;
two second electrode layers formed on the gas-sensitive film to be opposed to the first electrode layer and made of a nano-carbon material entangled to be three-dimensionally reticulated; and
a reinforcing resin layer having air permeability, made of a same material as the gas-sensitive film, and varying in capacitance according to a change in humidity and having hydrophilic properties;

wherein:
the two second electrode layers are formed at an interval on the gas-sensitive film to cross the first electrode layer;
the two second electrode layers are sized in width such that a part of the gas-sensitive film extends out around the two second electrode layers;
the reinforcing resin layer covers the two second electrode layers and at least a part of the gas-sensitive film that extends out of the two second electrode layers;
the material of the reinforcing resin layer gets into voids in the nano-carbon material of the second electrode layer that is entangled to be three-dimensionally reticulated, and a part of the reinforcing resin layer directly contacts the gas-sensitive film; and
both the gas-sensitive film and the reinforcing resin layer are made of fluorinated polyimide.

Assignees

• Hokuriku Elect Ind
• Univ Shinshu
• Shinshu Universtiy

Inventors

• Itoh Eiji
• Yamaguchi Yoshinori
• Nishida Tatsuya
• Matsubara Kousuke

Classifications

• G01N27/22 Primary

  by investigating capacitance · CPC title

• G01N2027/222

  for analysing gases · CPC title

• G01N27/223

  for determining moisture content, e.g. humidity (rain detectors on vehicle windows B60S1/0825) · CPC title

• G01N27/226 Primary

  Construction of measuring vessels; Electrodes therefor · CPC title