Decontamination system

Abstract

The present invention relates to a decontamination system consisting of a work surface and a UV excitation source (5) characterized in that said work surface (1) has an area coated with a vitreous material (4) comprising a phosphor powder. The invention also relates to a method for manufacturing a decontaminating work surface characterized in that it consists of preparing a mixture of: ten volumes of water ±10% three volumes of tetraethyl orthosilicate precursor ±10% one volume of hydrochloric acid ±10% then adding to 10 grams of solution thus prepared 1 to 3 grams of phosphor powder and depositing the vitreous material thus prepared on the work surface. Abstract figure: Figure 1

Description

Title of the invention: Title: Decontamination system Field of invention

[0001] The present invention relates to the fields of bio-decontamination and surface decontamination. It includes applications in the medical sector, for example to combat nosocomial diseases, but also in the pharmaceutical, food and agri-food, space and aeronautical industries.

[0002] Surface decontamination is the process of cleaning and disinfecting surfaces to eliminate, reduce, or kill pathogens, microorganisms, chemical contaminants, or other unwanted substances that may be present on these surfaces. According to NF EN 17272: 2020, decontamination is a temporary operation that only concerns contaminants present at the time of the operation. This procedure aims to reduce the risks of spreading disease, infection, or cross-contamination.

[0003] Ultraviolet (UV) radiation decontamination is a decontamination method based on the sensitivity of microorganisms to exposure to wavelengths below 400 nm, more particularly to UVC radiation emitted between 200 and 280 nm. The mechanism of inactivation of microorganisms by UVC is based on the absorption of the energy of UVC photons by the nucleic acids of the microorganisms, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

[0004] This absorption causes structural changes and irreversible damage that will impair the functioning of the host cell. Indeed, the energy of the photons emitted between 220 and 280 nm absorbed by the nucleic acids is sufficiently high to form a covalent bond between two adjacent bases to the detriment of the initial hydrogen bond. This then results in the formation of mutagenic lesions called pyrimidine dimers, most often thymine dimers in DNA and uracil dimers in RNA.

[0005] These abnormal bonds distort the structure of DNA and RNA, and can disrupt their biological function. They can interfere with the processes of replication, transcription, translation, and other biological processes that depend on the integrity of these nucleic acids. The absence of replication or translation causes defects that prevent the microorganism from being viable. In addition to direct modifications to nucleic acids (DNA and RNA), exposure to UV-C radiation (but also UV-B and UV-A, emitted respectively between 280 - 320 nm and 320 - 400 nm) causes oxidative stress and lipid peroxidation. This phenomenon is an indirect aggression linked to the accumulation of reactive oxygen species formed by UVs such as hydroxyl (OH) or superoxide (O2). State of the art

[0006] Patent EP1790224B1 is known in the state of the art, describing an antimicrobial and non-cytotoxic laminated material comprising:

[0007] a) a biocide layer having a biocidal active ingredient selected from the group consisting of silver, copper and zinc, their ions and their metal complexes, or a mixture or alloy comprising two or more of these elements, and

[0008] b) a transport control layer overlying the biocide layer having a thickness and porosity that are adjusted to deliver the biocidal active ingredient from the biocide layer through the transport control layer in an antimicrobial and non-cytotoxic amount, wherein the transport control layer has a silicon proportion of 20 to 60 atomic %, a carbon proportion of up to 50 atomic %, and an oxygen proportion of 25 to 66 atomic %, based on the total number of atoms of the atoms contained in the layer that can be demonstrated in the XPS analysis.

[0009] Patent application US20210253889 relates to the formulation of an antimicrobial matrix that can be applied to all types of substrates in the health and food sectors. The matrix comprises the up-conversion phosphor, at least one film-forming polymer having good UVC-VIS transmission and a curing agent. The substrate can be wood, metal, minerals (stone, glass), cellulosic substrates or polymers.

[0010] International application WO2021073915 relates to the formulation of an up-conversion UVC phosphor for converting excitation wavelengths below 530 nm into emissions between 220 and 425 nm. It allows a significant reduction in microorganisms after several hours of exposure.

[0011] The excitation source is ambient lighting, and more specifically blue LEDs emitting between 365 and 500 nm. The initial assumption is that this type of lighting represents the future and that it will spread to all lighting applications (exterior, interior, architectural, decorative, etc.). The phosphor is likely to be activated by the light radiation of the sun.

[0012] International application WO2016037773A2 relates to a lighting device comprising:

[0013] -a first semiconductor lighting source, designed to provide UV radiation having a wavelength of 380 to 420 nm;

[0014] -a second semiconductor lighting source configured to provide blue light having a wavelength in the range of 440 to 470 nm;

[0015] -a wavelength converter element, said wavelength converter element comprising:

[0016] -a first luminescent material, designed to provide, when excited by blue light from the second semiconductor lighting source, light of the first luminescent material having a wavelength selected from the green and yellow wavelength range, the excitability to UV radiation of said first luminescent material being lower than that to blue light and

[0017] -a second luminescent material designed to provide, when excited by blue light from the second semiconductor lighting source, light of second luminescent material having a wavelength selected from the red and orange wavelength range, the excitability to UV radiation of said second luminescent material being lower than that to blue light.

[0018] Patent application WO2011110191A1 describes a method and an assembly for treating an object contained in an envelope with a low-temperature plasma, in particular for sterilizing and / or disinfecting and / or decontaminating the object; the low-temperature plasma being applied to a surface of the object, and being applied so as to pass through an envelope to penetrate into it.

[0019] Patent FR2915313A1 proposes a flat lamp transmitting radiation in the ultraviolet, known as UV, comprising first and second facing flat dielectric walls, kept substantially parallel and sealed together, delimiting an internal space filled with gas emitting said UV radiation and / or capable of exciting a luminophore material emitting said UV radiation. By choosing radiation in the UVC range, the UV lamp can be used for disinfection / sterilization of air, water or surfaces by germicidal effect, particularly between 250 nm and 260 nm. By choosing radiation in the far UVC range or preferably in the VUV for ozone production, the UV lamp is used in particular for surface treatment, in particular before deposition of active layers for electronics, IT, optics, semiconductors. Disadvantages of the prior art

[0020] The solutions of the prior art are not entirely satisfactory because they are based either on a different technology (EP1790224B1), or on the emission of non-biocidal radiation (WO2016037773A2), or on the emission of a single biocidal UVC radiation going from the light device to the surface to be decontaminated (WO2011110191A1 and FR2915313A1). However, in the latter case, even if the germicidal efficacy of UVC has been demonstrated on several types of microorganisms, in particular on Gram-negative bacteria (Escherichia coli, Shigella sonnei, Salmonella typhi, Pseudomonas aeruginosa) and Gram-positive bacteria (Streptococcus faecalis, Staphylococcus aureus, Geobacillus stearothermophilus), spores (Bacillus subtilis, Bacillus atrophaeus) and viruses (Poliovirus type 1, Simian rotavirus), UV penetration remains low: around 1 to 3 pm. As a result, germicidal effectiveness is limited. Furthermore, prior art solutions entail risks incurred by the use of a UVC up-conversion phosphor activated by ambient lighting.

[0021] The object of the invention is to provide a more efficient UV radiation decontamination system. Solution provided by the invention

[0022] The innovative character provided by the invention consists of the following elements: - Simultaneous double UV radiation (excitation and emission, both being germicidal); - A UV-transparent surface located between the 2 radiation sources.

[0023] The invention relates to a decontamination system consisting of a work surface and a UV lighting source, characterized in that said work surface has an area coated with a vitreous material comprising a phosphor powder. This vitreous material is preferably coated with a UV-transparent protective surface, in particular a quartz sheet.

[0024] This transparent protective surface is advantageously positioned between said vitreous material and said UV excitation source.

[0025] Said UV-transparent protective surface is constituted by a quartz sheet.

[0026] The invention also relates to a method for manufacturing a decontaminating surface characterized in that it consists of preparing a mixture of: - ten volumes of water ±10% - three volumes of tetraethyl orthosilicate precursor ±10% - a volume of hydrochloric acid ±10%

[0027] then adding to 10 grams of solution thus prepared 1 to 3 grams of luminophore powder and depositing the vitreous material thus prepared either on the working surface (preferably) or on the quartz sheet.

[0028] Detailed description of a non-limiting example of embodiment

[0029] The present invention will be better understood on reading the following description, concerning a non-limiting example of embodiment, illustrated by the appended drawings where:

[0030] [Fig-1] [Fig.l] represents a schematic sectional view of a work plan according to the invention.

[0031] Controlling the contamination of surfaces by micro-organisms is a major issue in many sectors, and particularly in the biology laboratory. where the intentional handling of dangerous biological agents presents a significant risk of contamination of the workspace and more particularly of the workbenches.

[0032] The use of new processes to kill micro-organisms on surfaces is a major focus of public health (fight against bacterial resistance to antibiotics) but also of the individual health of workers (dangerous biological agents). General principle of the invention

[0033] The general principle of the invention relates to a disinfection tool which uses cold plasma technology for the purpose of decontaminating objects and surfaces. The invention is based on the use of a down-conversion type luminophore, i.e. involving a conversion of higher energy photons into lower energy photons (in English "down-conversion"); on the use of the excitation radiation emitted by a plasma source as a biocidal agent (in addition to the UVC emission radiation); and on the use of a transparent protective surface to protect the coating after deposition on a surface.

[0034] Inactivation of microorganisms by the synergistic action of excitation (plasma) and emission (luminophore) radiation. Decontamination is achieved by the combination of two UV radiations, denoted RI (excitation) and R2 (emission). The RI radiation is emitted by a light source, preferably a light source based on a cold plasma, preferably of the excimer lamp type, in the wavelength range 200-300 nm, corresponding to both the germicidal spectrum and the excitation spectrum of a luminophore from which the R2 radiation originates. The R2 radiation is the result of the conversion of the RI radiation by a luminophore. The luminophore, preferably of the down-conversion type, emits radiation in the wavelength range 200-300 nm after being excited by radiation of shorter wavelength. The RI and R2 radiations are germicidal. Example of realization

[0035] [Fig.l] illustrates a schematic sectional view of an exemplary embodiment of a work surface. The support (1) is covered with a deposit of luminophores (4) then with a protective surface (2). The activation of the decontaminating coating requires a plasma source (5) which generates in particular emissions specific to the luminophores used. This plasma source (5) is arranged at a distance from the support (1), without contact with the luminophores, such that its emission field extends over the support (1), typically at a distance greater than 0.5 times the largest dimension of the working surface of the support (1).

[0036] These emissions pass through the protective surface (2) and reach the phosphors (4). Excited by the emissions of the plasma emitted by the source (5), the phosphors of the coating (4) transform the emissions of the plasma into biocidal emissions in the wavelength range 200nm-300nm. These biocidal emissions then pass through the protective surface (2) and decontaminate its surface.

[0037] A synergy can also occur by considering the effects of the initial plasma emissions which directly reach the external surface of the protection. The surface of the support is not necessarily flat.

[0038] Method for preparing a decontaminating work surface according to the invention

[0039] As a non-limiting example, the protocol for preparing a vitreous material loaded with luminophores is produced using a sol-gel method for homogeneous and high-quality deposits.

[0040] For this purpose, a mixture of the following compounds is used: - Tetraethyl orthosilicate precursor (TEOS, reagent grade 98%); Water (H2O); - Hydrochloric acid (HCl, 37%); - Absolute ethanol (99%); - Luminophore powder.

[0041] UV-emitting phosphors belong, for example, to the family of phosphors having a composition represented by the formula Ca(2 wxyzJ Srx Ay Prz P2O 7, in which: - A is a 1+ metal cation; - w is between 0 and 0.1; - x ranges from 0 to 2-wyz; y is between 0 and 0.25; - and z is between more than 0 and 0.12.

[0042] Or to the family comprising a selected component: - in the group (Yi. x Lux )9 LiSi6 026:Ln ; - or in the group AE5 (P04 )3F:Ln, A, in which Ln is a trivalent rare earth metal, AE is a divalent alkaline earth metal and A is a monovalent alkali metal, x > 0.0 and < 1.0; - Luminophores based on strontium aluminates activated by europium and dysprosium ions; - Phosphors based on phosphors activated by Eu2+ (0.0025< x <0.025) Sr2SiO4:xEu2+ (SSO:xEu2+)

[0043] Or a photoluminescent material known to emit in the 200-300 nm wavelength band.

[0044] Preparation of the gel-luminophore solution for a surface area of ​​25 cm2:

[0045] In a 15 ml tube, VH2o = 1 ml, VTEOs = 30 μl and VHci = 10 μl are added using a micropipette. The tube is shaken for 2-3 minutes until a slightly viscous solution is obtained.

[0046] 0.2 g of phosphor powder is then added to the tube and the tube is shaken again for 2-3 minutes. The phosphor gel solution is then ready to be deposited.

[0047] Deposition of the gel-luminophore solution on the surface:

[0048] The surface of the support (1) is cleaned with ethanol and the residual ethanol is then allowed to evaporate in the ambient air. The previously prepared gel-luminophore solution is deposited in the center of a 25 cm2 surface using a micropipette. The gel-luminophore solution is spread with a spatula until a uniform and homogeneous layer is obtained and the gel-luminophore solution is left to dry at room temperature for approximately 1 hour. The surface is ready as soon as the deposit is completely dry.

[0049] The transparent protective material is cleaned with ethanol and then the residual ethanol is allowed to evaporate into the ambient air.

[0050] A transparent protective material, for example a sheet of quartz, silica, magnesium fluoride (MgF2) or calcium fluoride (CaF2) or any polymer transparent to UVC, is then gently placed on the dry luminophore sol-gel deposit. The edges of the transparent protective material are joined with silicone (3).

Claims

Claims

1. Decontamination system consisting of a work surface and a UV excitation source (5) characterized in that said work surface (1) has an area coated with a vitreous material comprising a luminophore powder (4).

2. Decontamination system according to claim 1 characterized in that said vitreous material comprising a luminophore powder (4) is coated with a UV-transparent protective surface (2).

3. Decontamination system according to claim 2 characterized in that said UV transparent protective surface (2) is positioned between said vitreous material comprising a phosphor powder (4) and said UV excitation source (5).

4. Decontamination system according to claim 2 characterized in that said UV-transparent protective surface (2) is constituted by a quartz sheet.

5. Decontamination system according to claim 1 characterized by simultaneous double UV radiation consisting of an excitation source (5) and an emission source, both being germicidal.

6. Method for manufacturing a decontaminating work surface characterized in that it consists of preparing a mixture of: - ten volumes of water ±10% - three volumes of tetraethyl orthosilicate precursor ±10% - one volume of hydrochloric acid ±10% then adding to 10 grams of solution thus prepared 1 to 3 grams of luminophore powder (4) and depositing the vitreous material comprising said luminophore powder (4) thus prepared on a work surface (1).

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