Humidity sensor element, device and method for manufacturing thereof

• US 20050081625A1
• Filed: 06/03/2004
• Published: 04/21/2005
• Est. Priority Date: 10/21/2003
• Status: Active Grant

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Sun, Yi Lu, Su, Pi Guey, Chen, Hui Wen, Wu, Ren Jang
• Granted Patent: US 7,270,002 B2
• Time in Patent Office: Days
• US Class Current: 73/335.20
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: G01N 2291/014 Resonance or resonant frequency
• CPC Class Codes: G01N 2291/0255 (Bio)chemical reactions, e.g. on biosensors
• CPC Class Codes: G01N 2291/0256 Adsorption, desorption, surface mass change, e.g. on biosensors
• CPC Class Codes: G01N 2291/02845 Humidity, wetness
• CPC Class Codes: G01N 2291/0426 Bulk waves, e.g. quartz crystal microbalance, torsional waves
• CPC Class Codes: G01N 29/022 Fluid sensors based on microsensors, e.g. quartz crystal-microbalance [QCM], surface acoustic wave [SAW] devices, tuning forks, cantilevers, flexural plate wave [FPW] devices microdevices per se B81B
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49007 Indicating transducer

Abstract

A humidity sensor element, a humidity sensor device and a method for manufacturing thereof are provided. The humidity sensor element includes a substrate having a nanocomposite film as sensing material, wherein said nanocomposite film consists of carbon nanotube/perfluorinated polymer with acid functional groups in weight ratio of 0.01-20; and at least a pair of electrodes, which contact with the sensing material at one or both side(s). The nanocomposite film increases the sensitivity of humidity sensor element such that even an infinitesimal amount of moisture can be detected with minimum detection limit of 15.76 ppm_v

Claims

1. A humidity sensor element, comprising:

a substrate having a nanocomposite film containing carbon nanotube and perfluorinated polymer with acid functional group as sensing material; and

at least a pair of electrodes which contact with said sensing material at one or both side(s);

wherein the mixing ratio of carbon nanotube to perfluorinated polymer with acid functional groups is 0.01-20 by weight.

2. The humidity sensor element according to claim 1, wherein said carbon nanotube is single-walled carbon nanotube.

3. The humidity sensor element according to claim 1, wherein said acid functional group is sulphonic group or carboxyl group.

4. The humidity sensor element according to claim 1, wherein said perfluorinated polymer with acid functional group is perfluorinated sulphonic acid type ion exchange resin.

5. The humidity sensor element according to claim 1, wherein said electrode is selected from gold, silver, platinum or nickel cadmium alloy.

6. The humidity sensor element according to claim 1, wherein said substrate is any inert material that does not react with nanocomposite material, comprising silicon material, ceramic material or plastic material.

7. The humidity sensor element according to claim 1, wherein said humidity sensor element can be further arranged with testing chamber, electron oscillator circuit, and frequency calculator to form a humidity sensor device.

8. A humidity sensor device, comprising:

a humidity sensor element containing a substrate having a nanocomposite film containing carbon nanotube and perfluorinated polymer with acid functional group as sensing material and at least a pair of electrodes, wherein the mixing ratio of carbon nanotube to perfluorinated polymer with acid functional groups is 0.01-20 by weight, and said electrodes contact with said sensing material at one or both side(s);

a testing chamber, wherein said humidity sensor element is disposed therein;

an electron oscillator circuit, which provides oscillating electric field to the humidity sensor element to produce mechanical oscillation; and

a frequency calculator, which can measure the oscillation frequency change of said humidity sensor element.

9. The humidity sensor device according to claim 8, wherein said carbon nanotube is single-walled carbon nanotube.

10. The humidity sensor device according to claim 8, wherein said acid functional group is sulphonic group or carboxyl group.

11. The humidity sensor device according to claim 8, wherein said perfluorinated polymer with acid functional group is perfluorinated sulphonic acid type ion exchange resin.

12. The humidity sensor device according to claim 8, wherein said electrode is selected from gold, silver, platinum or nickel cadmium alloy.

13. The humidity sensor device according to claim 8, wherein said substrate comprises AT-cut quartz crystal, ST-cut quartz crystal, T-cut quartz crystal, or XT-cut quartz crystal.

14. A method for manufacturing humidity sensor element, comprising the steps of:

providing a substrate;

disposing at least a pair of electrodes on said substrate;

mixing carbon nanotube and perfluorinated polymer solution with acid functional groups;

coating said nanotube/perfluorinated polymer mixture solution on said electrodes by means of spin-coating method; and

drying said mixture solution to form a humidity sensor element having a nanocomposite film.

15. The method according to claim 14, wherein said carbon nanotube is single-walled carbon nanotube.

16. The method according to claim 14, wherein said acid functional group is sulphonic group or carboxyl group.

17. The method according to claim 14, wherein said perfluorinated polymer with acid functional group is perfluorinated sulphonic acid type ion exchange resin.

18. The method according to claim 14, wherein the mixing ratio of carbon nanotube to perfluorinated polymer with acid functional groups is 0.01-20 by weight.

19. The method according to claim 14, wherein said electrode is selected from gold, silver, platinum or nickel cadmium alloy.

20. The method according to claim 14, wherein said substrate is any inert material that does not react with nanocomposite material, comprising silicon material, ceramic material or plastic material.