GB2498541A

GB2498541A - Apparatus and method for all-around dry disinfection

Info

Publication number: GB2498541A
Application number: GB201200826A
Authority: GB
Inventors: Diederik Corthouts; Johan Cruysberghs; Benny Kurt Rene Westaedt
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-01-18
Filing date: 2012-01-18
Publication date: 2013-07-24
Also published as: GB201200826D0

Abstract

A dry disinfection unit 10 comprises a housing 11 enclosing a chamber 12, a source of ultraviolet (UV) light 14 emitting ultraviolet light positioned within the chamber 12, a coating 15 applied to at least one surface within the chamber 12 wherein the coating 15 includes a nanoparticulate photocatalyst that is activated by the ultraviolet light, and a UV-transparent support 17 positioned within the chamber 12 to support an object 19 which is to be sterilised. The object is exposed all round to the ultraviolet light and to the activated nanoparticulate photocatalyst. The photocatalyst coating may be applied to the internal walls of the chamber, the UV transparent support or the ultraviolet light source. The photocatalyst may be titanium dioxide. The transparent support may be stationary or may comprises a conveyer belt for moving the object through the unit (fig 3).

Description

APPARATUS AND METHOD FOR ALL-AROUND DRY DISINFECTION

FIELD OF THE INVENTION

The present invention relates to apparatus and method of disinfection and, more particularly, to an apparatus and method for all-around dry disinfection of objects.

BACKGROUND OF THE INVENTION

Various methods and devices exist for the sterilization, decontamination, or disinfection of biological and non-biological materials. These methods include thermal destruction (e.g., burning), heat sterilization, irradiation (e.g., ultraviolet or ionizing irradiation), gas sterilization (e.g., using ethylene oxide), photosensitization, membrane sterilization, vacuum disinfection or the use of chemical disinfectants (e.g., formaldehyde, glutaraldehyde, alcohols, mercury compounds, quaternary ammonium compounds, halogenated compounds, solvent/detergent systems, or peroxides). While all of these methods are known to be effective, there are disadvantages, such as being time consuming, leaving chemical residue, having ecological impact, not completely eliminating the chance of cross-contamination or re-contamination, using expensive equipment, or having limited application.

For example, dentists currently employ typically either heat, cold or chemical disinfection and sterilization techniques. These techniques require often relatively expensive equipment and time-consuming procedures. By way of example, during the fabrication of a denture (medical aid) from the creation of a tooth print until the placement of the denture in the mouth of a patient several times different medical aids are being placed in the patient's mouth and send back and forth between a dental office and a dental technical lab. In the dental lab as well as in the dental office, the same instruments are used all over again during years with no easy, fast, and ecological way to clean them. Since all medical laboratories are confronted with this problem, there is a need for a more efficient and environmentally friendly method of disinfection.

In the book "Disinfection, Preservation and Sterilization", Russell et al, Blackwell Science 1999, it is stated that UV light causes excitation of atoms, i.e. there is an alteration of electrons within their orbits, but insufficient energy is possessed for electron ejection to produce an ion. UV radiation is not therefore, an ionizing radiation. Ultraviolet radiation has little penetrative power through solids and is extensively absorbed by glass and plastics. Sterilization is achieved only by irradiation levels beyond the limits of practicability.

It has been employed in the disinfection of drinking-water and for air purification in rooms.

The use of photocatalysis in purifying both gas and liquid media and in controlling bacteria and other microorganisms on the surfaces of solid objects is a relatively new and rapidly growing technology. This photocatalysis process entails the illumination of catalytic n-type semiconductor particles (such as Ti02 particles) with ultraviolet (UV) light. It is believed that the UV light promotes photoexcitation of valence band electrons and holes in the semiconductor particles, and that the electrons and holes migrate to the surface of the semiconductor particles to participate in reduction/oxidation reactions with matter adsorbed to or in the near vicinity of the surface of the particles. It is further believed that these reduction/oxidation reactions produce highly reactive hydroxyl radicals which oxidize and ultimately destroy certain organic species in the gas or liquid media, on the surface of exposed solid objects, or on the semiconductor-bearing surfaces being treated. It has been shown in the prior art that photocatalyst materials not only kill bacteria cells, but also decompose the cell itself.

The titanium dioxide photocatalyst has been found to be more effective than any other antibacterial agent, because the photocatalytic reaction works even when there are cells covering the surface and while the bacteria are actively propagating. The end toxin produced at the death of cell is also expected to be decomposed by photocatalytic action.

Titanium dioxide is known not to deteriorate and it shows a long-term anti-bacterial effect.

Generally speaking, disinfection by titanium dioxide is three times stronger than chlorine, and 1.5 times stronger than ozone.

For example, U.S Patent Application Publication No. 2009/0169425 Al provides an apparatus and method for disinfecting food objects in a water bath using ultraviolet light in combination with titanium oxide as a photocatalyst. A photocatalyst coating is applied to the outer surface of a quartz tube housing a UV lamp. Air is injected into the water bath so that the ultraviolet light is uniformly and sufficiently radiated onto a food item.

A conveyer belt transporting the food item through the water bath is also disclosed. Using water and air adds to the technical equipment requiring the disinfection apparatus to be positioned stationary. By transporting the food object on a conveyer belt, the surface of the food object contacting the belt is not exposed to the ultraviolet radiation and will most likely not be disinfected.

U.S Patent Application Publication No. 2003/0071790 Al discloses a seat for a computer mouse that has sterilizing and deodorizing abilities. By providing an ultraviolet lamp pipe within a chamber formed by the seat and by coating the inside walls of the seat with a titanium dioxide TiC2 layer the upper surface of the computer mouse is sterilized and deodorized through irradiation and photocatalyzing. Since the bottom surface of the computer mouse contacts the bottom of the seat, it is not exposed to the ultraviolet radiation and will most likely not be disinfected.

What is needed in the art is an apparatus and method that enables fast and efficient all-around dry disinfection of objects, that leaves no chemical or other residue, that significantly reduces or eliminates the chance for cross contamination and re-contamination, and that is compact and affordable.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an apparatus and method that enables all-around dry disinfection of objects by utilizing ultraviolet light in connection with a light activated photocatalyst.

It is a further object of the present invention to provide an apparatus for all-around dry disinfection that enables batch or continuous processing.

Briefly described, the present invention addresses the shortcomings of prior art disinfection apparatuses and methods by providing an apparatus and method that enables all-around dry disinfection of objects by utilizing germicidal ultraviolet light in connection with a light activated nanoparticulate photocatalyst in an enclosed chamber.

In one embodiment in accordance with the present invention, a dry disinfection unit for batch processing is provided. The dry disinfection unit for batch processing utilizes ultraviolet light at sufficiently short wavelength to break down microorganism in combination with a light activated nanoparticulate photocatalyst coating for fast and efficient disinfection without residue. By further providing a stationary UV-transparent support to hold the objects to be disinfected, all-around disinfection of these objects is enabled.

In an alternate embodiment in accordance with the present invention, a dry disinfection unit for continued processing is provided. The dry disinfection unit continued processing utilizes ultraviolet light at sufficiently short wavelength to break down microorganism in combination with a light activated nanoparticulate photocatalyst coating for fast and efficient disinfection without residue. By further providing a moving UV-transparent support to hold the objects to be disinfected, continuous all-around disinfection of these objects is enabled.

In another embodiment in accordance with the present invention, a dry disinfection unit for continued processing is provided that comprises a plurality of conveyor belts arranged in a stairway configuration, one above the other, so that the objects fall from one belt to the belt immediately below, and thus may change their orientation, which further improves the all-around disinfection.

By placing objects to be disinfected in one of the dry disinfection units in accordance with the embodiments of the present invention on a UV-transparent support, stationary or moving, by exposing all surfaces of the objects with ultraviolet light, preferably of a relative short wavelength, and by further activating the nanoparticulate photocatalyst included in a coating applied e.g. to surfaces inside the dry infection units with the ultraviolet light, fast, efficient, and ecological all-around disinfection of the objects is provided.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a dry disinfection unit for batch processing in accordance a first embodiment of the present invention; Fig. 2 is a cross-sectional view of the dry disinfection unit for batch processing in accordance with the first embodiment of the present invention; and Fig. 3 is a cross-sectional view of a dry disinfection unit for continued processing in accordance with a second embodiment of the present invention.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates exemplary embodiments of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE EMBODIMENTS

One of the problems addressed by the present invention is how to overcome the prejudice mentioned in the book "Disinfection, Preservation and Sterilization", Russell et al, Blackwell Science 1999. According to this book ultraviolet radiation has little penetrative power through solids and is extensively absorbed by glass and plastics. Sterilization is achieved only by irradiation levels beyond the limits of practicability, although it has been employed in the disinfection of drinking-water and for air purification in rooms. Thus LJV radiation conventionally has a very restricted usefulness in disinfection and sterlisation.

Referring to Figs. 1 and 2, a dry disinfection unit 10 for batch processing is illustrated in accordance with a first embodiment of the present invention. The dry disinfection unit 10 includes a housing 11 that encloses a chamber 12. Housing 11 may be shaped like a box and may have preferably, but is not limited to, a rectangular cross-section, as shown in Fig. 2. Alternatively, housing 11 may have, for example, a square cross-section. A door 13 may be included in housing 11 and may be incorporated into one of the wall panels of housing 11, as shown in Fig. 1. Alternatively, one of the wall panels of housing 11 may be entirely replaced by door 13. Chamber 12 may be accessible via door 13 by opening and closing door 13. While door 13 is shown without a door handle, a door handle may be included to facilitate opening and closing door 13. Door 13 may further be equipped with an inner seal, not shown.

A source of UV light 14, such as a UV lamp or UV LED (light emitting diode) is positioned within chamber 12. The source of UV light 14 may include a plurality of UV lamps and/or UV LEDs. Although, in the text below, the term UV lamp will mostly be used, it is to be understood that other sources of UV light as known in the art may be used as well.

UV lamp 14 may be preferably positioned under a top panel of housing 11 extending horizontally along the top panel, as shown in Fig. 2. More than one LJV lamps 14 may be positioned here. Additional UV lamps may be positioned along side panels or even along the bottom panel of housing 11. UV lamp 14 may be shaped as a tube, a ring or a bulb. UV lamp 14 may emit ultraviolet light at sufficiently short wavelength to break down microorganism and may be suitable for ultraviolet germicidal irradiation. UV lamp 14 may preferably be a UVC lamp emitting ultraviolet radiation subtype C in the wavelength range of about 100 nm about 280 nm. It may further be possible or for some applications desirable, to use UV lamps providing radiation in a different wave length range, such as UVA or UVB.

Preferably, the UV-transparent support 17 is positioned so that the object 19 is exposed all-around to UV light. This may e.g. be obtained by using a plurality of sources of UV light and/or by making use of UV reflectors, so that UV light also exposes the bottom side of the object 19 lying on the transparent support.

Referring again to the embodiment of Fig. 2, a coating 15 including a nanoparticulate photocatalyst is applied to at least one surface within chamber 12.

Nanoparticulate photocatalyst coating 15 may be applied to the inside surfaces of housing 11 to cover the inside surfaces completely or partially. Instead of or in addition to being applied to the inside surfaces of housing 11, nanoparticulate photocatalyst coating 15 may be applied to UV lamp 14, such that UV lamp 14 is partially or completely covered.

Additionally, UV lamp 14 may be covered with a Li V-transparent enclosure 16, which may be partially or completely covered with nanoparticulate photocatalyst coating 15, as illustrated in Fig. 3. In a particular embodiment, UV lamp 14 has a quartz glass body and nanoparticulate photocatalyst coating 15 is processed in the quartz glass. The nanoparticulate photocatalyst in coating 15 is activated by the ultraviolet light from lamp 14 and assists in deactivation of bio-contamination. Thus, fast disinfection is provided. A preferred nanoparticulate photocatalyst is titanium dioxide (TiC2), but other metal oxides, for example, 7i02, Cu02, AgO2, ZnO, W03, Si02, Sn02, Fe203, MoO3, Bi203 or SrTiO3 may also be utilized.

As can also be seen in Fig. 2, a UV-transparent support 17 is positioned within chamber 12. Support 17 may be formed as a table including legs 18. Alternatively support 17 may include a separate stand holding a plane top part, such as a tray or a panel.

Support 17 may have a surface area large enough to hold a plurality of objects 19 to be disinfected. While support 17 is designed to hold a batch of objects 19 to be disinfected, it may also be used to disinfect a single object 19. Support 17 may be made from a Liv-transparent material, such as quartz glass or a transparent polycarbonate resin and, therefore, may allow the surface of object 19 that is in contact with support 17 to be irradiated and, thus, disinfected. UV-transparent support 17 may be partially or completely covered with nanoparticulate photocatalyst coating 15. Instead of or in addition to being applied to the UV-transparent support 17, nanoparticulate photocatalyst coating 15 may be processed in the material, e.g. the quartz glass, of which the UV-transparant support 17 is made. UV-transparent support 17 may be placed on a sliding element, that may slide outwards to easily put the object or objects 19 on the support 17. Objects 19 may be any objects that need to be disinfected, for example, objects frequently and repetitively used in medical offices and laboratories.

Additionally, dry disinfection unit 10 may include a display and control component 22 that is integrated in housing 11 to be easily viewable and operable. For example, display and control component 22 may be positioned above door 13, as illustrated in Fig. 1. Furthermore, dry disinfection unit 10 may include afan 21 positioned inside chamber 12 to provide air circulation within chamber 12.

Referring now to Fig. 3, a dry disinfection unit 30 for continued processing is illustrated in accordance with a second embodiment of the present invention. Dry disinfection unit 30 includes a housing 31 that encloses a chamber 32. Housing 31 may be shaped like a box and may have preferably, but is not limited to, a rectangular cross-section. Alternatively, housing 31 may have, for example, a square cross-section. Housing 31 includes two openings 33 positioned across from each other and incorporated in side panels of housing 31. Openings 33 are sized to receive a conveyer belt 34 driven by at least one driving roller and supported by a plurality of driven rollers 36. Conveyer belt 24 functions as Liv-transparent support for objects 19. When operated, conveyer belt 34 moves objects 19 to be disinfected continuously through chamber 32. The operational speed of conveyer belt 34 may be variable and selectable. Conveyer belt 34 as well as driven rollers 36 positioned inside chamber 32 may be made from a UV-transparent material and, therefore, may allow the surface of object 19 that is in contact with belt 34 to be irradiated and, thus, disinfected.

Conveyer belt 34 may be partially or completely covered with nanoparticulate photocatalyst coating 15. Instead of or in addition to being applied to the conveyer belt 34, nanoparticulate photocatalyst coating 15 may be processed in the material of which the conveyer belt 34 is made. In the embodiment shown in Fig. 3, openings 33 are located ion opposing side panels of housing 31; in general, they may be located in other side panels -e.g. a plurality of conveyer belts may be used instead of a single belt, so that the object 19 is not transported along a straight line.

Instead of a single conveyer belt 34 as shown in the embodiment of Fig. 2, a plurality of conveyer belts may be provided that are arranged in a stairway configuration. In this embodiment, the conveyer belts are positioned one above the other one, as the stairs of a stairway, and overlapping each other at least partly in the horizontal or mainly horizontal transport direction. An object that is transported on the uppermost conveyer belt then drops, at the end of the belt, on the conveyer belt immediately below, is transported further, in the same direction (or possibly in the opposite direction), again drops at the end of the belt to the conveyer belt further below, etc. Each time the object drops on another belt, its orientation on the belt may change (e.g. a side of the object may now rest on the belt, and the bottom of the object may now become a side face), which further improves the all-around disinfection.

The conveyer belts arranged in stairway configuration may be made from a UV-transparent material. In another embodiment, the conveyer belts arranged in stairway configuration are made from a material that is not IJV-transparent.

UV lamp 14 and nanoparticulate photocatalyst coating 15 are further utilized in dry disinfection unit 30 as they are utilized in dry disinfection unit 10, as shown in Figs. 1 and 2 and as described above. A display and control component 22 as well as a fan 21 may also be included in dry disinfection unit 30.

By providing dry disinfection unit 10 and dry disinfection unit 30 in accordance with the present invention, objects 19 can be quickly and efficiently disinfected, either stationary or continuously, respectively. By utilizing at least one UV lamp 14 emitting UV light inside chamber 12 or chamber 32, a nanoparticulate photocatalyst included in coating 15 is activated and assists the ultraviolet germicidal irradiation in deactivation of bio- contamination. The photocatalytic action leaves no residue behind. By providing a UV-transparent support 17 and a UV-transparent conveyer belt 34, respectively, all-around dry disinfection of objects 19, in accordance with the present invention, is enabled.

While the invention has been described by reference to various specific embodiments, it should be understood that numerous changes may be made within to the described embodiments. Accordingly, it is intended that the invention is not limited to the described embodiments, but is defined by the following claims.

Claims

<claim-text>CLAIMS1. A dry disinfection unit (10, 30) comprising: -a housing (11, 31) enclosing a chamber (12, 32); -a UV-transparent support (17, 34) positioned within said chamber (12, 32) and for holding at least one object (19); -a source of ultraviolet (UV) light (14) for emitting ultraviolet light, positioned within said chamber (12); and -a coating (15) applied to at least one surface within said chamber (12, 32) and/or processed in a material of said source of ultraviolet light (14) and/or processed in a material of said UV-transparent support (17, 34), said coating (15) including a nanoparticulate photocatalyst that is activated by said ultraviolet light; wherein said UV-transparent support (17, 34) is positioned for all-around exposure of said at least one object (19) to said ultraviolet light and to said activated nanoparticulate photocatalyst.</claim-text> <claim-text>2. The dry disinfection unit (10, 30) according to claim 1, wherein said UV-transparent support (17) is stationary.</claim-text> <claim-text>3. The dry disinfection unit (10, 30) according to claim 1, wherein said UV-transparent support comprises a conveyer belt (34) arranged for moving said at least one object (19).</claim-text> <claim-text>4. The dry disinfection unit (10, 30) according to claim 3, wherein said UV-transparent support comprises a plurality of conveyer belts (34) arranged in a stairway configuration and arranged for moving said at least one object (19).</claim-text> <claim-text>5. The dry disinfection unit (10, 30) according to any one of claims ito 4, wherein said source of ultraviolet (LJV) light (14) is for emitting said ultraviolet light at sufficiently short wavelength to break down microorganism.</claim-text> <claim-text>6. The dry disinfection unit (10, 30) according to any one of claims ito 4, wherein said source of ultraviolet(UV) light (14) emits said ultraviolet light in a wavelength range of iOO nm to 280 nm.</claim-text> <claim-text>7. The dry disinfection unit (10, 30) according to any one of claims 1106, wherein said nanoparticulate photocatalyst included in said coating (15) is titanium dioxide (hO2).</claim-text> <claim-text>8. The dry disinfection unit (10, 30) according to any one of claims 1106, wherein said nanoparticulate photocatalyst included in coating (15) is selected from the group of metal oxides consisting of Ti02, Zi02, Cu02, AgO2, ZnO, W03, Si02, Sn02, Fe203, MoO3, Bi203, and SrTiO3.</claim-text> <claim-text>9. The dry disinfection unit (10, 30) according to any one of claims 1108, wherein said coating (15) is applied to at least one inside surface of said housing (11, 31) covering said inside surface at least partially.</claim-text> <claim-text>10. The dry disinfection unit (10, 30) according to any one of claims 1109, wherein said coating (15) is applied to said ultraviolet source of ultraviolet (LJV) light (14) covering said source of ultraviolet (UV) light (14) at least partially.</claim-text> <claim-text>11. The dry disinfection unit (10, 30) according to any one of claims 1 to 10, wherein said coating (15) is applied to a UV-transparent enclosure (16) covering said UV-transparent enclosure (16) at least partially.</claim-text> <claim-text>12. The dry disinfection unit (10, 30) according to any one of claims ito 11, wherein said coating (15) is applied to said UV-transparent support (17, 34) covering said UV-transparent support (17, 34) at least partially.</claim-text> <claim-text>13. The dry disinfection unit (10, 30) according to any one of claims ito 12, wherein said UV-transparent support (17, 34) is made from quartz glass.</claim-text> <claim-text>14. The dry disinfection unit (10, 30) according to any one of claims ito 13, further including: -a display and control component (22) integrated in said housing (11, 31); and -a fan (21) positioned inside said chamber (12, 32).</claim-text> <claim-text>15. A method for all-around dry disinfection of objects (19), comprising the steps of: -placing at least one of said objects (19) onto a UV-transparent support (17, 34) positioned in a chamber (12, 32) enclosed by a housing (11, 31); -irradiating said at least one object (19) all-around with UV light emitted by a source of UV light (14) breaking down microorganism; -activating a nanoparticulate photocatalyst, included in a coating (15) applied to at least one surface within said chamber (12, 32), with said UV light; and -deactivating bio-contamination of said at least one object (19) with said activated nanoparticulate photocatalyst.</claim-text>