Plasma sterilization system and methods

Patent metadata

Field	Value
Publication number	US-10933151-B2
Application number	US-201716307302-A
Country	US
Kind code	B2
Filing date	Jun 29, 2017
Priority date	Jun 30, 2016
Publication date	Mar 2, 2021
Grant date	Mar 2, 2021

Abstract

A system and methods for sterilizing or disinfecting articles, particularly the hollow internal areas of medical instruments are disclosed. The system includes a plasma generator having an electrode, a shield, and a dielectric gap between the electrode and the shield. A source of electrical power is connected to the plasma generator for applying an electron energy density between the electrode and the shield. A source of gas comprising water vapor, oxygen and nitrogen provides a flow of gas between the electrode and the shield, to form a plasma containing acidic and/or oxidizing species. In the exemplary system, the temperature at the shield's surface is <150° C. when the electron energy density is >0.05 eV/molecule of the gas. Also disclosed is a method for disinfecting an article contaminated with a bio-film or spores, by exposing the contaminated article to the plasma for an exposure time sufficient to achieve at least 2-log10 reduction in colony forming units.

First claim

The invention claimed is:

1. A system, comprising:
a plasma generator including:
an electrode,
a shield, and
a dielectric gap between the electrode and the shield;

a source of electrical power connected to the plasma generator, for applying an electrode energy density between the electrode and the shield;
a source of a gas comprising water vapor, oxygen, and nitrogen, configured to provide a flow of the gas through the plasma generator between the electrode and the shield to form a plasma containing acidic species from the gas; and
a filter for removing the acidic species from the gas, wherein the filter comprises one or more adsorbent or absorbent materials selected from activated carbon, a chemical species with a basic functionality, a basic ion exchange resin, a reducing species selected from one or more active metals selected from platinum and palladium; and a molecular sieve,

wherein a temperature at the surface of the shield is maintained at less than 150° C. when the electrode energy density is greater than 0.05 eV/molecule of the gas passing between the electrode and the shield, optionally wherein the system further comprises a device for conveying an article undergoing sterilization through a chamber fluently connected to the flow of the gas through the plasma generator containing the acidic and/or oxidizing species.

2. The system of claim 1 , wherein the gas includes one or more species selected from the group consisting of molecular oxygen, molecular nitrogen, nitric oxide, nitric acid, and nitrous oxide.

3. The system of claim 2 , wherein the gas comprises air, optionally wherein a relative humidity of the gas entering the plasma generator is at least 21%.

4. The system of claim 1 , further comprising a cooling apparatus.

5. A method of sterilizing a contaminated article, comprising:
providing a sterilizer including:
a plasma generator having:
an electrode,
a shield, and
a dielectric gap between the electrode and the shield;
a source of electrical power connected to the plasma generator for applying

an electrode energy density between the electrode and the shield; and
a source of a gas comprising water vapor, oxygen, and nitrogen, configured

to provide a flow of the gas through the plasma generator between the electrode and the shield to form a plasma containing acidic and/or oxidizing species from the gas;

providing the flow of the gas through the plasma generator between the electrode and the shield to form the plasma containing the acidic and/or oxidizing species from the gas, wherein a temperature at the surface of the shield is maintained at less than 150° C. when the electrode energy density is greater than 0.05 eV/molecule of the gas passing between the electrode and the shield;
directing the gas containing the acidic and/or oxidizing species from the plasma generator into an enclosed area enclosing at least a portion of the article undergoing sterilization to achieve a desired degree of sterilization of the article; and
exposing the contaminated article to the gas containing the acidic and/or oxidizing species for a time sufficient to sterilize the contaminated article, optionally wherein the time sufficient to sterilize the article is no greater than one hour.

6. The method of claim 5 , further comprising removing at least a portion of the acidic and/or oxidizing species from the gas upon achieving the desired degree of sterilization of the article.

7. The method of claim 6 , wherein the removing at least a portion of the acidic and/or oxidizing species from the gas is performed with an apparatus comprising one or more materials selected from the group consisting of activated carbon, a species with a basic functionality, a species providing a basic adsorbent, a reducing species, and a molecular sieve.

8. The method of claim 5 , wherein the enclosed area is a sterilization chamber.

9. The method of claim 5 , wherein the article undergoing sterilization is a medical device and the enclosed area is a hollow area of the medical device.

10. The method of claim 9 , wherein the medical device is an endoscope and the hollow area is a lumen of the endoscope, further wherein the gas containing the acidic and/or oxidizing species from the plasma generator is passed through the lumen of the endoscope.

11. The method of claim 9 , wherein the medical device is a medical instrument and the hollow area is at least one internal cavity of the medical instrument.

12. The method of claim 5 , wherein the gas includes one or species selected from the group consisting of molecular oxygen, molecular nitrogen, nitric oxide, nitric acid, and nitrous oxide.

13. A method of disinfecting a contaminated article, comprising:
providing a disinfecting system including:
a plasma generator having
an electrode,
a shield, and
a dielectric gap between the electrode and the shield,
a source of electrical power connected to the plasma generator for applying an electrode energy density between the electrode and the shield, and
a source of a gas comprising water vapor, oxygen, and nitrogen, configured to provide a flow of the gas through the plasma generator between the electrode and the shield to form a plasma containing acidic and/or oxidizing species from the gas, wherein the temperature at a surface of the shield is maintained at less than 150° C. when the electrode energy density is greater than 0.05 eV/molecule of the gas passing between the electrode and the shield,

providing the flow of the gas through the plasma generator between the electrode and the shield to form the plasma containing the acidic and/or oxidizing species from the gas;
directing the gas containing the acidic and/or oxidizing species from the plasma generator into an enclosed area enclosing at least a portion of the contaminated article, wherein the contaminated article is contaminated with at least one of a bio-film comprising a plurality of microorganisms, or a plurality of microbial or fungal spores; and
exposing the contaminated article to the gas containing the acidic and/or oxidizing species for an exposure time sufficient to disinfect the contaminated article by achieving at least a 2-log 10 and optionally up to an 11-log 10 reduction in colony forming units of the disinfected contaminated article relative to the contaminated article.

14. The method of claim 13 , wherein the contaminated article is a medical device and the enclosed area is a hollow area of the medical device.

15. The method of claim 14 , wherein the medical device is an endoscope and the hollow area is a lumen of the endoscope, further wherein the gas containing the acidic and/or oxidizing species from the plasma generator is passed through the lumen of the endoscope.

16. The method of claim 13 , wherein the bio-film comprises a plurality of microorganisms selected from the group consisting of Geobacillus stearothermophilus, Bacillus subtilis, Bacillus atrophaeus, Bacillus megaterium, Bacillus coagulans, Clostridium sporogenes, Bacillus pumilus, Aspergillus brasiliensis, Aspergillus oryzae, Aspergillus niger, Aspergillus nidulans, Aspergillus flavus, Clostridium difficile, Mycobacterium terrae, Mycobacterium tuberculosis, Mycobacterium bovis, Escherichia colt, Staphylococcus aureus, Pseudomonas aeruginosa, Staphylococcus epidermidis, Staphyolococcus lugdunensis, Staphylococcus saprophyticus, Enterococcus faecium, Enterococcus faecalis, Propionobacterium acnes, Klebsiella pneumoniae, Enterobacter cloacae, Proteus mirabilus, Salmonella enterica, Salmonella typhi, Shigella flexiniri , and combinations thereof.

Assignees

• 3M Innovative Properties Co

Inventors

• Nelson Caleb T
• Bennaars-Eiden Assumpta A G
• Scholz Matthew T
• Kohler Riedi Petra L
• Swanson Steven P
• Abadeer Nardine S

Classifications

• H05H1/2406 Primary

  using dielectric barrier discharges, i.e. with a dielectric interposed between the electrodes · CPC title

• H05H1/245

  the plasma being activated using internal electrodes · CPC title

• H05H2245/36

  Sterilisation of objects, liquids, volumes or surfaces · CPC title

• A61L2/14 Primary

  Plasma, i.e. ionised gases · CPC title

• H05H2245/1225

  Electricity · mapped topic