Amperometric gas sensor

• US 9,995,706 B2
• Filed: 09/30/2014
• Issued: 06/12/2018
• Est. Priority Date: 06/25/2012
• Status: Active Grant

• Current Assignee: Steris Corporation
• Original Assignee: Steris Corporation
• Inventors: Schenk, Elizabeth H., Burke, Peter A., Centanni, Michael A.
• Primary Examiner(s): Van, Luan V
• Assistant Examiner(s): Rosenwald, Steven E
• Application Number:
  US14/501,079
• Publication Number:
  US 20150021204A1
• Time in Patent Office: 1,351 Days
• Field of Search: 204411-429, 73 2331, 73 2332
• CPC Class Codes: A61L 2/202 Ozone
• CPC Class Codes: A61L 2/206 Ethylene oxide
• CPC Class Codes: A61L 2/208 Hydrogen peroxide
• CPC Class Codes: A61L 2/28 Devices for testing the effectiveness or completeness of sterilisation, e.g. indicators which change colour apparatus involving enzymes or microorganisms C12M1/34; methods involving enzymes or microorganisms C12Q1/00
• CPC Class Codes: A61L 2202/14 Means for controlling sterilisation processes, data processing, presentation and storage means, e.g. sensors, controllers, programs
• CPC Class Codes: G01N 27/126 comprising organic polymers
• CPC Class Codes: G01N 27/30 Electrodes, e.g. test electrodes; Half-cells G01N27/414 takes precedence
• CPC Class Codes: G01N 27/301 Reference electrodes
• CPC Class Codes: G01N 27/3335 the membrane containing at least one organic component G01N27/3271 takes precedence; aspects concerning the enzyme reagent in enzyme electrodes C12Q1/001
• CPC Class Codes: G01N 27/4072 characterized by the diffusion barrier
• CPC Class Codes: G01N 27/4074 for detection of gases other than oxygen
• CPC Class Codes: G01N 27/4076 Reference electrodes or reference mixtures
• CPC Class Codes: G01N 33/0036 specially adapted to detect a particular component physical analysis of gaseous biological material G01N33/497

Abstract

The disclosed invention relates to an amperometric gas sensor for measuring the concentration of an analyte, comprising: a solid support; and a working electrode in contact with the solid support; wherein the analyte comprises a dopant which when in contact with the solid support increases the electrical conductivity of the solid support. A sterilization process employing the amperometric gas sensor is disclosed.

Claims

1. A method for determining a concentration of a sterilant gas in a vacuum chamber during a sterilization process using an amperometric gas sensor, the method comprising:

placing the amperometric gas sensor in the vacuum chamber, the amperometric gas sensor consisting essentially of;

a solid support configured as an insulator prior to being contacted by the sterilant gas and configured for diffusion of the sterilant gas therethrough, the solid support consisting essentially of one or more ionically and electrically non-conductive polymers and optionally one or more non-conductive fillers, the solid support further configured to increase in electrical conductivity when in contact with the sterilant gas;

a working electrode in contact with the solid support; and

a reference electrode positioned on and in contact with the solid support, the reference electrode spaced apart and ionically and electrically insulated from the working electrode prior to the solid support being contacted by the sterilant gas;

conducting the sterilization process in the vacuum chamber under a vacuum using the sterilant gas, where the sterilization process allows the sterilant gas to be carried into, through, and out of the vacuum chamber during a portion of the cycle, and

whereby the sterilant gas increases the electrical conductivity of the solid support; and

determining the concentration of the sterilant gas in the vacuum chamber using the amperometric gas sensor.

2. The method of claim 1 wherein the sterilant gas flows in the vacuum chamber and contacts the amperometric gas sensor.

3. The method of claim 1 wherein the sterilant gas is mixed with a carrier gas to form a gaseous mixture, and the gaseous mixture flows in the vacuum chamber and contacts the amperometric sensor.

4. The method of claim 1 wherein the method comprises injecting pulses of the sterilant gas into the vacuum chamber.

5. The method of claim 1 wherein the method comprises injecting pulses of a gaseous mixture comprising the sterilant gas and a carrier gas into the vacuum chamber.

6. The method of claim 1 wherein the pressure within the vacuum chamber is below atmospheric pressure.

7. The method of claim 1 wherein the temperature in the vacuum chamber is in the range from about 15 to about 90°

C.

8. The method of claim 1 wherein the sterilant gas comprises vaporous hydrogen peroxide, ethylene oxide, ozone, or a mixture of two or more thereof.

9. The method of claim 8 wherein the sterilant gas further comprises an alkaline gas.

10. The method of claim 1 wherein the sterilant gas comprises vaporous hydrogen peroxide and ammonia.

11. The method of claim 1 wherein an article to be sterilized is positioned in the vacuum chamber.

12. The method of claim 11 wherein the article to be sterilized contains one or more apertures, holes, tubes, open ended lumens, internal cavities, deadlegs, flat surfaces, or a combination of two or more thereof.

13. The method of claim 11 wherein the article to be sterilized comprises a medical and/or dental device.

14. The method of claim 11 wherein the article to be sterilized comprises an endoscope.

15. The method of claim 11 wherein the article to be sterilized is contaminated with a bacterial spore, vegetative bacteria, virus, mold, fungus, or a mixture of two or more thereof.

16. The method of claim 1 wherein the one or more ionically and electrically non-conductive polymers comprises poly (ethylene terephthalate), poly (ethylene oxide), polyvinylidenefluoride, polyethylene, polypropylene, polyethylene-napthlate, polyphenylenesulfide, polycarbonate, polytetrafluoroethylene, polypropylene oxide, acrylic resin, polystyrene, poly(styrene-acrylonitrile), poly(acrylnitrile-butadiene-styrene), polyvinyl chloride, chlorinated polyether, poly(chlorotrifluoro ethylene), or a mixture of two or more thereof.

17. The method of claim 1 wherein the one or more ionically and electrically non-conductive polymers comprises poly (ethylene terephthalate).

18. A method for determining a concentration of a sterilant gas in a vacuum chamber during a sterilization process using an amperometric gas sensor, the method comprising:

placing the amperometric gas sensor in the vacuum chamber, the amperometric gas sensor consisting essentially of;

a solid support configured as an insulator prior to being contacted by the sterilant gas and configured for diffusion of the sterilant gas therethrough, the solid support consisting essentially of one or more non-conductive polymers and optionally one or more non-conductive fillers, the solid support further configured to increase in electrical conductivity when in contact with the sterilant gas, the one or more non-conductive polymers comprising poly (ethylene terephthalate), poly (ethylene oxide), polyvinylidenefluoride, polyethylene, polypropylene, polyethylene-napthlate, polyphenylenesulfide, polycarbonate, polytetrafluoroethylene, polypropylene oxide, acrylic resin, polystyrene, poly(styrene-acrylonitrile), poly(acrylnitrile-butadiene-styrene), polyvinyl chloride, chlorinated polyether, poly(chlorotrifluoro ethylene), or a mixture of two or more thereof;

a working electrode in contact with the solid support; and

a reference electrode positioned on and in contact with the solid support, the reference electrode spaced apart and insulated from the working electrode prior to the solid support being contacted by the sterilant gas;

conducting the sterilization process in the vacuum chamber under a vacuum using the sterilant gas, where the sterilization process allows the sterilant gas to be carried into, through, and out of the vacuum chamber during a portion of the cycle, and

whereby the sterilant gas increases the electrical conductivity of the solid support; and

determining the concentration of the sterilant gas in the vacuum chamber using the amperometric gas sensor.

19. The method of claim 18 wherein the one or more non-conductive polymers comprises poly (ethylene terephthalate).