WO2003059400A1

WO2003059400A1 - Chamber for ozone sanitation and sterilization of objects

Info

Publication number: WO2003059400A1
Application number: PCT/IL2003/000039
Authority: WO
Inventors: Uri Peiper; Yekutiel Alper
Original assignee: State Of Israel-Ministry Of Agriculture; Sterilion Ltd.
Priority date: 2002-01-16
Filing date: 2003-01-15
Publication date: 2003-07-24
Also published as: IL147671A0; AU2003208568A1

Abstract

The invention relates to a sealable chamber for ozone sanitation and sterilization of objects such as food, tools for surgery, laboratories, dentistry, veterinary and plant tissue etc. The chamber is based on producing the ozone within a closed and portable chamber, wherein the electrodes for ozone production are integrated with the structure of said improved chamber. The invention also relates to a method for sterilization of objects using the sealable chamber.

Description

CHAMBER FOR OZONE SANITATION AND STERILIZATION OF OBJECTS

FIELD OF THE INVENTION

The present invention relates, in general, to a chamber for sanitation and sterilization of objects. More specifically, the present invention relates to a sealable chamber for ozone sanitation and sterilization of objects such as food, tools for surgery, laboratories, dentistry, veterinary and plant tissue etc. The new chamber, according to the present invention, is based on producing the ozone within a closed and portable chamber, wherein the electrodes for ozone production are integrated with the structure of said improved chamber.

BACKGROUND OF THE INVENTION

Creation and maintenance of aseptic conditions is a very important requirement in many scientific medical and commercial activities. Sterilization of material, vessels and tools is an important task when these are to be used in biological or medical applications. Today, when the awareness of food safety, clean environment and clean work is higher, the importance of clean and sterile tools is trivial prerequisite when surgical equipment is concerned. Food products such as fruits, vegetables, and cereal, etc., can be made much safer for human consumption by reducing microorganism contamination. Food safety will also be enhanced by ozone sanitation of kitchen equipment, e.g., cutting boards and knives, both at home and in restaurants. Laboratories for medical work, or for biological research and development, need to function in sterile conditions. Any medical equipment has to be sterilized prior to its use. Dental and hairdressers tools may transfer sources of infection, and should therefore be sterilized every time before use. Vessels and tools for tissue culture work are often sterilized to provide an appropriate aseptic environment required for tissue culture applications. The plant tissue itself must also be sterilized before the propagation process can be started. Sterilization of medical tools such as endoscopes and other optical tools for medical examination imposes problems related to effective cleaning of the tools in a short period. The sterilization methods known today include heating, chemical disinfections, UV rays and nuclear radiation. Heating in autoclaves has been the most commonly used procedure because of its availability and application simplicity. However, high temperatures and pressures associated with steam autoclaving place very stringent property specifications on materials for vessels and tools. The sterilization of some materials by heat, particularly plastics, is very limited. Sterilization of devices, which include, optical and electronic components, which are not "autocalvable", is also problematic. Chemical sterilization techniques are commonly available, but these are usually limited by toxic residues, and require safety precautions for human laborers. Other difficulties that may be encountered with chemicals are special regulations for application and storage of potentially hazardous chemicals. In R&D laboratory work the chemical sterilization can also affect scientific experiments in an adverse way by its residual influence, mainly on biological matter. UV and other radiation techniques generally require special instruments and special care in usage. Nuclear radiation is very effective, but it can only be done in special installations. People are often reluctant to use it and it cannot be used to sterilize living plant material. Therefore "cold sterilization" techniques with minimal toxicity are highly desirable. One potential sterilization technology is ozone sterilization. Ozone acts as an environmentally sound alternative to other chemical disinfectants and has several advantages over other methods : no external chemicals are needed - ozone can be generated from oxygen in air;l no toxic residuals - ozone is naturally converted back to oxygen after treatment; and suitable for room (or ambient) temperature treatment.

Most ozone applications use ozone generators from which ozone is transferred to the sterilizing chamber. A significant portion of the gas generated is lost before it reaches the objects to be sterilized. The ozone is a gas produced on site by high voltage gas discharge or by ultra-violet radiation. Ozone sterilization has become a widely used technique for purification of municipal water systems. The use of ozone generators in swimming pool water treatment is very common. These commercial applications suggest that ozone sterilization might be viewed as a potential alternative for asepsis purposes. Advantages are simplicity of application, flexibility in operation, minimal toxic residue and relatively low costs. Only raw material that is readily available anywhere is needed, and almost no temperature differences are present. It enables sterilization of a wide range of materials for equipment, tools and growing vessels.

The conventional known technique for atmospheric and surface ozone sterilization is to use a remote, high voltage discharge ozone generator (ozonator) from which ozonized air is directed to a closed vessel holding the substance to be sterilized.

Since ozone is an unstable gas, its concentration is reduced rapidly along its way to the point of application. Thus, in order to get the required concentration at the application point, relatively large ozonators must be used. Larger ozonators require higher electric power and better electric insulation measures. The higher concentration of the ozone at the source calls for more precise sealing. The conventional method is more suitable for large-scale sterilization in relatively big chambers where many parts are sterilized together. After sterilization, the sterilized object has to be removed from the sterilization chamber. By the mere opening of the chamber, new infection may be caused if special precautions are not taken.

The same inventors have previously patented a method and a device for ozone sterilization inside a closed environment, PCT/IL96/00090, which is herein incorporated by reference. In its preferred embodiment, said previous invention provides a method and a device for ozone sterilization using an electric conductor (an interior electrode) inside the closed sterilization vessel (hereinafter called the "closed vessel"). The electric discharge occurs in the gap between the exterior electrodes and the neighboring surfaces of the conductor inside. The electric discharge produces the ozone in the closed chamber from the oxygen contained in the air inside. The efficiency of the process is high, due to the fact that the ozone is produced in the same place where it is used, and need not be transported. The continuous electric discharge also regenerates the ozone from the oxygen to which it degenerates, being an unstable gas as explained previously. This method will be used to sterilize the inside volume of the vessel itself, with whatever is inside, which will be kept closed and aseptic until it is opened for usage. The method and system according to said previous invention could be used on a small and a large scale. The closed vessel can be of various sizes and shapes, and can be moved while closed and stored, after treatment including the sterilized material inside. The advantages of the improved method and the device according to said previous invention is as follows :

1. To improve the reliability and effectiveness of sterilization.

2. To widen the scope of usage of ozone sterilization.

3. To lower power consumption.

4. To enable production of ozone in a closed vessel that can be kept closed for transportation to the point of usage while maintaining sterile conditions inside.

5. To provide a simple, relatively cheap and portable device for laboratory and other sterilization purposes.

6. To ensure production of the ozone inside the closed vessel ONLY.

The method according to said previous invention is based on producing the ozone in a closed and portable vessel or some other package where the sterilized object can be kept until its usage without having to expose it to the external hostile atmosphere.

The method according to said previous invention also utilizes the dielectric properties of the package in the high voltage discharge between the electrodes, thereby enabling sterilization of the inside atmosphere of closed vessels.

The closed chamber, in this case, becomes an inherent part of the generator, but, being removable, many such chambers may be used, one or more at a time, to house the objects to be sterilized. Part of the oxygen in the air inside the closed chamber is converted directly into ozone. This opens the possibility for operating small simple devices for use in household as well as in laboratory and other commercial purposes to sterilize small tools and even plant tissue and keep it closed as long as needed, or in larger enterprises, to sterilize material enclosed in containers on a continuously moving belt.

This method affords considerable flexibility in establishing dosage levels and in treating objects of various shapes and sizes.

SUMMARY OF THE INVENTION

Accordingly, it is a principal object of the present invention to overcome the disadvantages associated with prior art ozonation chambers.

It is a further object of the present invention to provide a device for ozone sanitation or sterilization of objects comprising: a sealable sterilization chamber; a cover for sealing said sterilization chamber; at least one high voltage exterior electrodes adhered to opposite or different exterior surfaces of said chamber, or to said cover of said chamber, and connected to a high voltage power supply; a high voltage source between 7 k Volts and 20kVolts connected to said exterior electrodes; an on-off mechanism for connecting and disconnecting said high voltage source to said two exterior electrodes; an interior frame for positioning and rigid support; at least one interior electrode located effectively inside said chamber, and positioned parallel to the high voltage external electrodes such that an air-gap intervenes in the chamber between the inner surface of said chamber and said at least one interior electrode; such that when said high voltage is applied, ozone is generated inside said chamber to disinfect any object placed inside said chamber.

It is appreciated that the phrase "located effectively inside said chamber" is meant to imply that said interior electrode (s) is located inside of the chamber or on the internal side of the cover of the chamber, such that when the chamber is closed by the cover, the internal electrode (s) is located inside of the chamber.

In one preferred embodiment, there are two interior electrodes and a conductor connected between said two interior electrodes, and adhered to one of two transverse members of said interior frame.

Alternatively, each of said at least one interior electrode has a separate collector which is in contact with an electric conduit through the bottom, side walls, or lid of the chamber.

The electric discharge is produced in the gap between the exterior electrodes and the neighboring surfaces of the interior electrode (the preferred position is that they will be parallel to each other) . The produced ozone diffuses into the entire volume of the closed chamber.

A fan may be placed inside said closed chamber. Any other gas moving device may also be used. An ultra-violet lamp may be used for ozone production and for ozone destruction inside or outside the chamber.

Furthermore, the invention provides a method for ozone sterilization of objects for use with the above mentioned chamber comprising: a) positioning the object that should be sterilized in said closed chamber, wherein the closed chamber has self-contained exterior electrodes and at least one interior electrode;

(b) placing the closed chamber between two high voltage electrical contacts so as to make contact with said exterior electrodes;

(c) applying a high voltage between the said exterior electrodes (and said at least one interior electrode) and thereby producing a corona or silent discharge, converting the oxygen in the air inside the closed chamber into ozone; and

(d) keeping the sterilized object inside the closed chamber as long as needed.

In the preferred embodiment of this device two electric conductors (interior electrodes) are placed in the closed chamber parallel and adjacent to the two exterior high voltage electrodes, and these two interior electrodes (conductors) are connected to each other by a conductor.

Said interior electrodes are adhered to a rigid frame and said exterior electrodes are adhered to the outer surface of said closed chamber. An air-gap intervenes between said interior electrodes and the inner surface of said closed chamber. Said exterior electrodes and said interior electrodes are fabricated of metal foil, which may be stainless steel or anodized or coated aluminum, or any other electrical conducting material.

The objects to be sterilized are tools for laboratories, medicine, dentistry and veterinary or plant tissues, including fruits, vegetables, seeds, kitchen appliances, or any food and substances needing sanitation or sterilization. BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention with regard to the embodiments thereof, reference is made to the accompanying drawings, in which like numerals designate corresponding elements or sections throughout, and in which:

Figure 1 illustrates a vertical center section of a first preferred embodiment of the present invention for use as a disinfecting container;

Figure 2 illustrates the details of a cut-away perspective view 400, according to a preferred embodiment of the present invention;

Figure 3 is a graph illustrating ozone production and decay with and without UV radiation;

Figure 4a is a schematic illustration of an ozone chamber inserted in a high voltage power supply, according to an exemplary embodiment of the present invention; and

Figure 4b is a schematic illustration of an ozone chamber removed from the high voltage supply, according to an exemplary embodiment of the present invention.

Figure 5 illustrates a vertical center section of a second preferred embodiment of the present invention for use as a disinfecting container.

Figure 6 illustrates a scheme of a commercially available microwave oven adapted to accommodate the ozone chamber. Figure 7 illustrates a scheme of ^microwave oven comprising the ozone chamber.

Figure 8 illustrates a vertical center section of a third preferred embodiment of the present invention for use as a disinfecting container.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be further described and clarified by figures 1, 2, 3, 4a and 4b, and 5. These figures do not intend to limit the scope of the present invention but to describe the preferred embodiments only.

Figure 1 illustrates a vertical center section of a preferred embodiment of the present invention for use as a disinfecting chamber. A disinfecting chamber 100 is sealed when cover 102 is push-snapped onto chamber bowl 104 to provide an air-tight seal. Cover 102, bowl 104 and an interior electrode structural housing 120 are all formed from plastic, for example, or other insulating material. Two surfaces (120a) and a pair of traverse spacers (120b) which hold the two interior electrodes (130) in place, parallel to the adjacent external electrodes (110) form the interior electrode assembly (The details of interior electrode structural housing 120 are shown hereinbelow in figure 2.)

Exterior surface electrodes 110 are adhered to or integrated with chamber bowl 104 by glue or any other means, so as to substantially preclude any intervening air pockets. Similarly, a pair of -interior surface electrodes 130 are adhered to interior electrode structural surface 120a. A conductor 150 connects two interior electrodes 130. An air-gap 140 between chamber bowl 104 and interior electrodes 130 provide a source of oxygen 0₂ molecules in the midst of the voltage gradient between exterior surface electrodes 110 and interior surface electrodes 130.

Electrodes 110 and 130 are preferably fabricated in the form of stainless steel foil, although any conductive foil may be used. Ozonation may be initiated by use of a 220 volt to 10,000 or 20,000-volt transformer to produce sufficient voltage. The high voltage side contacts of the transformer are contacted to exterior electrodes 110. Optionally a fan may be positioned inside self-contained chamber 100 to stir the air and distribute the ozone. The amount of ozone produced is proportional to the dimensions of electrodes 110 and 130, the volume of self-contained chamber 100 and the duration of voltage application, the gap between the electrode and the electric power.

Self-contained chamber 100 may be of any practical shape, (provided that there are large enough flat parallel surfaces to which to adhere the electrodes) and structural housing 120 may be integral with it, or physically separate and removable.

Figure 5 is similar to the preferred embodiment illustrated in Figure 1, except that the interior electrodes (130) are not interconnected by a conductor, as they are in Figure 1 (see conductor (150) of Figure 1). Instead, each interior electrode (130) has a separate collector (125), which is in contact with an electrical conduit (126) though the bottom of the chamber. It is appreciated that there may be any number of interior electrodes (at least one though) , and two are shown for the purposes of example only.

Figure 8 is similar to the preferred embodiments of Figure 1 and Figure 5, except that the exterior and interior electrodes are mounted on the cover (102) of the disinfecting chamber (100) . Usage of the cover (102) as the support for the electrodes maximizes the volume available inside of the chamber (100) and allows for ozone sanitation or sterilization to be carried out in a highly efficient and convenient manner. As seen in the Figure, two external electrodes (110) are mounted on the outer surface of the cover (102) and two internal electrodes (130) are mounted on the internal surface of the cover. Each external electrode/internal electrode pair is connected to a separate power supply, and thus no interconnecting conductor is needed in between the two internal electrodes.

Figure 2 illustrates the details of a cut-away perspective view 200, according to a preferred embodiment of the present invention. Reference block 120 is the interior electrode assembly (120a) that provide the surfaces to adhere the interior electrodes (130) . Also shown is air-gap 140 and exterior surface electrode 110 adhered to chamber bowl 104, as well as internal structural electrode assembly 120. Also shown is the conductor (150) between the two interior electrodes.

Figure 3 is a graph illustrating ozone production and decay 300 with and without UV radiation. Ozone has a half-life of about 20 minutes. Thus, the ozone remaining after sterilization may be allowed to decay naturally 310, or optionally, a mercury lamp, for example, may be used as a source of ultra-violet (UV) radiation to increase the rate of decay 320. For example, a mercury lamp may be mounted above or to the underside of cover 102, or alongside the chamber.

Figure 4a is a schematic illustration of ozone disinfecting chamber 100 in insertion mode 475 into the high voltage power supply 480, according to an exemplary embodiment of the present invention. Spring-loaded connectors 490 have high voltage connections 495, which make firm contact with exterior electrodes 110 on the two sides adjacent to connectors 490 during insertion mode 475.

Figure 4b is a schematic illustration of ozone chamber 100 in removal mode 480 from high voltage power supply 480, according to an exemplary embodiment of the present invention. Spring-loaded connectors 490 do not make contact with the exterior electrodes on the two sides adjacent to connectors 490 during removal mode 480.

Reference is made now to Figure 6, presenting one preferred embodiment of the present invention, wherein a commercial available microwave oven 600, as such as used for every day household purposes is adapted to accommodate the disinfecting chamber 100. According to said embodiment, said microwave oven comprises the slides 610a and 610b, that are having means to grasp the upper rim of the chamber 100. Said adapted microwave oven 600 additionally comprising at least one electric contact, here four contacts 620, located at a predetermined location on at least one interior wall of the microwave oven. Said contacts are further located in the interior wall of the microwave oven so the aforementioned electric current is transferred to the electrodes of the disinfecting chamber 100 when said chamber is accommodate in the microwave oven 600.

Reference is made now to Figure 7, presenting the said microwave oven 600, comprising the chamber 100 inserted in it, adapted so the door 610 can be closed. Then, by operating the operating board 602 of the microwave, the ozonation chamber 100 is safely activated.

Reference is now made to Figure 8, and to

Claims

CLAIMS :

1. A device for ozone sanitation or sterilization of objects comprising: a sealable sterilization chamber; a cover for sealing said sterilization chamber; at least one high voltage exterior electrodes adhered to opposite or different exterior surfaces of said chamber, or to said cover of said chamber, and connected to a high voltage power supply; a high voltage source between 7 k Volts and 20 k Volts connected to said exterior electrodes; an on-off mechanism for connecting and disconnecting said high voltage source to said two exterior electrodes; an interior frame for positioning and rigid support; at least one interior electrode located effectively inside said chamber, and positioned parallel to said high voltage external electrodes such that an air-gap intervenes in the chamber between the inner surface of said chamber and said at least one interior electrode.

2. A device for ozone sterilization according to claim 1, comprising two interior electrodes.

3. A device for ozone sterilization according to claim 2, wherein a conductor is connected between said interior electrodes, and adhered to one of two transverse members of said frame, such that when said high voltage is applied, ozone is generated inside said chamber to disinfect any object placed inside said chamber.

4. A device for ozone sterilization according to claim 1 or 2, wherein each interior electrode has a separate collector that is in contact with an electric conduit through a portion of the chamber.

5. A device for ozone sterilization according to claim 1 wherein a fan is placed inside said sealable chamber.

6. A device for ozone sterilization according to claim 1 wherein an ultra-violet lamp is used for ozone destruction.

7. A device for ozone sterilization according to claim 1 wherein said on-off mechanism is effected by insertion and removal of the chamber into and out of another chamber serving as a high voltage supply.

8. A device for ozone sterilization according to claim 1 wherein changes in the voltage level define the amount of ozone produced.

9. A device for ozone sterilization according to claim 1 wherein changes in the time period said voltage is applied define the amount of ozone produced.

10. A device for ozone sterilization according to claim 1 wherein changes in the electrode dimensions define the amount of ozone produced.

11. A device for ozone sterilization according to claim 1 wherein changes in said air-gap define the amount of ozone produced.

12. A device for ozone sterilization according to claim 1 wherein said frame is removable.

13. A device for ozone sterilization according to claim 1 wherein said frame is an integral part of said chamber.

14. A device according to claim 1, wherein said exterior electrodes, and said at least one interior electrode are fabricated of metal foil.

15. A device according to claim 14, wherein said metal foil is stainless steel.

16. A device according to claim 14, wherein said metal foil is aluminum.

17. A device according to claim 14, wherein said metal foil is gold.

18. A device according to claim 14, wherein said metal foil is copper.

19. A device according to claim 1 wherein the objects to be sterilized are food, tools for laboratories, surgery, medicine, dentistry and veterinary or plant tissues.

20. A device according to claim 1 wherein the source of said voltage is a generator.

21. A device according to claim 1 wherein the source of said voltage is a transformer.

22. A device according to claim 1, adapted to be accommodated and/or activated inside a microwave oven.

23. A method for sterilization of objects using the device as defined in any one of claims 1-22, comprising:

(a) placing the object to be sterilized in the sealable chamber, wherein said chamber has exterior electrodes and at least one interior electrode; (b) placing the sealable chamber between two rigid high voltage electrical contacts so that said contacts press against said exterior electrodes;

(c) applying a high voltage of between 7 k Volts and 20 k

Volts between said exterior electrodes, and thereby generating ozone in the air inside said chamber.