WO2021219860A2

WO2021219860A2 - Antiviral respiratory filter media

Info

Publication number: WO2021219860A2
Application number: PCT/EP2021/061433
Authority: WO
Inventors: Luke Ice; Clifford Dwyer; Peyton HOPSON; Stephen Christopher; Jonathan Hansen; Gary Eichenbaum
Original assignee: Cilag Gmbh International; Ethicon Llc
Priority date: 2020-05-01
Filing date: 2021-04-30
Publication date: 2021-11-04
Also published as: WO2021219860A3

Abstract

A removable filtration system for use in a respiratory mask device has a filter media having a three-dimensionally contoured form to fit over the face of a wearer; and a filter support joined to the filter media along at least a portion of either or both of the periphery, anterior, or posterior of the filter media and wherein the filter support is configured to securely engage the removable filtration system to a feature of an outer covering of the respiratory mask device. Additionally or alternatively, a respiratory filter media has multiple layers each having has at least one property selected from a cationic property, reduced pore size, pores with increased tortuosity, an antibacterial property, and an antiviral property.

Description

ANTIVIRAL RESPIRATORY FILTER MEDIA

I. BACKGROUND OF THE INVENTION a. Field of the Invention The described embodiments relate to personal protective equipment, specifically respiratory filter media for use alone or in conjunction with mask devices such as respiratory face masks and surgical masks. The present invention relates to protective barrier materials and equipment including protective barrier materials. The equipment includes a device including a protective barrier including a filtration system that prevents or reduces systemic exposure to infectious viral, bacterial and other pathogens. b. Background and Discussion of the Related Art

Personal protective mask devices are routinely used in the healthcare industry to help prevent the spread of disease by filtering pathogens and other contaminants from air inhaled by the wearer. In addition, these mask devices seek to protect patients and others near the wearer by filtering air exhaled from the wearer thereby reducing the number of viral, bacterial, or other pathogens released into the environment. Recently, widespread infectious diseases and growing public awareness about the mechanisms by which airborne pathogens spread among a population have greatly increased the demand among healthcare professionals and everyday citizens for improved highly protective, comfortable, economical, and convenient mask devices.

Surgical masks are a type of mask device that fit relatively loosely to the face and are designed primarily to protect others from contaminants expelled by the wearer. Surgical masks are generally low- cost, one-time use devices made of fabric material(s) that offer limited protection against the spread of airborne pathogens because the mask does not create a strong seal against the face. Thus, inhalation and exhalation vapors are permitted to pass around the perimeter of the mask and as a result they may not fully protect the wearer from inhaling contaminants or from being exposed to fluid splashes. Surgical masks are also typically flimsy and thus susceptible to soiling, fraying, and offer limited splash resistance to fluids such as blood spatter.

Relative to surgical masks, mask devices that qualify as "respirators" under standards set by relevant authorities offer increased protection by filtering a higher percentage of airborne particles using more effective filtering materials and/or sealing features. Disposable respirator mask devices, however, often fail to establish a robust seal against the wearer's face and generally have a design that physically exposes all or a significant portion of the filtration media to the surrounding environment. This exposure makes the filtration media of the mask device vulnerable to physical damage, soiling, and fluid splashing, all of which may reduce the useful life or compromise the protective efficacy of the mask device. Reusable respirator mask devices typically employ replaceable filter cartridges and are more robust in construction and materials than disposable devices. However, reusable mask devices come at a higher cost and, because they are traditionally tailored to more industrial applications, they suffer from a form factor, fit, or appearance that are not ideal for use in a healthcare setting or during everyday activities such as air travel or retail shopping. Furthermore, the filter cartridges conventionally used in reusable mask devices typically have a smaller footprint to support the replaceability and fitment of the cartridge within the body of the mask. The types of filter media capable of supporting normal breathing effort at this scale often suffer from reduced filtration capacity and thus require compensation through techniques such as pleating thereby adding further bulk to the overall design.

Furthermore, it is known that viral and bacterial pathogens may be spread through the air, such as via sneezing, coughing, or other methods of releasing such pathogens into the air. There is a need for methods to protect against the transmission of airborne viral and bacterial pathogens, particularly to prevent such pathogens from entering the mouth or nose of an uninfected individual. Surgical masks such as N95 particulate respirator masks are effective at protecting against pathogens but are not always readily available. Further, some masks may not be used on a day-to-day or all-day basis due to their comfort, aesthetics, cost and/or lack of re-usability. Other attempts at providing a protective mask that contains layered removable filters for protection against smoke inhalation have been made. Other previous mask devices have been made that include, for example: (i) copper oxide fibers, (ii) a copper oxide solution coating, (iii) a coating of ionic surfactant, (iv) a coating of salt on the fiber surface of a mask, and (v) infusing zinc and copper oxide into textiles for face masks.

Many individuals turn to using simple cloth fibers to cover their mouth or nose, however, it has been shown that cloth masks alone do not provide meaningful protection against pathogens. It has previously been shown that certain viruses are inactivated on exposure to certain metal and metal alloy surfaces including but not limited to copper and copper alloys. Known methods suffer from a number of defects, including cost and comfort deficiencies, ineffectiveness, lack of re-usability, and other such desired features. Therefore, there exists a need for providing a device having a protective barrier that is easy to assemble, effectively blocks pathogen entry, is comfortable, washable, re-usable and adjustable to different face sizes and shapes. The inventive system may be used in other devices other than masks, such as filtration systems for buildings, laboratories, airplanes, automobiles and other places in which filtration needs may arise.

II. SUMMARY

In view of the above, there remains a need for a respiratory media and respiratory mask devices that address the deficiencies and limitations of existing surgical masks and respirator mask devices. The objects and advantages of the present invention may be realized by providing a removable filtration system for use in a respiratory mask device having a filter media having a three-dimensionally contoured form to fit over the face of a wearer and a filter support wherein the filter media is joined to the filter media along at least a portion of either or both of the periphery, anterior, or posterior of the filter media and wherein the filter support is configured to securely engage the removable filtration system to a feature of an outer covering of the respiratory mask device.

Further objects of the invention may be achieved through a respiratory filter media having a plurality of layers, wherein each of the plurality of layers has at least one property selected from: a cationic property, reduced pore size, pores with increased tortuosity, an antibacterial property, and an antiviral property.

III. BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the invention will be apparent from the following, more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.

Figure 1 shows a perspective view of a respiratory mask device as worn on a face of a wearer according to an embodiment.

Figure 2A shows an exploded perspective view of a respiratory mask device according to an embodiment.

Figure 2B shows a cutaway perspective view of a respiratory mask device of an embodiment.

Figure 3A shows a perspective view of a face gasket of a respiratory mask device according to an embodiment.

Figure 3B shows a side view of a face gasket of a respiratory mask device according to an embodiment.

Figure 4A shows a perspective front view of a filter media of a respiratory mask device according to an embodiment.

Figure 4B shows a perspective rear view of a filter media of a respiratory mask device according to an embodiment. Figure 5A shows an exploded perspective view of a filtration system of a respiratory mask device according to an embodiment.

Figure 5B shows an underside perspective view of a filtration system of a respiratory mask device according to an embodiment. Figure 6A shows a top view of an outer covering of a respiratory mask device according to an embodiment.

Figure 6B shows a perspective view of an outer covering of a respiratory mask device according to an embodiment.

Figure 7 shows a perspective cross section of a respiratory mask device according to an embodiment.

IV. DETAILED DESCRIPTION

Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings wherein reference numerals indicate certain elements. The following descriptions are not intended to limit the myriad embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims.

References to "one embodiment," "an embodiment," "some embodiments," "an example embodiment," etc., indicate that the embodiment described may include a particular feature, structure, aspect, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, aspect, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. With reference to Figure 1, a perspective view of a representative respiratory mask device 100 is shown as worn on a face of a wearer 110. The respiratory mask device has a form contoured to be worn about the nose, cheeks, and chin of the face of the wearer. As will be described in more detail, in some aspects the respiratory mask device is composed of a stacked, self-sealing structure that offers improved comfort and protection against the inhalation pathogens and other contamination.

Respiratory mask device 100 is sized and shaped to fit over the mouth, nose, or mouth and nose of the wearer. Different lengths and widths to fit different sized wearers are contemplated herein and will be understood to those of ordinary skill in the art. The respiratory mask device may include securement elements, intended to secure the respiratory mask device to the face and/or head of the wearer. These securement elements should be comfortable for the wearer to wear and should be durable. Securement elements may include a single strap connecting the sides of the respiratory mask device, or may include first strap and second strap, which are disposed on opposite sides of the respiratory mask device. In the embodiment shown in Figure 1, the first strap and second strap are capable of being secured around the left and right ear, respectively, of the wearer. Straps (including 120a and 120b or single strap, not shown) may be elastic to provide a tight fit of the mask on the face of the wearer. In an alternative embodiment not illustrated, securement elements in the form of one or more headbands that secure around the head may offer an even more effective sealing pressure for the mask device and improved comfort over long periods of wear as compared to straps behind the ears.

Figure 2A provides an exploded perspective view of respiratory mask device 100. Outer covering 600 forms a protective barrier for filtration system 500, which outer covering 600 encases between itself and face gasket 300 of the respiratory mask device. Encasing the filtration system in this manner protects the filtration system from physical abrasion, premature soiling, and fluid exposure, any of which may increase the useful life of the filtration system. In this embodiment, nose bridge crimp 200, filter media

400, and filter support 550 together form a filtration system (also referred to interchangeably herein as a removable filtration system or a filter cartridge). However, in some embodiments the filtration system may exclude one or both of the nose bridge crimp or filter support or may be composed entirely of filter media 400. Accordingly, as used herein "filtration system" may refer collectively to a multiple-component filtration system, such as filtration system 500, or individually to refer to a single layer or multi-layered filter media. Filter media 400 serves as the functional component of respiratory mask device 100, removing contaminants, pathogens, and other harmful airborne particles from the air. Filter support 550 may be provided to lend additional structural integrity to filter media, help retain its shape, and serve as a point of engagement and/or attachment with the outer covering. Nose bridge crimp 200 aids with the fitment of the respiratory mask device over the nose bridge area of the wearer's face. Preferably, filtration system 500 or a portion of the filtration system is capable of being removed from the respiratory mask device, and the respiratory mask device may be cleansed by the wearer. The filtration system may be replaced by the wearer with a new filtration system, or the removable filtration system may be cleaned by the wearer prior to next use. Thus, the filtration system may have removable component(s), which may be separately cleansed or discarded and replaced with a new filtration system. The respiratory mask device may be washed or cleansed once the removable component(s) of the filtration system have been removed therefrom and then reused. For example, the respiratory mask device may be cleansed or washed, desirably under higher temperatures or using cleaning agents intended to kill pathogens.

Figure 2B shows a cutaway perspective view of respiratory mask device 100. Face gasket 300 appears at the bottom where gasket 300 and central opening 305 can be seen with the remaining components of respiratory mask device 100 being stacked above. Face gasket 300 includes an anterior flange 320 that circumscribes central opening 305. The filtration system includes filter media 400, which has a three-dimensional form shaped to seat the filtration system over anterior flange 320 of face gasket

300 and to substantially cover central opening 305 of face gasket 300. The filtration system depicted in this embodiment includes a filter support 500, which engages anterior flange 320 to effect a seal between face gasket 300 and the filtration system. Outer covering 600 is removably attached to face gasket 300 and dimensioned to encase the filtration system between face gasket 300 and outer covering 600. The outer covering 600 includes openings, which in this embodiment are represented by transverse louvers 240 (and additional transverse louvers not separately numbered), which permit the passage of air to or from the filtration system.

Turning now to Figures 3A and 3B, various aspects of an embodiment of a face gasket within the scope of the invention are described. In some aspects, face gasket 300 provides an enhanced fit and may avoid issues that result from a poor fit to the face such as airborne contaminants or pathogens breaching the respiratory mask device or exhalation vapors escaping the device and poses risks to others and/or fogging of eyewear worn by the wearer. Face gasket 300 may be formed of any number of flexible, elastomeric materials and made by various processes known in the art, including but not limited to injection molding and 3D printing. Preferably, the face gasket is composed of an injection molded thermoplastic elastomer material such as thermoplastic elastomer, thermoplastic polyurethane, or silicone. Other suitable materials include but are not limited to styrenic block copolymers, thermoplastic olefins, copolyesters, copolyamides, silicone urethanes, acrylonitrile copolymers, fluoroelastomers, or combinations thereof. A particularly suitable material for this application and the injection molding process is a thermoplastic vulcanizate (TPV) such as Santoprene™, a dynamically vulcanized EPDM (ethylene propylene diene monomer) rubber in a thermoplastic matrix of polypropylene (PP). The physical properties such as hardness, modulus and flexibility should be selected so that the face gasket forms a secure seal against the face but is also comfortable for the wearer. The face gasket preferably has Shore hardness less than that of the outer covering and preferably between about 40 and 50.

Face gasket 300 has a central opening 305 with a profile that generally traces the area around the nose and mouth of the wearer along the posterior side 310. More particularly, posterior side 310 is contoured to create a seal with a face of a wearer and anterior side 315 includes an anterior flange 320 that circumscribes the central opening. In this embodiment, anterior flange 320 surrounds the entire periphery of the face gasket and provides a surface upon which other components of the mask may rest and/or engage to hold the components together in a self-sealing, stacked assembly. For example, referring back to Figure 2B, it may be seen that anterior flange 320 slopes inward toward the central opening whereby a seal is effected between face gasket 320 in filtration system 500 when pressure is applied inward in a direction normal to outer covering 600. In this aspect, anterior flange 320 acts as a surface for the filtration system to seat at a point of matching circumferences between anterior flange 320 and the filtration system 500. In an alternative aspect not shown, the stacking structure of the respiratory mask device instead could be configured such that the point of engagement with the face gasket occurs instead with outer covering 600 when inward pressure such at that a seal is effected between the face gasket and the outer covering.

Referring again to Figures 3A and 3B, in another aspect, anterior flange 320 also may include a ridge 325 arranged to oppose an edge 630 of outer covering 600 when pressure is applied inward in a direction normal to outer covering 600. Thus, ridge 325 may prevent outer covering 600 from encroaching on the periphery of face gasket 300 and potentially disrupting the seal between face gasket 300 and the face or otherwise causing discomfort to the wearer. In still other alternative embodiments not shown, a ridge or other engagement feature upon the anterior flange could be used to create a seal between the gasket and the filtration system or component thereof rather than with an outer covering. In another aspect, face gasket 300 includes attachment members, in this embodiment loops 330a,

330b, 330c, and 330d, which are configured to attach to a corresponding attachment member, such as a protrusion on the outer covering in order secure the outer covering in place, as will be discussed further below. As noted previously, it may be preferable, particularly in embodiments employing loops, that the face gasket have of Shore hardness approximately about 40 and 50 to allow loops to be easily folded over onto corresponding protrusions on the outer covering by hand when reattaching the outer covering, such as when replacing the filter cartridge. Aspects using loops as attachment members are described in more detail with reference to Figure 7, below. In another aspect, face gasket 300 may also include reinforcement structures 340a, 340b, 340c, and 340d positioned adjacent to each respective first attachment member, in this embodiment 330a, 330b, 330c, and 330d. Reinforcement structures 340a, 340b, 340c, and 340d increases lateral stability and may reduce the possibility that the folding over of loops 330a, 330b, 330c, and 330d onto attachment members on outer covering 500 may adversely affect the seal between face gasket 300 and the face.

Exemplary filter media 400 is illustrated in Figures 4A and 4B, which illustrate perspective front and perspective rear views, respectively. The filter media serves to remove contaminants and pathogens from the air and is preferably made from a biocompatible material that removes at least ninety-five percent (95%) of airborne particles from the air. Suitable materials for the filter media include but are not limited to cellulose, polyester, spun-bond polypropylene, melt-blown polypropylene, and mesh synthetic polymers such as nonwoven polypropylene fabric. The filter media may be formed of a single layer or multiple layers. In some aspects, the material of the filter media is capable of being formed into a three-dimensional form (such as by a die cutting and thermoforming processes) shaped to seat the filter media over the face gasket and substantially cover the central opening of the face gasket. The three- dimensional form of filter media 400 is sized and shaped to substantially cover the central opening of the face gasket and is generally convex in order to provide space about the breathing area below the nostrils and above the mouth when worn. The aspect of dimensioning and forming the filter such that it sits upon and substantially covers the face gasket advantageously creates a relatively larger surface area than conventional reusable-type respirators. In preferred embodiments, the surface area of the filter media may be at least about 7,000 mm² . Dimensioning and arranging the filter media in this manner spreads the particulate matter over a larger area and improves breathing efficiency. For example, at a surface area approaching at least about 7,000 mm², materials and constructions that have a relatively high pressure drop may be utilized. As used herein, pressure drop refers to the differential pressure (DR), which is the measured pressure drop across a material. Pressure drop determines the resistance of the filter media to air flowing through it and therefore relates to the breathability and comfort of the respiratory mask device. In general, a lower pressure translates to increased breathability. The filter media material should include a tight enough matrix to entrap unwanted particles, but the pressure drop through the media should be low enough so that breathing effort is tolerable. However, breathability for a given filter media is also a function of its surface area with breathability increasing with surface area. Thus, a relatively higher surface of this aspect creates the possibility for selecting from a broader array of filter media that would have a pressure drop too high for comfortable breathing were it confined to the smaller surface area typically available for cartridge-type, reusable respirator respiratory mask devices. Moreover, this configuration may obviate the need for other compensatory techniques commonly used to increase breathability such as inhalation and/or exhalation valves. In some embodiments, the filter media 400 may be composed of multiple layers of material (not shown), where the layers have one or more of the following properties: cationic properties, reduced pore size, pores with increased tortuosity, antibacterial properties, antiviral properties, and combinations thereof. In one embodiment, each layer in the filter media has a different property than each other layer, and when used in combination, the resulting filter media has a plurality of desirable properties. In another embodiment one of the layers may be encased by two layers resulting in a filter media with a plurality of desirable properties, for example, as described below, a metal-containing layer may be encompassed by or encased within one or more layers having a cationic charge.

The filter media may include at least one fabric layer, such as cotton, at least one layer of material having antiviral properties, such as a metal or metal alloy containing layer, and at least one layer having cationic properties. Any or all of the layers may be secured to each other, or any or all of the layers may be capable of being separated from each other. In one aspect, the filter media includes first and second cotton layers, with one layer of a copper (or copper alloy) material and one layer of a cationic material. In some embodiments, the copper layer and cationic material are separated by another fabric material, such as a cotton layer.

In one embodiment, a first filter media layer is a fabric layer, which may be cotton. In some aspects, the first layer is a cationic cotton material. A second layer may be a material including antiviral properties. The second layer may be, for example, copper or copper alloy, or may be made of a material that has been coated or impregnated with copper or copper alloy materials. Alternatively, or in addition to copper or copper alloy, the second layer may be made with other metals or metal alloys that may have an activity against viruses, or may inactivate viruses such as iron, manganese, zinc and combinations thereof. A third layer may be a material including a cationic charge, for example, materials commonly used in fabric softening sheets. A fourth layer may be a fabric layer, that may be cotton, or cationic cotton. The first layer and fourth layer may be the same or may be different materials. It may be desired that the second layer be disposed between the first layer and third layer, and that the third layer be disposed between the second layer and fourth layer. In some aspects, the second layer may be encompassed by or encased within third layer. For example, third layer may completely surround second layer in a permanently or removable fashion.

In alternative aspects, the filter media may include a cotton layer disposed between the second layer and the third layer, thereby providing a filter media having five layers of material. In use in a device, each layer is substantially in contact with each adjacent layer (with the exception of the first and fourth layers, which form outer layers of the filter media). It is desired that each layer has a pore size that allows for restriction of particles therethrough, but allows for breathability when in use. Each layer may have the same or different average pore sizes, and the average pore sizes of each layer may overlap. For example, it may be desired that one or more of the layers has an average pore size of from 100 microns to 0.01 microns, or from 20 microns to 0.1 microns, or from 5 microns to 0.1 microns, or from about 1 micron to about 0.1 microns. For example, the layer having an antiviral property may have an average pore size of about 1 micron to about 0.1 microns, while the layer having the cationic charge (e.g., the third layer 30 in Figure 1) may have an average pore size of 10 microns to 1 micron. Each layer may have the same or may have different pore sizes. It should be appreciated, as well, in some embodiments filter media described herein may be used alone to form a respiratory mask, without the need for any additional support structures other than a strap or other fixation device to hold the filter media about the face of the wearer. Such embodiments may be especially useful when personal protective equipment is scarce or in the case of disposable masks.

Referring now Figures 5A and 5B, in one aspect, filter media 400 is reinforced about its periphery and posterior by filter support 550 so that the filter media 400, filter support 550, and nose bridge crimp 200 combine to form removable filtration system 500. Filter support 550 lends structural integrity to filter media 400 and may serve as a point of engagement and/or attachment with outer covering 600 allowing filter media 400 to be secured within the respiratory mask device 100, as detailed further below. Filter support 550 may be joined to filter media 400 using any acceptable adhesive, including for example cyanoacrylates, urethanes, vinyl acetates, phenol formaldehyde, epoxy, polyolefin, acrylates, and combinations thereof. Alternatively, filter support 550 may be joined to filter media 400 by mechanical fastening (e.g., snap or friction fit), ultrasonic welding, or the like. Preferably, filter support 550 is joined to the underside of filter media 400, however the reverse arrangement with the filter support being positioned over the filter media is possible as well. Likewise, in other embodiments not depicted, the filter support could be embedded within the filter media, such as within multiple layers of filter media material. Alternatively, the two parts may remain separable components that stack together within the respiratory mask device. In some aspects not shown, filtration system 500 may include an exhalation valve that allows exhaled air to more easily escape from the filtration system as will be understood to those of skill in the art.

In one aspect, nose bridge crimp 200 aids with the fitment of the respiratory mask device over the nose bridge area of the wearer's face. Nose bridge crimp 200 may be made of a malleable, linear, strip of aluminum; a molded polymeric material, or any material capable of deforming into a shape and position that causes one or more components of the respiratory mask device to fit more securely and/or comfortably against the nose bridge. Nose bridge crimp 200 attaches to filter media 400 in a region corresponding to the nose bridge area of the face. Attachment may be achieved using adhesives, mechanical fastening, ultrasonic welding or by other similar means. It should be noted that nose bridge crimp 200 may be integrated into a respiratory mask device in alternative manners and locations, or, in some cases may be omitted altogether. Within filtration system 500, for example, nose bridge crimp 200 alternatively could attach to either of filter media 400 or filter support 550. Or, as an alternative to providing nose bridge crimp within filtration system 500, nose bridge crimp 200 could be made part of outer covering 600 or face gasket 300. In either case, nose bridge crimp 200 could be either adhered to or made integral with the material of the respective component, for example in an injection molded process by over molding the nose bridge crimp by disposing the nose bridge crimp into the mold part corresponding to the outer covering or the face gasket prior to injecting the mold material into the part.

Referring now to Figures 6A and 6B, top view and perspective views of outer covering 600 of respiratory mask device 100 are provided. Exemplary outer covering 600 is preferably removably attachable to the face gasket and dimensioned to encase the filtration system between the face gasket and the outer covering as previously discussed with reference to Figure 2B. Outer covering 600 includes openings, for example transverse louvers 610a and 610b (as well as other substantially similar openings not indicated with separate numerals in the figures) to permit passage of air to or from the filtration system. Suitable openings may take on various shapes and sizes but should expose sufficient surface area in the outer covering to allow the passage of a volume of air that supports comfortable breathing effort.

As used herein, a "louver" is an opening with a fixed or movable fins to allow flow; and a "transverse louver" is a louver positioned horizontally across the outer covering with fins angled downward. Openings in the form of transverse louvers such as 610a and 610b are preferred due to their ability to reduce the ingress of fluids, including blood spatter, to the underlying filtration system by the action of gravity driving spatter downward over the fin side of the louvers.

Outer covering 600 may be made from any number of materials and processes including injection- molded acrylonitrile butadiene styrene (ABS), polyethylene, polycarbonate, polyamide (Nylon), high impact polystyrene, polypropylene, and/or 3D-printed polylactic acid (PLA), acrylic styrene acrylonitrile (ASA), polyethylene terephthalate (PET), polycarbonate (PC), high performance polymers (HPPs), thermoplastic elastomers (TPE), or thermoplastic polyurethane (TPU). Preferably, outer covering 600 is composed of polypropylene and has a Shore hardness of between about 60 and 80. Preferred embodiments are also configured so that outer covering 600 has a higher Shore hardness than that of the face gasket, which may improve the fitment of the respiratory mask device as well as create a more secure attachment in embodiments utilizing loops to attach the face gasket to the outer covering as discussed in more detail below.

Outer covering 600 has a three-dimensional shape that conforms with the form of the filtration system, which configuration may aid in the self-sealing effect between outer covering and the face gasket as well as creating a lower-profile stack and appearance more suitable to healthcare settings than other reusable masks, which are often tailored toward industrial applications. Outer covering 600 may include strap harnesses, such as strap harnesses 620a, 620b, 620c, and 620d, to which a single or multiple straps may be tied or attached by other mechanical means such as stitching, snapping, welding, or gluing. Outer covering 600 also includes attachment members, in this example protrusions 640a, 640b, 640c, and 640d, which are integral to each of strap harnesses 620a, 620b, 620c, and 620d. Attachment members on the outer covering may be configured so that corresponding attachment members on the face gasket, such as loops, may attach, thereby securing outer covering 600 in place by creating pressure inward in a direction normal to the outer covering. In other embodiments, attachment members may be omitted. For example, in one aspect the mere action of assembling the outer covering, filtration system, and face gasket into a stack and then secure the outer covering around the head to the face gasket may provide sufficient pressure inward in a direction normal to the outer covering to effectively seal the respiratory mask device's components and hold the assembly together against the face.

In another aspect, outer covering 600 may include a nose bridge region in the form of a raised area in the outer covering positioned above a nose bridge crimp. Alternatively or additionally, a nose bridge region may serve as a visual indication to the wearer of the location of the nose bridge crimp. Nose bridge region 650 is a raised area in outer covering 600 that provides an area of relief for a nose bridge crimp in the interior compartment of respiratory mask device 100 such as part of the filtration system. Nose bridge region 650 also functions as a visual indication to the wearer of the location of the nose bridge crimp as a guide to the wearer of where to apply pressure to adjust the fitment of the nose bridge crimp over the nose. The visual indication may result merely from the presence of the raised material of the nose bridge region or the visual indication may be made more deliberate by means via stamping, molding, 3d printing, or other printing methods, including pad printing, screen printing, inkjet printing, or heat transfer.

Referring now to Figure 7, a perspective cross section of a respiratory mask device 100 is provided. The zoomed-in portion of the cross section details an aspect of this embodiment whereby anterior flange 320 of face gasket 300 slopes inward toward the central opening of the face gasket whereby a seal is effected between the face gasket 300 and the filtration system, in this embodiment filter support 550 in particular, when pressure is applied inward in a direction normal to the outer covering.

The seal can be noted as the area of contact between anterior flange 320 and the underside of filter support 550. In other embodiments not shown, the device could be configured such that the area of contact and corresponding seal may instead be formed between the face gasket and outer covering. In yet another aspect, anterior flange 320 includes a ridge 325 arranged to oppose an edge of outer covering 600 when pressure is applied inward in a direction normal to the outer covering. In this way, ridge 325 may prevent outer covering 600 from encroaching on the periphery of the face gasket 300 and potentially disrupting the seal between face gasket 300 and the face or otherwise causing discomfort to the wearer. In still other alternative embodiments not shown, a ridge or other engagement feature upon the anterior flange could be used to create a seal between the gasket and the filtration system or component thereof rather than with an outer covering. The posterior of outer covering 600 also includes a shelf member 710 that has a shape and position configured to securely engage outer covering 600 to a portion of the filtration system, in this embodiment filter support 550. This configuration may simplify the assembly process of the mask by allowing the wearer to "snap" the filtration system into outer covering 600 before placing the assembly over face gasket 300 to form a fully assembled respiratory mask device. Pressing filter support 550 into the outer cover forces filter support 550 to deform momentarily and pass over shelf member 710 before snapping into place under tension inside outer covering 600. The interior of outer covering may include multiple shelf members (not shown) at locations around the interior configured to hold the filtration system in place. Alternatively, the shelf member may form a continuous shelf around the interior of the outer covering or omitted altogether. Also shown in more detail are loop 330b of face gasket 300 and protrusion 640b, which serve as means of attaching face gasket 300 to outer covering 600. Loop 330b is sized and positioned such that when it is pulled over protrusion 640b it, along with additional loops and protrusions (not shown but previously described with reference to Figures 6A and 6B), hold the face gasket 300 and outer covering

600 together under tension. In this embodiment, it is desirable for the outer covering to have a higher Shore hardness than that of the face gasket. For example, where the Shore hardness of the face gasket is between about 40 and 50, it is preferable for the outer covering to have a Shore hardness of between about 60 and 80. This configuration may improve the fitment and overall comfort of the respiratory mask device as well as create a more secure attachment in embodiments utilizing loops. The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that many of the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for the purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

The Summary and Abstract sections may set forth one or more but not all exemplary embodiments of the present invention as contemplated by the inventors, and thus, are not intended to limit the present invention and the appended claims in any way. The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present invention. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance. The breadth and scope of the present invention should not be limited by any of the above- described exemplary embodiments but should be defined only in accordance with the following claims and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A removable filtration system for use in a respiratory mask device comprising: a filter media having a three-dimensionally contoured form to fit over the face of a wearer; and a filter support wherein the filter media is joined to the filter media along at least a portion of either or both of the periphery, anterior, or posterior of the filter media and wherein the filter support is configured to securely engage the removable filtration system to a feature of an outer covering of the respiratory mask device.

2. The removable filtration system of claim 1 further comprising a nose bridge crimp.

3. The removable filtration system of claim 1, wherein the filter media has a surface area of at least about 7,000 mm².

4. The removable filtration system of claim 1, wherein the filter support is composed of polypropylene.

5. The removable filtration system of claim 1, wherein the filter support and the filter media are joined via an adhesive.

6. The removable filtration system of claim 1, wherein the filter media comprises a plurality of layers, wherein each of the plurality of layers has at least one property selected from: a cationic property, reduced pore size, pores with increased tortuosity, an antibacterial property, and an antiviral property.

7. The removable filtration system of claim 6, wherein the property of each of the plurality of layers is different from the property of each of the other plurality of layers.

8. The respiratory mask device of claim 6, wherein one of the plurality of layers is a metal-containing layer encompassed by or encased within one or more layers having a cationic charge.

9, The respiratory mask device of claim 6, wherein the plurality of layers comprises a fabric layer, a layer having an antiviral property, and a layer having cationic properties.

10. A respiratory filter media comprising a plurality of layers, wherein each of the plurality of layers has at least one property selected from: a cationic property, reduced pore size, pores with increased tortuosity, an antibacterial property, and an antiviral property.

11. The respiratory filter media of claim 10, wherein the property of each of the plurality of layers is different from the property of each of the other plurality of layers.

12. The respiratory filter media claim 10, wherein one of the plurality of layers is a metal-containing layer encompassed by or encased within one or more layers having a cationic charge.

13. The respiratory filter media claim 10, wherein the plurality of layers comprises a fabric layer, a layer having an antiviral property, and a layer having cationic properties.