Technical Field of the Invention

The invention is concerned with a filter for a dynamic airflow carrying airborne particles. In related aspects, the invention is concerned with an associated insert, housing, system and uses.

Background to the Invention

The removal of particulates from the air by an air filter is an establish practice in many fields for capturing unwanted materials such as biological or chemical matter. Such filter devices typically work on the principle of a moving stream of air (i.e. a dynamic airflow) passing through a porous element, such as a metal or material (e.g. cotton) mesh, ensuring particles of a desired size are captured while enabling the filtered air to pass through for onward use or dispersion.

US 4,235,609 discloses an oil bath air cleaner for removing air contaminants, the cleaner comprising an outer casing 50 having an air inlet and air outlet, in particular providing conduit portions 56, 59, 89 and 90 through which air is drawn. The air cleaner deploys oil 95 as a medium via which air passes into contact to remove airborne particles. Flowever, the oil bath air cleaner of US 4,235,609 further cleans the air via additional metal mesh filter cartridges 62 and 118 and paper filter cartridge 35. The air cleaner of US 4,235,609 is suited for poor quality air environments, such as for internal combustion engines, for example for those found in tractors and earth working machines.

In light of the coronavirus (SARS-CoV-2) pandemic that emerged in 2019 (COVID-19), many new hygienic measures have been implemented that focus on safeguarding individuals in a population by reducing exposure to, or spreading of, aerosolised virus. One primary measure has been the mandatory wearing of masks in public. In light of the widespread incidence of COVID-19, there is a continued need to consider alternative personal protective equipment (PPE).

It is therefore an object of the invention to provide an alternative filter for a dynamic airflow, in particular a low-cost air filter that is amenable to widespread distribution and effective in reducing the exposure of individuals to airborne microbes, particularly via integration of the filter into existing PPE measures or systems enabling air filtration.

Summary of the Invention

According to a first aspect, the invention provides a filter for a dynamic airflow carrying airborne particles, the filter comprising: a. a housing forming an enclosure to provide an internal volume; b. an air inlet and an air outlet in fluid communication; c. a deflecting means, located within the housing, for directing the dynamic airflow; and d. at least one adhesive layer, located within the housing, for capturing at least a portion of the airborne particles within the dynamic airflow; wherein in use, the deflecting means directs the dynamic airflow from the air inlet to the air outlet via the at least one adhesive layer.

The term ‘airborne particles’ includes, but is not limited to material of a biological, chemical and/or radiological nature. Material of a biological nature includes entities such as bacteria, viruses, fungi or allergens such as pollen, as well as products capable of being generated by such entities, for example proteins such as toxins. Bacteria and fungi include cells in either a vegetative- or more environmentally hardy spore-state. Material of a chemical nature includes one or more chemical(s) in a gaseous phase. Radiological agent(s) include those agents capable of emitting, and thus contaminating, the surrounding environment with radioactive material. The term ‘at least one adhesive layer’ includes at least one, or a plurality of, permanently attached, or non-permanently attached (i.e. attachable and removable), adhesive layer(s) within the housing. The at least one adhesive layer may be directly or indirectly attached within the housing. For example, the at least one adhesive layer may be applied directly onto a surface within the housing. Alternatively, the at least one adhesive layer may be applied to a supporting element such as a reservoir, trough or plate, or soaked into an absorptive material or strip, wherein the supporting element is attached (either permanently or non- permanently) within the housing.

It is to be understood that the at least one adhesive layer is provided at a suitable location wherein the deflecting means can direct the dynamic airflow to or towards the at least one adhesive layer. The at least one adhesive layer may be located on an interior surface of the housing. However, the at least one adhesive layer may be (additionally) attached to a region of the directing means. In particular, the at least one adhesive layer may be attached to all, or a substantial portion of, the directing means. The at least one adhesive layer may be located circumjacent to the air inlet, for example in the instance that the dynamic airflow entering the housing, via the air inlet, is directed by the deflecting means back towards the air inlet.

It is to be understood that the primary property of the at least one adhesive layer is the ability to capture airborne particles due to the sticky or glue-like nature of the at least one adhesive layer. However, the at least one adhesive layer may be designed or selected on account of other desirable properties e.g. an antimicrobial ability to eradicate captured biological matter such as bacteria and/or viruses and/or a capacity to neutralise or degrade certain chemicals. The types of material that comprise the at least one adhesive layer are described in more detail below.

The filter of the invention provides a low-cost, easy-to-manufacturer device for capturing particles in a dynamic airflow. In particular, the filter utilises a deflecting means, typically a surface or arrangement of surfaces, to direct a dynamic airflow from the air inlet to the air outlet via at least one adhesive layer, wherein the at least one adhesive layer offers a simple means for capturing, and potentially neutralising, airborne particles passing through the filter housing. This form of filter offers a cost effective option for low-to-middle income countries requiring air filtering processes, as well as quick-to-produce means for air filtration to address pressing healthcare situations such as the COVID-19 pandemic.

It is to be understood that the filter may be engineered such that the air inlet, air outlet and/or deflecting means are integral to the housing. In the case of the at least one, or a plurality of, adhesive layer(s) being permanently attached within the housing, this element is thus also integral to the housing.

Preferably, the housing is adapted to incorporate an insert, or a plurality of inserts, comprising the at least one adhesive layer. This provides the advantage of a filter that can be easily refitted with fresh adhesive layer(s) uncontaminated with particulate matter. In such an arrangement, the air inlet, air outlet and deflecting means may be directly associated/integral with the housing. However, it is to be understood that other arrangements may be provided. For example, the housing may be adapted to incorporate an insert comprising the deflecting means and the at least one adhesive layer. In such an arrangement, the air inlet and air outlet may be directly associated/integral with the housing. Alternatively, either the air inlet and/or air outlet may be associated with one of the housing or insert. For example, an air inlet and air outlet may be incorporated into the insert, in particular if a plurality of inserts are incorporated in the housing (as described below).

Preferably, the at least one adhesive layer may comprise one or more glue(s) (including an adhesive sheet such as film adhesive, adhesive powder, plant- based adhesive such as soybean or dextrin, adhesive derived from an animal source such as casein or honey, chemical adhesive such as expoy-, polyurethane- or polyimide-based adhesive material), cement, paste or mucilage. Further preferably, the at least one adhesive layer may comprise one or more glue(s) (including an adhesive sheet such as film adhesive, adhesive powder, plant-based adhesive such as soybean or dextrin, adhesive derived from an animal source such as casein or honey, chemical adhesive such as expoy-, polyurethane- or polyimide-based adhesive material).

Most preferably, the at least one adhesive layer may comprise the ability to further augment the effectiveness of the air filter in terms of neutralising the threat posed by the captured material. For example, the at least one adhesive layer may comprise a material or compound that would be understood by the skilled person to be capable of exerting an antimicrobial effect. For example, the material or compound may be a disinfectant, antiseptic or other agent e.g. an antibiotic, anti viral agent, anti-fungal agent, antimicrobial polymer (e.g. natural polymers such as chitosan, heparin, polylysine; polymers containing quaternary nitrogen atoms). The material may be (or further include) antimicrobial peptides, antimicrobial nanoparticles, an antimicrobial plastic and/or antimicrobial ceramic. The inclusion of such a material(s) or component(s) may ensure the inactivation of any captured biological material. The at least one adhesive layer may (additionally) comprise a material or compound that would be understood by the skilled person to be capable of exerting a capturing effect to a chemical agent, for example activated charcoal to adsorb captured chemical impurities.

Preferably, the at least one adhesive layer comprises Manuka® honey. Manuka® honey is a sticky material with antimicrobial properties, and is particularly suited to being applied as an adhesive layer in the filter of the invention.

Preferably, the air inlet comprises a tube with an end region defining an opening, the tube extending into the housing. This feature offers the advantage of directing the dynamic airflow towards the deflecting means (or even a specific region of the deflecting means), to aid in the dissemination of any particulate matter, carried in the dynamic airflow, towards the at least one adhesive layer. Preferably, the deflecting means comprises a convoluted flow path from the air inlet to the air outlet. The term ‘convoluted flow path’ includes a means for ensuring the dynamic area transverses a greater surface area in its journey from the air inlet to the air outlet (relative to e.g. passing in a direct line from the air inlet to the air outlet). The convoluted flow path may be achieved by a series of separate deflecting surfaces, arranged in the inner volume of the housing, which ensure the dynamic airflow is guided from the air inlet to the air outlet.

The convoluted flow path may be formed from a maze-like, zigzag or similarly alternating, from an airflow direction of travel perspective, passage or series of passages. Thus, preferably the convoluted flow path is an arrangement of undulating ridges. This arrangement offers the advantage of increasing the filtering ability of the filter, in particular due to increasing the area to which the at least one adhesive layer can be applied. Furthermore, this arrangement offers a uniformly arranged convoluted flow path which may assist from a manufacturing perspective, as well as ensuring a more predictable passage of a dynamic airflow within the filter, which may facilitate modelling or other assessments in terms of filter performance.

Preferably, the undulating ridges are a plurality of co-aligned surfaces arranged such that the dynamic airflow transverses all, or a substantial portion of, the internal volume of the housing when being directed from the air inlet to the air outlet. This arrangement offers the advantage of maximising the time taken for the dynamic airflow to pass from the air inlet to the air outlet, which in turn can lengthen the contact time between the dynamic airflow and the at least one adhesive layer to increase the filtering capability of the filter.

Alternatively, the deflecting means comprises an element with a concave surface, the concave surface arranged to: a. face the air inlet; and b. extend across at least a substantial portion of the internal volume of the housing between the air inlet and air outlet.

Thus, the concave surface provides a recess within the internal volume of the housing. This arrangement is particularly efficient for re-directing the dynamic airflow provided by the air inlet, and indeed more preferable wherein the adhesive layer is located circumjacent to the air inlet.

The deflecting means has an edge region which may be arranged proximal to the housing. The arrangement enables fluid communication between the air inlet and the air outlet i.e. wherein the dynamic airflow can pass between the edge region and the interior wall of the housing. However, it is to be understood that alternative arrangements are envisaged. For example, the edge region may abut the housing (i.e. be in contact with the internal surface of the housing). This arrangement may provide a greater stringency in terms of all the dynamic airflow being directed to the at least one adhesive layer prior to reaching the air outlet. In this instance, the filter further comprises an additional means for ensuring fluid communication between the air inlet and the air outlet. For example, the additional means for providing fluid communication between the air inlet and the air outlet may be at least one hollow member arranged to enable the dynamic airflow to bypass the deflecting means, following the dynamic airflow being directed to or towards the at least one adhesive layer. For example, the at least one hollow member is arranged at least in part between the deflecting means and the air inlet, so that air is preferentially directed from the air inlet to the at least one adhesive layer via the deflecting means, and subsequently transferred from the vicinity of the at least one adhesive layer to the air outlet via the at least one hollow member.

Wherein the air inlet comprises a tube with an end region defining an opening, the tube extending into the housing, preferably the concave surface extends past the end region of the air inlet. This arrangement ensures that the tube extends into the internal volume within the recess provided by the concave surface i.e. the concave surface acts akin to an umbrella cover relative to the stem of an umbrella handle, providing the advantage of greater direction of the dynamic airflow both to the concave surface, and being directed by the concave surface back in the direction of the air inlet. This arrangement is preferable wherein the adhesive layer is located on the concave surface and/or circumjacent to the air inlet. This arrangement is particularly preferable wherein the adhesive layer is solely located circumjacent to the air inlet.

Preferably, the deflecting means comprises a protrusion, extending from the concave surface. Further preferably, the protrusion is aligned with the air inlet. This arrangement provides the advantage of increasing the arc of the dynamic airflow around the concave surface, ensuring the air is directed back towards the air inlet. This arrangement is particularly preferable wherein the air inlet comprises a tube with an end region defining an opening, the tube extending into the housing, and wherein the concave surface extends past the end region of the air inlet.

Further preferably, the protrusion extends into the air inlet. This arrangement provides the advantage of further increasing the arc of the dynamic airflow around the concave surface of the deflecting means.

Preferably, the deflecting means and the at least one adhesive layer, and optionally the air inlet and air outlet, are arranged within the housing in a consecutive repeating arrangement. This arrangement offers the advantage of an easy-to-assemble, repeating arrangement of elements within the housing that offers an increased filtering capacity.

Preferably, the filter further comprises means to provide a positive airflow into the housing. Such means may include a fan to blow air into the filter, or a suction element to draw air into the filter. This arrangement provides the advantage of improved functionality of the filter in terms of airflow through the housing. According to a second aspect, the invention provides an insert for a filter according to the first aspect.

It is to be understood that the insert in use comprises the at least one adhesive layer. Thus, the insert may be provided without the at least one adhesive layer, but capable of receiving the at least one adhesive layer for when the filter is to be used.

Preferably, the insert further comprises a deflecting means. Such deflecting means may comprises a convoluted flow path from the air inlet to the air outlet. The convoluted flow path may be achieved, as described above, by a series of separate deflecting surfaces, capable of being arranged in the inner volume of the housing, which ensure the dynamic airflow is guided from the air inlet to the air outlet. The convoluted flow path may be formed from a maze-like, zigzag or similarly alternating, from an airflow direction of travel perspective, passage or series of passages. Thus, preferably the convoluted flow path is an arrangement of undulating ridges. Further preferably, the undulating ridges are a plurality of co-aligned surfaces arranged such that when the insert is arranged within the housing, the dynamic airflow transverses all, or a substantial portion of, the internal volume of the housing when being directed from the air inlet to the air outlet.

Alternatively, the deflecting means of the insert comprises a concave surface as described above. Thus, the concave surface provides a recess when the insert is arranged within the internal volume of the housing. When the insert is arranged within the housing, the concave surface is arranged to: a. face the air inlet; and b. extend across at least a substantial portion of the internal volume of the housing between the air inlet and air outlet.

The deflecting means has an edge region which may be arranged proximal to the housing. However, it is to be understood that alternative arrangements are envisaged. For example, the edge region may abut the housing (i.e. be in contact with the internal surface of the housing). In this instance, the filter further comprises an additional means for ensuring fluid communication between the air inlet and the air outlet (as described above). Preferably, the deflecting means further comprises a protrusion aligned with the air inlet when the insert is arranged within the housing. Further preferably, the protrusion extends into the air inlet.

Preferably, the insert further comprises an air inlet and/or an air outlet Preferably, the insert comprises: a. a first element defining a trough for receiving at least one adhesive layer, the trough comprising an aperture to form an air inlet; b. a second element comprising a deflecting means, the second element connectable or alignable with the first element; and c. a means for providing an air outlet.

The first element can be formed from a base with a perimeter region at which is located a surrounding wall, to provide a trough-like element in which be situated at least one adhesive layer. The aperture may be present in any part of the first element to ensure airflow when the insert is positioned in the housing of the filter. Flowever, it is envisaged that the aperture is located in the base of the trough forming the first element.

The second element may be directly or indirectly connected to the first element, or positioned relative to the first element when the inset is positioned in the housing of the filter, to ensure that the airflow passing through the aperture of the first element is subsequently directed as desired by the deflecting means of the second element. The air outlet of the insert may be associated with the second element, for example, the air outlet may be formed from an aperture in, or formed by, the deflecting means of the second element. Flowever, other variations may be provided as would be considered by the skilled person. For example, the connection forming between the first and second elements may provide for an aperture/slit, or series of apertures/slits, that enable the airflow to pass from the at least one adhesive layer (having been directed by the deflecting means) out of the insert, wherein the air e.g. leaves the air filter or passes into another insert for further filtration.

It is to be understood that any means of connection may be provided between the housing and insert(s), for example any suitable mating connection, adhesive application, magnet(s) or Velcro® application.

According to a third aspect, the invention provides a housing for a filter according to the first aspect, the housing arranged to accommodate at least one insert according to the second aspect.

According to a fourth aspect, the invention provides a system comprising the filter according to the first aspect, or the insert according to the second aspect and the housing according to the third aspect.

The term ‘system’ includes any component or parts that ensures or requires a dynamic airflow to be filtered to ensure the removal of particular matter.

The system may include at least one pre-filter, for example a pre-filter that acts to remove relatively large items of contamination (e.g. airborne debris, dust plume) from the dynamic airflow, prior to the dynamic airflow passing through the filter according to the first aspect, or the insert according to the second aspect and the housing according to the third aspect. Thus, the at least one pre-filter provides an initial filtration step(s), ensuring finer particulate matter is removed from the dynamic airflow via the filter, or insert and housing, of the invention.

Preferably, the system comprises a mask. Thus, the filter of the first aspect, or the combined insert and housing of the second aspect and third aspect respectively, are combined with a mask (i.e. a face mask) to be worn by a user. Such a system is particularly advantageous with respect to offering protection against the COVID-19 pandemic. The system may also be applied to or incorporated in other types of PPE e.g. respirators.

According to a fifth aspect, the invention provides the use of a filter according to the first aspect, the inset according to the second aspect, the housing according to the third aspect or the system according to the fourth aspect.

According to a sixth aspect, the invention provides the use of an adhesive layer comprising Manuka® honey for a filter.

The invention further extends to a kit, for example a kit comprising the insert of the second aspect and the housing of the third aspect, as well as replacement adhesive layers.

Any feature in one aspect of the invention may be applied to any other aspects of the invention, in any appropriate combination. In particular, filter aspects may be applied to the insert, housing and system aspects. The invention extends to a filter, insert, housing, system or use substantially as herein described, with reference to the accompanying drawings.

The invention will now be described, purely by way of example, with reference to the accompanying drawings, in which:

Figure 1 shows a schematic representation from a side view of a filter according to one preferred embodiment of the invention;

Figure 2 shows a schematic representation from a side view of a system according to one preferred embodiment of the invention; Figure 3 shows a schematic representation from a side view of a filter according to another preferred embodiment of the invention;

Figure 4 shows a schematic representation from an angled side view of the filter of Figure 3;

Figure 5 shows a schematic representation from an expanded side view of the filter of Figure 3 and Figure 4;

Figure 6 shows a schematic representation from a side view of a system according to another preferred embodiment of the invention;

Figure 7 shows a schematic representation from a side view of an insert according to one preferred embodiment of the invention; and

Figure 8 shows a schematic representation from a plan view of the insert of Figure 7.

The drawings are for illustrative purposes only and are not to scale.

Figure 1 shows a filter (1) according to one preferred embodiment of the invention. Filter (1) is formed from a housing (2) comprising an air inlet (3) in a base region of the housing (1) and an air outlet (4) extending from the top region of the housing (1 ). Arranged within housing (1 ) is a deflecting means in the form of six columns (5a-f), providing a plurality of co-aligned undulating ridges (exemplified by reference as 6a, 6b) in a zigzag manner, to define a convoluted path, that transverses substantially all the internal volume of the housing (2), for a dynamic airflow passing from the air inlet (3) to the air outlet (4). At the turn of each column (5a-f) is a curved element (7a-d) that also helps direct the dynamic airflow along the convoluted path. On the surface of each curved element (7a-d), facing the direction of the dynamic airflow, is an adhesive layer (8) consisting of an adhesive strip coated with Manuka® honey.

With reference to Figure 1 , in use, a dynamic airflow entering the housing (2) via the air inlet (3) is directed via the plurality of co-aligned undulating ridges (6a, 6b) of columns (5a-f) to curved elements (7a-d), upon which particulate matter in the dynamic airflow is captured by the Manuka® honey of adhesive layer (8), thus filtering the dynamic airflow. The dynamic airflow transverses substantially all the internal volume of the housing (2) of the filter (1) until the filtered air reaches the air outlet (4) and is dispersed from the housing (2).

Figure 2 shows a system (10) according to one preferred embodiment of the invention. System (10) is formed from filter (1) (as shown in Figure 1) contained in a protective cover (11) (shown in a part-cutaway form). A connecting tubing (12) links the air outlet (not shown) of the filter (1) to a face mask (13) via mask extension element (14).

With reference to Figure 2, in use, system (10) can be worn by a user to enable the inhalation of filtered air as a consequence of the air passing through filter (1) before reaching the mouth/nostrils of the user.

Figure 3 and Figure 4 show a filter (100) according to one preferred embodiment of the invention. Filter (100) is formed from a housing (101 ) comprising an air inlet (102a, 102b) provided by a tube (shown in Figure 3 as a part-cutaway form) with an end region defining an opening, the tube extending into the housing (101 ) from base regions (103a, 103b) respectively. Air outlet (104) is shown as an aperture formed in the upper surface (105) of housing (101 ). Arranged within housing (101 ) are a pair of elements (106a, 106b) with a concave surface arranged to face air inlet (102a, 102b) respectively and extend across a substantial portion of the internal volume of housing (101) between their associated air inlet (102a, 102b respectively) and the air outlet (104). (See Figure 5 and associated description for an explanation of the proximity of elements (106a, 106b) to the housing (101 )). The pair of elements (106a, 106b) each act as a deflecting means for a dynamic airflow within housing (101) and provide a recess within the internal volume of the housing (101). Elements (106a, 106b) each have a protrusion (107a, 107b) aligned with, and extending into, their respective air inlets (102a, 102b).

Figure 3 shows two adhesive layers (108a, 108b) each consisting of an adhesive strip coated with Manuka® honey, on the surface of base regions (103a, 103b), facing the direction of the dynamic airflow deflected from elements (106a, 106b).

Figure 4 shows a series of apertures (referenced singularly as 109a and 109b) located in an upper region the elements (106a, 106b). The upper region of elements (106a, 106b) is attached to housing (101) i.e. element (106a) is shown attached to the underside of base region (103b) and element (106b) is shown attached to the underside of upper surface (105). Apertures (109a, 109b) enable the dynamic airflow to pass from air inlets (102a, 102b) to the air outlet (104).

Figure 5 shows an expanded side view of filter (100). Element (106a) defines an edge region (110a) arranged proximal to the housing (101 ). (Element (106b) has an equivalent edge region (110b); not shown). The arrangement enables fluid communication between the air inlet (102a (102b; not shown)) and the air outlet (104; not shown) i.e. wherein the dynamic airflow can pass between the edge region (110a) of element (106a) and the interior wall of the housing (101 ). Edge region (110a) of element (106a) is shown extending past the end region of the air inlet (102a).

With reference to Figures 3-5, in use, a dynamic airflow entering the housing (101) via the air inlet (102a) is directed via protrusion (107a) and the concave surface of element (106a), facing air inlet (102a), to base region (103a) upon which is located an adhesive layer (108a) consisting of an adhesive strip coated with Manuka® honey. Passing the dynamic airflow over the adhesive layer (108a) ensures particulate matter in the dynamic airflow is captured by the Manuka® honey, thus filtering the dynamic airflow. The dynamic airflow passes between edge region (110a) of element (106a) and the interior surface of the housing (101 ), through the series of apertures (109a) and through air inlet (102b) to repeat the process. Thus, the dynamic airflow is directed via protrusion (107b) and the concave surface of element (106b), facing air inlet (102b), to base region (103b) upon which is located an adhesive layer (108b) consisting of an adhesive strip coated with Manuka® honey. Passing the dynamic airflow over the adhesive layer (108b) ensures remaining particulate matter in the dynamic airflow is captured, thus further filtering the dynamic airflow. The dynamic airflow passes between edge region (110b; not shown) of element (106b) and the interior surface of housing (101), through the series of apertures (109b) and dispersed from the housing (101 ) via air outlet (104).

Figure 6 shows a system (200) according to another preferred embodiment of the invention. System (200) is formed from filter (100) (as shown in Figures 3, 4 and 5) in association with a mask extension element (140) which links the air outlet of the filter (100) to a face mask (130).

With reference to Figure 6, in use, system (200) can be worn by a user to enable the inhalation of filtered air as a consequence of the air passing through filter (100) before reaching the mouth/nostrils of the user.

Figure 7 and Figure 8 show an insert (300) according to one preferred embodiment of the invention. Inset (300) is provided in two separate parts: trough (301) and element (302). Trough (301) is formed from a base (303) from which extends a wall (304) in a perpendicular manner from the perimeter of base (303). Air inlet (305) is provided by a tube with an end region defining an opening, the tube extending into trough (301) from base (303). Located on the surface of base (303), circumjacent to the air inlet (305), is an absorptive tissue (306) coated with Manuka® honey. The upper edge of wall (304) defines a plurality of slits (exemplified by slit 307). Element (302) defines an inner concave surface (308) with edge (309), wherein protrusion (310) extends from the central region of concave surface (308). Element (302) defines an outer convex surface (311) on which are situated a series of plate-like extensions (312).

With reference to Figures 7 and Figure 8, in use, insert (300) is assembled by connecting element (302) with trough (301) by inserting the lower region of each plate-like extension (311) of element (302) within a corresponding slit (307) of wall (304), such that edge (309) of element (302) sits inside trough (301). Insert (300) is then arranged within the housing of the filter, via a suitable attachment means in a manner akin to filter 100 shown in Figure 3 and Figure 4. A dynamic airflow entering insert (300), via the air inlet (305) which extends into the concave recess of element (302), is directed via protrusion (310) and concave surface (308), facing air inlet (305), to base (303) upon which is located an absorptive tissue (306) coated with Manuka® honey. Passing the dynamic airflow over the adsorptive tissue (306) ensures particulate matter in the dynamic airflow is captured by the Manuka honey®, thus filtering the dynamic airflow. The nature of the circulating dynamic airflow is such that the filtered airflow can pass out of element (300) by passing over convex surface (311) which, due to its curvature, can provide an air outlet, thus ensuring the filtered dynamic airflow can be dispersed from the housing (not shown).

It will be understood that the present invention has been described above purely by way of example, and modification of detail can be made within the scope of the invention. For example, with respect to Figure 1 , the at least one adhesive layer (8) may (also) be located on the plurality of co-aligned undulating ridges (6a, 6b) of columns (5a-f). With respect to Figures 3-5, the at least one adhesive layer (108a, 108b) may (also) be located on the concave surface of elements (106a, 106b). With respect to Figures 7 and Figure 8, the at least one adhesive layer may (also) be located on the inner concave surface (308) of element (302). Any consecutive repeating number of deflecting means, at least one adhesive layer, and/or air inlet and air outlet can be arranged within the housing as envisaged by the skilled person. Each feature disclosed in the description, and (where appropriate) the claims and drawings may be provided independently or in any appropriate combination.

Moreover, the invention has been described with specific reference to filtering of biological and chemical particulate matter. It will be understood that this is not intended to be limiting and the invention may be used more generally. For example, the invention may be used in other industrial field for the purpose of filtration. Additional applications of the invention will occur to the skilled person.