Method and apparatus for ozone sterilization

• US 20070258855A1
• Filed: 10/31/2006
• Published: 11/08/2007
• Est. Priority Date: 04/30/1999
• Status: Active Grant

• Current Assignee: Stryker Corporation
• Original Assignee: TSO3 Inc (Stryker Corporation)
• Inventors: Dufrese, Sylvie, Turcot, Richard, Robitaille, Simon
• Granted Patent: US 7,588,720 B2
• Time in Patent Office: Days
• US Class Current: 422/33
• CPC Class Codes: A61L 2/202 Ozone
• CPC Class Codes: C01B 13/11 by electric discharge
• CPC Class Codes: C01B 2201/62 Air
• CPC Class Codes: C01B 2201/70 Cooling of the discharger; Means for making cooling unnecessary
• CPC Class Codes: C01B 2201/80 Additional processes occurring alongside the electrical discharges, e.g. catalytic processes
• CPC Class Codes: C01B 2201/90 Control of the process
• CPC Class Codes: Y10S 422/906 Plasma or ion generation means
• CPC Class Codes: Y10S 422/907 Corona or glow discharge means

Abstract

The present invention provides a method and apparatus for sterilizing articles using an ozone-containing gas, where condensation of water from the sterilization atmosphere during the sterilization process is substantially prevented. The inventive sterilization method includes providing a sterilization chamber and placing an article into the sterilization chamber. The sterilization chamber is sealed prior to equalizing the temperature of the article and the atmosphere in the sterilization chamber. A vacuum is applied to achieve a preselected vacuum pressure in the sterilization chamber. Once the vacuum pressure is set, water vapour is supplied to the sterilization chamber. Ozone-containing gas is then supplied to the sterilization chamber and the sterilization chamber remains sealed for a preselected treatment period, where the sterilization chamber remains sealed throughout the whole process. Finally, vacuum in the sterilization chamber is released.

Claims

1. A method for sterilizing an article in a sterilization gas atmosphere, comprising the steps of:

a) providing a sterilization chamber;

b) placing an article into the sterilization chamber;

c) sealing the sterilization chamber;

d) equalizing a temperature of the article and an atmosphere in the sterilization chamber while the chamber is sealed,

e) applying a vacuum of a preselected vacuum pressure to the sterilization chamber;

f) supplying water vapour to the sterilization chamber under vacuum;

g) supplying ozone-containing gas to the sterilization chamber;

h) maintaining the sterilization chamber sealed for a preselected treatment period; and

i) releasing the vacuum in the sterilization chamber, wherein the sterilization chamber remains sealed throughout the whole process.

2. The method of claim 1, wherein the equalizing step comprises equalizing the temperature of the article, the atmosphere in the sterilization chamber and any components and materials in contact with the atmosphere by evacuating the sealed sterilization chamber and re-circulating evacuated air into the chamber for a preselected period of time to equalize the temperature of the article with the temperature of the evacuated air.

3. The method of claim 1, wherein the equalization temperature in the sterilization chamber is between 25 to 60°

C.

4. The method of claim 3, wherein the equalization temperature in the sterilization chamber is between 25 to 35°

C.

5. The method of claim 3, wherein the equalization temperature in the sterilization chamber is between 40 to 60°

C.

6. The method of claim 1, wherein the vacuum pressure is between 0.1 and 10 mbar.

7. The method of claim 6, wherein the vacuum pressure is between 0.5 and 2 mbar.

8. The method of claim 1, wherein during step c) the temperature of the evacuated and recirculated air increases and the relative humidity of the evacuated air decreases.

9. The method of claim 1, wherein the amount of water vapour supplied is selected to achieve a level of humidity in the sterilization chamber of 85 to 100%.

10. The method of claim 7, wherein the amount of water vapour supplied is selected to achieve a level of humidity of at least 95%.

11. The method of claim 1, wherein the steps (c) to (g) are repeated at least once.

12. The method of claim 9, wherein the steps (c) to (g) are repeated a number of times sufficient to ensure complete sterilization of the article.

13. The method of claim 1, further comprising the step of passing all gases evacuated from the sterilization chamber through a means for destroying ozone to prevent emission of ozone to the atmosphere.

14. An apparatus for sterilization of an article, comprising

a sterilization chamber;

a means for sealing the sterilization chamber to ambient;

a means for equalizing the temperature of the sterilization chamber, any materials placed therein, and an atmosphere in the sterilization chamber by re-circulating the atmosphere;

a means for supplying ozone-containing gas to the sterilization chamber;

a means for supplying water vapour to the sterilization chamber; and

a means for applying a sufficient vacuum to the sterilization chamber to lower the boiling temperature of water below the temperature inside the sterilization chamber.

15. The apparatus of claim 14, wherein the means for equalizing include a vacuum pump for evacuating the atmosphere in the chamber and a recirculation valve for returning at least a portion of the evacuated atmosphere to the chamber.