GB2594302A

GB2594302A - Filter element for personal protective equipment

Info

Publication number: GB2594302A
Application number: GB2005882.2A
Authority: GB
Inventors: Michael Mennie Trevor
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-04-22
Filing date: 2020-04-22
Publication date: 2021-10-27
Also published as: GB202005882D0

Abstract

A filter element 100 300 for a piece of personal protective equipment comprising an air permeable body 102 made of copper or copper alloy, preferably using a method of pressing copper powder or copper alloy powder into a compact and then sintering the compact to create an air permeable body. The porous body will have a tortious airflow route between the copper powder particles. This means any airborne virus will be in contact with the copper. The personal protective equipment is preferably a face mask, face shield or respirator and the filter may either be integrally formed with the item or removable, for example to allow the item to be washed e.g. with an ultrasonic bath. Attachment methods include an interference fit, clips, straps, adhesive or an external enclosure. The filter may be in the form of a disc 300 but the method can include pressing the powder together in any shaped die. The rest of the PPE could be made from aluminium or an aluminium allot.

Description

FILTER ELEMENT FOR PERSONAL PROTECTIVE EQUIPMENT

TECHNICAL FIELD

This disclosure relates to a filter element for a piece of personal protective equipment. This disclosure also relates to a piece of personal protective equipment comprising the filter element, a method of producing a filter element and a method of assembling a piece of personal protective equipment.

BACKGROUND

Pieces of personal protective equipment (i.e. PPE) such as facemasks, face shields and respirators are commonly worn by medical professionals, carers and the like when treating or looking after patients. Such PPE is designed to provide a barrier between the patient and the wearer of the equipment to prevent the spread of potential airborne pathogens from the patient to the wearer or vice versa. The recent spread of a pathogen in the form of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to the global spread of coronavirus disease 2019 (COVI D-19), that has since reached pandemic levels.

Due to the widespread impact of COVI D-19, such PPE is now also being commonly worn by members of the general public in order to protect themselves or the people around them as they go about their normal daily lives.

Although the aforementioned pieces of PPE are worn in an attempt to protect both the wearer and the people around them from further spread of COVID- 19, these pieces of equipment commonly offer a fabric or plastic body that is considered to offer little protection to the wearer or the people they come into contact with. Indeed, such PPE can often act as a hospitable surface onto which the pathogen (i.e. SARS-CoV-2) can accumulate and possibly spread from.

Such equipment is usually a single use item that is disposed of after each use, and increased demand during a pandemic can make sourcing enough of such PPE to satisfy the demand therefor difficult.

Accordingly, a need exists for improved pieces of PPE that provide better protection to both the wearer and the people around them from the spread of such pathogens. Such an improvement should also be capable of cost-effective mass manufacture in order to meet increased demands therefor during a pandemic. -2 -

Moreover, if the improvement was a multi-use product rather than single use, this could also help alleviate the sourcing issues for such equipment.

SUMMARY

From one aspect, the present disclosure relates to a filter element for a piece of personal protective equipment (PPE) comprising an air permeable body made of copper or copper alloy. The air permeable body allows communication of air through the body.

In an embodiment of the above, the body is porous.

In a further embodiment of any of the above, the body comprises interconnected copper or copper alloy particles interspersed with pores.

In a further embodiment of any of the above, the body is formed using a powder of the copper or copper alloy that has been pressed and sintered.

From another aspect, the present disclosure relates to a piece of personal protective equipment (PPE) comprising the filter element of any of the above embodiments.

In an embodiment of the above, the piece of PPE is configured to cover at least one of the mouth and nose of a wearer of the piece of PPE. In one particular embodiment, the piece of PPE covers at least the mouth and nose of the wearer.

In another particular embodiment, the piece of PPE covers at least the mouth, nose and eyes of the wear.

In a further embodiment of any of the above, the piece of PPE is a facemask, a face shield, or a respirator.

In a further embodiment of any of the above, the piece of PPE is configured to allow air to pass between a wearer's face and the exterior of the piece of PPE via the filter element.

In a further embodiment of any of the above, the filter element is removably fixed to the piece of PPE. In other embodiments, the filter element is integrally formed with the piece of PPE.

From yet another aspect, the present disclosure relates to a method of producing a filter element for a piece of personal protective equipment (PPE). The method comprises the steps of providing a copper or copper alloy powder; pressing the powder together to form a compact; and sintering the compact to provide an air permeable body made of copper or copper alloy. -3 -

In an embodiment of the above, the step of pressing the powder together to form a compact includes pressing the powder together in a die to shape the compact.

BRIEF DESCRIPTION OF DRAWINGS

One or more non-limiting examples will now be described, by way of example only, and with reference to the accompanying figures in which: Figure la shows an example filter element in accordance with the present disclosure; Figure 1b shows another example filter element in accordance with the

present disclosure;

Figure 2 shows a filter element and facemask in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

Copper and its alloys have been recognised as materials having innate antimicrobial properties. More recently, copper and its alloys have be shown to provide an inhospitable surface for pathogens, such as SARS-CoV-2, and effectively kill them on contact therewith (e.g. in a matter of minutes, compared to days or weeks on some other materials). Furthermore, such surfaces appear to maintain this anti-microbial property throughout their lifetime, and so may be suitable for being reused multiple times in such applications.

Following on from these findings, the present disclosure looks at providing a suitable implementation of copper or an alloy thereof into PPE to address the aforementioned needs.

In order for copper or an alloy thereof to be utilised effectively to address the aforementioned needs in a piece of personal protective equipment (i.e. PPE) it should allow for airflow there through, whilst preferably ensuring as much air-tocopper contact as the air passes through it (i.e. to maximise its anti-microbial effectiveness). In other words, the copper/copper alloy element must be permeable to air, and preferably provide a tortuous route to airflow there through. To this end, the present disclosure relates to a filter element that comprises an air permeable copper/copper alloy body.

Figures la and lb show high schematic examples of filter elements 100, 200 in accordance with the present disclosure. As shown, the filter elements 100, comprise bodies 102, 202 made of copper. The copper bodies 102, 202 have been formed using a powder process in which a copper powder is pressed together to form a compact and then sintered to form a porous copper structure that includes a plurality of interconnected copper particles 104, 204 interspersed with pores 106, 206. At least some of the pores 106, 206 in the bodies 102, 202 are also interconnected to provide a route for airflow to pass through the bodies 102, 202, and making the filter elements 100, 200 permeable to air.

The amount of porosity in the bodies 102, 202 can be controlled in a known manner by varying various powder processing parameters, such as: the amount of pressure used to compact the powder; the temperature, pressure and atmosphere used during sintering; the duration of sintering; and/or the size and size distribution of copper particles in the starting powder.

In this manner, the amount and distribution of the porosity 106, 206 in the bodies 102, 202 can be varied to make airflow through the filter elements 100, 200 less or more tortuous. For example, the bodies 102, 202 have the same thickness T but body 102 provides larger copper particles 104 and fewer pores 106 than body 202, which has a larger number of smaller copper particles 204 and pores 206 in comparison. As shown in Figures la and lb this can be seen to provide a more tortuous route to airflow passing through the filter element 200 compared to filter element 100 (e.g. see airflow path arrow A compared to airflow path arrow B).

It is to be appreciated that the more tortuous the airflow route through the filter element, the more surface area of copper particles the airflow passing through the filter element comes into contact with before exiting the filter element. This results in a greater amount of pathogen in the airflow contacting the copper and possibly being trapped and killed before it can leave the filter element. A more tortuous airflow route may also provide a greater resistance to airflow through the filter element, meaning more force may be needed to force air through it.

Accordingly, the above process variations can be tailored to provide a correct balance of resistance to airflow and air-to-copper contact to provide effective pathogenic filtration of airflow there through for a given application.

It is thought that the above powder processing route is the most suitable route to achieve the aforementioned needs than other options.

For example, as discussed above, the process parameters can be varied in known ways to adjust the filter element airflow and anti-microbial efficacy for different applications with relative ease. -5 -

Filter elements 100, 200 can be made into any suitable shape e.g. by shaping the powder using a die before sintering. Therefore, the powder processing route can allow the filter elements 100, 200 to be made into a variety of shapes quickly and more easily, which means they can be integrated into many different PPE designs without much process modification or additional expense.

Moreover, the filter elements 100, 200 can be made by the powder processing route on a large scale and with a short number of process steps using existing equipment. This can provide a particularly cost-effective mass manufacture route for the filter elements 100, 200 that is suitable to meet the demands of a pandemic level event, such as that found in the case of COVID-19.

Alternate ways of making a filter element are thought to be less suitable.

For example, providing a filter element using layers of copper mesh may be possible. However, the mesh first has to be fabricated to an appropriate filter size and then intricately layered together with sufficient thickness to provide adequate copper-to-air contact to trap and kill the pathogen. It is thought to be more difficult to control the filtration characteristics of such a configuration and provide a tortuous enough airflow route to provide an effective filter element compared to the powder processing route discussed above. It is also thought that such a configuration would take more process steps to manufacture, and would be both more expensive and time consuming to produce.

Although the embodiments above have mentioned bodies 102, 202 being made specifically of copper (i.e. pure copper metal with incidental impurities), it is to be understood that any suitable copper alloy (e.g. brass and bronze) known to provide an inhospitable surface to a particular pathogen may also be used within

the scope of this disclosure.

The disclosed filter elements 100, 200 can be integrated into any suitable existing or new PPE designs.

Figure 2 shows a highly schematic view of one such piece of PPE in the form of a facemask 400.

As shown in Figure 2, a filter element 300 in accordance with the embodiments discussed above is shaped in the form of a disc (although as discussed above, any suitable shaped filter element 300 can be used within the scope of this disclosure). Facemask 400 comprises a body 402 and straps 404a, 404b for securing the mask in place on a wearer by passing around their ears. The body 402 includes an aperture 406 therein which is sized and shaped to correspond -6 -to that of the filter element 300 and receive the filter element 300 therein. The facemask body 402 is designed in this particular example to cover at least the wearer's mouth and nose, which are common points for airborne pathogens to enter or exit the wearer's body.

The filter element 300 is fixed in place in the aperture 406 to allow the communication of air through the mask 400 via the filter element 300.

The aperture 406 may fit the filter element 300 in a snug manner, such that it provides enough interference fit to hold the filter element 300 in place during use. Alternatively or additionally, the filter element 300 may be fixed in place in the aperture 406 in any other suitable manner, for example, using a grommet, adhesive, air permeable covering or the like.

In some embodiments, the filter element 300 can be removably fixed in the aperture 406 (e.g. using the fixing methods discussed above). In this manner, even if the facemask body 402 cannot be re-used, the filter element 300 can be removed from the aperture 406 after use of the face mask 400. The filter element 300 can then be cleaned/sterilized (e.g. using an ultrasonic bath or other suitable means) as required and then re-used in a new facemask 400 by being placed in the aperture 406 thereof.

Although the filter element 300 is depicted as being fixed/removably fixed in place in the aperture 406 in Figure 2, it is to be understand that within the scope of this disclosure the filter element 300 may be operatively connected to the piece of PPE in any suitable manner, e.g. via clips, straps, adhesive on the body or an external enclosure.

The body 402 and straps 404a, 404b can be made of any suitable material, such as a fabric or plastic and/or elasticated material. The body 402 can be air permeable or air non-permeable. It is thought that if the body 402 is air non-permeable, a greater proportion of the airflow inhaled and exhaled by the wearer will be forced through the filter element 300 specifically, which can provide improved filtration of pathogens from the air before entering the wearer or leaving the facemask 400 to the environment, respectively.

Although the depicted example only discussed the use of one filter element 300, the present disclosure extends to cover any suitable number of filter elements being used in a piece of PPE. It should also be noted that although a particular positioning of the filter element 300 is shown, any number of other suitable -7 -positions for filter element(s) can be applied within the scope of this disclosure, and will depend on the design of the piece of PPE and its intended application. Moreover, Figure 2 is only one example of a particular piece of PPE that may benefit from the use of the filter elements 100, 200, 300 disclosed herein.

Several other examples exist within the scope of the present disclosure, some of which will be discussed below.

In one such example, rather than provide a separate filter element that is fixed or assembled to a body of the piece of PPE, the filter element is integrally formed with the piece of PPE itself. In other words, in one example, the body of the piece of PPE that covers the wearer is formed using the air permeable copper or copper alloy. In other examples, a portion of the body of the piece of PPE is formed integrally with the filter element, with other portion(s) of the body of the piece of PPE formed of other material(s). In this manner, the piece of PPE can be adapted to have a particular combination of properties. In one such example, the other portion of the body could be formed from aluminum or aluminum alloy which can be mixed and shaped in the same die as the copper/copper alloy powder during the powder processing stage. Accordingly, the aluminium/aluminium alloy portion may provide enhanced lightweight and malleability to allow the body to conform better to the wearer's face and be more comfortable to wear, whilst the copper body portion may provide the airflow and pathogen protection characteristics discussed above.

In any of the above examples, further intermediate parts, such as straps to secure the body in place around the wearer or seals around the body to space it from the wearer's face may be used as necessary.

It is to be appreciated that by making at least a portion of the body of the piece of PPE itself out of the filter element/copper or copper alloy, rather than being a removable filter element, the entirety of the piece of PPE may be made re-usable (not just a separate filter element). For example, the entire piece of PPE can be cleaned/sterilized (e.g. using an ultrasonic bath or any other suitable method) and then re-used. This may alleviate demand and supply issues caused by single use pieces of PPE.

In another example, where a higher degree of pathogen infection precaution is needed, a piece of PPE may be used that covers the entirety of the wearer's head, for example, in the manner of a fish-bowl or astronaut-type helmet. Such applications are generally applicable to medical staff or researchers who are more likely to come into continuous direct contact with the pathogens. In such examples, -8 -the helmet can take any suitable shape and comprise any suitable materials (e.g. glass or transparent plastic), but include one or more of the filter elements 100, 200, 300 incorporated therein, or operatively connected thereto.

It is to be appreciated that this disclosure extends to any suitable piece of PPE that may make use of the filter elements 100, 200, 300 disclosed herein. Such pieces of PPE may generally intend to provide a covering over at least one of the wearer's mouth and/or nose, which are common points for airborne pathogens to enter or exit the wearer's body. Such pieces of PPE may also additionally cover the eyes of wearer (which are also a common point of entry for airborne pathogens into the wearer's body). Accordingly, in some embodiments, such pieces of PPE cover at least both the mouth and nose of the wearer and in other embodiments cover at least the mouth, nose and eyes of the wearer. Some pieces of such PPE may surround the entirety of the wearer's head (as discussed above). Such pieces of PPE include, but are not limited to, facemasks, face shields, respirators, or the like. -9 -

Claims

CLAIMS1 A filter element (100; 200; 300) for a piece of personal protective equipment (PPE) comprising an air permeable body (102; 202) made of copper or copper alloy.
2. The filter element of claim 1, wherein the body (102; 202) is porous.
3 The filter element of claim 1 or 2, wherein the body (102; 202) comprises interconnected copper or copper alloy particles (104; 204) interspersed with pores (106; 206).
4. The filter element of claim 1, 2 or 3, wherein the body (102; 202) is formed using a powder of the copper or copper alloy that has been pressed and sintered.
5. A piece of personal protective equipment (PPE) comprising the filter element of any preceding claim.
6. The piece of PPE of claim 5, wherein the piece of PPE is configured to cover at least one of a mouth and a nose of a wearer of the piece of PPE.
7. The piece of PPE of claim 6, wherein the piece of PPE is configured to cover at least the mouth and the nose of a wearer of the piece of PPE.
8. The piece of PPE of claim 5, 6 or 7, wherein the piece of PPE is a facemask (400), a face shield, or a respirator.
9 The piece of PPE of any of claims 5 to 8, wherein the piece of PPE is configured to allow air to pass between a wearer's face and an exterior of the piece of PPE via the filter element (100; 200; 300).
10. The piece of PPE of any of claims 5 to 9, wherein the filter element (100; 200; 300) is removably fixed to the piece of PPE.
11. The piece of PPE of any of claims 5 to 9, wherein the filter element (100; 200; 300) is integrally formed with the piece of PPE.
12. A method of producing a filter element (100; 200; 300) for a piece of personal protective equipment (PPE), the method comprising: -10 -providing a copper or copper alloy powder; pressing the powder together to form a compact; and sintering the compact to provide an air permeable body (102: 202) made of copper or copper alloy.
13. The method of claim 12, wherein the step of pressing the powder together to form a compact includes pressing the powder together in a die to shape the compact.