WO2021219886A1

WO2021219886A1 - An article of personal protective equipment with a pump

Info

Publication number: WO2021219886A1
Application number: PCT/EP2021/061475
Authority: WO
Inventors: Ernest Wai Yin LAU
Original assignee: Lau Ernest Wai Yin
Priority date: 2020-04-30
Filing date: 2021-04-30
Publication date: 2021-11-04
Also published as: GB202106255D0

Abstract

An article of personal protective equipment (PPE) formed from a semipermeable arrangement, wherein the semipermeable arrangement comprises a self-cleaning means that is formed at least partially from polytetrafluoroethylene (PTFE) and which, in use, defines the exterior surface of the article of PPE. The self-cleaning means comprising a self-cleaning web and the semipermeable arrangement comprises a support means for supporting the self-cleaning web, the support means being a mesh fabric. The support means and the self-cleaning web are bound together via a binding means disposed between the self-cleaning web and the support means with gaps such that there are areas not covered by the binding means.

Description

AN ARTICLE OF PERSONAL PROTECTIVE EQUIPMENT WITH A PUMP

The present invention relates to an article of personal protective equipment (PPE), in particular, an article of (PPE) formed from a semipermeable arrangement, and a pump that may be integrated into said PPE.

The COVID-19 outbreak which sweeps across the world in 2020 has not only highlighted the importance of personal protective equipment (PPE) in the fight against infectious disease but also exposed many of the deficiencies of the existent designs.

PPE, if properly used, should protect the user against contracting the infection with a high degree of certainty. This is not so with the currently available PPE as healthcare professionals wearing high grade PPE (including those working in intensive care with full body cover) still became infected. The user may have to wear PPE for a protracted period of time (several hours). In order to ensure and enhance compliance, the PPE has to be comfortable for the user. In this light, comfort does not just affect the user’s wellbeing but also his or her safety.

In one way or another, PPE aims to isolate and insulate the user from the external environment by establishing some form of barrier between the two. The effectiveness of this barrier often goes against the comfort of the PPE for the user. For a face mask to be effective against an airborne infective agent (“pathogen”), the face mask needs to fit tightly around the user’s nose and mouth, which can cause major discomfort for the user. If a tight-fitting face mask is worn for a protracted period of time, the pressure exerted can even damage the user’s skin, which may paradoxically increase the user’s risk of infection. On the other hand, if the face mask is only fitted loosely around the user’s nose and mouth, it may not be effective in blocking the entry of pathogens as airflow finds alternative routes to bypass the face mask.

The face mask has to contain a filter that blocks pathogens but allows air to pass through. If the pores in the filter are too large, they may not be able to block the passage of pathogens, which can be as small as 0.3 pm in diameter. If the pores are too small, the filter will pose a heavy resistance to airflow. The situation may worsen with use as the pores in the filter become clogged up with trapped particles or covered with water droplets from the user’s own breath. The user has to make stronger and stronger respiratory efforts over time. After a while, the user feels exhausted as his or her respiratory muscles fatigue.

For a gown/suit to be water repellent, it is typically lined with a thin layer of plastic. The plastic lining traps water vapour, making it difficult for the user to keep cool by sweat evaporation. The user feels hot and sticky in the humid environment artificially created inside the gown/suit.

The existent PPE typically comprises multiple separate pieces covering different body parts: 1. a face mask covering the nose and the mouth; 2. a visor or a pair of goggles covering the eyes; 3. a hat, bonnet or hood covering the head and the neck; 4. a pair of gloves covering the hands and the wrists; 5. a gown, a suit or an apron covering the torso, shoulders, arms and legs.

The separate PPE pieces have to be put on (“donned”) individually. When the PPE set is in use, the gaps between the pieces are vulnerability points that expose the user’s mucous membranes (eyes, nose and mouth), skin, and clothes under the PPE to possible contamination. When the user takes off (“doff”) the PPE after use, he or she may accidentally contaminate himself or herself if the PPE pieces have become contaminated. The risk is especially significant for goggles and face masks, as these pieces may have to be tight-fitting to be effective and cover the user’s mucous membranes. Furthermore, if the PPE becomes contaminated with pathogens, it may become a mean for spreading pathogens around as the user interacts with the environment and other people (i.e. becomes a fomite).

The existent PPE is intrinsically inefficient both in terms of time and cost. The donning and doffing of PPE can be cumbersome and time consuming, especially when the user wants to ensure the PPE is properly fitted and avoid accidental self-contamination. Most of the existent PPE is designed to be single use and disposable. In practice, frequent changes of PPE by a single user are needed (or may be desirable) in order to avoid spreading pathogens around in the environment, avoid transmitting pathogens from an infected person to other uninfected people, give the user a break from wearing PPE because of discomfort from prolonged use, and allow the user to perform certain self-caring activities (e.g. going to the bathroom, drinking, eating).

The consequences of frequent changes of single use disposable PPEs are: 1. Users can spend a sizeable portion of their working days donning and doffing PPE (an enabling activity) and not performing the core work (e.g. caring for patients); 2. Worldwide PPE production capacity is not able to meet the demands; 3. Financial resources have to be expended on the procurement of PPE rather than on other efforts (e.g. vaccine development, mass testing, support for the economy); 4. Single use disposable PPE may have to be recycled and reused outside indications.

Accordingly, it is the purpose of this invention to produce a piece of REusable Comfortable Integrated Personal Protective Equipment (RECIPPE). The RECIPPE may just protect the user person, in which case it will be designated as RECIP¹PE. However, the RECIPPE can also be modified to isolate not just the user from the environment and other people, but also the environment and other people from the user and the people and objects the user may have been in close physical contact with. In the latter scenario, the protective equipment is not just Personal, but in fact RECIProcal, and the RECIPPE will be designated as RECIP²PE.

According to an aspect of the invention there is provided an article of personal protective equipment (PPE) formed from a semipermeable arrangement.

Ideally, the semipermeable arrangement comprises a structural means.

Preferably, the structural means is formed at least partially from a material having an affinity to a lubricating fluid and being adapted such that it can be infused with a lubricating fluid. Ideally, the semipermeable arrangement is arranged with means to prevent or limit the movement of a lubricating fluid through the structural means.

Ideally, the article of PPE may be shaped to protect the user’s face or hands or any desirable part of the user from contamination.

Preferably, the article of PPE is or comprises a face mask, hood, gloves or mittens, gown, trousers, front and/or back torso pieces or one-piece suit.

Ideally, the one-piece suit covers the head and upper body of the user and ideally also the hands.

Preferably, the one-piece suit covers the head and upper body and legs of the user and ideally also the hands.

Ideally, the article of PPE is made of panels of a semipermeable arrangement.

Preferably, the article of PPE comprises a circulatory system for a lubricating fluid such as liquid perfluorocarbon.

Ideally, the circulatory system comprises a network of tubing arranged to transport lubricating fluid.

Preferably, the tubing is in fluid communication with the semipermeable arrangement at predetermined locations.

Ideally, the tubing at or about the upper portion of the suit is more permeable to perfluorocarbon than the tubing at or about the bottom portion of the suit.

Ideally, the underside of the tubing at the bottom of the suit is less permeable to perfluorocarbon than the topside of said tubing.

Ideally, the underside of the tubing at the bottom of the suit is impervious to perfluorocarbon than the topside of said tubing.

Ideally, the panels of semipermeable arrangement are joined at the seams, most preferably by fluorinated ethylene propylene (FEP), to the tubing.

Preferably, the tubing is formed from expanded polytetrafluoroethylene (ePTFE).

Ideally, the tubing is flexible but non-extendible and/or non-expandable.

Preferably, the tubing is variably covered by FEP laminate glue to control porosity of the tubing.

Ideally, the tubing runs along the entire outline of the article of PPE in the coronal plane, and around the shoulder joints in the sagittal plane.

Preferably, the circulatory system comprises a pump means arranged to pump fluid through the tubing.

Preferably, the pump means comprises one or more positive-displacement pumps.

Ideally, the one or more positive-displacement pumps are one or more bellows in fluid communication with the tubing.

Preferably, the one or more bellows are disposed in the axillary (armpit) region and/or in the crotch region of the PPE suit. Ideally, the one or more bellows are fashioned out of semi-rigid polytetrafluoroethylene (PTFE) sheets (although FEP or other suitable material such as ethylene tetrafluoroethylene ETFE may be used) and covered on the outside with ePTFE membranes.

Ideally, the one or more bellows comprises an input arranged to receive fluid such that additional fluid can be input into the circulatory system.

Ideally, the input on the bellows comprises a three-way check valve or a valved connector.

Preferably, the tubing has a plurality of one-way check valves spaced apart around the network of tubing.

Ideally, the front of the article of PPE has a transparent visor.

Preferably, the visor is welded to the semipermeable arrangement.

Ideally, the visor is fashioned out of ETFE or FEP welded to the semipermeable arrangement.

Ideally, the article of PPE has a parting to provide easier access for donning or doffing.

Preferably, the back of the article of PPE has a mid-line parting over the torso.

Ideally, the two edges of the parting are releasably fixable to one another via a releasable fixing means.

Ideally, the releasable fixing means is a ziplock.

Preferably, the releasable fixing means involves the edges of the parting being lined with dovetailing double ziplock seals moulded out of ePTFE rods.

Advantageously, the article of PPE is easy and safe to take off (“doffing”). This is the most vulnerable process in the use of PPE. During the recent and ongoing coronavirus pandemic, it is the most likely point at which most healthcare professionals become contaminated with SARS-CoV-2, potentially leading to said professionals becoming ill with COVID-19. The article of PPE protects the user from self-contamination by covering the entire head in one continuous surface. The article of PPE can further be worn comfortably for hours without losing effectiveness (most healthcare professionals find it very difficult to wear the currently available PPE for 8 - 12 hours on end); it does not require a tight fit around the user’s nose and mouth to be effective whereas chaffing and pressure from other PPE can cause severe damage to the user’s skin. The present PPE retains effectiveness even after prolonged use; is reusable (in theory, the same piece of the article of PPE herein described can be reused by different personnel and on different patients with periodic re-conditioning, provided it has not been damaged and that is easy to check); will not transmit viral contamination to other people or objects (i.e. will not become a “fomite”), and; can be mass produced at a reasonable cost per unit. Yet a further advantage is that the PPE suit is effective even when loosely worn by the user. Many widely used PPE articles must be tightly fitted to the user to be effective. This can be uncomfortable for the user and prolonged use results in skin damage and pain for the user. This PPE could be made available to the general public allowing them to travel safely and allow certain sectors of the economy to safely return to work.

In one embodiment, the one or more positive-displacement pumps are one or more bending-actuated pumps.

Ideally, the bending-actuated pump is integrated into the circulatory system of the PPE, such that the fluid in the circulatory system can be moved through the circulatory system via the bending-actuated pump.

Ideally, the bending-actuated pump comprises a chamber having an inlet and an outlet.

Preferably, the inlet comprises a one-way valve arranged to permit fluid to enter the chamber but not leave the chamber.

Ideally, the outlet comprises a one-way valve arranged to permit fluid to be discharged from the chamber but not enter the chamber.

Ideally, the bending-actuated pump has longitudinal and transverse dimensions.

Preferably, the bending-actuated pump comprises a chamber support means for maintaining the transverse dimension of the chamber.

Ideally, the chamber-support means comprises a helical coil arranged to provide structural support to the chamber.

Ideally, the chamber-support means is disposed within the chamber, preferably between the inlet and the outlet.

Ideally, the helical coil is an extension spring with adjacent coil turns directly stacked on top of one another with no gaps between when it is in the neutral unstressed (no extending or bending) state.

Ideally, the chamber is tubular.

Preferably, the chamber is formed from elastomer tubing.

Ideally, the inlet is located proximal one end of the elastomer tubing and the outlet is located proximal the other end of the elastomer tubing.

Ideally, the helical coil supports the transverse dimension of the elastomer tubing.

Ideally, the bending-actuated pump comprises valve housings.

Ideally, the bending-actuated pump comprises connection means for connecting to a fluid network.

Ideally, the connection means are disposed proximal to the inlet and distal to the outlet.

Ideally, the connection means is suitable for connecting the bending-actuated pump to tubing.

Preferably, the connection means is a lock.

Ideally, one lock is located proximal to the inlet and another at the outlet.

Ideally, one or both locks are Luer locks, male Luer locks, or female Luer locks.

Ideally, the connection means and the valve housings are integrally formed. Ideally, one or both valves are duckbill valves. Advantageously, duckbill valves are of simpler construction and are less bulky than other valve types.

Preferably, in use, when the bending-actuated pump is bent, the coil turns cannot get any closer on the compression side of the bend as they are already stacked up but can open up on the extension side of the bend. Advantageously, the chamber also extends on the extension side of the bend and is prevented from collapsing as it is propped open by the turns of the helical coil. This increases the volume of the chamber and the pressure within drops. The inlet valve opens, and the outlet valve closes. Fluid is sucked into the chamber from the inlet. When the pump straightens as the bending stress is released, the extension side of the chamber returns to its original dimensions. The volume of the pump chamber decreases and the pressure within rises. The inlet valve closes, and the outlet valve opens. Fluid is squeezed out of the pump chamber from its outlet.

In one embodiment, the article of PPE comprises both at least one bending-actuated pump and at least one bellow.

In one embodiment, the article of PPE comprises a plurality of bending-actuated pumps.

Ideally, the article of PPE comprises a source of perfluorocarbon.

Preferably, the source is located at or about the upper anatomical points in the PPE when the user is in the upright position.

Ideally, the source is formed from ePTFE.

Ideally, the source comprises an inner cavity for retaining an amount of perfluorocarbon.

Preferably, the source is a tube with a slit, or a folded over sheet of material, forming an inner cavity capable of retaining an amount of perfluorocarbon.

Ideally, the source is welded to a semipermeable arrangement or an ePTFE laminate by FEP or other suitable material, wherein the semipermeable arrangement or ePTFE laminate is in fluid communication with the interior of the source.

Preferably, where the source is in fluid communication with an ePTFE laminate, said ePTFE laminate is further in fluid communication with a semipermeable arrangement of the PPE.

Ideally, the source comprises a means for slowing movement of the perfluorocarbon from the source to the ePTFE laminate or semipermeable arrangement.

Ideally, the welded FEP is formed in a wave-like pattern to slow the movement of perfluorocarbon from the source to the ePTFE laminate or semipermeable arrangement.

Ideally, the source has an access means to enable perfluorocarbon to be added or removed as required.

Ideally, the access means is a valved connector having a female Luer lock connection, although other access means may be suitable.

Preferably, the article of PPE comprises perfluorocarbon sinks located at or about the lowest anatomical points in the PPE when the user is in the upright position.

Ideally, the sink is formed from ePTFE. Ideally, the sink comprises an inner cavity for retaining an amount of perfluorocarbon.

Preferably, the sink is a tube with a slit, or a folded over sheet of material, forming an inner cavity capable of retaining an amount of perfluorocarbon.

Ideally, the sink is welded to an ePTFE laminate or semipermeable arrangement by FEP or other suitable material, wherein the ePTFE laminate or semipermeable arrangement is in fluid communication with the interior of the sink.

Preferably, where the sink is in fluid communication with an ePTFE laminate, said ePTFE laminate is further in fluid communication with a semipermeable arrangement of the PPE.

Ideally, the sink comprises a means for slowing movement of the perfluorocarbon from the source to the ePTFE laminate or semipermeable arrangement.

Ideally, the welded FEP is formed in a wave-like pattern to slow the movement of perfluorocarbon from the ePTFE laminate or semipermeable arrangement to the sink.

Ideally, the sink has an access means to enable perfluorocarbon to be added or removed as required.

Preferably, the source and/or sink comprises a support means in and/or around the source or sink to prevent the source or sink from collapsing.

Ideally, the support means is a perforated convoluted ETFE or FEP tube disposed within the source or sink.

Ideally, the article of PPE comprises a serviceable channel, wherein at least one of the source or sink access means, tubing, or bending actuated-pump is housed within the serviceable channel.

Ideally, the serviceable channel being openable to provide access to the interior of the serviceable channel.

Ideally, the serviceable channel comprises a releasable fastening means for opening/closing the channel.

Ideally, the releasable fastening means comprising a double ziplock.

Preferably, the serviceable channel and/or releasable fastening means is formed from ePTFE or other suitable material.

In one embodiment, the semipermeable arrangement comprises a structural means and at least one porous member, the at least one porous member being located on, within and/or supported by the structural means.

Ideally, at least part of the structural means is impermeable to water and dissolved substances. Advantageously, passage of water and dissolved substances through the membrane occurs via the porous member(s). Altering the properties of the porous member(s) can alter the flowrate and filtration capabilities of the semipermeable arrangement. In one embodiment, the structural means is arrangeable as a layer, most preferably, comprising a single layer. In another embodiment, the structural means comprises a plurality of layers. Ideally, the plurality of layers are interconnected and/or are arranged adjacent to each other.

Preferably, the structural means comprises a means for retaining and/or supporting the at least one porous member. By retaining we mean holding in place, either by directly abutting and retaining or by acting on a secondary structure which abuts and retains the porous member.

Preferably, the structural means defines a structural plate, structural box, structural frame, clamp and/or other suitable geometric formation or combination thereof that provides structure and is capable of supporting at least one porous member.

Ideally, the porous member retaining means comprises structural rods.

Preferably, the structural rods have a diameter/width between 0.1 and 10 mm, between 0.1 and 1 mm, or between 0.5 and 5 mm. In one embodiment, the structural rods have a diameter/width of around 1 mm. In another embodiment, the structural rods have a diameter/width of around 0.4 mm, preferably having an average diameter/width of around 0.39 mm.

Ideally, the structural rods are spaced apart.

Ideally, the structural means, most preferably, the structural rods comprise a polymeric substance, ideally the substance being a fluoropolymer and most preferably PTFE and/or ePTFE.

Preferably, the structural rods are polymeric rods, fluorpolymer rods, or are formed from ePTFE. Advantageously, ePTFE is flexible relative to PTFE and therefore the structural rods and the structural frame are flexible and easy to handle.

Ideally, the structural rods have a circular or oval cross-section.

In one embodiment, the structural rods are arranged as a mesh.

Ideally, the structural frame comprises a first group of structural rods and a second group of structural rods. Preferably, the first and second group of structural rods each comprise a plurality of structural rods in a spaced apart, parallel arrangement. Preferably, the first group of structural rods are arranged perpendicular to the second group of structural rods.

Ideally, the structural rods are reticulated, wherein one group of spaced apart structural rods is overlaying and/or is intertwined with another group of spaced apart structural rods.

Preferably, the spacing between the structural rods in the first and/or second group of structural rods is between 0.1 and 10 mm, 0.5 and 5 mm, 2 and 4 mm, or around 3 mm.

Ideally, the spacing between the structural rods in the first and/or second group of structural rods defines a mesh network having a plurality of openings, each opening having an area of between 0.25 and 25 mm², between 4 and 16 mm², or around 9 mm².

In one embodiment, a plurality of mesh networks are arranged to create layers of mesh networks. Ideally, the plurality of mesh networks are arranged as a lattice structure.

Ideally, the at least one porous member is sized such that it can be located in an opening of the mesh network. Ideally, when the at least one porous member is located in an opening of the mesh network the mesh network abuts the porous member. Preferably, the abutment between the mesh network and the porous member retains the porous member in the mesh network. In one embodiment, the at least one porous member is retained in the mesh network via an interference fit.

Preferably, the at least one porous member comprises at least one polymeric substance, most preferably, at least one thermoplastic polymeric substance.

Preferably, the at least one porous member is formed from sintering of loosely compacted powders. Ideally, the loosely compacted powered are thermoplastic polymers. Advantageously, this process can be modified to adjust the properties of the semipermeable arrangement. For example, the particle size will affect the rate of movement of fluid through the porous member.

Preferably, the at least one porous member comprises a plurality of particles adhered and/or sintered together. Ideally, the plurality of particles are adhered and/or sintered together with gaps therebetween defining a pore size. Advantageously, this enhances permeability of the porous member. The pore size can be modified depending on manufacturing conditions and particle size.

Preferably, the pore size is less than or equal to 250 pm, 125 pm, 75 pm or 50 pm.

It will be understood that a small powder particle size will result in smaller spacings between the particles and a smaller average overall pore size. This reduces the average cross- sectional area of the pore size and will reduce the flow rate through the porous member and therefore the semipermeable arrangement. The manufacturing process of the porous member(s) can be adjusted to produce the desired properties in the semipermeable arrangement.

In one embodiment, at least one porous member is spherical, roughly spherical, or a flattened sphere, spherical cap, hemisphere, ovoid, cube or cuboid in shape. Alternatively, at least one porous member is disc-shaped.

In one embodiment, the structural means defines a plane and the porous member is arranged relative to the structural means such that the shortest dimension of the porous member is substantially perpendicular to the plane of the structural means.

Ideally, the porous member has a diameter or width of about 1.5 mm.

Preferably, the porous member has a thickness greater than that of the structural means. Advantageously, generally any three-dimensional geometric shape with a thickness greater than the structural means can be used provided it is capable of interacting with the structural means.

Ideally, the porous member has a thickness of equal to or greater than 0.25 mm, 0.4 mm, 0.75 mm, or a thickness of about 1 mm.

It will be understood that the semipermeable arrangement may comprise a range of shapes and sizes of porous members.

In one embodiment, the at least one porous member is sized between 0.1 and 10 mm, 0.5 and 8 mm, 1 and 5 mm or around 3 mm, most preferably, the at least one porous member is spherical, roughly spherical, a flattened sphere, spherical cap, hemisphere, ovoid or disc-shaped having a diameter/width between 0.1 and 10 m , 0.5 and 8 mm, 1 and 5 mm or around 3 mm.

Ideally, the at least one porous member extends out of the plane of the structural means, either above and/or below the plane.

Preferably, the at least one porous member has a raised profile relative to the plane of the structural means.

Ideally, the at least one porous member extends out of the plane of the structural means by at least 0.05 mm, or 0.5 mm, or by about 1 mm.

Advantageously, in one embodiment, the at least one porous member has a diameter/width of 3 mm and the structural rods have a diameter/width of around 1 mm, so the at least one porous member extends out of the plane of the structural means by around 1 mm at either side of the structural means. This increases the surface area of the semipermeable arrangement providing a large filtration surface. Additionally, the domed shape of the porous members within the structural means prevent matter from settling as matter will be predisposed to rolling off the surface of the dome shape. In another embodiment, the at least one porous member extends out of the plane of the structural means by about 0.3 mm.

Ideally, the semipermeable arrangement comprises a plurality of porous members.

Ideally, the plurality of porous members are located interspersed on or within the structural means.

Preferably, the plurality of porous members are located in a spaced apart relationship on or within the structural means, or within the mesh network of the structural frame.

Ideally, the plurality of porous members are arranged in a pattern within and/or on the structural means.

Ideally, the plurality of porous members are arranged in or on the structural frame adjacent to an opening in the structural frame, the opening being vacant from any porous member.

Preferably, the plurality of porous members are arranged in rows within the structural means, most preferably, they are arranged in rows within the structural frame such that every other opening in each row of the mesh network of the structural frame contains a porous member.

Preferably, the plurality of porous members are arranged within the structural frame in a chequered pattern such that every other opening in the row of the mesh network of the structural frame contains a porous member and that a row above or below this row contains a similar pattern but is offset relative to the row such that the plurality of porous members are arranged in a diagonal relationship within the mesh network but not laterally or longitudinally adjacent to one another.

Ideally, the semipermeable arrangement comprises a filter means.

In one embodiment, the filter means is provided by the structural means.

Ideally, the filter means can filter particles of matter from a fluid. Preferably, the filter means can exclude particles or microbes less than 1.0 pm in size from entering the at least one porous member.

Ideally, the filter means comprises a filter web having spacings, the spacings being equal to or less than 2.0 pm, 1.0 pm, or 0.5 pm. A filter web spacing of equal to or less than 0.5 pm provides a satisfactory trade-off between permeability and filtration capabilities, wherein bacteria including Staphylococcus aureus and other pertinent pathogens are prevented from passing through the web, but wherein an acceptable flow-rate of fluid (liquid or gas) through the web is maintained. The thinness of the filter web (e.g. 0.1 - 0.3 pm) permits particles with diameter < 0.5 pm to pass through.

In one embodiment, the filter means comprises a filter web having spacings, the spacings being equal to or less than 0.2 pm. Advantageously, the filter means is permeable to gas, water and dissolved substances but not large particles and bacteria.

Preferably, the filter means, most preferably the filter web, is arranged on a surface of the structural means and/or the at least one porous member.

In one embodiment, the filter means, most preferably the filter web, is arranged on a plurality of surfaces of the structural means and/or the least one porous member.

Preferably, the filter web comprises at least one polymeric substance.

Ideally, the filter web is formed by electrospinning, most preferably, by electrospinning of polymers.

Preferably, the filter web comprises a plurality of filter web fibres. By fibres we mean any threadlike form and including fibrils or filaments.

Preferably, the filter web comprises a plurality of filter web fibres irregularly arranged.

Ideally, the filter web comprises a plurality of filter web fibres arranged overlapping one another and having spacings therebetween.

Ideally, the filter web comprises a plurality of filter web fibres arranged overlapping one another and having spacings therebetween, the spacings being equal to or less than 2.0 pm, 1.0 pm, 0.5 pm or 0.2 pm.

Preferably, the filter web fibres are polymer fibres.

Ideally, during electrospinning of the filter web, the average diameter/width of filter web fibres can be controlled by altering the syringe arrangement.

Ideally, the filter means is formed at least partially from a polymeric substance that does not contain fluorine atoms. Advantageously, the filter means does not have an affinity to perfluorocarbons.

Ideally, the filter means is formed at least partially from polyurethane.

Preferably, the filter means is formed at least partially from electrospun polyurethane.

Preferably, the size of the spacing between the filter web fibres can be controlled via the manufacturing process and through stretching after manufacture. Preferably, the filter web fibres have an average diameter/width of between 0.01 and 100 pm, 0.01 and 10 pm, or about 0.1 pm.

In one embodiment, the filter means is formed, placed and/or stretched over the structural means and/or the at least one porous member.

In one embodiment, wherein the structural means is planar, the filter means is located on at least both planar surfaces of the structural means wherein the structural means is sandwiched by the filter means.

Alternatively, the filter means may be located within/between the structural means such that filter means is sandwiched by all or part of the structural means.

In one embodiment, the spacing between the filter web fibres is wider at or around the at least one porous member than the spacing between the filter web fibres at or around the structural means.

Ideally, the filter web comprises a plurality of filter web fibres arranged overlapping one another and having spacings therebetween, the spacing being equal to or less than 2.0 pm, 1.0 pm, 0.5 pm, 0.2 pm.

Preferably, the filter means has a melting point less than or equal to 330°C, 200°C, 150°C, or 100°C. Advantageously, parts of the filter means can be melted to adhere it to the structural means and/or other component parts of the semipermeable arrangement, or for melting one portion of the filter means to another portion of the filter means.

Preferably, the semipermeable arrangement comprises a self-cleaning means.

By self-cleaning we mean repels substances that result in fouling. Advantageously, the self-cleaning means reduces the rate of fouling of the semipermeable arrangement or obviates it entirely.

In one embodiment, the self-cleaning means is provided by the structural means.

Ideally, the self-cleaning means comprises a self-cleaning web.

Ideally, the self-cleaning means, most preferably, the self-cleaning web is arranged on a surface of the filter means and/or the at least one porous member.

Ideally, the self-cleaning means, most preferably the self-cleaning web, is arranged on a plurality of surfaces of the filter means and/or the at least one porous member.

In one embodiment, the self-cleaning means is arranged on a surface of some of the porous members but not all the porous members.

In another embodiment, the self-cleaning means, most preferably, the self-cleaning web is arranged on a surface of the structural means.

Preferably, the self-cleaning means, most preferably the self-cleaning web, is arranged on a plurality of surfaces of the structural means.

In one embodiment, wherein the structural means is planar, the self-cleaning means is located on at least both planar surfaces of the structural means wherein the structural means is sandwiched by the self-cleaning means. Alternatively, the self-cleaning means may be located within/between the structural means such that the self-cleaning means is sandwiched by all or part of the structural means. It will be understood that in this embodiment portions of the structural means that are not covered by the self-cleaning means may be subject to fouling, and so the semipermeable arrangement may be only partially self-cleaning.

In another embodiment, the filter means, most preferably the filter web, is arranged on a surface of the self-cleaning means and/or the at least one porous member.

Preferably, the filter means, most preferably the filter web, is arranged on a plurality of surfaces of the self-cleaning means and/or the at least one porous member.

Ideally, at least part of the filter means is adhered to at least part of the self-cleaning means and/or the structural means.

Ideally, at least part of the filter means is bound to at least part of the self-cleaning means and/or the structural means, most preferably by the components being pressed and/or melted together. Advantageously, the filter means provides additional structure to the semipermeable arrangement by holding together the self-cleaning means and the structural means.

Alternatively, an adhesive, melted substance and/or mechanical clamp in addition to or instead of the filter means can be provided to hold parts of the self-cleaning means together and/or to hold the self-cleaning means and the structural means together.

In one embodiment, the semipermeable arrangement comprises a means for retaining the self-cleaning means, the structural means and/or the filter means together.

Ideally, the means for retaining the self-cleaning means, the structural means and/or the filter means together comprises a clamp, a mechanical fixing means, adhesives or other such means fitted to the self-cleaning means, the structural means and/or the filter means.

Preferably, the self-cleaning means, most preferably the self-cleaning web, comprises at least one polymeric substance. Ideally, the self-cleaning web is formed by electrospinning, most preferably, by electrospinning of polymers.

Preferably, the self-cleaning web comprises a plurality of self-cleaning web fibres.

Preferably, the self-cleaning web fibres are irregularly arranged.

Ideally, the self-cleaning web comprises a plurality of self-cleaning web fibres arranged overlapping one another and having spacings therebetween.

Preferably, the spacings being formed to enable capillary action of liquid, most preferably, of perfluorocarbon liquid.

Ideally, the self-cleaning web comprises a plurality of self-cleaning web fibres arranged overlapping one another and having spacings therebetween, the spacing being equal to or less than 2.0 pm, 1.0 pm, or 0.5 pm. Advantageously, in one embodiment wherein the self-cleaning web is untreated with lubricating fluid, a self-cleaning web spacing of equal to or less than 0.5 pm provides a satisfactory trade-off between permeability and filtration capabilities, wherein bacteria including Staphylococcus aureus and other pertinent pathogens are prevented from passing through the web, but wherein an acceptable flow-rate of fluid through the web is maintained.

Ideally, the self-cleaning web comprises a plurality of self-cleaning web fibres arranged overlapping one another and having spacings therebetween, the spacing being equal to or less than 0.2 pm.

Preferably, the self-cleaning web fibres are polymer fibres.

Ideally, the average diameter/width of the self-cleaning web fibres can be controlled during the manufacture process.

Preferably, the self-cleaning web fibres have an average diameter/width of between 0.01 and 100 pm, 0.01 and 10 pm or about 0.1 pm.

Ideally, the self-cleaning means is formed at least partially from a polymeric substance that contains fluorine atoms. Advantageously, the self-cleaning means has an affinity to perfluorocarbons.

Ideally, the self-cleaning means is formed at least partially from PTFE, expanded or electrospun (es) PTFE, or sintered PTFE.

Advantageously, PTFE is omniphobic and repels both hydrophobic and hydrophilic substances that could result in fouling.

Preferably, the size of the spacing between the self-cleaning web fibres can be controlled via the manufacturing process and through stretching.

Ideally, the self-cleaning web is formed, placed and/or stretched over the filter means and/or the at least one porous member.

In one embodiment, the self-cleaning web is formed, placed and/or stretched over the structural means and/or the at least one porous member. Advantageously, the self-cleaning means prevents degradation of at least part of the filter means by isolating a part of the filter means from the surrounding environment.

In one embodiment, the semipermeable arrangement comprises at least one supplementary substance.

Ideally, the at least one supplementary substance comprises a lubricant.

Preferably, the self-cleaning means comprises at least one supplementary substance.

Ideally, the at least one supplementary substance is hydrophobic or omniphobic.

Ideally, the lubricant is hydrophobic or omniphobic.

Preferably, the at least one supplementary substance has an affinity for the self-cleaning web and/or the support frame.

Preferably, the at least one supplementary substance comprises perfluorocarbon liquid.

Ideally, the perfluorocarbon liquid comprises perfluoropolyether (PFPE), perfluoroperhydrophenanthrene (PFPH), perfluorodecalin (PFD) and/or other perfluorocarbon compounds. Advantageously, perfluorocarbons are chemically relatively inert and have a chemical affinity for PTFE, ePTFE and electrospun PTFE. In an embodiment where the support frame and/or the self-cleaning web are formed from PTFE, the lubricant has a natural affinity for these components.

Preferably, the self-cleaning web is saturated with at least one supplementary substance.

Preferably, the at least one supplementary substance is dispersed throughout the self cleaning web by capillary action.

Ideally, the at least one supplementary substance is held throughout the self-cleaning web by capillary action.

In one embodiment, the structural means is saturated with the at least one supplementary substance.

In one embodiment, the spacing between the self-cleaning web fibres is wider at or around the at least one porous member than the spacing between the self-cleaning fibres at or around the structural means and/or filter means.

Preferably, the spacing between the self-cleaning web fibres at, around or covering the at least one porous member is too large to support capillary uptake of the at least one supplementary substance. Advantageously, the at least one supplementary substance is not located covering the at least one porous member. This enables movement of fluid into and through the at least one porous member.

In one embodiment, the at least one supplementary substance is present throughout the structural means in sufficient quantity such that the volume of the at least one supplementary substance is redistributed throughout the structural means when the structural means is misshapen, deformed and/or bent, so that the at least one supplementary substance infusing a part of the surface of the semipermeable arrangement is not diminished by bending.

Ideally, when the semipermeable arrangement is misshapen, deformed and/or bent the lubricant is redistributed around the structural means. Advantageously, this ensures that lubricant is always present on the surfaces of the semipermeable arrangement and the slipperiness conferred by the lubricant is not diminished by bending or deforming.

Ideally, the structural means provides a reservoir for the lubricant such that the self cleaning web is replenished with lubricant when required.

In another embodiment, the self-cleaning means comprises gaps sized and corresponding to the location of the at least one porous member in the structural means. Ideally, the gaps are large enough to prevent the at least one supplementary substance from bridging across the gap. In one embodiment, the gaps provide corresponding gaps in the continuity of the at least one supplementary substance.

Ideally, the gaps are roughly equal in size to at least one porous member or smaller than at least one porous member. Preferably, the gaps have a width and/or diameter of between 1 and 5 m , or about 3 mm. Advantageously, when the lubricating fluid is applied to the structural means, the movement of lubricating fluid through the structural means is restricted, and there are areas on the semipermeable arrangement that are completely or substantially free from the presence of lubricating fluid.

Ideally, the structural means is porous. Advantageously, the pores of the structural means can be infused with lubricating fluid or any fluid having an affinity to the material of the structural means. By applying a lubricating fluid, such as perfluorocarbon liquid, to the structural means, this prevents the likelihood of fouling occurring.

Ideally, the means to prevent or limit movement of the lubricating fluid through at least part of the structural means is arranged having one or more passageways to permit the movement of fluids such as air, water and dissolved substances through the structural means.

Preferably, the means to prevent or limit movement of the lubricating fluid through at least part of the structural means comprises at least one porous member.

Alternatively or additionally, the means to prevent or limit the movement of the lubricating fluid through the structural means comprises at least one substantially hollow member, the hollow member having a first opening arrangeable at one side of the structural means and a second opening. In one embodiment, the second opening is arranged at, or is directed towards, another side of the structural means.

Ideally, the substantially hollow member is a tube.

Preferably, the substantially hollow member is formed at least partially from one or more polymeric substances, for example polyurethane (PU), FEP and/or PTFE.

Ideally, the substantially hollow member is formed at least partially from a relatively rigid polymeric substance such as PTFE. Advantageously, this prevents the substantially hollow member from easily collapsing in use thereby blocking the passageway.

Ideally, the substantially hollow member is formed having a rigid innermost portion and less rigid outermost portion.

Preferably, the substantially hollow member comprises an outermost portion formed of a pliable substance or substance having a relatively low melting point (i.e. lower than that of PTFE) such as FEP or PU. Advantageously, the outermost portion can be integrated into the structural means.

Ideally, the structural means is formed from one or more layers, most preferably, from one or more layers of ePTFE. Preferably, the structural means comprises a first layer and a second layer of ePTFE. Ideally, the first layer is arranged relative to the second layer such that the longitudinal direction of the fibrils in the first layer is misaligned with the longitudinal direction of the fibrils in the second layer. Preferably, the first layer is arranged relative to the second layer such that the longitudinal direction of the fibrils in the first layer is oblique to the longitudinal direction of the fibrils in the second layer.

Ideally, the first layer is arranged relative to the second layer such that the longitudinal direction of the fibrils in the first layer extend parallel or orthogonal, or any angle therebetween, to the longitudinal direction of the fibrils in the second layer. Most preferably, the first layer is arranged relative to the second layer such that the longitudinal direction of the fibrils in the first layer extend orthogonal to the longitudinal direction of the fibrils in the second layer. The tensile strength of ePTFE varies depending on the direction of the force acting on the ePTFE, relative to the orientation of the ePTFE fibrils. By arranging the first and second layers such that the fibrils in the first layer run orthogonally to the fibrils in the second layer, the tensile strength of the structural means is uniform and cannot be easily deformed regardless of the direction of any disruptive force acting on the structural means.

Preferably, where the structural means is formed from a plurality of layers of ePTFE, each layer is bound together. Expanded PTFE layers can be bound together by pressing the layers together. Alternatively, a binding polymer such as FEP can be placed between the layers and when the layers are pressed together the soft polymer fills gaps between fibrils in each layer and binds the layers together, thereby the binding polymer extends between the layers. Additionally, or alternatively, heat can be applied to melt the binding polymer to bind the layers of the structural means together.

Ideally, the means to prevent or limit movement of the lubricating fluid through at least part of the structural means is retained within the structural means, most preferably, it is retained by the structural means.

Preferably, the means to prevent or limit movement of the lubricating fluid through at least part of the structural means is disposed between the first and second layers of the structural means.

Preferably, the means to prevent or limit movement of the lubricating fluid through at least part of the structural means extends out from a main plane of the structural means in at least one direction. Advantageously, this provides a break in the plane of the structural means and the capillary action of perfluorocarbon liquid is disrupted when it reaches the means to prevent or limit movement of the lubricating fluid.

Ideally, the spacing between fibres in the structural means is equal to or less than 2.0 pm, most preferably equal to or less than 1.0 pm.

Ideally, the means to prevent or limit movement of the lubricating fluid through at least part of the structural means includes barriers located within the pores of the structural means.

Ideally, the barriers are provided by pressing and/or heat-melting a polymer such as PU or FEP into the gaps. Advantageously, movement of the lubricating fluid is restricted by the presence of the barriers. Preferably, the substantially hollow member has a flange adapted to be disposed between the first and second layers of the structural means.

Ideally, the flange can be heat-melted and/or pressed to fill the gaps between the fibrils of the structural means thereby providing a barrier to movement of lubricating fluid.

Ideally, the outermost portion of the substantially hollow member can be heat-melted and/or pressed to fill the gaps between the fibrils of the structural means thereby providing a barrier to movement of lubricating fluid.

Preferably, the outermost portion of the substantially hollow member is arranged such that it extends into the structural means thereby retaining the substantially hollow member within the structural means and providing a barrier to movement of lubricating fluid through the structural means.

Ideally, the structural means extends over the openings of the passageways of the means to prevent or limit movement of the lubricating fluid through at least part of the structural means. Advantageously, the barriers to movement of the lubricating fluid, as provided by the substantially hollow member or otherwise, prevent the lubricating fluid from extending through the portion of the structural means that extends over the passageways. As the structural means is porous, this permits movement of fluids such as air and water through the passageways. In one embodiment, the structural means further acts as a filter to prevent movement of pathogens through the passageways. When impregnated with lubricating fluid, the semipermeable arrangement is thereby both self-cleaning (as provided by the lubricant) and permeable to air or water, but also impermeable to particles and pathogens sized greater than the minimum pore size of the structural means.

Preferably, the semipermeable arrangement, most preferably the structural means, comprises lubricating fluid, most preferably, the lubricating fluid is perfluorocarbon liquid.

Preferably, at least part of, most preferably the passageways of, the means to prevent or limit movement of the lubricating fluid through at least part of the structural means comprises additives, non-limiting examples of possible additives include soluble particles of one or more chemical substances and/or a water- and/or air-purifying substance such as activated charcoal.

Ideally, the portion of the structural means that extends over the passageways of the means to prevent or limit the movement of the lubricating fluid through the structural means is at least partially hydrophilic.

In one embodiment, the semipermeable arrangement is formed at least partially from sintered PTFE.

The skilled person will understand that the semipermeable arrangement may be non- uniformly permeable wherein part of the arrangement is impermeable, and another part is permeable or semipermeable. This thereby renders the arrangement as a whole semipermeable, even though parts of the arrangement are impermeable. Ideally, the semipermeable arrangement comprises a self-cleaning web formed at least partially from sintered PTFE. Preferably, the semipermeable arrangement comprises a support means for supporting the self-cleaning web. In use, the self-cleaning means defines the exterior surface of the article of PPE.

In one embodiment, the support means is a mesh fabric.

Ideally, the support means and the self-cleaning web are bound together, most preferably via a binding means.

Ideally, the binding means is an adhesive. Preferably, the binding means is an elastomer. Ideally, the binding means is non-porous.

Preferably, the binding means is disposed between the self-cleaning web and the support means with gaps such that there are areas not covered by the binding means. Advantageously, these gaps render the arrangement non-uniformly permeable, as the gaps provide permeable or semipermeable channels.

Ideally, the binding means is located throughout the entirety of the semipermeable arrangement, with gaps interspersed throughout.

Preferably, the binding means is arranged as spots throughout the semipermeable arrangement. Ideally, there is a pattern of gaps in the binding means, or the binding means is arranged as a pattern of spots or patches throughout the semipermeable arrangement. Most preferably, the pattern of gaps or spots/patches is a regular pattern.

Ideally, the binding means extends only partway into the self-cleaning web. Advantageously, the outer surface can thereby be infused with perfluorocarbons.

Preferably, the semipermeable arrangement comprises at least one protrusion.

Ideally, the protrusion is formed such that the self-cleaning web protrudes relative to the support means.

Ideally, the protrusion is substantially dome-shaped.

Preferably, the semipermeable arrangement comprises a protrusion-support means. Advantageously, the protrusion-support means prevents the protrusion from collapsing.

Ideally, the protrusion-support means comprises a supporting structure disposed between the self-cleaning web and the support means.

Preferably, the supporting structure is a cone cap.

Ideally, the supporting structure is formed from resilient material such that, if it is deformed, it returns to a rest configuration upon removal of the deforming force.

Preferably, the supporting structure is permeable.

Ideally, the supporting structure comprises one or more perforations. Advantageously, the hollow inside the supporting structure provides the physical space for additional substances, such as antibiotics, to be stored if desired.

Ideally, the self-cleaning web that forms a part of the protrusion is sealed off from the adjacent self-cleaning web. This can be done by applying the binding means such that it fills the depth of the self-cleaning web in an area around the protrusion. Therefore, if perfluorocarbon is applied to the arrangement, the protrusion is sealed off, will not become infused with perfluorocarbon, and will remain permeable.

In one embodiment, the self-cleaning web is present on both sides of the support means such that the support means is sandwiched between the self-cleaning web. Advantageously, both surfaces of the semipermeable arrangement may be infused with perfluorocarbon to become self cleaning.

In this embodiment, protrusions may be present on one or both sides.

In another embodiment, the self-cleaning web is sandwiched between the support means.

In one embodiment, the semipermeable arrangement is formed from a plurality of pieces joined together, each piece comprising a self-cleaning web and support means.

Ideally, the support means is joined to an adjacent support means by sewing or stitching together.

Preferably, the self-cleaning webs of adjacent pieces are arranged overlapping one another and are bonded to the support means via the binding means.

According to another aspect of the invention there is provided an ultraviolet light sterilisation system comprising a single or few UV light sources in an enclosure lined with sintered PTFE.

According to another aspect of the invention there is provided a bending-actuated pump.

Ideally, the bending-actuated pump can be integrated into the circulatory system of a PPE article having a circulatory system, such that the fluid in the circulatory system can be moved through the circulatory system via the bending-actuated pump.

Ideally, the bending-actuated pump has longitudinal and transverse dimensions.

Ideally, the chamber-support means is disposed within the chamber, preferably between the inlet and the outlet. Ideally, the helical coil is an extension spring with adjacent coil turns directly stacked on top of one another with no gaps between when it is in the neutral unstressed (no extending or bending) state.

Ideally, the chamber is tubular.

Preferably, the chamber is formed from elastomer tubing.

Ideally, the inlet is located proximal one end of the elastomer tubing and the outlet is located proximal to the other end of the elastomer tubing.

Ideally, the bending-actuated pump comprises valve housings.

Ideally, the connection means are disposed proximal to the inlet and the outlet.

Preferably, the connection means is a lock.

Ideally, one lock is located proximal to the inlet and another at the outlet.

Ideally, one or both locks are male Luer locks.

Ideally, the connection means and the valve housings are integrally formed.

Ideally, one or both valves are duckbill valves. Advantageously, duckbill valves are of simpler construction and are less bulky than other valve types.

Preferably, in use, when the bending-actuated pump is bent, the coil turns cannot get any closer on the compression side of the bend as they are already stacked up but can open up on the extension side of the bend.

Advantageously, the chamber also extends on the extension side of the bend and is prevented from collapsing as it is propped open by the turns of the helical coil. This increases the volume of the chamber and the pressure within drops. The inlet valve opens, and the outlet valve closes. Fluid is sucked into the chamber from the inlet. When the pump straightens as the bending stress is released, the extension side of the chamber returns to its original dimensions. The volume of the pump chamber decreases and the pressure within rises. The inlet valve closes, and the outlet valve opens. Fluid is squeezed out of the pump chamber from its outlet.

According to another aspect of the invention there is provided a semipermeable arrangement, the semipermeable arrangement being formed at least partially from sintered PTFE.

According to an aspect of the invention there is provided a method for cleaning a filter, the method comprising the step of applying perfluorocarbon liquid to the filter or immersing the filter in perfluorocarbon liquid, then subsequently removing the perfluorocarbon from the pores of the filter. The filter may be a semipermeable arrangement or an article of PPE as herein disclosed. Advantageously, when the filter is immersed in a sufficient quantity of perfluorocarbon, particles are dislodged from the pores in the filter by specific gravity and form a sediment or a skim layer distinct from the perfluorocarbon and the filter.

Ideally, the method comprises the step of mechanically agitating the filter and/or the perfluorocarbon when the filter is immersed in the perfluorocarbon.

Preferably, the mechanical agitation involves shaking and/or sonication or other suitable method of agitation.

Additionally or alternatively, perfluorocarbon may be removed from the pores by spinning the filter, most preferably, in a centrifuge.

Additionally or alternatively, perfluorocarbon may be removed from the pores by elevating the temperature of the filter.

In one embodiment, the method involves heating the filter under a reduced atmospheric pressure if necessary to further improve removal of the perfluorocarbon from the pores.

In another embodiment, the method involves blowing air, most preferably hot air, through the filter. Advantageously, the filter is then ready for reuse.

Advantageously, the majority of perfluorocarbon used for cleaning the filter can be easily recovered and reused.

In one embodiment, the method further comprising the step of removing contaminant particles from the perfluorocarbon liquid such that the perfluorocarbon liquid may be reused.

Ideally, the contaminants are decanted out through selective pouring.

Additionally or alternatively, the contaminants are sucked out of the perfluorocarbon (e.g. with a pipette).

Additionally or alternatively, the contaminants may be removed by passing the perfluorocarbon through a second filter, the second filter having finer pores than the filter that was cleaned in the perfluorocarbon.

Advantageously, the second filter can have pores selected such that the contaminant particles will be blocked by the pores but not become trapped within the pores.

Ideally, the second filter may be shaped as a bag or other such enclosure to hold the perfluorocarbon within while it drains through the filter.

Ideally, the second filter is formed from expanded polytetrafluoroethylene (ePTFE) and the contaminants can thereby by easily scraped off the surface of the second filter due to the intrinsic non-stick property of PTFE.

Ideally, the method comprises the step of urging perfluorocarbon through the second filter, for example, by exerting pressure on the second filter.

In one embodiment, the filter to be cleaned by the method is an ePTFE membrane having a desired pore size.

In one embodiment, the filter to be cleaned by the method is an article of PPE. In one embodiment, the filter to be cleaned by the method is semipermeable arrangement.

It will be appreciated that optional features applicable to one aspect of the invention can be used in any combination, and in any number. Moreover, they can also be used with any of the other aspects of the invention in any combination and in any number. This includes, but is not limited to, the dependent claims from any claim being used as dependent claims for any other claim in the claims of this application.

The invention will now be described with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a first example of a semipermeable arrangement for use in forming an article of PPE according to the invention. The semipermeable arrangement is shown in expanded view with the lower filter web located away from the structural frame with arrows indicating the assembly direction.

Figure 2 is a front elevation view of a first example of a porous member of the semipermeable arrangement of Figure 1.

Figure 3 is a perspective view of a second example of a porous member.

Figure 4 is a perspective view of a third example of a porous member.

Figure 5 is a perspective view of the structural frame and the plurality of porous members of the semipermeable arrangement of Figure 1.

Figure 6 is a cross-sectional view of a second example of a semipermeable arrangement wherein the self-cleaning web is not extended over the surface of the porous member and wherein the lubricant is present on one side of the semipermeable arrangement, further illustrating crystallized antimicrobial particles within the porous member.

Figure 7 is a cross-sectional view of a third example of a semipermeable arrangement wherein the porous member is a spherical cap.

Figure 8 is a cross-sectional view of a fourth example of a semipermeable arrangement wherein the porous member is disc-shaped.

Figure 9 is a cross-section view of a fifth example of a semipermeable arrangement wherein the self-cleaning web is extended over the surface of the porous member and wherein the lubricant is present on one side of the semipermeable arrangement.

Figure 10 is a cross-sectional view of a sixth example of a semipermeable arrangement wherein the self-cleaning web is not extended over the surface of the porous member and wherein the lubricant is present on both sides of the semipermeable arrangement and throughout the structural frame.

Figure 11 is a cross-sectional view of a seventh example of a semipermeable arrangement wherein the porous member is a spherical cap. Figure 12 is a cross-sectional view of an eighth example of a semipermeable arrangement wherein the porous member is disc-shaped.

Figure 13 is a cross-sectional view of a ninth example of a semipermeable arrangement wherein the self-cleaning web is extended over the surface of the porous member and wherein the lubricant is present on both sides of the semipermeable arrangement and throughout the structural frame.

Figure 14 is a cross-sectional view of a tenth example of a semipermeable arrangement wherein the semipermeable arrangement is bent, showing redistribution of the lubricant through the structural frame.

Figure 15 is a perspective view of a semipermeable arrangement having disc-shaped porous members.

Figure 16 is a plan view of a filter web comprising spherical or hemispherical porous members.

Figure 17 is a perspective view of the filter web in Figure 16.

Figure 18 is a side elevation view of the filter web in Figure 16.

Figure 19 is a plan view of a filter web comprising disc-shaped porous members.

Figure 20 is a perspective view of the filter web in Figure 19.

Figure 21 is a side elevation view of the filter web in Figure 19.

Figure 22 is a plan view of the filter web and the self-cleaning web arranged on top of the filter web and as present in the fifth and ninth examples of the semipermeable arrangement shown in Figures 9 and 13 respectively. The self-cleaning web is illustrated as dashed lines.

Figure 23 is a perspective view of the filter web and self-cleaning web of Figure 22.

Figure 24 is a side elevation view of the filter web and self-cleaning web of Figure 22.

Figure 25 is a plan view of a self-cleaning web.

Figure 26 is a plan view of the self-cleaning web shown in Figure 25 overlaying a filter web and as present in the second and sixth examples of the semipermeable arrangement shown in Figures 6 and 10 respectively.

Figure 27 is a perspective view of the self-cleaning web and filter web of Figure 26.

Figure 28 is a side-elevation view of the self-cleaning web and filter web of Figure 26.

Figure 29 is a side elevation, cross sectional view of an eleventh example of a semipermeable arrangement.

Figure 30 is a side elevation, cross sectional view of a twelfth example of a semipermeable arrangement.

Figure 31 is a perspective view the eleventh example as shown in Figure 29.

Figure 32 (a) is a front elevation view of a schematic of an article of personal protective equipment (PPE) formed from a semipermeable membrane according to the invention; (b) is a cross-sectional view through a part of a pumping arrangement that forms a part of the PPE, and; (c) is a cross-sectional view through a further part of a pumping arrangement that forms a part of the PPE.

Figure 33 is a rear elevation view of the PPE of Figure 32.

Figure 34 is a front elevation view of a schematic of a full body suit of PPE formed from a semipermeable membrane according to the invention.

Figure 35 is a rear elevation view of a schematic of the PPE of Figure 34.

Figure 36 is a cross sectional view of the semipermeable arrangement of the re-useable

PPE.

Figure 37 is a cross sectional view of the semipermeable arrangement of the re-useable PPE further containing activated charcoal.

Figure 38 is a schematic view of the arrangement of protuberances in the semipermeable arrangement of the re-useable PPE.

Figure 39 is a schematic front view of a further embodiment of PPE gown without a circulation system.

Figure 40 is a schematic rear view of the PPE gown of Figure 39 without a circulation system.

Figure 41 is a schematic front view of a further embodiment of PPE body suit without a circulation system.

Figure 42 is a schematic rear view of the PPE body suit of Figure 41 without a circulation system.

Figure 43 is a perspective view of a schematic of a further embodiment of an article of

PPE.

Figure 44 is a cross-sectional view of a bending-actuated pump according to the invention.

Figure 45 is a cross-sectional view of the bending-actuated pump of Figure 44 when bent.

Figure 46 is a cross-section view of the bending-actuated pump of Figure 44 after it has been bent and then straightened.

Figure 47 is a schematic front elevation view of a further embodiment of an article of PPE according to the invention.

Figure 48 is a schematic rear elevation view of the embodiment of Figure 47.

Figure 49 is a schematic front elevation view of a further embodiment of an article of PPE according to the invention.

Figure 50 is a schematic rear elevation view of the embodiment of Figure 49.

Figure 51 is a flow diagram illustrating the perfluorocarbon circulatory system of an article of PPE according to the invention.

Figure 52 is a schematic illustration of the upper portion of an article of PPE according to the invention. Figure 53 is a schematic illustration of the lower portion of an article of PPE according to the invention.

Figure 54 is a cross-sectional view of a serviceable channel in an article of PPE according to the invention.

Figure 55 is a cross-sectional view of a semipermeable arrangement according to an aspect of the invention.

Figure 56 (a) and (b) are plan views of the semipermeable arrangement of Figure 55.

Figure 57 is a cross-sectional view of a further embodiment of a semipermeable arrangement according to an aspect of the invention.

Figure 58 is a cross-sectional view of a further embodiment of a semipermeable arrangement according to an aspect of the invention.

Figure 59 (a), (b) and (c) are cross-sectional views of embodiments of semipermeable arrangements according to aspects of the invention.

Figure 60 is a cross-sectional view of a further embodiment of a semipermeable arrangement according to an aspect of the invention.

Figure 61 is a cross-sectional view of a semipermeable arrangement according to the invention, illustrating how two pieces may be joined.

Figure 62 is a schematic illustrating UV sterilization of an article of PPE formed from the semipermeable arrangement.

Figure 63 is an illustration of a step of the method according to the invention wherein: (a) depicts a clogged filter, (b) depicts the filter immersed in perfluorocarbon, and (c) shows removal of the clogging particles.

Figure 64 is an illustration of a step of the method according to the invention wherein the filter is dried after removal of particles.

Figure 65 is an illustration of a step of the method according to the invention wherein perfluorocarbon is separated from particles contained within said perfluorocarbon.

Figure 66 is an illustration of a step of the method according to the invention wherein perfluorocarbon is separated from particles contained within said perfluorocarbon wherein (a) is during separation of the perfluorocarbon from the particles, and (b) is after separation of perfluorocarbon and particles.

Figures 1 and 2 show a first example of a semipermeable arrangement that may be used to form an article of PPE as according to the invention, and components thereof indicated generally by reference numeral 1. The semipermeable arrangement has a structural frame 2 and a plurality of porous members 3 that are arranged within the structural frame 2. The structural frame 2 is a single layered frame formed from a plurality of structural rods 4. The structural rods 4 are arranged as a first group of structural rods 5 and a second group of structure rods 6, wherein each group of structural rods 5, 6 have a plurality of structural rods arranged in a spaced apart, parallel relationship. The spacing between the structural rods 4 in the first group of structural rods 5 and the second group of structural rods 6 is 3 mm. The first group of structural rods 5 is arranged perpendicular to the second group of structural rods 6 and the they are woven together to form a mesh network 8 with square-shaped openings 9 having an area of around 9 mm² each (see Figure 5). The structural rods 2 have a circular cross-section and a diameter of around 1 mm and are formed from ePTFE.

Figure 2 shows an enlarged view of a porous member 3. The porous members 3 are roughly spherical and have a diameter of around 3 mm enabling them to be located in the openings 9 within the mesh network 8. When they are located in openings 9 of the mesh network 8 the structural rods 4 press against, hold and retain the porous members 3 in the structural frame. The porous members 3 are formed from polypropylene but may be formed from PTFE or other suitable substance and are manufactured by sintering together small, loosely compacted particles 10 of polypropylene. This provides gaps between the particles which act as pores to permit passage of fluid into and through the porous members 3. The pore size of the porous members 3 is varied but they are less than or equal to 50 pm. The porous members 3 are arranged in the structural frame 3 and extend out of the plane of the structural frame by 1 mm each side of the structural frame.

Figure 3 shows an alternative porous member indicated by reference numeral 103. The porous member 103 is a truncated sphere or spherical cap. The porous member 103 can be formed, for example, in the same way as the spherical porous member 3 and then removing a portion. The porous member 103 is arranged in a structural frame with the plane of the flat surface of the porous member 103 being parallel with the plane of the frame, and the rounded surface extending beyond the plane of the structural frame at the opposing surface of the frame. The flat, circular surface has a radius of 1.4 mm.

Figure 4 shows a further alternative porous member indicated by reference numeral 203. The porous member 203 is disc-shaped and can be formed, for example, by producing a spherical porous member as in Figure 3 and removing two portions, or by producing a porous sheet and punching out round porous members having a radius of 1.5 mm and a thickness of 1 mm. When arranged in a structural frame, the plane of the flat surfaces are parallel with the plane of the structural frame.

As shown in Figure 5, the plurality of porous members 3 are located interspersed within the structural frame 2 in rows within the structural frame 2 such that every other opening in the row of the mesh network 8 of the structural frame 2 contains a porous member 3 and that a row above or below this row contains a similar pattern but is offset relative to the row such that the plurality of porous members 3 are arranged in a diagonal relationship within the mesh network 8 but not laterally or longitudinally adjacent to one another.

The semipermeable arrangement 1 further has a filter arrangement 11 having two filter webs 12a, 12b with spacings (see Figure 1). The filter webs 12a, 12b are formed by electrospinning polyurethane to form filter web fibres that are irregularly arranged, overlapping and have spacings therebetween. The spacings are equal to or less than equal to or less than 0.2 p , thereby filtering out any matter with a diameter larger than 0.2 pm. The filter webs 12a, 12b are arranged on the surface of the structural frame 2 and the porous members 3 and are stretched tight over them. The filter arrangement 11 is arranged on both sides of the structural frame 2 creating a bilayer effect. Figure 1 shows an expanded view of the semipermeable arrangement 1 wherein the lower filter web 12b is located away from the structural frame 2 for illustration purposes.

In the second example illustrated in Figure 6 there is shown a semipermeable arrangement indicated generally by reference numeral 201 having a structural frame 2 with a porous member 3 formed from particles 10. The semipermeable arrangement 201 further has soluble particles 70 of an antimicrobial located within the porous member 3. The semipermeable arrangement 201 further has two filter webs 12a, 12b and two self-cleaning webs 14a, 14b arranged at each side of the structural frame 2 to create a bilayer effect. The self-cleaning webs 14a, 14b are formed from electrospinning PTFE to form self-cleaning web fibres that are irregularly arranged, overlapping and have spacings therebetween. The self-cleaning webs 14a, 14b are adapted, through control of the spacings between the self-cleaning web fibres, to receive and uptake a lubricant via capillary action. The semipermeable arrangement 201 further has perfluorocarbon liquid 20 at one surface of the semipermeable arrangement 201. The perfluorocarbon liquid 20 is dispersed through the self-cleaning web 14a. The self-cleaning web 14a is formed from PTFE and so the perfluorocarbon liquid 20 has a natural affinity for the self cleaning web 14a. In addition, the spacings of the self-cleaning web 14a are sized to allow capillary uptake of the perfluorocarbon liquid 20, dispersing it over the surface of the semipermeable arrangement 201. The filter web 12a, however, does not contain any fluorine atoms and the ionophilicity of the perfluorocarbon liquid prevents it from dispersing through the filter web 12a. The self-cleaning web 14a contains gaps at the location of the porous member 3. Therefore, none of the perfluorocarbon liquid 20 extends over the surface of the porous member 3. Fluid (e.g. water and air) can enter and pass through the filter webs 12a, 12b and the porous member 3 even when the perfluorocarbon liquid 20 is present within the self-cleaning web 14a.

In the third example illustrated in Figure 7 there is shown a semipermeable arrangement indicated generally by reference numeral 301. The third example 301 is similar to the second example 201 but in that the porous member is a spherical cap porous member 103. In use, the surface of the semipermeable arrangement 301 with the flat surface of the porous members 103 can be orientated to abut a flat surface with the rounded portion of the porous members 103 arranged projecting out from the flat surface. The rounded portions help prevent fouling whereas the flat portion allows the semipermeable arrangement 301 to sit neat against the surface and can help anchor the semipermeable arrangement 301 to a surface. In addition, the porous member 103 has a larger internal void volume than the disc-shaped porous member 203. However, it may not be as technically straightforward as the disc-shaped porous member 203 to manufacture, which can simply be punched out of a porous sheet.

In the fourth example illustrated in Figure 8 there is shown a semipermeable arrangement indicated generally by reference number 401. The fourth example 401 is similar to the second example 201 but in that the porous member is a disc-shaped porous member 203. In use, both planar surfaces of the semipermeable arrangement 401 are identical with the exception that one surface has a layer of perfluorocarbon 20. Both planar surfaces of the porous member 203 are almost flush and just slightly outset from the planar surfaces of the structural frame 2. The thickness of the semipermeable arrangement 401 is close to being equal to the thickness of the structural frame 2.

In the fifth example illustrated in Figure 9 there is shown a semipermeable arrangement indicated generally by reference numeral 501 having a structural frame 2 with a porous member 3 formed from particles 10. The semipermeable arrangement 501 further has soluble particles 70 of an antimicrobial located within the porous member 3. The semipermeable arrangement 501 further has two filter webs 12a, 12b and two self-cleaning webs 514a, 514b arranged at each side of the structural frame 2 to create a bilayer effect. The semipermeable arrangement 501 further has a perfluorocarbon liquid 20 at one surface of the semipermeable arrangement 501. The perfluorocarbon liquid 20 is dispersed through the self-cleaning web 514a. In this example, the self-cleaning webs 514a, 514b extend over the porous member 3. As a result of stretching, the spacings between the self-cleaning webs 514a, 514b are greater around the porous member 3 than the spacings between the self-cleaning webs 14a, 14b located at an opening of the structural frame 20. The increase in spacings of the self-cleaning webs 14a, 14b at the porous member 3 prevents dispersion of the perfluorocarbon liquid 20 through the self-cleaning webs 514a, 514b at the porous member 3 by capillary action. Therefore, none of the perfluorocarbon liquid 20 extends over the surface of the porous member 3. Air can enter and pass through the filter webs 12a, 12b, the self-cleaning webs 514a, 514b and the porous member 3 even when the perfluorocarbon liquid 20 is present within the self-cleaning web 514a.

In the sixth example illustrated in Figure 10 there is shown a semipermeable arrangement indicated generally by reference numeral 601. The structural frame 2, filter webs 12a, 12b, self-cleaning webs 14a, 14b and porous member 3 are the same as that of the second example 201 (Figure 7). The sixth example 601 differs in that the perfluorocarbon liquid 20 is located throughout the structural frame 2 and is present on both sides of the semipermeable arrangement 601 and throughout both self-cleaning webs 14a, 14b. The self-cleaning webs 14a, 14b contains gaps at the location of the porous member 3 so none of the perfluorocarbon liquid 20 extends over the surface of the porous member 3. The structural frame 2 acts as a reservoir to replenish perfluorocarbon liquid 20 at the surfaces of the semipermeable arrangement 601 when the perfluorocarbon liquid 20 is depleted. In the seventh example illustrated in Figure 11 there is shown a semipermeable arrangement indicated generally by reference numeral 701. The seventh example 701 is similar to the third example 301 (Figure 7) but in that the perfluorocarbon liquid 20 is located throughout the structural frame 2 and is present on both sides of the semipermeable arrangement 701 and throughout both self-cleaning webs 14a, 14b.

In the eighth example illustrated in Figure 12 there is shown a semipermeable arrangement indicated generally by reference number 801. The eighth example 801 is similar to the fourth example 401 (Figure 8) but in that the perfluorocarbon liquid 20 is located throughout the structural frame 2 and is present on both sides of the semipermeable arrangement 801 and throughout both self-cleaning webs 14a, 14b. In use, the semipermeable arrangement 801 has self-cleaning properties on both planar surfaces and as such it may be orientated in either way, where self-cleaning is desired on both surfaces. The eighth example is further illustrated in Figure 16.

In the ninth example shown in Figure 13 there is shown a semipermeable arrangement indicated generally by reference numeral 901. The semipermeable arrangement 901 is similar to that of the fifth example 501 shown in Figure 9, but differs in that the perfluorocarbon liquid 20 extends throughout structural frame 2 and is present on both sides of the semipermeable arrangement 801 and throughout both self-cleaning webs 14a, 14b.

In the tenth example illustrated in Figure 14, there is shown a semipermeable arrangement 1001 with a structural frame 2 and perfluorocarbon liquid 20. The tenth example is similar to the ninth example (Figure 13) but differs in that there are no soluble antimicrobial particles 70. As shown, when the structural frame 2 is bent the perfluorocarbon liquid is redistributed. The outer perimeter of the curve of the semipermeable arrangement 1001 is stretched in the direction of the arrow 30 whereas the inner perimeter of the curve contracts in the direction of the arrows 31. The contraction at the inner perimeter of the curve reduces the volume at this portion of the structural frame and forces redistribution of the perfluorocarbon liquid 20, in the direction of the arrows 32, to the outer perimeter of the curve, thus ensuring that the outer perimeter of the curve remains lubricated by the perfluorocarbon 20 even when the structural frame 20 is bent.

Figures 16 to 18 illustrate a filter web 12 as it would appear in situ over a spherical or hemispherical porous member 3 for illustration purposes. The filter web 12 comprises a plurality of filter web fibres 35 formed from electrospun polyurethane with gaps defining pores 36. The pores are no greater than 1 pm in size and therefore prevent passage of matter with dimensions greater than 1 pm from passing through the filter web 12. Figures 19 to 21 illustrate the filter web 12 as it would appear in situ over a disc-shaped porous member 203 for illustration purposes.

Figures 22 to 24 illustrate a filter web 12 and a self-cleaning web 514 as it would appear in situ over a porous member 3 for illustration purposes. In this arrangement, the self-cleaning web 514 extends over the filter web 12 in accordance with the first, fifth, ninth and tenth examples. The self-cleaning web 514 is formed from self-cleaning web fibres 38, which are formed from electrospun PTFE having pores 39. The pore size of the self-cleaning 514 is greater around the porous member and this prohibits uptake of a lubricant via capillary action, leaving the surface of the porous member free for passage of water and dissolved substances. Figures 25 to 28 illustrate a filter web 12 and a self-cleaning web 14 as it would appear in situ over a porous member 3 for illustration purposes. In this arrangement, the self-cleaning web 14 has gaps sized to accommodate a porous member in accordance with the second, third, fourth, sixth, seventh and eighth examples.

Figures 29 and 31 illustrate an eleventh example indicated by reference numeral 1101, and Figure 32 shows a twelfth example indicated by reference numeral 1201. Each of these semipermeable arrangements 1101, 1201 have a structural arrangement 1102, 1202 formed from a first layer 1102a, 1202a and a second layer 1102b, 1202b of ePTFE, pressed together. As illustrated in Figure 31, the longitudinal direction of the fibrils - represented by solid black lines - in the first layer 1102a is orthogonal to that of the second layer 1102b and this provides a structural arrangement 1102 of uniform tensile strength. The spacings between fibrils of the ePTFE is equal to or less than 0.5 pm such that pathogens are excluded from moving through the first or second layers 1102a, 1202a, 1102b, 1202b. The semipermeable arrangements 1101, 1201 have a plurality of tubes 1103, 1203 that extend between the first layer 1102a, 1202a and the second layer 1102b, 1202b. The tubes 1103, 1203 provide a barrier to movement of lubricating fluid through the structural arrangement 1102, 1202 whilst permitting the movement of fluids such as air, water and dissolved substances across the structural arrangement 1102, 1202 via the interior of the tubes 1103, 1203.

Each tube 1103, 1203 is formed from an interior cylinder of PTFE 1180, 1280 and a coating of FEP 1181, 1281. In the eleventh example, the tubes 1103 each have a flange 1182 that extends around the base of the tube 1103 and is sized to fit between the first layer 1102a and second layer 1102b of the structural arrangement 1102. During manufacture, the FEP coating 1181 , 1281 extends into spacings between fibrils of the structural arrangement 1102 and this provides a barrier to movement of lubricating fluid through the structural arrangement 1102. The FEP coating can be extending into the spacings by pressing the first and second layers 1102a, 1102b into the FEP or by applying heat to melt the FEP into the spacings. Alternative materials to FEP may be used provided they can fill the gaps between fibrils of PTFE and create a barrier to lubricating fluid. The tubes 1103 of the eleventh example are sized having a diameter of 3 mm and a height of 1 mm and are arranged to extend out of main plane of the first layer 1102a only. The second layer 1102b is thereby planar without any projections extending from the main plane of the second layer 1102b. In contrast the twelfth example 1201 is arranged with tubes having a diameter of 3 mm and a height of 2 mm, wherein approximately 1 mm of the height of each tube extends out at either side of the structural arrangement 1202, creating a symmetrical semipermeable arrangement 1201. The structural arrangement 1102, 1202 extends over the openings of the tubes 1103, 1203. However, the barrier provided by the coating 1181, 1281 of the tube 1103, 1203 prevents any lubricating fluid from tracking up the side of the tube 1103, 1203 and over the openings of the tube 1103, 1203. The openings thereby remain clear of any lubricating fluid when lubricating fluid is applied to the semipermeable arrangement 1101, 1201 and fluids such as water or air can pass freely through the semipermeable arrangement 1101, 1201. The portion of the structural means that extends over the tubes 1103, 1203 can be formed form chemically modified PTFE (e.g. with the addition of hydroxyl groups), heat-treated PTFE, or formed from an alternative polymeric, hydrophilic substance such as hydrophilic PU to ensure hydrophilicity and movement of water therethrough. The structural arrangement 1102, 1202 is further infused with perfluorocarbon liquid 20 to render the structural arrangement 1102, 1202 self-cleaning. The tubes 1103, 1203 contain soluble particles 70 of an antimicrobial substance but it should be noted that any desirable substance could be confined within the tubes 1103, 1203, for example, activated charcoal.

Figures 32 to 35 show a piece of personal protective equipment (PPE) 83 formed from a semipermeable arrangement as described above or in the further examples below. The PPE 83 of Figures 32 and 33 is a one-piece gown and the PPE 183 of Figures 34 and 35 is a one- piece body suit and both embodiments are made of panels of the semipermeable arrangement. A semipermeable arrangement having filter web having spacings being equal to or less than 0.5 pm will be adequate to allow the user to breathe through the semipermeable arrangement while stopping movement of microbes, including viruses, across the semipermeable arrangement. While many individual viral particles (including coronaviruses) are smaller than 0.5 pm, they do not exist in free particles and are attached to some water droplets or secretions from their last host. Accordingly, a filter size of 0.5 pm is adequate to prevent the user from becoming contaminated with viral particles.

The PPE 83 is formed from a semipermeable arrangement 1301 as depicted in Figures 36 to 38 but may be formed from other semipermeable arrangements as described herein. The semipermeable arrangement has a structural arrangement 1302 formed from a first layer 1302a and a second layer 1302b of ePTFE, pressed together. The longitudinal direction of the ePTFE fibrils in the first layer 1302a are substantially orthogonal to that of the second layer 1302b and this provides a structural arrangement 1302 of uniform tensile strength. The spacings between fibrils of the ePTFE in the structural arrangement 1302 is equal to or less than 0.3 pm.

The semipermeable arrangement 1301 has tubes 1303 formed from an interior cylinder of PTFE 1380 and a coating of FEP 1381 welded to the PTFE 1380, forming an impervious surface even to perfluorocarbon 20. Perfluorocarbon 20 is infused between but not within the tubes 1380. The tubes 1303 are spaced apart with a typical gap between the tubes 1303 of 3 mm. The PTFE cylinder 1380 has, although not essentially, a 3 mm outer diameter, a 2 mm inner diameter and a height of 2 mm. The structural arrangement 1302 extends over the openings of the tubes 1303, wherein the barrier provided by the coating 1381 of the tube 1303 prevents the perfluorocarbon 20 from tracking up the side of the tube 1303 and over the opening of the tube 1303. The openings thereby remain clear of perfluorocarbon 20 and air can pass freely through the semipermeable arrangement 1301. The tubes 1380 can be filled with adsorbents such as activated charcoal 71 to remove noxious chemicals from the fluid (e.g. nitrous oxides from car exhausts) passing through (see Figure 37). Figure 38 shows a schematic plan view of the semipermeable membrane 1301 of the PPE gown 83 or body suit 183 where the structural arrangement 1302 is infused with perfluorocarbon 20 between but not within the tubes 1303 which studs have a typical diameter of 3 mm. ePTFE membranes are already widely used as filters. The effective blockage of particles requires the pores of the ePTFE membrane to be below a certain size, but a low flow resistance requires the pores to be large. The conflicting requirements on pore size is generally resolved by making the ePTFE membranes very thin, but that undermines the structural strength of the ePTFE membrane. Typically, ePTFE membranes used as filters are mounted on a stronger backing material with high porosity (e.g. a woven fabric or a knitted mesh). Ordinary ePTFE membrane filters do not handle mechanical deformation well. The flimsy ePTFE membranes may develop tears, which compromises the effective blockage of pathogens. The pores in the ePTFE membrane may become blocked if the membrane is compacted on the backing material. The inability of ordinary ePTFE membrane filters to handle mechanical deformation makes them unsuitable for use in PPE unless they are shielded in some form of rigid enclosures.

The semipermeable arrangement 1301 also contains ePTFE membrane filters (first and second layers 1302a, 1302b), but they are dispersed in numerous independent tiny units contained and protected in the protuberances formed by the denser ePTFE tube segments 1380. The small area of each ePTFE membrane filter means it is less likely to be directly damaged by a sharp instrument. Each ePTFE filter unit (located at each tube 1380) has two physically separated filter membranes 1302a, 1302b and both need to be independently breached before the filter unit becomes compromised. The denser ePTFE tube segment 1380 can absorb mechanical deformation and protect the two filter membranes 1302a, 1302b from compacting on each other and blocking off their pores. The raised geometric profile of the filter unit encourages any droplets (which may contain contaminants) to roll off the filter membranes 1302a, 1302b. ePTFE is intrinsically hydrophobic and slippery, further discouraging the adherence to the filter unit by contaminants. These performance attributes allow the semipermeable arrangement 1301 to be Porous and Self-Cleaning.

The portion of the structural arrangement 1302 between the tubes 1380 contains double layers of ePTFE membranes (first and second layers 1302a, 1302b) but in other embodiments even larger numbers of layers of ePTFE could be used. The portion of the structural arrangement 1302 between the tubes 1380 provides structural integrity but not filtration for the membrane. As a filter, the structural arrangement 1302 between the tubes 1380 may be very effective in blocking the passage of contaminants but is too dense to allow an adequate flow across. The PPE 83 has a circulatory system 85 for liquid perfluorocarbon. The circulatory system 85 involves the panels of the semipermeable arrangement 1301 panels being joined to a network of tubing 84 and being arranged to transport liquid perfluorocarbon. The panels of semipermeable arrangement 1301 are joined at the seams (not shown) by FEP (although other means of joining will be suitable) to the tubing 84. In the embodiment shown, the tubing 84 is ePTFE tubing 84 and it is flexible but non-extendible and non-expandable. The tubing 84 is variably covered by FEP laminate glue to control perfluorocarbon porosity. The tubing 84 runs along the entire outline of the PPE 83 in the coronal plane, and around the shoulder joints in the sagittal plane. The circulatory system 85 further involves a pump arrangement 86 that is arranged to pump perfluorocarbon liquid through the tubing 84. The pump arrangement 86 involves one or more positive-displacement pumps. In the embodiment shown in Figures 32 and 33, the pump arrangement 86 involves each axillary (armpit) region of the PPE 83 suit having a bellow 87a, 87b and In the embodiment shown in Figures 32 and 33, the pump arrangement 86 involves each axillary (armpit) region and crotch region of the PPE suit 183 having a bellow 87a, 87b, 87c. A further positive-displacement pump suitable for use in the PPE suit is a bending-actuated pump, as shown in Figures 44 to 46 and as described in further detail below. The PPE suit 183 also comprises leg portions 184 made from the semipermeable arrangement 1301. The bellows 87a, 87b and 87c are fashioned out of semi-rigid PTFE sheets 93 (although FEP or other suitable material may be used) and covered on the outside with ePTFE membranes. The bellows 87a, 87b, 87c are connected to the network of tubing 84. The tubing 84 has a plurality of one-way check valves 88 spaced apart around the network of tubing 84. The front of the PPE 83 has a transparent visor 89. In these embodiments, the visor 89 is fashioned out of ETFE or FEP welded to the semipermeable arrangement 1001.

Figures 44 to 46 show a positive-displacement pump that may be used in the PPE suit (see Figures 49 and 50), but has other uses in other fields. The positive-displacement pump is a bending-actuated pump indicated generally by reference numeral 40. The bending-actuated pump 40 can be integrated into the circulatory system of the PPE, such that the fluid in the circulatory system can be moved through the circulatory system via the bending-actuated pump 40. The bending-actuated pump 40 comprises a chamber 41 having an inlet 42 and an outlet 43. The inlet 42 has a one-way valve 44 arranged to permit fluid to enter the chamber 41 but not leave the chamber 41, and the outlet 43 has a one-way valve 45 arranged to permit fluid to be discharged from the chamber 41 but not enter the chamber 41. In this embodiment, the one-way valves 44, 45 are duckbill valves, although other valve types will be suitable and apparent to the skilled person.

The bending-actuated pump 40 has longitudinal and transverse dimensions, and a chamber support arrangement 46 for maintaining the transverse dimension of the chamber 41. The chamber-support arrangement 46 involves a helical coil 47 arranged to provide structural support to the chamber 41. The chamber-support arrangement 46 is disposed within the chamber 41 between the inlet 42 and the outlet 43. The helical coil 47 is an extension spring with adjacent coil turns directly stacked on top of one another with no gaps between when it is in the neutral unstressed (no extending or bending) state. The helical coil 47 is formed from nitinol in the specific embodiment described herein but may be formed from stainless steel or other suitable material.

The chamber 41 is tubular and in particular it is formed from elastomer tubing. In this embodiment, the elastomer tubing is made of silicone, but it may be formed from fluoro-silicone, or other elastomers with a low Young’s modulus, with or without reinforcement with other fibres within. The inlet 42 is located proximal one end of the elastomer tubing and the outlet 43 is located proximal to the other end of the elastomer tubing. The helical coil 47 supports the transverse dimension of the elastomer tubing. The bending-actuated pump 40 further has valve housings 48. The bending-actuated pump further involves a connection arrangement 49 for connecting the bending-actuated pump 40 to a fluid network. The connection arrangement 49 is disposed proximal to the inlet 42 and the outlet 43. The connection arrangement 49 is suitable for connecting the bending-actuated pump 40 to tubing. The connection arrangement 49 involves a lock, in particular, a male Luer lock 50a, 50b, although other lock types or connecting arrangement will be suitable. The male Luer locks 50a, 50b are oppositely facing, such that one is orientated axially in one direction and the other is orientated in the opposing axial direction. The valve housing 48 and the connecting arrangement 49 are integrally formed. Such an arrangement will allow the bulkier and more complex structural components to be concentrated on the pump 40 and the tubing to which the pump 40 is connected will be smaller sized endings (female Luer lock connectors) with no moving parts.

In use, when the bending-actuated pump 40 is bent, the coil 47 turns cannot get any closer on the compression side 51 of the bend as they are already stacked up but can open up on the extension side 52 of the bend. The chamber 41 also extends on the extension side 52 of the bend and is prevented from collapsing as it is propped open by the turns of the helical coil 47. This increases the volume of the chamber 41 and the pressure within drops. The inlet valve 44 opens and the outlet valve 45 closes. Fluid is sucked into the chamber 41 from the inlet 42 (see directional arrow 53a in Figure 45). When the pump 40 straightens as the bending stress is released, the extension side 52 of the chamber 41 returns to its original dimensions. The volume of the pump chamber 41 decreases and the pressure within rises. The inlet valve 44 closes and the outlet valve 43 opens. Fluid is squeezed out of the pump chamber 41 from its outlet 45 (see directional arrow 53b in Figure 46).

The bending-actuated pump 40 can pump fluid (gas or liquid) and is actuated by bending without any significant changes in its longitudinal or transverse dimensions. Where the bending- actuated pump 40 is integrated into the circulatory system of the PPE suit, the bending-actuated pump 40 is actuated by movements of the body parts of the user of the PPE, thereby obviating the need for the need for a pump powered by an external power source such as a battery. The semipermeable arrangement used in the PPE can be bent but generally not stretched significantly without tearing. Accordingly, it is advantageous that the bending-actuated pump 40 can stay largely constant in its longitudinal and transverse dimensions and can be actuated by bending. Even though the bending-actuated pump 40 is designed primarily for use in the PPE, it may have applications in other areas.

Turning now again to Figures 32 to 34, the back of the PPE gown 83 and PPE suit 183 suit has a mid-line parting 90 over the torso. The two edges of the parting 90 are releasably fixable to one another via a releasable fixing arrangement 91. In this embodiment, the releasable fixing arrangement 91 involves the edges of the parting 90 being lined with dovetailing double ziplock seals 92a, 92b moulded out of flexible but non-extendible and non-expandable ePTFE rods, although alternative connecting formations and alternative materials may be used.

Figures 39 and 40 are front and rear views of a PPE gown made of a semipermeable arrangement but excluding a circulating system. Figures 41 and 42 are front and rear views of a PPE body suit made of a semipermeable arrangement but excluding a circulating system.

In use, all the tubing 84 and the bellows 87a, 87b, 87c are filled with liquid perfluorocarbon with no air or gas trapped inside. When the user’s arms are “adducted” (move towards the midline), the bellows 87a, 87b are squeezed and decrease in volume. A positive pressure is created inside the bellows 87a, 87b. The system of one-way check valves 88 makes sure perfluorocarbon is pushed up against gravity around the shoulder joints towards the user’s head and not down towards the user’s hands or feet. When the user’s arms are “abducted” (move away the midline), the bellows 87a, 87b are stretched and expand in volume. A negative pressure is created inside the bellows 87a, 87b. The system of one-way check valves 88 makes sure perfluorocarbon is sucked up against gravity from the user’s hands and feet but not the head and neck towards the shoulders. Analogous results apply to the bellows in the crotch. The ePTFE tubing 84 and the bellows 87 together form a circulatory system for perfluorocarbon around the gown/suit 83/183, with the tubing 84 acting as vessels and the bellows 87 acting as pumps. The ePTFE vessels sending perfluorocarbons above the bellows 87 towards the user’s head and top of the shoulders against gravity act like arteries. The ePTFE vessels 84 returning perfluorocarbons to the bellows 87 from the user’s legs and hands act like veins. The membrane across which perfluorocarbons can diffuse acts like a large capillary bed spanning between the ePTFE arteries and veins.

The tubing 84 is porous to perfluorocarbon (similar to the capillaries in the human or other animal bodies). The ePTFE arteries are lightly sealed with melted FEP on the outside and remain porous to perfluorocarbon. The ePTFE veins are sufficiently sealed with melted FEP on the outside and become impermeable to perfluorocarbon 20. Perfluorocarbon 20 slowly oozes out of the tubing 84 under hydrostatic pressure, capillarity and gravity. Only the flat base but not the protuberances of the semipermeable arrangement 1301 will be infused with perfluorocarbon 20, as the walls of the protuberances (tubes 1380) are sealed with melted FEP 1381 and become impervious to perfluorocarbon 20. The perfluorocarbon 20 infuses and then gradually moves downwards within the semipermeable arrangement 1301 under gravity. This slow perfluorocarbon flow will heal any gaps in the semipermeable arrangement 1301 created by bending and exposure of ePTFE fibrils in the structural arrangement 1302 and picks up and moves on any dirt or particles attached to them. The visor 89 may be continuously cleaned by this slow perfluorocarbon flow as well. The tubing 84 around the bottom of the PPE 83 catches the perfluorocarbon 20 and prevents it from dripping onto the floor. Any dirt and particles carried by the perfluorocarbon flow falls off the PPE 83 when they reach the end of the perfluorocarbon flow “conveyor belt”. The perfluorocarbon contained in the bottom tubing 84 is sucked up back by the bellows 87a, 87b for re-circulation. In this manner, the PPE 83 is protected against contamination not only by the perfluorocarbon liquid and the geometric shape of the geometric shapes of the protuberances in the semipermeable arrangement 1301 caused by the porous members 3, but also by a continuous downward flow of liquid perfluorocarbon.

Because of the large surface area of semipermeable membrane needed to form a whole- body gown/suit, the PPE will lose perfluorocarbon due to evaporation over time. The perfluorocarbon content of the PPE 83 can be periodically replenished by either directly spraying or pouring liquid perfluorocarbon onto the semipermeable arrangement 1301 or injection into the tubing 84 or bellows 87 through a valved connector or three-way check valve (not shown). Any dried-up area of the semipermeable arrangement 1301 membrane will be easy to spot as the material changes from being transparent to being white in colour. The protuberances formed by the tubes 1303 in the semipermeable arrangement 1301 are covered by ePTFE membranes that serve as filters in order give selective permeability of the arrangement 1301.

In a simpler embodiment of the design illustrated in Figures 39 to 42, the PPE 283, 383 does not have any bellows in the armpits and crotch of the gown/suit or anyone-way check valves along the ePTFE tubing network. The user “dons” (puts on) the PPE 283, 383 in the dried state with no perfluorocarbon on it. If required, the user can periodically spray perfluorocarbon directly onto the long-glove (hand, wrist and half-way up the forearm) parts of the PPE 283, 383 during use. The filter pores in those parts may be blocked off by perfluorocarbon, but the user can still breathe and sweat through the filter pores in other parts of the PPE 283, 383. Because of the perfluorocarbon in the long-glove parts of the PPE 283, 383, the user will not pick up and transmit contamination and pathogens between patients and objects (“fomites”). The user can visually inspect the long-glove parts of the PPE 283, 383 to be aware of the need for perfluorocarbon top- up. (The parts of the PPE 283, 383 will change from transparent to white in colour.)

When the user is ready to “doff’ (take off) the PPE 283, 383, any potential contamination on the outside of the PPE 283, 383 is washed off with a gentle jet of perfluorocarbon (like having a shower - any run-off perfluorocarbon can be captured for reuse after removal of contaminants). The user can then doff the PPE 283, 383 safely with minimal risk of contamination. The inside of the PPE 283, 383 can also be washed with a gentle jet of perfluorocarbon so that any materials from the user will be removed as well. The washed PPE 283, 383 can be cleaned by being warmed to a heat temperature (say 100°C), which will help the evaporation of perfluorocarbon and kill of any remaining pathogens without affecting the structural integrity of the PPE 283, 383 (melting points of ePTFE, PTFE and FEP all > 250°C).

A part-body PPE consisting of only the long-glove parts of the whole-body PPE (not shown) can be constructed and used in the same way. A part-body PPE 483 consisting of only the head, neck and upper torso (i.e. a hood-vest) of the whole-body PPE (see Figure 43) can be lined with inflatable compliant torus balloons 94 around both shoulder joints and the cross-section of the upper-chest. These inflatable balloons 94 can be inflated and deflated independently with a syringe through valved connector or 3-way check valves 95 situated on the front of the hood- vest. The inflatable balloons 94 will be able to provide a good seal against air flow without excessive pressure around the arms and the chest. (Inflatable compliant balloons are used to provide seals in medical instruments such as endotracheal tubes and laryngeal masks.)

Turning now to Figures 47 and 48 there is shown a further embodiment of an article of PPE according to the invention, indicated generally by reference numeral 583. PPE 583 is constructed entirely of semipermeable arrangement 1301 except for a transparent visor 589 which is made of ETFE but may alternatively be made of any other suitable material, such as FEP. The visor 589 is located at the front and there is further a releasable fixing arrangement 591 at the back, provided in this embodiment by a double ziplock seal moulded out of solid ePTFE rods (no central channels) on the back.

PPE 583 is an integrated whole-body suit comprising 6 separate units joined together with no gaps between: a head-neck unit 554 (a hood which also contains the visor); left 555a and right 555b arm units (long gloves extending from the hands to the shoulders); a front chest unit 556 (a flat panel extending from the shoulders around the base of the neck to the waist); a back chest unit 557 (a flat panel extending from the shoulders around the base of the neck to the waist and containing a central opening lined on either side by the two halves of a double ziplock seal); and a pelvis and leg unit 558 (a pair of trousers extending from the waist to the ankles). By virtue of being constructed entirely of fluoropolymers, PPE 583 can be easily and thoroughly cleaned of all biological and most chemical contaminants by a perfluorocarbon bath and hence is Reusable. PPE 583 is Comfortable for the user as: (1) the air filter does not require tight-fitting and has low flow resistance; (2) water vapour from the user’s sweat can escape. PPE 583 is an integrated whole body suit that is easy and fast to don and doff, with greatly reduced risk of contamination during use and doffing.

The head-neck 554 and arm units 555a, 555b of PPE 583 can form independent products. The hood 554 is an integrated visor/goggle - face-mask - hat/bonnet unit. When the head-neck unit 554 is used on its own, its opening can be loosely secured around the user’s neck with a neckerchief, a scarf or even a necklace. The head-neck unit 554 can be used to reduce the inhalation of noxious chemicals the user inhales if the semipermeable arrangement 1301 forming the head-neck unit 554 contains activated charcoal (see Figure 37). The arm units 555a, 555b are extra long gloves extending from the hands to above the elbows. When in use, the user can secure the arm units 555a, 555b by applying elasticated bands around the units and the upper arms. Outside the context of pandemic control, the arm units 555a, 555b may be worn in food processing, food preparation, cleaning, people caring, cash handling.

Turning now to Figures 49 and 50 there is shown a further embodiment of an article of PPE according to the invention, indicated generally by reference numeral 683. PPE 683 is equipped with an ambulatory perfluorocarbon circulatory system 685 in order to produce a slippery-liquid- infused porous surface (SLIPS) continuously running down over most of its surface area. When perfluorocarbon infuses an ePTFE membrane, it forms a SLIPS which resists attachment by all biological and most chemical entities. This means PPE 683 will not be picking up pathogens and contaminants in the external environment and transmitting them to other people or objects (i.e. it will not become a fomite). However, perfluorocarbon will flow through and down a vertically oriented SLIPS under gravity. This means the top half of PPE 683 will become unprotected by SLIPS as perfluorocarbon drains away and perfluorocarbon will drip off the bottom of the PPE 683. A circulatory system for perfluorocarbon is thus needed for PPE 683. A steady continuous downward running perfluorocarbon stream over the surface of PPE 683 produces the additional advantages of: 1. healing any gaps in SLIPS created by bending of the surface (which can be created as PPE 683 is wrinkled by user’s movements), and; 2. washing down (by bulk flow) any contaminants which have managed to attach to the PPE 683 through gaps in SLIPS.

The perfluorocarbon circulatory unit 685 comprises a source 659 of perfluorocarbon situated at the highest anatomical points in the PPE 683 when the user is in the neutral upright position. The sources 659 are made of denser ePTFE 660a (either a slit open tube segment or a sheet, Figure 52) folded around and welded to the edge of an ePTFE laminate 661a with FEP 662a. The FEP welding 662a creates a triangular wave pattern at the joint in order to slow down the release of perfluorocarbon 20 from the sources while ensuring the mechanical strength of the joint. The sources 659 have the capacity of hold a significant volume of perfluorocarbon 20 either in the central channels or within their walls. The sources 659 slowly release perfluorocarbon 20 into a cascade down the ePTFE laminate 661a under gravity, capillarity and hydrostatic pressure. As ePTFE is permeable to air, a vacuum will not be created within the sources 659 as they slowly empty of perfluorocarbon 20. The sources 659 are equipped with integrated valved connectors 663 (commonly used medical practices; female Luer lock connection) to allow injection or removal of perfluorocarbon 20 as needed. The ePTFE laminate 661a forms the downstream course for perfluorocarbon 20 to flow down under gravity.

The circulatory system 685 further involves sinks 664 situated at the lowest anatomical points in the suit when the user is in the neutral upright position. The sinks 664 are made of denser ePTFE 660b (either a slit open tube segment or a sheet, Figure 53) folded around and welded to the edge of an ePTFE laminate 661b with FEP 662b. The FEP welding 662b creates a triangular wave pattern at the joint in order to capture all the perfluorocarbon 20 flowing into the sinks while ensuring the mechanical strength of the joint. The sinks 664 have the capacity of hold a significant volume of perfluorocarbon 20 either in the central channels or within their walls. The sinks 664 periodically have perfluorocarbon 20 sucked out of them by bending actuated pumps 40. To ensure the sinks 664 do not collapse under negative pressure, the sinks 664 may need to contain perforated convoluted ETFE or FEP tubes 665 in their centres. As ePTFE is permeable to air (even though the flow may be slow), air will be displaced out of the sinks 664 as they gradually fill up with perfluorocarbon 20. The sinks 664 are equipped with integrated valved connectors 663 to allow injection or removal of perfluorocarbon 20 as needed.

Bending actuated pumps 40 equipped with male Luer lock connectors 50a, 50b at both ends are placed over key joints in the human body. The pumps 40 harness the natural body movements of the users to suck perfluorocarbon 30 out of the sinks 664 and inject it into the sources 659 against gravity.

Tubing 684 equipped with male 50 and female 66 Luer lock connectors with or without appropriately oriented one-way check valves 67 join the sinks 664 to the bending actuated pumps 40 to the sources 659. The tubing 684 can be made to be stiffer if necessary in order to serve as levers so that the pumps 40 can be actuated more effectively by bending of the user’s joints.

The valved connectors 63, pumps 40, and connecting tubing 684 are housed in serviceable channels 68. The serviceable channels 68 are fashioned out of ePTFE rods moulded with half of a double ziplock seal 69 on one edge and attached to ePTFE laminate 661c with FEP 662c on the other edge (Figure 54). The serviceable channels 68 run along some of the seams of the PPE 683. The serviceable channels 68 give room for the bending actuated pumps 40 to deform without tearing the PPE suit 683 and can be opened up so that the components of the perfluorocarbon circulatory system 685 can be connected or replaced as necessary. The sources 659 and sinks 664 can also have perfluorocarbon 20 injected into or removed from them with Luer lock syringes commonly used in clinical practice.

In use, perfluorocarbon 20 will gradually evaporate from the semipermeable arrangement 1301 and ePTFE laminate 661 a-c and needs to be replenished periodically. Any dried-up area of the semipermeable arrangement 1301 will be easy to spot as the material changes from transparent to white in colour.

The PPE 83, 183, 283, 383, 483, 583, 683 is easy and safe to take off (“doffing”). This is the most vulnerable process in the use of PPE. During the recent and ongoing coronavirus pandemic, it is the most likely point at which most healthcare professionals become contaminated with SARS-CoV-2, potentially leading to said professionals becoming ill with COVID-19. The PPE 83, 183, 283, 383, 483, 583, 683 protects the user from self-contamination by covering the entire head in one continuous surface. The PPE 83, 183, 283, 383, 483, 583, 683 can further be worn comfortably for hours without losing effectiveness (most healthcare professionals find it very difficult to wear the currently available PPE for 8 - 12 hours on end); it retains effectiveness even after prolonged use; is reusable (in theory, the same piece of PPE 83, 183, 283, 383, 483, 583, 683 can be reused by different personnel and on different patients with periodic re-conditioning, provided it has not been damaged and that is easy to check); will not transmit viral contamination to other people or objects (i.e. will not become a “fomite”), and; can be mass produced at a reasonable cost per unit. Yet a further advantage is that the PPE 83, 183, 283, 383, 483, 583, 683 is effective even when loosely worn by the user. Many widely used PPE articles must be tightly fitted to the user to be effective. This can be uncomfortable for the user and prolonged use results in skin damage and pain for the user.

In theory, widespread adoption of the PPE 83, 183, 283, 383, 483, 583, 683 by a large section of the population will allow them to protect themselves from being infected by or infecting others. This reciprocal protection can provide a way out of the lockdown imposed globally, allowing the economy to restart without risking another surge in COVID-19 infection.

Referring now to Figure 55 there is shown a semipermeable arrangement that may be used to form an article of PPE as according to the invention, indicated generally by reference numeral 1401. It should be noted that the semipermeable arrangement 1401 is not semipermeable across the entirety of its surface, but rather has areas that are semipermeable and areas that are impermeable. The semipermeable arrangement 1401 may therefore also be referred to as being non-uniformly permeable. The semipermeable arrangement 1401 comprises a self-cleaning web 1414 that is formed from sintered PTFE. Sintered PTFE is made of tiny PTFE particles fused together by controlled melting and re-solidification under compression. Sintered PTFE can be flexible if sufficiently thin. Sintered PTFE has limited elasticity and low tear resistance, and cannot on its own form a durable article that will be subjected to significant mechanical forces in use.

The semipermeable arrangement 1401 further has a support arrangement 1402 for supporting the self-cleaning web 1414. The support arrangement 1402 is formed from mesh fabric. The mesh fabric layer can flex but will not stretch, and does not tear easily. The inextendibility and mechanical strength of the mesh fabric layer protect the sintered PTFE layer against mechanical damage. The support arrangement 1402 and the self-cleaning web 1414 are bound together by a binding substance 72 so that the two layers will not separate easily under mechanical forces. The mechanical forces can be significant and in multiple directions (flexing, tearing and shearing) if the article is a piece of personal protective equipment (PPE). PTFE is intrinsically slippery (“low surface energy”) and chemically difficult to bind to. Porous PTFE has pre-existent crevices on its surface that will allow adhesives to penetrate and gain purchase. The binding substance is an adhesive and in this embodiment is formed from a non-porous elastomer (the semipermeable arrangement 1401 therefore remains flexible). The binding substance 72 is disposed between the self-cleaning web 1414 and the support arrangement 1402 with gaps such that there are areas not covered by the binding substance 72. The gaps not covered by the binding substance 72 form permeable channels surrounded by impermeable rims in the non-uniformly permeable arrangement 1401. The binding substance 72 extends only partway into the self-cleaning web 1414. The outer surface of the self-cleaning web 1414 will remain porous and hence can be infused with perfluorocarbons. This will allow the outer surface of the self-cleaning web 1414 to form a slippery liquid infused porous surface (SLIPS), and be effectively cleaned by a perfluoro-carbon wash or an agitated perfluorocarbon bath.

Referring now to Figure 57 there is shown a further embodiment of a non-uniformly permeable arrangement indicated generally by reference numeral 1501. In this embodiment, the non-uniformly permeable arrangement 1501 has a plurality of protrusions 73. The protrusions 73 provide a macro texture to the non-uniformly permeable arrangement 1501. The protrusion 73 is formed such that the self-cleaning web 1514 protrudes relative to the support arrangement 1502. The protrusion 73 is dome-shaped. The protrusion 73 has a protrusion-support arrangement 74 to prevent the protrusion form collapsing. The protrusion-support arrangement 74 involves a supporting structure 75 disposed between the self-cleaning web 1514 and the support means 1502. The supporting structure 75 is a cone cap. The supporting structure 75 is formed from resilient material such that, if it is deformed, it returns to a rest configuration upon removal of the deforming force. The supporting structure 75 further has a perforation 76, thereby rendering the supporting structure 75 permeable. The perforation 76 is located in the centre of the cone cap. The resistance to flow across the non-uniformly arrangement 1501 is reduced as the major restrictions to flow are confined to the perforations 76 in the supporting structure 75. The hollow inside the supporting structure 76 provides the physical space of extra substances (e.g. antibiotics) to be stored within the non-uniformly arrangement 1501. (These substances can be subsequently released from the non-uniformly arrangement 1501 under specific circumstances.)

The self-cleaning web 1514 that forms a part of the protrusion 73 is sealed off from the adjacent self-cleaning web 1514. This can be done by applying the binding substance 72 such that it fills the depth of the self-cleaning web 1514 in an area around the protrusion 73, to the full thickness of their rims. This seal protects the dome protrusions 73 from being covered (so that they remain permeable) when the rest of the self-cleaning web 1514 is infused with perfluorocarbons to form a porous self-cleaning (“Porseclean”) membrane. The dome protrusions 73 encourage any contaminants to roll off them by their geometric shape. The flat part of the porous PTFE surface is a SLIPS and chemically unfavourable for the attachment of any water- or oil-based substances.

Referring now to Figure 58 there is shown a further embodiment of a non-uniformly permeable arrangement according to the invention, indicated generally by reference numeral 1601. The non-uniformly permeable arrangement 1601 is a bi-porous PTFE surface - mesh fabric - elastomer adhesive laminate. The non-uniformly permeable arrangement 1601 has a support arrangement 1602 sandwiched by self-cleaning webs 1614. The binding substance 72 infiltrates the full thickness of the support arrangement 1602 but only part of the thickness of both self cleaning webs 1614. Both surfaces of the non-uniformly permeable arrangement 1601 are covered with porous PTFE, and hence can form SLIPS and are amenable to perfluorocarbon wash/bath cleaning.

In an embodiment illustrated in Figure 59(b), the non-uniformly permeable arrangement 1701 has a protrusion 73 on one surface. In an embodiment illustrated in Figure 59(c), the non- uniformly permeable arrangement 1801 has a protrusion 73 on both surfaces. The permeable patches in both self-cleaning webs 1814 need to aligned in order to maintain the permeability across the whole non-uniformly permeable arrangement 1801.

In another embodiment illustrated in Figure 60, the non-uniformly permeable arrangement 1901 is an alternative mesh fabric - porous PTFE - elastomer adhesive laminate. The non-uniformly permeable arrangement 1901 is has two support arrangements 1902 arranged to sandwich a self-cleaning web 1914. The support arrangement 1902 protects the self-cleaning web 1914 from mechanical damage from both of its surfaces. The self-cleaning web 1914 provides a barrier permeable to some substances (e.g. air, water vapour) but impermeable to other substances (e.g. water droplets). Semipermeable arrangement 1902 can be used to form waterproof clothing, among other possible uses.

Referring now to Figure 61 there is illustrated an embodiment of a non-uniformly permeable arrangement indicated generally by reference numeral 2001. The non-uniformly arrangement 2001 is formed from a plurality of pieces joined together to form larger pieces or complex geometric shapes. The support arrangements 2002 of the pieces are joined together by sewing or stitching together with threads 77. The self-cleaning webs 2014 of adjacent pieces are arranged overlapping one another and are bonded to the support arrangement 2002 via the binding substance 72. The binding substance 72 infiltrates only part of the thickness of the outermost self-cleaning web 2014, so that join can still be infused with perfluorocarbons. The threads 77 holding the support arrangement 2002 and hence the pieces together should form a joint as strong as that of ordinary garments. The threads and crevices around them are secluded by the binding substance 72 and protected from contamination by the self-cleaning web 2014.

Referring now to Figure 62 there is shown an ultraviolet light sterilisation system 78. The system 78 has a UV light source 79 disposed within an enclosure 96. The enclosure 96 is lined with sintered PTFE 97. Sintered PTFE is highly reflective (97.4%) of ultra-violet (UV) light through diffuse reflectance (i.e. the incident UV light beam will be scattered in all directions, cf. specular reflectance, in which the UV light is reflected in a concentrated narrow beam). The system 78 can be used to effectively and rapidly sterilise a piece of PPE covered with an outermost layer of sintered PTFE (e.g. glove 98). The PPE can be sterilised when it is still worn as the outermost layer of sintered PTFE very effectively protects the PPE wearer from UV light exposure. Diffuse reflectivity (indicated by arrows 99) means all the crevices and irregularities in the surface and shape of the PPE would still be irradiated by UV light.

Figure 63 shows an ePTFE membrane filter 21 clogged with particles 22. The ePTFE membrane filter 21 is immersed in a bath 25 of perfluorocarbon 20 (see Figure 63b). Perfluorocarbon 20 is adsorbed on to the ePTFE micro-fibrils of the ePTFE membrane filter 21 by capillarity, and perfluorocarbon 20 seeps between the ePTFE micro-fibrils and the trapped particles 22 at a microscopic level, and lifts the trapped particles 22 out of the pores between the ePTFE micro-fibrils. The dislodged particles 22 will tend to form globules in perfluorocarbon 20 as the latter tries to minimise its surface area (and energy). The particles 22 that are microscopically dislodged from the pores in the ePTFE membrane filter 21 can then be macroscopically separated from the filter 21 (Fig 63b) by mechanical agitation (e.g. shaking, sonication; see Figure 63c) or specific gravity (the globules can form separate layers of “sediments” or “skims” distinct from perfluorocarbon 20 and the filter 21, but a larger volume of perfluorocarbon is needed).

Figure 64 depicts a step according to the invention wherein the ePTFE membrane filter 21 is dried for reuse. The filter 21 “wet” with perfluorocarbon 20 can be put into a centrifuge (step depicted by arrows 24 in Figure 64) in a clean air/gas environment and the perfluorocarbon 20 spun off (similar to extracting honey from the combs with a honey extractor). Alternatively, the perfluorocarbon 20 can be removed by heating, under a reduced atmospheric pressure if necessary, or having hot air blown through it. The “dried” ePTFE membrane filter 21 and recovered perfluorocarbon 20 can be reused.

Figure 65 depicts a step according to the invention wherein the perfluorocarbon 20 is sucked out of the bath 25 with a pipette 26. Figure 66 depicts a step wherein the perfluorocarbon 20 from the bath 25 is filtered out through a second filter, provided by a denser ePTFE bag 27 with finer pores (Fig 66a). The pores in the denser ePTFE bag 27 can be selected such that the contaminant particles 22 will become blocked by but not trapped within. (The ePTFE bag 27 cannot replace the ePTFE membrane filter 21 to be cleaned as the pores might be too small, causing the fluid flow to become too low or the pressure required to drive fluid flow too high.) Given sufficient time, the perfluorocarbon 20 will drain through and out of the ePTFE bag 27 spontaneously under gravity or externally applied pressure 28, given sufficient time. The contaminants 22 can then be easily scraped off the surface of the ePTFE bag 27 because of the intrinsic non-stick property of PTFE (Fig 66b). The recovered perfluorocarbon 20 can be reused. The method is not limited to use with ePTFE filters, but may be used with any filter having an affinity to perfluorocarbon.

In the preceding discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of the values is more highly preferred than the other, is to be construed as an implied statement that each intermediate value of the parameter, lying between the more preferred and the less preferred of the alternatives, is itself preferred to the less preferred value and also to each value lying between the less preferred value and the intermediate value.

The features disclosed in the foregoing description or the following drawings, expressed in their specific forms or in terms of a means for performing a disclosed function, or a method or a process of attaining the disclosed result, as appropriate, may separately, or in any combination of such features be utilised for realising the invention in diverse forms thereof.

Claims

1. An article of personal protective equipment (PPE) formed from a semipermeable arrangement, wherein the semipermeable arrangement comprises a self-cleaning means that is formed at least partially from polytetrafluoroethylene (PTFE) and which, in use, defines the exterior surface of the article of PPE, wherein the self-cleaning means comprises a self-cleaning web and wherein the semipermeable arrangement comprises a support means for supporting the self-cleaning web, the support means being a mesh fabric, and wherein the support means and the self-cleaning web are bound together via a binding means, the binding means being disposed between the self-cleaning web and the support means with gaps such that there are areas not covered by the binding means.

2. An article of PPE as claimed in claim 1 wherein the binding means extends only partway into the self-cleaning web.

3. An article of PPE as claimed in claim 1 or claim 2 wherein the self-cleaning means is formed at least partially from sintered PTFE.

4. An article of PPE as claimed in any preceding claim wherein the semipermeable arrangement comprises at least one protrusion, the protrusion being formed such that the self-cleaning web protrudes relative to the support means.

5. An article of PPE as claimed in claim 4 wherein the semipermeable arrangement comprises a protrusion-support means, wherein the protrusion-support means comprises a supporting structure disposed between the self-cleaning web and the support means.

6. An article of PPE as claimed in claim 4 or claim 5 wherein the self-cleaning web that forms a part of the protrusion is sealed off from the adjacent self-cleaning web.

7. An article of PPE as claimed in any preceding claim wherein the self-cleaning web is present on both sides of the support means such that the support means is sandwiched between the self-cleaning web.

8. An article of PPE as claimed in any preceding claim wherein the semipermeable arrangement is formed from a plurality of pieces joined together, each piece comprising a self-cleaning web and support means.

9. An article of PPE as claimed in any preceding claim further comprising a circulatory system for a lubricating fluid such as liquid perfluorocarbon.

10. An article of PPE as claimed in claim 9 wherein the circulatory system comprises a network of tubing arranged to transport lubricating fluid.

11. An article of PPE as claimed in claim 10 wherein the tubing has a plurality of one-way check valves spaced apart around the network of tubing.

12. An article of PPE as claimed in claim 10 or claim 11 wherein the tubing is in fluid communication with the semipermeable arrangement at predetermined locations.

13. An article of PPE as claimed in any one of claims 9 to 12 wherein the circulatory system comprises a pump means arranged to pump fluid through the tubing.

14. An article of PPE as claimed in claim 13 wherein the pump means comprises one or more positive-displacement pumps.

15. An article of PPE as claimed in claim 14 wherein the one or more positive-displacement pumps are one or more bending-actuated pumps, wherein the bending-actuated pump is integrated into the circulatory system of the PPE, such that the fluid in the circulatory system can be moved through the circulatory system via the bending-actuated pump.

16. An article of PPE as claimed in claim 15 wherein the bending-actuated pump comprises a chamber having an inlet and an outlet and wherein the inlet comprises a one-way valve arranged to permit fluid to enter the chamber but not leave the chamber.

17. An article of PPE as claimed in claim 16 wherein the bending-actuated pump comprises a chamber support means for maintaining the transverse dimension of the chamber and wherein the chamber-support means comprises a helical coil arranged to provide structural support to the chamber.

18. An article of PPE as claimed in claim 14 wherein the one or more positive-displacement pumps are one or more bellows in fluid communication with the tubing.

19. An article of PPE as claimed in any preceding claim further comprising a source of perfluorocarbon, wherein the source comprises an inner cavity for retaining an amount of perfluorocarbon.

20. An article of PPE as claimed in any preceding claim further comprising perfluorocarbon sinks located at or about the lowest anatomical points in the PPE when the user is in the upright position.

21. An article of PPE as claimed in claim 19 or claim 20 wherein the source and/or sink comprises a support means in and/or around the source or sink to prevent the source or sink from collapsing.

22. An article of PPE as claimed in claim 19 or claim 20 further comprising a serviceable channel, wherein at least one of the source or sink access means, tubing, or bending actuated-pump is housed within the serviceable channel.

23. An article of PPE as claimed in any preceding claim wherein the binding means is located throughout the entirety of the semipermeable arrangement, with gaps interspersed throughout.

24. An article of PPE as claimed in claim 23 wherein the binding means is arranged as spots throughout the semipermeable arrangement.

25. An article of PPE as claimed in any preceding claim wherein the semipermeable arrangement comprises a structural means and at least one porous member, the at least one porous member being located on, within and/or supported by the structural means.