Nanofilter System for Personal and Medical Protective Equipment with Nano-Facemask, Resp. Nano-Faceshield and Method of Manufacturing Thereof

Abstract

The present invention relates to nanofilters and nanofliter systems for personal and health care protective equipment to protect against health and safety hazards having application in healthcare, industrial, public, domestic environments, They are applied to face masks, respirators, face shields, protective glasses and clothes, to protect healthcare workers and other individuals against microparticles, dust, bacteria, fumes, vapors, gases, allergens, air pollutants, airborne microorganisms and especially nanosized viruses such as influenza, HIV, SARs, SARs-CoV-2. It also relates to a method for fabricating thereof with higher filtration efficiency, and to Nano-face masks, respirators, Nano-face shields exhibiting antibacterial, anti-viral protection and particulate-filtering due to the excellent barrier and filtration properties of the nanofliter system. It is also applied to the delivery of nanoparticles, organic or inorganic with antibacterial, antiviral properties, drugs, therapeutic agents, nanomedicines, or/and compounds, sensors,

Claims

1. Nano-filter system for personal and medical protective equipment against health and safety hazards, characterised in that it comprises: an external, coarse filter thick layer with microporosity for filtration of microparticles, an intermediate nanofilter forming middle filter nanolayer, onto a functional, thick, microporous, fiber-based filter layer, wherein the nanofilter consists of multi-functional, nanoporous nanolayers involving single or more discrete layers, possibly with a nanoparticulate layer, either a single or a plurality of discrete nanoporous layers, an inner filter of thick layer with microporosity, wherein the inner, outer, and filtration materials are of a single or multiple layer design.

2. Filter system according to claim 1, characterised in that said external and inner filter layers are made of non-woven fibers, which are selected among polypropylene (PP), cellulose, polystyrene, polycarbonate, polyethylene and combinations thereof or polyesters, other hydrophobic polymers, hydrophobic fluoropolymers, or polymers with hydrophobic surfactants, fluoro-surfactants, wherein the micropores block microparticles, dust, bacteria, fumes, vapors, gases, allergens, fungi, molds, air pollutants, airborne microorganisms.

3. Filter system according to claim 1, characterised in that said intermediate nanofilter is composed of: a nanoporous nanolayer consisting of single layer biodegradable polymeric (BP) blends or of multi-layer BP thin films, preferably with multi-sized nanopores and nanometer thickness, characterized by tailored nanopores, a controllable thickness of the layers so as to entrap nanoscale viruses and to allow fluent breathing, a layer of nanoparticles as functional agents, for nanolayer biofunctionalization, wherein the nanofilter is possibly biofunctionalized with the nanoparticulate layer and it is deposited onto a functional, thick, microporous filter layer which is preferably fiber-based and made of non-woven fabrics, notably Polyamide (PA); wherein said middle filter nanolayer, single layer biodegradable polymeric (BP) blends or two multilayer BP thin films are characterized by tailored nanoporosity and nanoscale to pm thickness, to entrap airborne nanoparticles, nanometer sized substances, viruses, toxins, chemicals, gases, allergens, air pollutants, bacteria; and In that the nanoporous layers of the filter are constituted by biodegradable polymers BP consisting of different types of Poly (DL-lactlde-co-glycolide) (PLGA) in terms of lactlde:glycolide ratio, polycaprolactone (PCL), Polylactic acid (PLA), polysaccharides, polyesters, natural polymers with variations in degradation rates, particularly wherein other BPs, BP aliphatic polyesters notably homopolymers and copolymers of lactic acid, glycolic acid, trimethylene carbonate, and blends, are included.

4. Method for manufacturing a filter system as defined in claim 1, characterised in that the surface and structural properties, the nanoporosity, thickness of the said BP thin films of the filter nanolayer for high filtration capability, is tailored by alteration in deposition parameters in line with the derived spectroscopic ellipsometry and Atomic Force Microscopy (AFM) data for thin films characterization and quality control, particularly wherein the control of nanoporosity and thickness of the engineered nanomaterials is performed upon the fabrication method, by alterations in deposition parameters, polymer types, material and ratios, in line with ultrasensitive measurements and monitoring by Atomic Force Microscopy (AFM) and Spectroscopic Ellipsometry (SE), for a detailed characterization of the structural properties of the engineered systems for the achievement of their functionality.

5. Method according to claim 4, characterised in that, in terms of a biofunctionalization process of said intermediate layer, a diversity of nanoparticles (NPs) is loaded in the filter layers for enhancing the anti-bacterial and anti-viral activities of the filter system, and in that silver nanoparticles are delivered in said filter layers, mostly in the nanoporous layer, for obtaining an anti-bacterial and anti-viral nanofilter system; particularly wherein nanomedicines, theranostics, sensors and said loaded NPs are ranging from inorganic ones apart from silver, including titanium nitride, gold, metal oxide, zinc oxide, titanium dioxide, copper, on the one hand, and organic, polymeric NPs loaded with antibacterial, anti-virus and other therapeutic agents, natural, silver/metal compounds, quaternary ammonium compounds, N-halamines and anti-septic agents, on the other hand.

6. Method according to claim 4, characterised In that a highly nanoporous filter consisting of BP blends or BP multilayers onto inorganic and organic substrates and of the nanoparticulate filters, is manufactured by wetting and printing techniques among slot die coating, gravure printing and other coating and printing techniques respectively, including electro-spraying, ink-jet printing, electrospinning, dipping, spin coating, spray coating, and vacuum deposition techniques, which are selectively applied for the functionalization of said nanoporous BP layers onto said organic and inorganic substrates.

7. Method according to claim 4, characterised in that said nanofilter is applied for various surfaces to polymeric organic substrates selected among Poly(Ethylene Terephthalate) (PET), polycarbonate, cellulose acetate, natural polymers, plastics, non-woven fabrics and other flexible substrates, as well as inorganic substrates selected among stainless steel, silicon, titanium and other metals, glass; particularly wherein the process is optimized in that working parameters are set among the monomers ratio, molecular weight, crystallinity, hydrophilicity and surface free energy of the BPs, the BPs deposition in a specific order, the polymerblend ratio, the polymerNPs ratio in the thin films, combined with their desirable concentration, therapeutic actions, wherein said method for fabricating the nanofilters has a high filtration efficiency,

8. The method according to claim 4, characterised in that said filter system is applied in the case of monolayer and multilayer thin films of organic polymeric, possibly biodegradable, nanomaterials, for the production of nanofilters for personal, medical protection equipment, with application in healthcare, industrial, public, domestic, particularly wherein these nanotechnology-enabled products are used for healthcare workers, any workers subject to harsh environmental conditions, or individuals during a pandemic notably of COVID-19, wherein the nanoporous filters are applied mainly to face masks, respirators, face shields, protective glasses, gloves and clothes, but also to air and gases filtration, food processing applications, food packaging, kidney filtration membranes, skin patches, pharmaceuticals, fine chemicals, flavor, fragrance, cosmetics, implants, biomedical devices.

9. Face mask, incorporating the said nanofilter system as defined in claim 1, characterised in that said face mask comprises an exhalation valve enhancing the wearer's ease of breathing, and a nanofilter with the microporosity of the external and internal layer and the nanoporosity combined with the nm thickness of the middle nanolayer that generates a reduced airflow resistance and pressure differential—internal to ambient air—thus yielding a declined deflection of inhaled or exhaled air and airborne particles, thereby enhancing the filtration efficiency and mask wearer's comfort.

10. Face mask according to claim 9, characterised in that the external filter layer is disposed on the middle layer and in that it is made of non-woven fiber material that is microporous and breathable, notably selected among polypropylene (PP), polystyrene, polycarbonate, polyethylene, and combinations thereof or polyesters, other hydrophobic polymers, hydrophobic fluoropolymers, or polymers with hydrophobic surfactants, fluoro-surfactants, wherein the tailored multi-functional multilayer serves as the middle layer disposed on the inner layer made of nonwoven fiber material suitable both to contact the wearer's face and for comfortable use, wherein the intermediate multi-functional layer is not permeable to viruses, allergens, bacteria, mold, nanosized particles, chemicals also allowing breathability through the whole surface area.

11. Face mask according to claim 9, characterised in that it further comprises an external plastic cap provided with holes serving as protective filter seal, which is fastened tightly to the nanofilter system apparatus to avoid filter removal during the movement of the user.

12. Face mask according to claim 9, characterised in that for surgical or medical face masks, the nanofilters replace the middle layer, the melt-blown filter layer, or in that it is deposited onto the melt-blown one.

13. Face mask according to claim 9, characterised in that it is 3D printed.

14. Face mask according to claim 9, wherein said mask is extended to a respirator, wherein said nano-face device exhibits antibacterial, anti-viral protection and particulate-filtering due to the high efficiency of said nanofilter system incorporated therein.

15. Face shield, incorporating said nanofilter as defined in claim 1, characterised in that is composed of a notably 3D printed headband with strap and a nanoparticulate nanofilter with transparency, antiviral and anti-bacterial properties that is deposited onto the plastic shield after an adapted surface treatment, wherein said face shield exhibits an antibacterial and anti-viral protection as well as a particulate-filtering due to the high efficiency of said incorporated nanofilter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] FIG. 1a shows a schematic representation of the structure of a Nanofilter System 100 for Nano facemasks composed of an external, coarse filter layer with microporosity 101, b Intermediate nanofilter with multi-functional, nanoporous filter layers involving single thin film (BP1:BP2 blend) 102, deposited onto the functional, thick, microporous filter, fiber-based layer 103, and c) an inner layer 104,

[0040] FIG. 1b depicts a schematic representation of the structure of the Nanofilter System 100 composed of a) an external, coarse filter layer with microporosity 101, b) an intermediate nanofilter, with a nanoparticulate layer, on top or embedded in a multi-functional, nanoporous filter layer involving single thin film (BP1:BP2 blend) 102, deposited onto the functional, thick, microporous, fiber-based filter layer 103, and c) an inner layer 104.

[0041] FIG. 1c shows a schematic representation of the structure of the Nanofilter System 100 composed of: a) an external, coarse filter layer with microporosity 101, b) Intermediate Nanofilter 102, made of multi-functional, nanoporous filter layers (involving bi-layer to multi-layer nanoporous BP thin films BP1, BP2, etc. deposited onto the functional, thick, microporous, fiber-based filter layer 103, and c) an inner layer 104.

[0042] FIG. 1d shows a schematic representation of the structure of the nanofilter system 100 composed of a) an external filter, microporous layer 101, b) an intermediate nanofilter 102 with a nanoparticulate layer, on top or embedded in multi-functional, nanoporous filter layers involving bi-layer or multi-layer BP thin films BP1, BP2, etc, deposited onto the functional, thick, microporous, fiber-based filter layer 103, c) an inner layer 104.

[0043] FIG. 2a depicts a schematic representation of the nanoporous BP blend in a single nanolayer structure by having a specific polymer blend ratio BP1:BP2, leading to controlled nanoporosity, nanopores size, and surface distribution.

[0044] FIG. 2b shows the schematic representation of the nanoporous BP multi-layer by characterizing a specific deposition order of the BP1, BP2, etc.

[0045] FIG. 3a shows AFM topography images of the nanofilter of the present invention produced by the slot-die technique (scan size 5 μm×5 μm).

[0046] In FIG. 3b the corresponding cross-section of FIG. 3a depicts the nanoporosity features.

[0047] FIG. 4 shows AFM topography images of the nanofilter of the filter system fabricated by gravure printing under variable experimental conditions including (A) a polymer concentration of 10 mg ml.sup.−1, gravure printed with cell density of 150 line/inch, (scan size 5×5 μm); (B) a cross-section of a nanopore in FIG. 4a, (C) Polymer concentration of 10 mg ml.sup.−1, gravure printed with cell density of 120 line/inch, (scan size 6×6 μm).

[0048] FIG. 5 depicts an AFM topography image of the silver Nanoparticles that can be applied for further functionalization of the body of the invention (scan size 2×2 μm).

[0049] FIG. 6 illustrates an embodiment of a sectional view of the Nano-facemask according to the invention with nanofilter position where the nanofilter System 100 apparatus will be placed and fixed 105 and its exhalation valve 106.

[0050] FIG. 7a illustrates a graphic illustration of the nanofilter system apparatus according to the invention with a protective molding seal 107 towards nano-facemask placement.

[0051] FIG. 7b depicts the adjustment of the nanofilter System apparatus 107 to the nano-facemask according to the invention and the external plastic cap 108 exhibiting holes that will be screwed tightly to the nanofilter apparatus to guarantee the non-removal of the nanofilter system during movements of the mask wearer.

[0052] FIG. 8a illustrates a paradigm of the protective nano-faceshield wherein the nanofilter is deposited to block nanometer sized and micrometer sized hazards.

[0053] FIG. 8b shows the functional layer of nanoparticles that is deposited onto the substrate of the nano-faceshield to advance its properties.

DESCRIPTION

[0054] The invention relates to a method for design and development of nanofilters with high efficiency filtration for personal and protective equipment against microparticles, dust, bacteria, fumes, vapors, gases, allergens, air pollutants, airborne microorganisms and nanosized viruses, e.g. influenza, HIV, SARs, SARs-CoV-2, that are composed mainly of nanoporous, multi- or single layers of biodegradable polymeric (BP) thin films, which are featured by nanopores with tailored properties for the case of the following embodiments:

[0055] A first embodiment consists of a design of an advanced nanofilter system for Nano-face masks comprising an external, coarse filter thick layer with microporosity 101 for filtration of microparticles; further an intermediate nanofilter onto a functional, thick, microporous, fiber-based filter layer, wherein the nanofilter consists of multi-functional, nanoporous nanolayers involving single or more discrete layers, with or without nanoparticulate layer; and still further an inner filter of thick layer with microporosity and comfortable use. However, appropriate inner, outer, and filtration materials may be of a single or multiple layer design.

[0056] The materials used for the external and inner filter layers may be non-woven fibers like polypropylene (PP), cellulose, polystyrene, polycarbonate, polyethylene, and combinations thereof or polyesters, other hydrophobic polymers, hydrophobic fluoropolymers, or polymers is with hydrophobic surfactants, fluorosurfactants, without being limited thereto. The micropores block microparticles, dust, bacteria, fumes, vapors, gases, allergens, fungi, molds, air pollutants, airborne microorganisms. The nanopores provide a filter at the nanoscale against hazards like harmful nanoparticles, chemicals, viruses, gases and others.

[0057] A further embodiment consists of a design and synthesis of the intermediate nanofilter onto a functional, thick, microporous, fiber-based filter layer that serves as substrate for thin films deposition. The nanofilter consists of multi-functional, nanoporous layers involving: i) single layer BP blends or bi-layer/multilayer BP thin films characterized by tailored nanoporosity and nanoscale thickness, which can entrap airborne nanoparticles, nanometer sized substances, viruses, toxins, chemicals, gases, allergens, air pollutants, bacteria, and ii) a functionalization layer made of nanoparticles, or other agents, therapeutic compounds with nanoscale thickness. The nanofilter may be biofunctionalized or not with the nanoparticulate layer depending on the application.

[0058] The nanoporous layers of the filter may be constituted of a diversity of biodegradable polymers including different types of Poly (DL-lactide-co-glycolide) (PLGA) in terms of lactide: glycolide ratio, polycaprolactone (PCL), Polylactic acid (PLA), polysaccharides, polyesters, natural polymers with variations in degradation rates. In addition, other BPs can also be used, such as BP aliphatic polyesters, e.g. homopolymers and copolymers of lactic acid, glycolic acid, trimethylene carbonate, and blends, without being limited thereto. The nanolayers are deposited onto a functional, thick, microporous, fiber-based filter layer that is preferably fiber-based and made of non-woven fabrics, PA and other to enhance the filtration capacity of the nanofilter system.

[0059] A yet other example consists of tailoring the surface and structural properties, the nanoporosity, thickness of the BP thin films of the intermediate nanofilter for high filtration capability, by alteration in deposition parameters in line with the derived AFM and SE data for thin films characterization and quality control.

[0060] A still further example consists of a design and fabrication of an advanced anti-bacterial and anti-viral nanofilter system, by the delivery of silver nanoparticles in the filter layers and mostly either on top or embedded in the intermediate nanofilter. A diversity of NPs can be loaded ranging from inorganic ones besides silver, like titanium nitride, gold, zinc oxide, copper, without being limited thereto, and organic, polymeric NPs with anti-bacterial, anti-virus and other therapeutic agents, silver/metal compounds, quaternary ammonium compounds, N-halamines and anti-septic agents. Moreover, metal and polymeric NPs, sensors, theranostics, substances can be applied to enhance the functionality of the nanofilter system in regard to each specific application.

[0061] Another example consists of the development of the highly nanoporous nanofilter that consists of BP blends/or multi BP layers on inorganic and organic substrates like microporous PA and of the nanoparticulate nanofilters by slot die coating and gravure printing, though not limited, by other coating and printing techniques, such as electro-spraying, dipping, ink-jet printing, electrospinning, spin coating and vacuum deposition techniques. The nanofilter can be applied for all kinds of surface, and to all polymeric substrates such as PET, polycarbonate, cellulose acetate, PA, natural polymers, plastics, non-woven fabrics, etc. and other flexible substrates as well as inorganic ones like stainless steel, silicon, titanium and other metals, glass and other.

[0062] A yet further example consists of a design and development of nano-facemasks, respirators, based on the nanofilter system with exhalation valve, wherein the valve enhances the wearer's ease of breathing. The specific architecture of the mask nanofilter system with the microporosity of the filter layers and the nanoporosity combined with the nanometer thickness of the middle nanofilter allows for reduced airflow resistance and pressure differential (internal to ambient air) and therefore declined deflection of inhaled or exhaled air and airborne particles, which enhances filtration efficiency and wearer's comfort.

[0063] A yet other example consists of the design and fabrication of a nano-face shield that is composed of a 3D printed headband with strap and its main, functional and advanced part involving the nanofilter either alone or further functionalized with NPs with controlled transparency, antiviral and anti-bacterial properties after proper surface treatment.

[0064] This method can be generally applied, notably in the case of monolayer and multilayer thin films of organic polymeric, biodegradable or not, nanomaterials that can be used for the production of nanofilters and nanofilter systems for personal, medical protection equipment and may have application in healthcare, industrial, public, domestic, or other settings. Hence, these nanotechnology-enabled products can be used for healthcare workers, any workers subject to harsh environmental conditions or individuals during a pandemic like COVID-19.

[0065] The nanofilters and nanofilter systems may be applied but not limited to face masks, respirators, face shields, protective glasses, gloves and clothes, air and gases filtration, food processing applications, food packaging, kidney filtration membranes, skin patches, pharmaceuticals, fine chemicals, flavor, fragrance, cosmetics, implants and biomedical devices.

[0066] Measurements were realized based on a series of experiments performed for the presentation and the use of the proposed technique which are set out below.

[0067] FIG. 1 depicts the architecture of the nanofilter system for Nano-face masks and its components.

[0068] Specifically, FIG. 1a shows a schematic representation of the structure of the nanofilter system 100 for nano-facemasks composed of a) an external, coarse filter layer with microporosity 101, b) an intermediate nanofilter with multi-functional, nanoporous filter layers involving single thin film (BP1:BP2 blend) 102, deposited onto the functional, thick, microporous filter, fiber-based layer 103, and c) an inner layer 104.

[0069] FIG. 1b depicts a schematic representation of the structure of the nanofilter system 100 composed of: a) an external, coarse filter layer with microporosity 101, b) an intermediate nanofilter, with a nanoparticulate layer, on top or embedded in a multi-functional, nanoporous filter layer involving single thin film (BP1:BP2 blend) 102, deposited onto the functional, thick, microporous, fiber-based filter layer 103, c) an inner layer 104.

[0070] FIG. 1c presents a schematic representation of the structure of the nanofilter system 100 composed of: a) an external, coarse filter layer with microporosity 101, b) an intermediate nanofilter 102, made of multi-functional, nanoporous filter layers involving bi-layer to multi-layer nanoporous BP thin films BP1, BP2, etc. deposited onto the functional, thick, microporous, fiber-based filter layer 103, and c) an inner layer 104.

[0071] FIG. 1d presents a schematic representation of the structure of the Nanofilter system 100 composed of: a) External filter, microporous layer 101, b) Intermediate Nanofilter 102 with a nanoparticulate layer, on top or embedded in multi-functional, nanoporous filter layers (involving bi-layer or multi-layer BP thin films BP1, BP2, etc.), deposited onto the functional, thick, microporous, fiber-based filter layer 103, c) Inner layer 104.

[0072] The design of the nanofilter system is based on the requirements of each application. Different type of materials may comprise the layers to enhance the filtration capacity. The multi-functional, intermediate nanofilter with controllable nanoporosity and thickness can provide protection against different particles, nanometer sized viruses, nanoscale hazards, bacteria, and others.

[0073] In the case of the Nano-facemasks, the external layer should be microporous and hydrophobic and may be composed of, but not limited to, non-woven fabrics, PP, polystyrene, polycarbonate, polyethylene, and combinations thereof or polyesters, other hydrophobic polymers, hydrophobic fluoropolymers, or polymers with hydrophobic surfactants, fluoro-surfactants, etc. The micropores can block microparticles, dust, bacteria, fumes, vapors, gases, allergens, air pollutants, airborne microorganisms. For the production of the intermediate, multi-functional nanofilters, different classes of biodegradable polymers, e.g. BP1, BP2, etc., in terms of molecular weight, monomers ratio, crystallinity, hydrophobicity, surface free energy and surface charge can be deposited in a multi-layer structure or in a single layer—blend of BP polymers—onto the microporous, thick filter substrate [18],

[0074] The intermediate nanoporous layers of the nanofilter can be biofunctionalized with diversity of anti-bacterial, anti-viral, therapeutic agents, inorganic or organic nanoparticles, nanomedicines, chemical and natural compounds to enhance its effectiveness not only by blocking and trapping the nanosized viruses—such as influenza, SARs-CoV-2, and others—within the nanopores, but also inactivate them. The NPs can be deposited by different wetting and printing techniques either onto the surface or embedded in the nanoporous layers of the nanofilter—or onto the other filter layers of the system—to meet the requirements for each need. However, it will be understood by those of ordinary skill in the art that sensors, diagnostic and theranostic NPs, substances can be loaded as well.

[0075] FIG. 2a depicts a schematic representation of the nanoporous BP blend in a single nanolayer structure by having a specific polymer blend ratio BP1:BP2, leading to controlled nanoporosity, nanopores size, dimensions and surface distribution.

[0076] FIG. 2b presents the schematic representation of the nanoporous BP two to multilayer by characterizing of a specific deposition order of the BP1, BP2, etc. [18]. The appropriate blend of the biodegradable polymers can be applied by, slot-die coating, gravure printing, but not limited to spraying, dipping, ink-jet printing, spin coating, electro-spraying, and other, onto polyamides, inorganic or organic substrates.

[0077] FIG. 3a shows AFM topography images of the nanoporous layer of the nanofilter onto the PA microporous filter layer of the present invention produced by the slot-die technique (scan size 5 μm×5 μm). The dimensions, density of the nanopores in line with the thickness of the layer are essential factors that determine the filter functionality. The nanoporosity and thickness can be tailored under different deposition parameters like pump rate in line with polymer concentration, polymer ratio as measured by SE, AFM. Slot-die coating is an extremely versatile deposition technique that possesses the advantages of the simple relationship between wet-film coating thickness, the flow rate of solution, and the speed of the coated substrate relative to the head; the ability of producing uniform films across large areas and its ease of integration into scale-up processes including roll-to-roll coating and sheet-to-sheet deposition systems. The technique itself offers high levels of coating uniformity across the length/width of the coating surface and can deposit thin-films with thicknesses ranging from a few nanometers to many microns. It can do this for a wide range of solution types and viscosities at rates ranging from a few centimeters per second to several meters per second.

[0078] In FIG. 3b, the corresponding cross-section of FIG. 3a depicts the nanoporosity features. Characterization of the single nanopores revealed a variation in diameter ranging from 100 to 350 nm, of the double nanopores the diameter is measured to be approximately 700 nm i.e. 350 nm for each nanopore. The AFM measurements showed that the polymer concentration, the polymer blend ratio and the pump rate affect mainly the nanoporosity and thickness of the nanoporous layers. Especially, by controlling the pump rate during the slot-die process, the thicknesses of the nanoporous thin films as measured by SE can be achieved to allow higher filtration efficacy without increasing the air resistance within the filter.

[0079] FIG. 4 shows AFM topography images of the nanoporous layer of the Nanofilter onto PA substrate fabricated by gravure printing under variable experimental conditions set as follows: [0080] (A) polymer concentration of 10 mg gravure printed with cell density of 150 line/inch with scan size 5×5 μm, [0081] (B) Cross-section of a nanopore in FIG. 4a, [0082] (C) Polymer concentration of 10 mg ml.sup.−1, gravure printed with cell density of 120 line/inch with scan size 6×6 μm.

[0083] The polymeric mixture was printed by the gravure printing technique using a printing pattern with cell density of 150 line/inch, or 120 line/inch and cell depth of 40 μm.

[0084] The AFM images demonstrated that by varying the polymer blend ratio, the polymer concentration, the gravure printing parameter (lines per inch), multi-sized nanopores with controlled dimensions and density as well as desirable layer thickness (SE derived data) can be produced to allow breathability with maximum filter efficacy.

[0085] Due to the outbreak of the emerging infectious diseases caused by different pathogenic viruses like the COVID19 pandemic, NPs have emerged as novel antimicrobial and anti-viral agents thanks to the observation of their high surface area to volume ratio and their unique chemical and physical properties.

[0086] In some embodiments, the agent that can be loaded into the nanofilter for biofunctionalization includes the following one or more substances without being limited thereto: anti-bacterial, anti-viral agents, silver, titanium, titanium nitride, zinc, copper, gold, metal oxide nanoparticles such as iron oxide, zinc oxide, and titanium dioxide NPs and other, nanomedicines, chemical and natural compounds, peptides, resin-based composites, drugs, chlorhexidine, sensors, diagnostic NPs, etc,

[0087] Thus, the anti-bacterial and anti-viral activities of the nanofilter system can be enhanced by the deposition of metal nanoparticles onto the filter layers, especially onto the intermediate nanofilter.

[0088] The selection of the NPs in terms of material type, size and physicochemical properties is based on the viral or bacterium invader characteristics that need to be blocked and inactivated, involving its size, structure, surface charge, membrane receptors and binding proteins. For example, the SARS-CoV-2 virus with the size of 60-140 nm and spherical shape entries the host cells by a transmembrane spike (S) glycoprotein comprises two functional subunits responsible for binding to the host cell receptor (S1 subunit) and fusion of the viral and cellular membranes (S2 subunit).

[0089] Silver nanoparticles are the most effective of the metallic NPs against bacteria, viruses and other eukaryotic microorganisms, particularly due to the inherent inhibitory and bactericidal potential of silver, but also because of their good conductivity, catalytic properties, and chemical stability. The key mechanisms of action of silver NPs are the release of silver ions which enhances antimicrobial activity-, cell membrane disruption, and DNA damage [19].

[0090] Taking all these into account, a paradigm of functionalized silver NPs with the sizes of 10 nm is depicted in FIG. 5, wherein AFM topography images of the silver NPs that can be applied for further functionalization of the body of the invention are presented (scan size 2×2 μm).

[0091] The silver NPs can be functionalized for capture of specific gaseous airborne threats by different agents, surfactants, like Polyvinyl alcohol (PVA), and Polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), cationic surfactants, anionic sodium dodecylbenzenesulfonate (LAS), cationic dodecyltrimethylammoniumchloride (DTAC) and non-ionic Berol 266 (Berol), etc. to enhance stability, to minimize toxicity and to reduce NPs agglomeration.

[0092] In some embodiments, the anti-bacterial, anti-viral nanoparticles can be deposited onto nano-facemasks, respirators, face shields, protective clothes, glasses, and shoes, personal and medical protective equipment and may have application in health care, industrial, public, domestic, or other.

[0093] The nanoparticles can be loaded into the nanofilters, facemasks, face shields and other protective equipment by slot die coating, gravure printing and by other coating and printing techniques, such as electrospraying, electrospinning, dipping, ink-jet printing, spin-coating, spraying and vacuum deposition techniques, without being limited thereto.

[0094] In some embodiments, functional organic and metal nanoparticles, sensors, substances can be applied to enhance the properties of the nanofilters and systems in regard to each specific application.

[0095] FIG. 6 illustrates an embodiment of a sectional view of the nano-facemask with nanofilter position where the nanofilter system 100 apparatus gets placed and fixed 105 and its exhalation valve 106. The current medical masks, like N95 respirators, incorporate filter materials wherein the fiber diameter and density are the main parameters that maintain the balance between filtration efficacy and pressure gradient between inside and outside the mask. The prior art teaches that the higher fibers density and diameter provide more air resistance to the wearer and difficulty in breathing. The pressurized gas will seek equivalence to ambient (lower) air pressures through the pathway of less resistance, namely any leak around the mask, rather than through the dense filtration material. This creates a condition whereby airflows are deflected off of the mask material (inner, and filter layers) rather than passing through it.

[0096] The main advantage of this embodiment lies on the fact that the nanofilter system as a crucial component of the nano-facemask with the controllable thickness—ranging from a few nanometers up to a few micrometers—and nanoporosity—dimensions of nanopores, density—of the nanofilter will lead to lower pressure gradients—internal to ambient air—and less leakage around the mask. The specific architecture of the nano-facemasks with the microporosity of the external, intermediate functional and internal layer and the advantageous nanoporous layer of the nanofilter allows for a reduced airflow resistance and therefore declined deflection of inhaled or exhaled air and airborne particles, which enhances filtration efficiency and wearer's comfort. The diversity of pores of the filter layers—in terms of size micrometers up to nanometers, and of morphology—may block the passage of airborne micro to nanoparticles including viruses, bacteria, dust, spores, and mold and chemical pollutants.

[0097] Another advantage of the embodiment is the fact that both the nano-facemasks and nanofilter systems are re-useable with enhanced durability after proper sterilization.

[0098] In some embodiments, the nanoporous layers of the nanofilter—either single or multi-layer structure—can be in a discrete layer(s) between the outer and inner layer. In some embodiments, the nanofilter can make up the middle layer or can be disposed on the middle layer of the facemask.

[0099] In some embodiments, the nanoporous thin films can be disposed on the inner, middle and/or outer layer by slot-die, gravure printing, spraying, dipping, ink-jet printing, electro-spraying and other coating and printing techniques.

[0100] In some embodiments, the nanofilter system can be adapted to all type masks, standard surgical and N95 masks, shapes, sizes, made of different materials to meet the demand for different technical requirements.

[0101] Especially in the case of surgical or medical face masks, the nanofilters can replace the middle layer, the melt-blown filter layer, or can be deposited onto the melt-blown one by the methods of the invention.

[0102] The mask can be made of a diversity of filtration materials including but not limited to woven and non-woven fabrics, plastics, polypropylene melt-blown fibers, polymers, hydrophobic materials, cellulose, thermoplastics, thermosets, elastomers, polymers with incorporated fillers, biopolymers, and polymers blended with biological materials and can be produced by versatile techniques involving Additive manufacturing (AM) like 3D printing, ink jet printing, roll-2-roll printing, thermoplastic processes, extrusion and injection molding, melt blown processes and other in accordance with the specific application.

[0103] In this embodiment, the Nano-face mask can be produced by 3D-printing and comprises of the nanofilter system position, exhalation valve, elastic bands around head and a soft, flexible material, soft rubber or elastomer seal against face like thermoplastic polyurethane, or TPU, to guarantee the tight fit with the face of the wearer.

[0104] The exhalation valve is to ensure a regular air flow, heat and moisture reduction inside the filtering face mask as it allows hot and humid air outflow. The mask can cover the nose, the mouth and cheeks of the user. Hence, it will be understood by those of ordinary skill in the art that other shapes of the face mask can be made in order to cover both the eyes, hair, and throat of the wearer, with or without exhalation valve.

[0105] FIG. 7a illustrates a graphic illustration of the nanofilter system apparatus with a protective molding seal 107 towards nano-facemask placement.

[0106] However, it will be understood by those of ordinary skill in the art, that the materials, shapes, structures, fabrication processes of the protective filter seals can be adapted to different technical requirements, material substrates, designs and processes for facemasks, nanofilter systems, filters, and other products.

[0107] FIG. 7b depicts the adjustment of the nanofilter system apparatus 107 to the nano-facemask and the external plastic cap 108 exhibiting holes that will be screwed tightly to the nanofilter system apparatus.

[0108] In some embodiments, the external plastic cap is screwed tightly to the nanofilter system apparatus to avoid filter removal during the movement of the user.

[0109] In some embodiments, different shapes, designs, structures, materials and production techniques can be applied for the external protective cap of the nanofilter system.

[0110] In some embodiments, the nano-facemask can be either be comprised of a more rigid part involving polymeric filaments of PLA and of a flexible part made of TPU, shape memory filaments, or combination of both. The thermoplastic can provide a secure fit of the mask onto the face which prevents gaps and passage of material between the nostrils and mouth and the surrounding environment. Besides 3D printing, the thermoplastics can be produced and reshaped though not limited by injection molding, compression molding, calendaring, melt blown processes and extrusion.

[0111] The architectural design and choice of polymers can lead to materials with enhanced functionalities, mechanical properties, porosity, and stability. However, it will be understood by those of ordinary skill in the art that the design of the mask can be adapted to different material substrates, conditions and processes for large scale production.

[0112] FIG. 8a illustrates a paradigm of the protective nano-faceshield wherein the nanofilter is deposited to block nanometer sized and micrometer sized hazards. FIG. 8b shows the functional layer of nanoparticles that is deposited onto the plastic substrate of the Nano-face shield to advance its properties.

[0113] Besides NPs, other agents, substances are deposited onto the substrate e.g. PET, polycarbonate, cellulose acetate, plastics to advance the protection of the user. Metal or organic NPs with anti-bacterial, anti-viral activities can be loaded to provide anti-viral and anti-bacterial protection for healthcare workers, workers in industrial, public, domestic environment. In some embodiments, functional organic and metal nanoparticles, sensors, substances, nanomedicines, chemical and natural compounds, peptides can be applied to enhance the barrier and filter properties of the nanofilter in regard to each application.

[0114] The surface chemistry, wettability, optical or other material properties, including, but not limited to different material composition are taking into account for the appropriate surface treatment of the shield substrate for the successful deposition of the nanofilter with or without NPs or NPs alone. The nanofilter can provide a high filtration efficiency to advance the nano-shield protective function against microorganisms, dust, chemicals, air pollutants, mold, viruses and other.

[0115] The applications of the device body of the present invention includes but not limited to the following ones: personal, medical protection equipment, face masks, respirators, face shields, protective glasses, gloves and clothes, air and gases filtration, food processing applications, agriculture, food packaging, kidney filtration membranes, skin patches, pharmaceuticals, fine chemicals, flavor, fragrance, cosmetics, implants, biomedical devices, medical equipment. The nanofilters and nanotechnology-enabled products may have application in healthcare, industrial, public, domestic, or other settings as they can be used by healthcare workers, any workers subject to harsh environmental conditions, or individuals during a pandemic like COVID-19.

[0116] In some embodiments, the nanofilter system can be adapted to all type masks, standard surgical and N95 masks, shapes, sizes, made of different materials to meet the demand for different technical requirements. Especially in the case of surgical or medical face masks, the nanofilters can replace the middle layer, the melt-blown filter layer, or can be deposited onto the melt-blown one by the methods of the invention.

[0117] To summarize, the present invention relates to nanofilters and nanofilter systems for personal and health care protective equipment to protect against health and safety hazards having application in healthcare, industrial, public, domestic environments. it also relates to a robust, reliable method for fabricating thereof with higher filtration efficiency, and to Nano-face masks, respirators, Nano-face shields exhibiting antibacterial, anti-viral protection and particulate-filtering due to the excellent barrier and filtration properties of the nanofilter system.

[0118] This invention lies on the design and production of tailored Nanofilters and nanofilter systems with high efficiency filtration for personal protective equipment to overcome the objections in the prior art. These Nanofilters and nanofilter systems are applied to face masks, respirators, face shields, protective glasses and clothes, to protect healthcare workers and other individuals against microparticles, dust, bacteria, fumes, vapors, gases, allergens, air pollutants, airborne microorganisms and especially nanosized viruses such as influenza, HIV, SARs, SARs-CoV-2.

[0119] The Nanofilters and systems may be also applied to the delivery of nanoparticles, organic or inorganic ones with antibacterial, antiviral properties, drugs, therapeutic agents, nanomedicines, or/and compounds, sensors.

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