Patent Grant
12194205
The invention relates to an air filtration media for use in medical or other areas where the air is contaminated or potentially contaminated with pathogens.
Air filtration media are used to capture airborne or aerosol particles and prevent them from being inhaled in the lungs, absorbed through the skin, or transferred through the mouth, eyes, and nose. Air filtration media can be comprised of non-woven materials formed by random arrangement of fibers (e.g., nanofibers, microfibers) or porous media (e.g., Gore-tex) that allow air to pass through the structure but also permit the capture of particles through a variety of mechanisms (e.g., interception, impaction, diffusion, electrostatic attraction). The efficiency of particle collection for the filtration media is a function of media composition (i.e., pore size and media thickness). Certain constructs of nanofiber filters have been shown to have high collection efficiency with minimal pressure drop. These constructions as described in part by the following U.S. Pat. Nos. 7,789,930; 8,652,229; 9,988,664; 10,099,165; 10,188,973; 10,208,331; 10,378,042.
In addition, nanofiber and nanoporous media have been shown to provide the ability to diffusely scatter electromagnetic radiation, and the ability of such media to scatter electromagnetic radiation is dependent on the ratio of the wavelength of electromagnetic radiation and the pore size of the media. This technology is described in multiple patents including the following U.S. Pat. Nos. 7,999,455; 8,714,776; 8,864,341; 8,884,507; 9,228,716.
As in air filter, the pore size in nanofiber materials used to scatter electromagnetic radiation is defined as the three-dimensional interstitial spacing between nanofibers comprising the mat. In nanoporous materials (e.g., DRP® diffuse reflector from W.L. Gore), scattering of electromagnetic radiation occurs at small porous sites in the expanded polytetrafluoro-ethylene (e-PTFE) material. This technology is described in U.S. Pat. No. 5,892,621 (the entire contents of each of which are incorporated herein by reference). Both nanofiber and e-PTFE materials can provide diffuse scattering of electromagnetic radiation solely due to the index of refraction mismatch that occurs at the interface of solid materials (e.g., fiber or PTFE, material) and pores.
The following patents and patent applications (the entire contents of which are incorporated herein by reference) are characteristic of the background:
In one embodiment, there is provided an air filtration media with integrated disinfection capability. The media has a collection filter for capture of pathogens, and an ultraviolet (UV) radiation source integrated into the collection filter such that the pathogens collected by the collection filter are exposed to UV radiation from the UV radiation source.
In one embodiment, there is provided at least one of a respirator, a laminated face mask, a garment, an air flow filter, and a HVAC unit comprising the air filtration media with integrated disinfection capability discussed above.
In one embodiment, there is provided a method for sterilizing pathogens using the air filtration media with integrated disinfection capability discussed above.
It is to be understood that both the foregoing general description of the invention and the following detailed description are exemplary, but are not restrictive of the invention.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
The present invention is directed to a multi-layer air filtration media 100 with an integrated disinfection function having the capability to destroy any viruses, bacteria, or biological agent that has been retained by the media. In one embodiment, a high efficiency media effectively and efficiently captures most particles, and the integrated disinfection function provides a way to neutralize the biological material so that the air filtration media can be safely reused without further threat or risk of re-exposure. In one embodiment of the invention (as noted above), air filtration media with integrated disinfection capability is provided. The air filtration media with integrated disinfection capability comprises a collection filter for capture of pathogens, and an ultraviolet (UV) radiation source integrated into the collection filter such that the pathogens collected by the collection filter are exposed to UV radiation from the UV radiation source. As used herein and unless otherwise defined in the claims, pathogens are any kind of bacterium, virus, fungi, or other microorganism or toxin that can cause disease or otherwise sicken a patient. As used herein and unless otherwise defined in the claims, integrated means made with, composed with, attached to, assembled together, combined together, made into a structure, and/or working together to form a complete unit with the recited “integrated” elements. As used herein, disinfection means destruction. sterilization, inactivation, making void of and/or nullifying any kind of bacterium, virus, fungi or other microorganism or toxin that would normally be expected to cause disease or otherwise sicken a patient. As used herein, disinfection includes complete or partial reduction in infectious activity of any kind of bacterium, virus, fungi, or other microorganism or toxin that normally would be expected to cause disease or otherwise sicken a patent. Disinfection is typically expressed in logarithm decrease in activity with 2 to 4 log reduction being considered complete disinfection. As such disinfection used herein means any reduction in activity including as low as 0.5 to 1 log and as much as 4 or greater log reduction. Note that disinfection is not cleaning or removal of accumulated material, just the removal of activity. As used here disinfection may include degradation or partial delegation of biological material present.
Housing 10 has a substantially cylindrical shape with an annular peripheral wall 12, an upper edge 14, a lower edge 16, a base with a peripheral filter support surface 18, a peripheral sealing surface 20 extending outwardly from upper edge 14, and a second annular peripheral wall 22 extending upwardly from an outer edge of sealing surface 20.
A respirator latch 42, filter element 36, and a vented opening 28 on the opposite end of cartridge 70 form an air passage through cartridge 70. Although, functionally, respirator latch 42 could be located on either end of cartridge, it is located on cover 40 and vented opening 28 is located on the bottom of housing 10.
Replaceable filter 30 has a filter element 36 molded into an annular peripheral frame 32 with a sealing lip 34 extending outwardly from one end. When filter 30 is disposed in housing 10, sealing lip 34 rests on sealing surface 20 of housing and bottom of filter frame 38 rests on filter support surface 18. The distance between bottom of filter frame 38 and bottom of sealing lip 34 is the same as the distance between filter support surface 18 and sealing surface 20 of housing. Filter frame 32 diameter at bottom of sealing lip 34 is the same as the inner diameter of annular peripheral wall 12, but tapers to a smaller diameter at bottom of filter frame 38 to facilitate insertion and removal of filter 30.
Meanwhile,
The composite structure shown in
The composite structure shown in
Returning to
The first and second electromagnetic radiation scattering and diffuser layers 104, 112 shown in
The particle capture layer 106 shown in
Other materials that could be used in the high efficiency air filtration media that behave like e-PTFE or the other medium above. The optional wire mesh layer shown in
In one embodiment of the invention, the high efficiency media comprises for the particle capture layer 106 a nanofiber mat. In one embodiment of the invention, the high efficiency nanofiber mat comprises patterned nanofibers formed onto a base dielectric coarse filtration material (hereinafter “base material”) supported by a wire mesh having macroscopic openings. As used herein, patterned nanofibers are fibers formed on the base material in compliance with a predefined pattern of the wire mesh and thereby forming an organization and orientation of the fibers above the wire mesh. The patterned nanofibers can be formed on a wire mesh as described in U.S. Pat. No. 10,188,973. This patterning can include simple patterns as well as nested or complex patterns. The following procedures are suitable for production of a nanofiber mat useful in the present invention, wherein the nanofiber mat comprises a) base having openings for fluid flow there through and a filtration medium, and b) a plurality of patterned nanofibers formed on the base. The nanofiber mat as a filtration medium itself would preferably have a figure of merit greater than 30 kPa−1, where the figure of merit is given by −Log (Pt)/ΔP, where Pt is the fractional penetration of a specific aerosol particle diameter and ΔP is a pressure drop in kPa across the filtration medium corresponding to a face velocity of 5.3 cm/s and particle size of 0.3 microns. A filter media with high efficiency and high FoM is able to provide a high level of protection with minimal burden (i.e., filter is easier to breathe through and/or it can be a smaller size). However, lower figures of merit would not make the present air filtration media with integrated disinfection unworkable, and in one embodiment the present invention is not limited to using nanometer sized fibers in the fiber mat of the air filtration media with integrated disinfection.
A comparison of different nanofiber filter technologies is shown in a plot of FoM versus Pt in
This plot in
One configuration for patterned deposition of electrospun nanofibers onto a flexible, light-weight nonwoven substrate is shown in
For production of a patterned nanofiber mat, a negative bias voltage is applied directly to the wire mesh. In some embodiments, voltages can range from a few hundred to up to ten thousand volts, or more depending upon the materials and needed processing conditions. Positively charged nanofibers are highly attracted to the negative bias on the grid and began to deposit onto the base material in a rapidly growing pattern. The result is that, during the spinning of the nanofibers, the fibers take the same pattern of the wire mesh underneath.
Conventional nanofiber electrospinning methods rely on a high positive voltage (+20 kV to +40 kV or higher) applied to a needle (i.e., spinneret) or other device that holds or manages the liquid solution to be spun into nanofibers. The target area (or substrate) for the spun nanofibers has to be at a ground potential (or significantly lower potential than the spinneret) in order to attract the highly positively charged fibers. These charged fibers land onto the grounded surface and form a layer of fibers (also called a mat). Typically, the fibers collect in random orientations forming a nonwoven fibrous mat on top of the substrate. With current methods the substrate is usually made of conductive materials (e.g., metal mesh), or materials with a conductive coating such as carbon paint. Alternately, a thin, minimally-insulating substrate, such as a light-weight nonwoven backing, is placed on top of a grounded target and then the fibers are deposited onto the substrate.
In contrast, for production of a patterned nanofiber mat, a patterned grid mechanism (e.g., the wire mesh shown in
While described below with regard to patterned fiber production, this invention for an air filtration media with integrated disinfection capability is not limited to those structures although the patterned fiber mats are preferred. While illustrated below with a Psu polymer, other polymeric materials can be used in a similar manner to that discussed below to obtain a high figure of merit filtration medium. In the illustrated embodiment below, a polymer solution containing PSu polymer in a solvent (using standard formulations) is fed to a 30 G needle. CO2 gas mixed with water vapor and heated to 30° C. flows over the syringe and syringe needle. Additional relative humidity (RH) controlled CO2 gas is injected into the electrospinning chamber. A positive power supply is connected to the spinneret and shares a common earth ground with a negative power supply connected to the patterned grid used to drive the patterned deposition of the nanofibers. The nonwoven substrate is mounted on a frame above the patterned grid.
Further, the grid can be in contact with or with a small air gap between the substrate and the grid. Auxiliary electrodes can be used that are connected to the negative power supply to aid in broadening the overall electric field to provide for even dispersion of fibers over the substrate. The substrate can be rotated relative to the spinneret to improve fiber dispersion. The RH- and temperature-controlled CO2 gas flows through the substrate and out the chamber venting system. This flow of gas may help dry the fibers and more generally controls the drying rate.
Using the patterned deposition method (which is preferred but not necessarily needed for this invention), filters were electrospun with high FoMs and high efficiencies (low Pt). Samples with the following performance metrics were made: 1) a FoM of 45.7 kPa−1 and a Pt of 2.34×10−4, 2) a FoM of 44.1 kPa−1 and a Pt of 6.99×10−4. Performance was measured with 0.3 μm particles at 5.33 cm/s. In general, the particle capture layer 106 shown in
The present invention can utilize filtration medium with a large range of figures of merit but with preferred values of figures of merit being 30 kPa−1 to 60 kPa−1 or higher. . In various embodiments, the figures of merit can range from 1 kPa−1 to 60 kPa−1. In various embodiments, the figures of merit can range from 10 kPa−1 to 50 kPa−1. Intermediate range values can be used.
Using this process of a conductive patterned grid (or surface) behind the substrate with deposition of charged fibers onto a substrate, a variety of fiber deposition configurations are possible. With the present invention, the metal mesh is used to create the pattern in conjunction with the use of a negative electric potential applied to the mesh. Accordingly, the nanofibers can be deposited onto a flexible substrate (for example a thin nonwoven that is not inherently conductive).
The electrospinning conditions (choice of polymer, electric field conditions, controlled environment conditions with for example CO gas flow) can be the same or similar to those described in the '973 patent referenced above describing techniques for formation of an integrated metal-mesh fiber structure. For example, a mixture of dry and wetted (via bubbling through DI water) CO2 can be used to obtain an RH in the range of 26 to 38%. A 21 wt % PSu (Udel P3500 LCD by Solvay Advanced Polymers) in dimethylacetamide (DMAC) with the 0.2 wt. % TBAC can be used as the polymer solution. This polymer solution can be spun from a 30G (ID−0.152 mm) stainless steel needle with a flow rate of 0.05 ml/hr, a gap of 25.4 cm, an applied potential of 29.5 kV DC, and a CO2 gas jacket flow rate of 8 L/min.
In addition to electrospinning, other techniques can be used for production of fibers and/or nanofibers for use in the particle collector layers and in the surrounding radiation scattering and diffusion layers (described below). These techniques include electroblown spinning as described in U.S. Pat. No. 7,585,451 (the entire contents of which are incorporated by reference), centrifugal spinning as described in U.S. Pat. Appl. Publ. No. 2009/0160099 (the entire contents of which are incorporated by reference), force spinning as described in U.S. Pat. Appl. Publ. No. 2009/02329020 (the entire contents of which are incorporated by reference), and rotary spinning as described in U.S. Pat. Appl. Publ. No. 2010/0247908 (the entire contents of which are incorporated by reference).
For example, one alternative method to fabricate nanofibers and/or fibers for use in this invention is through the process of centrifugal spinning or a closely related process called Force™ spinning. The details of centrifugal spinning are described in U.S. Pat. Appl. Publ. No. 2009/0160099 (the entire contents of which are incorporated by reference), the details of force spinning are described in U.S. Pat. Appl. Publ. No. 2009/02329020 (the entire contents of which are incorporated by reference), and the details of rotary spinning as described in U.S. Pat. Appl. Publ. No. 2010/0247908 (the entire contents of which are incorporated by reference). In these methods, shear forces arising from the high speed ejection of the polymer from a rotating spinnerette thin the film down to the nanofiber range. The nanofibers can be collected in layers either as they are ejected from the rotating spinnerette or formed into a mat using conventional means including air and electrostatic charging. Centrifugal spinning can be used on either polymer solutions (typical polymer concentration of 10% to 50%) or polymer melts. When polymer solutions are used in the nanofiber spinning process, common organic solvents including but not limited to formic acid, toluene, dimethyl formamide may be used. Common polymer nanofibers fabricated using centrifugal spinning include polyethylene, polypropylene, polyethylene terephthalate, polybutyleneterephthalate, nylon, polyimide, polyetherimide, polysulfone, polymethyl methacrylate, and blends thereof.
In making a nanofiber radiation scattering diffusion layer (i.e., a reflector) or a fiber collection layer for use in this invention, centrifugal spinning or FORCE spinning can be used. First, the spinning solution must be of the appropriate composition and viscosity to achieve the intended average fiber diameter (<500 nm). For centrifugal spinning, this can be achieved either through the use of a polymer solution (concentrations ranging from 10% to 50%) or a polymer melt heated to a sufficient temperature to reduce its viscosity. The solution composition in conjunction with the rotary rate of the centrifugal spinerette control the average fiber diameter of the end product. More viscous solutions require higher rotary spinning rates to achieve a fiber diameter <500 nm, compared to less viscous solutions. However, more viscous solutions will typically have a higher throughput and be able to produce more material in a given time frame. Second, the centrifugal spinning system is designed to produce sufficient fiber densities to achieve the bulk substrate properties as measured by mean flow pore diameter and bubble point required to achieve high reflectance across the entire nanofiber reflector substrate. In a centrifugal spinning system for producing the large amounts of material needed for lighting, this is typically achieved with a multiple spinerette architecture that can produce uniform fiber densities across a broad area. If the fiber density is too low, the substrate exhibits higher transmittance than desired. If the fiber density is too low, the reflectance of the material will decrease. Third, the collection belt for the nanofiber substrate is operated at a sufficient speed to ensure that the substrate basis weight remains below 40 gsm, more preferably below 30 gsm, and most preferably below 20 gsm. If the belt speed is operated at too high a rate, then sub-optimal basis weight is obtained. If the belt speed to too high, then excess material is incorporated into the substrate, increasing costs and decreasing flexibility, with significantly improving reflectance.
Another alternative method to fabricate nanofibers and/or fibers for use in this invention is through nanofiber melt-blowing. In this process, polymer resin is heated above its melting point and then forced under high through a specially designed fiber extrusion head to produce fibers in the 300 nm to >1,000 nm range. The combination of fiber extrusion head and air velocity and direction are adjusted to achieve AFD values <500 nm, as required for high reflectance substrates. The fibers are typically collected on a belt using either air knives or electrostatic charge accumulation. Common polymer nanofibers fabricated using melt-blowing include polyethylene, polypropylene, polyethylene terephthalate, polybutyleneterephthalate, and similar polyolefin and polyester materials.
The nanofiber and fiber structures described herein can also be fabricated using a roll-to-roll spinning process as in an Elmarco Nanospider tool, as described in U.S. Pat. Appl. Publ. Nos. 2009/0148547 and 2010/0034914, the entire contents of these patent documents incorporated by reference herein. As described therein, production of nanofibers through electrostatic spinning of polymer solutions occurs by way of a spinning electrode which rotates around its longitudinal axis and having spinning elements positioned uniformly along the circumference of end faces which are subsequently plunged under the level of polymer solution in the reservoir of polymer solution. Due to the physical properties of the polymer solution and the spinning electrode, the spinning elements emerge from the reservoir covered by the polymer solution. Having emerged, the spinning elements with polymer solution subsequently approach to a collecting electrode, which is grounded or connected to an opposite voltage source other than that of the spinning elements of the spinning electrode. In the moment, when the spinning element approaches sufficiently to the collecting electrode, between it and the collecting electrode as a result of difference of their electric potentials, there is created a sufficiently strong electric field, which along the whole length of the spinning element initiates the spinning process. During the spinning process the polymer nanofibers are created from the polymer solution on surface of the spinning element, which through the action of force of electrostatic field move towards the collecting electrode.
In this roll-to-roll process, the spinning element remains in a position suitable for spinning of the polymer solution on its surface only for a certain time interval. After expiration of this time interval, the spinning element is moved away from vicinity of the collecting electrode and again plunged into the polymer solution in the reservoir of polymer solution. Meanwhile, other spinning elements containing the polymer solution for spinning on their surface are in position to electrospin, permitting a continuous production of nanofibers in this roll-to-roll process.
Various polymers available for production of nanofibers (or fibers) of the present invention include, but are not limited to, acrylonitrile/butadiene copolymer, cellulose, cellulose acetate, chitosan, collagen, DNA, fibrinogen, fibronectin, nylon, poly(acrylic acid), poly(chloro styrene), poly(dimethyl siloxane), poly(ether imide), poly(ether sulfone), poly(ethyl acrylate), poly(ethyl vinyl acetate), poly(ethyl-co-vinyl acetate), poly(ethylene oxide), poly(ethylene terephthalate), poly(lactic acid-co-glycolic acid), poly(methacrylic acid) salt, poly(methyl methacrylate), poly(methyl styrene), poly(styrene sulfonic acid) salt, poly(styrene sulfonyl fluoride), poly(styrene-co-acrylonitrile), poly(styrene-co-butadiene), poly(styrene-co-divinyl benzene), poly(vinyl acetate), poly(vinyl alcohol), poly(vinyl chloride), poly(vinylidene fluoride), polyacrylamide, polyacrylonitrile, polyamide, polyaniline, polybenzimidazole, polycaprolactone, polycarbonate, poly(dimethylsiloxane-co-polyethyleneoxide), poly(etheretherketone), polyethylene, polyethyleneimine, polyimide, polyisoprene, polylactide, polypropylene, polystyrene, polysulfone, polyurethane, poly(vinylpyrrolidone), poly(2-hydroxy ethyl methacrylate) (PHEMA), gelatin, proteins, SEBS copolymer, silk (natural or synthetically derived), and styrene/isoprene copolymer.
Additionally, polymer blends can also be produced as long as the two or more polymers are soluble in a common solvent or mixed solvent system. A few examples would be: poly(vinylidene fluoride)-blend-poly(methyl methacrylate), polystyrene-blend-poly(vinylmethylether), poly(methyl methacrylate)-blend-poly(ethyleneoxide), poly(hydroxypropyl methacrylate)-blend poly(vinylpyrrolidone), poly(hydroxybutyrate)-blend-poly(ethylene oxide), protein blend-polyethyleneoxide, polylactide-blend-polyvinylpyrrolidone, polystyrene-blend-polyester, polyester-blend-poly(hydroxyethyl methacrylate), poly(ethylene oxide)-blend poly(methyl methacrylate), poly(hydroxystyrene)-blend-poly(ethylene oxide).
Other embodiments of the present invention include the use of polymers that are resistant to UV degradation which include for example cyclic olefin copolymers (COC) such as TOPAS® (see topas.com/uv-transparency), PTFE, e-PTFE, polyvinylidene fluoride, fluorinated ethylene propylene, polyether ether ketone (PEEK), quartz, and other mineral materials.
The thickness of a suitable nanofiber mat can vary from about 0.10 μm (100 nm) to 500 μm or beyond if needed to millimeter size, where most filters had an average mat thickness in the range of 2 to 5 microns. The average mat thickness numbers represent the average thickness of the total nanofiber mat in a filter. Alternately the mat thickness can be defined as layers of nanofibers with the thickness including from 4 to 4000 layers where 4 to 400, or 5 to 100, or 2 to 15 layers were typical in various embodiments.
Regardless of fiber production technique or the type of fiber used, in one embodiment of the invention, additives (e.g., white pigments such as titanium oxide) may be added to promote diffuse reflection of electromagnetic radiation and for germicidal purposed. Additives included with the fiber structures or provided as a coating throughout or on a part of a fibrous medium (or fabric) of the particle capture layer 106 or the optical diffusion layers 104, 112 could be used to destroy viruses and other microbes on the product surfaces (e.g., silver ionic coating or imbedded particles are well known anti-microbial additives to textiles). These additives could also mitigate microbial growth on surfaces within the apparatus.
Returning to
A more directional “leak” of electromagnetic radiation from an optical fiber can be achieved by applying a condensed material (e.g., polymer) along at a length of the optical fiber at bends in the fiber (at www.youtube.com/watch?v=MSdpRzBbR2E&t=3s). Suitable condensed materials for the present invention include (but are not limited to) the following commercial products: Epotek 305 (transparent to below 260 nm) Norland NOA88 (transparent to 300 nm), Epoxies Etc. 20-3302 (transparent to 300 nm), Master Bond EP3OLV or EP29LPSP (“optically clear”). For those “optically clear” and transparent to 300 nm materials, relatively thin layers should be used to minimize absorption of UV radiation.
In addition, the optical fiber may have LEDs embedded along its length to create LED fibers such as those described by U.S. Patent Application 2018/0039036 (the entire contents of each of which are incorporated herein by reference). In the '036 patent application, there is provided a fiber including a fiber body with a fiber body material having a longitudinal axis along a fiber body length. A plurality of devices (e.g., LEDs) is disposed as a linear sequence of devices within the fiber body. Each device includes at least one electrical contact pad. At least one electrical conductor is disposed within the fiber body.
Here, in this invention, ultraviolet light emitting diode UVLED devices (which can emit UV radiation) can be placed in the milled pockets on the fiber body, with the anodes of all devices oriented in the same direction, which was marked on the preform. Additional information on such LED fibers is provided at www.ll.mit.edu/news/fibers-embedded-electronics-are-putting-fabrics-work. Here, in the present invention, electronic fibers (to contain the UVLEDs) start out as a block of polycarbonate (PC) called a preform. Other preform materials include but are not limited to COC (e.g., Topas) or silica. The UVLEDs are embedded down the center of the preform, and copper wire is fed into small channels running down the preform on both sides of the diodes. Wire mesh layer 110 may be used to power the embedded UVLEDs in this construction. The preform is then heated up at the top of a draw tower, which pulls the warm, taffy-like substance into a long fiber strand. This stretching of the preform spaces out the embedded UVLEDS and forces the wires into contact with them. As a result, hundreds of UVLEDs can become electrically connected in parallel inside a single fiber thin enough to be threaded through a needle.
In one embodiment of the present invention, there can be multiple optically active layers 108. For example, a first optically active layer could exist to one side of the particle capture layer 106, and another optically active layer could exist to the opposite side of the particle capture layer 106. In one embodiment, the optically active layer 110 (and a battery for powering the optically active layer) may be removable from and/or installable in a housing containing the first and second electromagnetic radiation scattering and diffuser layers 104 and 112, the particle capture layer 106, and the optional wire mesh layer 108.
In one embodiment of the present invention, the first and second electromagnetic radiation scattering and diffuser layers 104 and 112, the particle capture layer 106, the optional wire mesh layer 108, the optically active layer 110 can provide the component of a garment. In this embodiment, the garment could be part of a head and/or neck covering or could be part of sleeve extending for example past the wrist and covering skin not covered by gloves. As pathogens diffuse migrate through the coverings, the optically active layer 110 can generate UV radiation for disinfection of the pathogens.
Exemplary Respirator
In one embodiment of the present invention, included in filter frame 38 shown in
As noted above, in one embodiment, the optically active layer 110 (and a battery for powering the optically active layer) may be removable from and/or installable in a housing (e.g., filter frame 38). As shown in
When cartridge is assembled (as shown in the side view of
Means for sealing cartridge 70 are provided by filter frame 32 and concentric sealing rings 24,26,46 on sealing surfaces 20,44 and on filter support surface 18. Filter 30 is first sealed by a series of concentric sealing rings 24,46 on sealing surfaces 20,44 providing repetitive gasketing and sealing when sealing lip 34 is compressed between sealing surfaces 20,44. Sealing rings on housing 24 correspond to sealing rings on cover 46 to provide localized pressure which concentrates force over a smaller area, enhancing the seal integrity. An additional sealing location is provided by concentric sealing rings 26 on filter support surface 18 when bottom of filter frame 38 is compressed against filter support surface 18.
Filter frame 32 is preferably spin molded from a resilient plastic material of such a durometer that it can be deformed to provide for gasketing and sealing. In the preferred embodiment, filter frame 32 is molded from polyurethane with a durometer of less than 50 Shore A hardness. Housing 10 and cover 40 are made of injection-molded plastic sufficiently hard t deform filter frame 32 when cover 40 is releasably connected to housing 10.
In Use Disinfection
The disinfection of the air filtration media described above is advantageous since it allows the filtration media to be reused with a greatly reduced risk of the trapped biological material becoming resuspended and inhaled by humans. A second advantage is that a majority if not all of the captured biological material can be destroyed with the germicidal radiation eliminating the safety and handling issues associated with removing and disposing of spent personal protective equipment.
The disinfection function of the subject invention can be activated by supplying appropriate electrical power to the LED(s) that provide the actinic/germicidal radiation. This process can be done in situ while masks and respirators containing the filtration media are being worn, and the activation can be either continuous or pulsed at a desired duty cycle through a battery and control circuit. This process can also be done in situ for flat or pleated filtration media containing the subject injection using a control circuit and either a continuous or pulsed waveform to operate the LEDs at a desired duty cycle. The power source for the flat or pleated media can be either a battery, an electrical bus provided by the HVAC system, or an external power supply.
The electromagnetic radiation used for the device can be chosen to provide a high kill rate of any biological materials trapped on the high efficiency air filter media. The wavelength of the LEDs/ microLEDs used in this device can range from UV-C (200-280 nm) up to blue (˜450 nm), with the UV-C radiation providing the highest probability for killing biological materials (see D. H. Sliney, “Introduction to Ultraviolet Germicidal Irradiation (UVGI) and Visible Lighting Disinfection. Part 1: Introduction”, IES webinar, Sep. 19, 2019 community.ies.org/events/event-description?CalendarEventKey=58fd1791-78e7-420f-b91c-7ae9d36668c9&Home=%2fevents%2fevent-description and see International Ultraviolet Association Fact Sheet on UV Disinfection for COVID-19 www.iuva.org/COVID-19).
Packaged LEDs emitting at such wavelengths are provided by multiple manufacturers including Nichia (e.g., NCSU334A product with p at 280 nm see nichia.co.jp/en/product/uvled.html) and Osram www.osram.com/os/press/press-releases/unique_project_for_developing_mass_market_uv_leds_for_disinfection.jsp). Unpackaged LEDs can also be obtained from the manufacturers listed above or from distributors such as III-V Compounds Inc. with offices in New York, NY (see www.35compounds.com/home.html).
In one embodiment of the present invention, the LEDs are either coupled to an optical fiber configured for emitting diffuse electromagnetic radiation (as shown in
Alternatively, the air filtration media described in this invention can be disinfected at a location remote from its use site. The multi-layer air filtration media is removed to the location for disinfection, and one or more media are connected to a source of electrical power at the appropriate voltage and current (e.g., battery, power supply). A control 116 as shown in
Currently any air filtration media that is potentially subjected to biohazards (e.g., germs, viruses, biological agents) must be carefully handled and disposed of as biohazardous waste. This increases the costs associated with disposal of such materials. The subject invention would allow any biological material contained within the structure to be deactivated, which would greatly simplify the disposal of the material and reduce disposal costs.
Control
It will be understood that the control 116 schematically illustrated in
In step 901, pathogens are collected by an air filtration media with integrated disinfection capability. The air filtration media can be any of the filtration media described herein.
In step 903, the UV radiation source integrated with the filtration medium is activated on a predetermined schedule, typically under the direction of a control, such as controller 116.
In step 905, UV radiation is emitted into the filtration medium according to the predetermined schedule including at least one of a constant illumination mode, a duty cycle illumination mode, and an on-demand illumination mode (activated by a user).
It will be understood that one or more of the processes, sub-processes, and process steps described herein may be performed by hardware, firmware, software, or a combination of two or more of the foregoing, on one or more electronic or digitally-controlled devices for example adjusting the variable capacitors and/or the relative bobbin positions and/or the power level of the AC source 130. The software may reside in a software memory (not shown) in a suitable electronic processing component or system such as, for example, control 116. The software memory may include an ordered listing of executable instructions for implementing logical functions (that is, “logic” that may be implemented in digital form such as digital circuitry or source code, or in analog form such as an analog source such as an analog electrical, sound, or video signal). The instructions may be executed within a processing module, which includes, for example, one or more microprocessors, general purpose processors, combinations of processors, digital signal processors (DSPs), or application specific integrated circuits (ASICs). Further, the schematic diagrams describe a logical division of functions having physical (hardware and/or software) implementations that are not limited by architecture or the physical layout of the functions. The examples of systems described herein may be implemented in a variety of configurations and operate as hardware/software components in a single hardware/software unit, or in separate hardware/software units.
The executable instructions may be implemented as a computer program product having instructions stored therein which, when executed by a processing module of an electronic system (e.g., control 116), direct the electronic system to carry out the instructions. The computer program product may be selectively embodied in any non-transitory computer-readable storage medium for use by or in connection with an instruction execution system, apparatus, or device, such as a electronic computer-based system, processor-containing system, or other system that may selectively fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this disclosure, a computer-readable storage medium is any non-transitory means that may store the program for use by or in connection with the instruction execution system, apparatus, or device. The non-transitory computer-readable storage medium may selectively be, for example, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device. A non-exhaustive list of more specific examples of non-transitory computer readable media include: an electrical connection having one or more wires (electronic); a portable computer diskette (magnetic); a random access memory (electronic); a read-only memory (electronic); an erasable programmable read only memory such as, for example, flash memory (electronic); a compact disc memory such as, for example, CD-ROM, CD-R, CD-RW (optical); and digital versatile disc memory, i.e., DVD (optical).
It will also be understood that the term “in signal communication” as used herein means that two or more systems, devices, components, modules, or sub-modules are capable of communicating with each other via signals that travel over some type of signal path. The signals may be communication, power, data, or energy signals, which may communicate information, power, or energy from a first system, device, component, module, or sub-module to a second system, device, component, module, or sub-module along a signal path between the first and second system, device, component, module, or sub-module. The signal paths may include physical, electrical, magnetic, electromagnetic, electrochemical, optical, wired, or wireless connections. The signal paths may also include additional systems, devices, components, modules, or sub-modules between the first and second system, device, component, module, or sub-module.
Statements of Invention
The following statements of the invention represent non-limiting aspects of the invention.
Statement 1. An air filtration media with integrated disinfection capability, comprising: a collection filter for capture of pathogens; and an ultraviolet (UV) radiation source integrated into the collection filter such that the pathogens collected by the collection filter are exposed to UV radiation from the UV radiation source.
Statement 2. The media of statement 1, further comprising: a housing holding the collection filter, and the UV radiation source is integrated into the collection filter via a light emitting diode disposed inside of a housing holding the collection filter.
Statement 3. The media of statement 2, wherein the light emitting diode is coupled to a radiation scattering and diffuser layer.
Statement 4. The media of statement 2, further comprising an optical fiber extending into the housing and configured to distribute the UV radiation along a length thereof.
Statement 5. The media of statement 4, wherein the optical fiber comprised Bragg gratings formed into outer surfaces of the optical fiber at different points along the length.
Statement 6. The media of statement 1, wherein the collection filter comprises a particle capture layer formed of nanofibers.
Statement 7. The media of statement 1, wherein the collection filter comprises a particle capture layer formed of patterned nanofibers.
Statement 8. The media of statement 1, wherein the collection filter comprises a high efficiency air filtration media having a figure of merit between 10 and 60 kPa−1.
Statement 9. The media of statement 1, wherein the collection filter comprises in sequence: a particle capture layer which capture pathogens and an optically active layer which distributes radiation from the UV radiation source.
Statement 10. The media of statement 1, wherein the collection filter comprises in sequence: a first electromagnetic radiation scattering and diffuser layer, a particle capture layer which capture pathogens, an optically active layer which distributes radiation from the UV radiation source, and a second electromagnetic radiation scattering and diffuser layer.
Statement 11. The media of statement 1, wherein the collection filter comprises in sequence: a first shell layer, a first electromagnetic radiation scattering and diffuser layer, a particle capture layer which capture pathogens, an optically active layer which distributes radiation from the UV radiation source, a second electromagnetic radiation scattering and diffuser layer, and a second shell layer.
Statement 12. The media of statement 9 or statement 10 or statement 11, further comprising a wire mesh layer disposed against the particle capture layer.
Statement 13. The media of statement 9 or statement 10 or statement 11, wherein the ultraviolet radiation source comprises a light emitting diode which, when powered, emits the UV radiation into the optically active layer.
Statement 14. The media of statement 13, wherein the optically active layer distributes the UV radiation such that at least the particle capture layer is exposed to the UV radiation.
Statement 15. The media of statement 1, further comprising: a programmed controller configured to operate the UV radiation source on a predetermined schedule.
Statement 16. The media of statement 15, wherein the predetermined schedule programmed into the controller comprises at least one of a constant illumination mode, a duty cycle illumination mode, and an on-demand illumination mode.
Statement 17. The media of statement 1, wherein the collection filter comprises a nanofiber mat, wherein a thickness of the mat ranges from 0.10 vim to 10 mm.
Statement 18. The media of statement 1, wherein the collection filter comprises a nanofiber mat, wherein a thickness of the mat ranges from 2 to 5 microns.
Statement 19. The media of statement 1, wherein the collection filter comprises a nanofiber mat, wherein the mat comprises layers of nanofibers ranging from 4 to 4000 layers.
Statement 20. The media of statement 1, wherein the collection filter comprises a nanofiber mat, wherein the mat comprises layers of nanofibers ranging from 4 to 400 layers.
Statement 21. The media of statement 1, wherein the collection filter comprises a nanofiber mat, wherein the mat comprises layers of nanofibers ranging from 5 to 100 layers.
Statement 22. The media of statement 1, wherein the collection filter comprises a nanofiber mat, wherein the mat comprises layers of nanofibers ranging from 2 to 15 layers.
Statement 23. The media of statement 1, wherein the collection filter comprises a fiber mat having fibers of an average fiber diameter of less than 500 nm.
Statement 24. The media of statement 1, wherein the collection filter comprises a fiber mat having fibers of an average fiber diameter of less than 200 nm.
Statement 25. The media of statement 1, wherein the collection filter comprises a fiber mat having fibers of an average fiber diameter of less than 100 nm.
Statement 26 The media of statement 1, wherein the collection filter comprises a fiber mat having fibers of a diameter less 1 micron.
Statement 27. The media of statement 1, wherein the collection filter comprises a filtration medium having a figure of merit between 20 kPa−1 and 40 kPa−1.
Statement 28. The media of statement 1, wherein the collection filter comprises a filtration medium having a figure of merit between 40 kPa−1 and 80 kPa−1.
Statement 29. The media of statement 1, wherein the collection filter comprises a filtration medium having a figure of merit between 70 kPa and 80 kPa−1.
Statement 30. A respirator comprising the media of any of statements 1-29.
Statement 31. A laminated face mask comprising the media of any of statements 1-29.
Statement 32. An air flow filter comprising the media of any of statements 1-29.
Statement 33. A HVAC unit comprising the media of any of statements 1-29.
Statement 34. A method for sterilizing pathogens utilizing the media of any of statements 1-29.
Statement 35. A garment comprising: in sequence, a first electromagnetic radiation scattering and diffuser layer, a particle capture layer which captures pathogens, an optically active layer which distributes ultraviolet radiation, and a second electromagnetic radiation scattering and diffuser layer.
Statement 36. The garment of statement 35, further comprising an ultraviolet radiation source coupling radiation into the optically active layer.
Statement 37. The garment of statement 36, wherein the ultraviolet radiation source in integrated into the garment.
Statement 38. The garment of statement 37, further comprising a fiber optic receiving ultraviolet radiation from the ultraviolet radiation source and dispersing the ultraviolet radiation along a length of the fiber optic.
Statement 39. A garment comprising: in sequence, a particle capture layer which captures pathogens, an optically active layer which distributes ultraviolet radiation.
Numerous modifications and variations of the invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.
This is application is related to and claims priority to U.S. Ser. No. 63/017,950, entitled “MULTI-LAYER AIR FILTRATION MEDIA WITH INTEGRATED DISINFECTION CAPABILITY,” the entire contents of which are incorporated herein by reference. This application is also related to the following patents and patent applications, the entire contents of each of which are incorporated herein by reference. U.S. Pat. Nos. 7,789,930; 8,652,229; 9,988,664; 10,099,165; 10,188,973; 10,208,331; 10,378,042; 7,999,455; 8,714,776; 8,864,341; 8,884,507; 9,228,716.
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