Patent Description:
Antibiotic and anti-microbial resistant bacteria and viruses are sometimes referred to as "superbugs. " At least some known superbugs are derived from preferential selectivity of microorganisms in a strain as a result of exposure to an antibiotic or anti-microbial agent, for example. The preferential selectivity is based on the resistance of the microorganisms to the antibiotic or anti-microbial agent. For example, the antibiotic or anti-microbial agent may be effective at killing or inhibiting the growth of weaker microorganisms in the strain, but may be ineffective in regards to stronger microorganisms in the strain. Survival of the stronger microorganisms enables the creation of superbugs that are increasingly resistant to antibiotics, anti-microbial agents, and other forms of wet chemistry. The proliferation and prevalence of superbugs is an important health issue that is taken into consideration in the design of air supply systems that provide and recirculate air within confined spaces designed for human occupancy, such as confined spaces of vehicles. At least some known air supply systems use anti-microbial filter media designed to collect microorganisms before they can be provided to the confined spaces. However, the filter media has a limited service life, which may increase the cost and complexity of the air supply system.

This section is intended to introduce the reader to art that may be related to various examples of the disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the present disclosure.

<CIT> discloses an air purification filter which can be incorporated into an air handling system of an aircraft. The nonwoven fibers of filter media are coated with a QUAT monomer or polymer. The QUAT coating reduces the enzyme activities of pathogen membrane proteins, ultimately leading to membrane lysis, rupture of the cellular envelope, and destruction of the pathogen. A second embodiment uses a combination of cooperative chemicals to attract, bind, and destroy the pathogen. A fusing chemical binds a membrane lysing chemical to the pathogen cell surface. The fusing and lysing agents act together to reduce bacterial clumping, degrade the outer pathogen capsule, penetrate the porous cell wall, and degrade the cell membrane by disrupting the phospholipids and sterols comprising the pathogen capsule and inner cell membrane. The fusing and lysing chemicals may be blended into the filter micro-fiber melt before filter fibers are extruded or blown. Alternatively, these may be coated onto the fibers or the assembled mat.

<CIT> discloses an air-treatment device comprising: a housing with an intake end and a discharge end, an air mover for forcing air through the housing, and an antimicrobial filter for killing, or at least significantly damaging, pathogenic cells and microbes that pass through it. More specifically, the antimicrobial filter is provided by a non-woven, pleated, filter medium, with copper and/or silver molecules embedded in the media. The copper molecules can lyse cell membranes of bacteria and the silver molecules can disrupt DNA and result in microbial cell death.

<CIT>, according to its abstract, states that a pathogen-deactivating fibrous material is coated with salt crystals or salt crystal layer. The salt crystals or coating on the supporting fibrous material layer dissolves upon exposure to pathogenic aerosols and recrystallizes during evaporation of water from the pathogenic aerosols. Recrystallization of the salt deactivates pathogens. The pathogen- deactivating fibrous material can be used in a sanitizing fabric, an air filtering device, such as respiratory devices, masks, furnace filter devices, air conditioning device, vehicle cabin filter device, etc., and can provide a universal personal protection for preventing infections.

<CIT>, according to its abstract, states that there is a graphene antimicrobial air conditioner filtering cloth, which comprises graphene composite non-woven fabric and buckles, wherein the graphene composite non-woven fabric comprises two graphene non-woven fabric layers; a graphene active carbon power filtering layer is clamped and arranged between the two graphene non-woven fabric layers.

There is described herein an aircraft that includes a confined space, and an air supply system configured to provide a flow of purified air to the confined space. The air supply system includes a conduit for channeling a flow of air therethrough, wherein the flow of air has microorganisms entrained therein. The air supply system also includes an anti-microbial filter in flow communication with the flow of air. The anti-microbial filter includes a plurality of atomically sharp surface features for non-selectively lysing at least some of the microorganisms that contact the anti-microbial filter such that the flow of purified air is discharged from the anti-microbial filter.

There is also described herein, a method of purifying air in the aircraft. The method includes channeling a flow of air having microorganisms entrained therein towards the anti-microbial filter. The method also includes controlling a velocity of the flow of air, wherein the velocity is selected to facilitate non-selective lysing of at least some of the microorganisms that contact the anti-microbial filter, and discharging a flow of purified air from the anti-microbial filter.

Various refinements exist of the features noted in relation to the above-mentioned examples of the present disclosure. Further features may also be incorporated in the above-mentioned examples of the present disclosure as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated examples of the present disclosure may be incorporated into any of the above-described examples of the present disclosure, alone or in any combination.

The implementations described relate to an anti-microbial air supply system that purifies air by lysing microorganisms, such as viruses, bacteria, fungi, and protists, entrained therein. The air supply system includes an anti-microbial filter positioned to be in flow communication with a flow of air, having the microorganisms entrained therein, channeled through a conduit. The anti-microbial filter includes a filtration surface having a plurality of atomically sharp surface features defined thereon. The atomically sharp surface features facilitate forming a micro-machined spike field designed to mechanically damage (i.e., lyse) microorganisms that come into contact with the atomically sharp surface features, thereby destroying the microorganisms regardless of their resistance to antibiotics, anti-microbial agents, or other forms of wet chemistry (i.e., non-selectivity). It will be understood that lysis of a microorganism through interaction with one or more of the atomically sharp surface features of the anti-microbial filter may entail the disintegration of the microorganism by rupture of its cell wall or membrane. It will also be understood that non-selective lysing of a microorganism may entail lysing of the microorganism without regard to its resistance to antibiotics, anti-microbial agents, or other forms of wet chemistry. Accordingly, the systems and methods described herein facilitate reducing the propagation of microbial life and improving air quality without contributing to the formation of superbugs as a result of preferential selectivity (i.e., the antithesis of non-selectivity).

As used herein, an element or step recited in the singular and preceded with the word "a" or "an" should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to "example implementation" or "one implementation" of the present disclosure are not intended to be interpreted as excluding the existence of additional implementations that also incorporate the recited features.

As used herein, the term "aircraft" may include, but is not limited to only including, airplanes, unmanned aerial vehicles (UAVs), gliders, helicopters, manned spacecraft, and/or any other object that travels through airspace. Further, in an alternative implementation, the systems and methods described herein may be used with any vehicle or confined space designed for human occupancy.

<FIG> is a cross-sectional illustration of an example aircraft fuselage <NUM>. In the example implementation, aircraft fuselage <NUM> includes an upper lobe <NUM> located above a floor beam <NUM>, and a lower lobe <NUM> located below floor beam <NUM>. Upper lobe <NUM> includes a confined space <NUM> and a crown <NUM>, and lower lobe <NUM> includes a cargo compartment <NUM>. An air supply system <NUM> is positioned within crown <NUM>, and is operable to provide a flow of purified air to confined space <NUM>. Although air supply system <NUM> is depicted as being positioned within crown <NUM>, one or more components of air supply system <NUM> may be positioned within other areas of upper lobe <NUM> or lower lobe <NUM>.

<FIG> is a schematic illustration of air supply system <NUM> used with aircraft fuselage <NUM> (shown in <FIG>). In the example implementation, air supply system <NUM> includes an air source <NUM> in flow communication with confined space <NUM> via a conduit <NUM> that includes a first conduit section <NUM> and a second conduit section <NUM>. Air source <NUM> may be any source of air that enables air supply system <NUM> to function as described herein. For example, air source <NUM> may provide confined space <NUM> with a flow of ambient air <NUM>.

Air supply system <NUM> also includes a particulate filter <NUM> and an anti-microbial filter <NUM>, which are in flow communication via first conduit section <NUM>. Particulate filter <NUM> is in flow communication with air source <NUM> and confined space <NUM>, and facilitates removing particulates entrained in air received at particulate filter <NUM> such that a flow of filtered air <NUM> is discharged therefrom. Anti-microbial filter <NUM> is positioned downstream from particulate filter <NUM>, and receives the flow of filtered air <NUM> channeled through first conduit section <NUM>. As will be described in more detail below, anti-microbial filter <NUM> facilitates lysing microorganisms entrained in the flow of filtered air <NUM> such that a flow of purified air <NUM> is discharged therefrom. The purified air <NUM> is therefore considered to be air which has been received at and passed on from the anti-microbial filter <NUM>; in particular, air in which at least some microorganisms have been lysed by the anti-microbial filter <NUM>. The flow of purified air <NUM> is provided to confined space <NUM> via second conduit section <NUM>, and a recirculation duct <NUM> provides flow communication between confined space <NUM> and particulate filter <NUM>. Accordingly, a flow of recirculated air <NUM> discharged from confined space <NUM> may be channeled through recirculation duct <NUM> and mixed with ambient air <NUM> for further circulation within air supply system <NUM>. In this way, the first conduit section <NUM>, the second conduit section <NUM>, and the recirculation duct <NUM> may form a loop for circulating air.

<FIG> is a partial view illustration of an example anti-microbial filter <NUM> that may be used in air supply system <NUM> (shown in <FIG>). In the example implementation, anti-microbial filter <NUM> is formed from at least one substrate <NUM> having a filtration surface <NUM> and a plurality of atomically sharp surface features <NUM> formed on filtration surface <NUM>. Each surface feature <NUM> includes at least one atomically sharp edge <NUM> that provides a point or points of impact for microorganisms <NUM> entrained in the flow of filtered air <NUM>. As will be explained in more detail below, causing microorganisms <NUM> to contact surface features <NUM> with a force greater than a threshold level facilitates lysing a membrane <NUM> of microorganisms <NUM>, thereby resulting in its eventual destruction.

As used herein, "atomically sharp" refers to an edge, grain, or crystal boundary that ends in a single atom of a subject material, or an edge/crystal boundary with a nanometer or sub-nanometer order of dimension as defined by one or more atoms. The subject material may include, but is not limited to, mono-crystalline silicon, graphene, and noble metals such as ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold. The size of the edge/crystal boundary may be determined using scanning profilometers, atomic force microscopy, and/or scanning electron microscopy. Thus, an atomically sharp surface feature may include a point or a plurality of points, a spike or a plurality of spikes, and/or an edge or a plurality of edges, configured to lyse a microorganism upon contact therewith when the microorganism is entrained in a flow of air and directed at the atomically sharp surface feature. In particular, the point(s), spike(s), and/or edge(s) may be considered to be atomically sharp by comprising one or more portions whose physical dimensions are at the atomic scale; for example, having nanometer or sub-nanometer dimensions.

The use of mono-crystalline silicon to form surface features <NUM> is advantageous because of its ability to form an atomically sharp tip and atomically sharp side edges, and because it has an ultimate tensile strength (i.e., about <NUM> MPa) substantially equivalent to stainless steel. The use of mono-crystalline silicon facilitates producing durable, repeatable, and resilient surface features <NUM>.

Substrate <NUM> may be formed from any material that enables anti-microbial filter <NUM> to function as described herein. An example substrate material includes, but is not limited to, mono-crystalline silicon. In one implementation, atomically sharp surface features <NUM> are formed as a result of anisotropic etching of the substrate material to produce a micro-machined spike field on filtration surface <NUM>. For example, a masking material (e.g., metals, nitrides, oxides, and positive and negative photoresists) may be applied to the substrate material in a predetermined pattern, and portions of the substrate material may be removed from around the masking material. Accordingly, anti-microbial filter <NUM> may be fabricated from multiple etched substrates <NUM> arranged in an array, or may be fabricated from a single substrate <NUM> having a surface area approximately equal to that of the array.

The surface features <NUM> resulting from the anisotropic etching of substrate <NUM> are illustrated as having a pyramidal shape. However, the anisotropic etching may be performed to define surface features <NUM> having any suitable shape, geometric or otherwise, having at least one atomically sharp edge <NUM>. In an alternative implementation, surface features <NUM> are grown on substrate <NUM>, such as in an epitaxial growth process. The epitaxial growth process is defined as the condensation of gas precursors to form a film on a substrate. Liquid precursors are also used, although the vapor phase from molecular beams is more commonly used. Vapor precursors are obtained by Chemical Vapor Deposition (CVD) and laser ablation. It is also possible to anodically bond materials together. Anodic bonding is a wafer bonding process to seal glass to either silicon or metal without introducing an intermediate layer, and is commonly used to seal glass to silicon wafers in electronics and microfluidics.

Surface features <NUM> can have any size that enables anti-microbial filter <NUM> to function as described herein. For example, surface features <NUM> may have an average pyramid size of less than about <NUM> microns, less than about <NUM> microns, less than about <NUM> microns, less than about <NUM> microns, less than about <NUM> microns, or less than about <NUM> microns in both the width and height dimensions relative to filtration surface <NUM>. In addition, in the example implementation, the plurality of atomically sharp surface features <NUM> includes first atomically sharp surface features <NUM> and second atomically sharp surface features <NUM> that differ from each other by at least one physical characteristic (e.g., shape or size). Accordingly, a turbulent and non-uniform array of surface features <NUM> is defined on filtration surface <NUM> to facilitate enhancing lysis of microorganisms <NUM> by creating a surface with randomly shaped and positioned surface features. Alternatively, surface features <NUM> of uniform shape and size are defined on filtration surface <NUM>, and/or filtration surface <NUM> is defined by regions including non-uniform surface features <NUM>, and regions including uniform surface features <NUM>.

In the example implementation, a layer <NUM> of coating material extends across filtration surface <NUM> and the plurality of atomically sharp surface features <NUM>. Any coating material may be used that enables anti-microbial filter <NUM> to function as described herein. In one implementation, the coating material is selected to enhance the durability of surface features <NUM>, and may be fabricated from a crystalline material such as diamond or sapphire. Alternatively, or additionally, layer <NUM> is formed from an electrically conductive material (e.g., noble metals). The electrically conductive material may have a greater electrical conductivity than the material of substrate <NUM> such that the electrical conductivity of anti-microbial filter <NUM> is enhanced. Layer <NUM> may be distributed across the entire surface area, or substantially the entire surface area, of filtration surface <NUM> to facilitate providing uniform conductivity across filtration surface <NUM>. Accordingly, as will be described in more detail below, enhancing the electrical conductivity of filtration surface <NUM> enables anti-microbial filter <NUM> to more efficiently lyse microorganisms <NUM>. In alternative implementations, the coating material may be an anti-microbial material such as copper, silver, and alloys thereof. It will be understood that the coating material enhancing at least one of the durability or the conductivity of the plurality of atomically sharp surface features <NUM> means providing increased durability and/or electrical conductivity relative to the material of the substrate <NUM> without the coating material.

As shown in <FIG>, the flow of filtered air <NUM> is channeled through first conduit section <NUM>, and filtration surface <NUM> is oriented to initiate contact between microorganisms <NUM> and surface features <NUM>. For example, filtration surface <NUM> may be oriented obliquely or perpendicularly relative an airflow direction <NUM> of the flow of filtered air <NUM>. In other words, the filtration surface <NUM> may be oriented obliquely or perpendicularly relative to an airflow direction defined by a portion of the first conduit section <NUM> which is configured to channel the flow of air to the filtration surface <NUM>. The airflow deflected from filtration surface <NUM> forms the flow of purified air <NUM>. As described above, the flow of purified air <NUM> may be recirculated towards anti-microbial filter <NUM>, as a part of the flow of recirculated air <NUM>, after passing through confined space <NUM> (shown in <FIG>) to further enhance lysing of microorganisms <NUM> entrained therein.

<FIG> is a partial view illustration of an alternative anti-microbial filter <NUM> that may be used in air supply system <NUM> (shown in <FIG>). In the example implementation, anti-microbial filter <NUM> includes a first substrate <NUM> having a first filtration surface <NUM>, and a second substrate <NUM> having a second filtration surface <NUM>. First filtration surface <NUM> and second filtration surface <NUM> are spaced from each other to define an airflow path <NUM> therebetween, and at least a portion of the flow of filtered air <NUM> is routed through airflow path <NUM>. The spacing between first filtration surface <NUM> and second filtration surface <NUM> is based at least partially on the size of microorganisms <NUM>, which can be defined within a range between about <NUM> nanometers to about <NUM> nanometers.

The spacing is selected to facilitate initiating contact between microorganisms <NUM> and surface features <NUM> on at least one of first filtration surface <NUM> or second filtration surface <NUM>. For example, in one implementation, a gap <NUM> defined between adjacent surface features <NUM> on first filtration surface <NUM> and second filtration surface <NUM> may be smaller than an average size of microorganisms <NUM> entrained in the flow of filtered air <NUM>. Accordingly, contact is initiated between microorganisms <NUM> and surface features <NUM> as microorganisms <NUM> are forced through airflow path <NUM>. In an alternative implementation, gap <NUM> may be larger than the average size of microorganisms <NUM>, and contact is facilitated to be initiated via electrical biasing of anti-microbial filter <NUM>, as will be explained in more detail below. To ensure a sufficient amount of purified air <NUM> is received in confined space <NUM>, multiple substrate <NUM> and <NUM> pairs may be arranged in a stacked array to increase the flow through capacity of anti-microbial filter <NUM>. For example, by virtue of the size of gap <NUM>, each pair has a limited flow through capacity for channeling airflow therethrough. Accordingly, multiple substrate pairs can be arranged to receive and discharge airflow to satisfy airflow needs of confined space <NUM>, for example.

In the example implementation shown in <FIG>, each atomically sharp surface feature <NUM> may be provided with at least one atomically sharp edge <NUM>. The first and second filtration surfaces <NUM>, <NUM> may then be oriented such that the at least one atomically sharp edge <NUM> is oriented obliquely or perpendicularly relative to an airflow direction of the flow of air <NUM>. In other words, the at least one atomically sharp edge <NUM> may be oriented obliquely or perpendicularly relative to an airflow direction defined by a portion of the first conduit section <NUM> which is configured to channel the flow of air to the first filtration surface <NUM> and the second filtration surface <NUM>.

Referring again to <FIG>, air supply system <NUM> includes a power source <NUM> electrically coupled with anti-microbial filter <NUM>, a controller <NUM> in communication with power source <NUM>, and a sensor <NUM> coupled to anti-microbial filter <NUM>. Sensor <NUM> is also in communication with controller <NUM>. Operation of power source <NUM> is controlled by controller <NUM>, and controller <NUM> can control operation of power source <NUM> based on feedback received from sensor <NUM>.

In one implementation, power source <NUM> provides a voltage to anti-microbial filter <NUM> to facilitate lysing microorganisms <NUM> entrained in the flow of filtered air <NUM>. For example, in operation, power source <NUM> electrically biases anti-microbial filter <NUM> with a positive charge or a negative charge. As shown in <FIG>, filtration surface <NUM> can be either positively charged or negatively charged and, as shown in <FIG>, first filtration surface <NUM> may be positively charged and second filtration surface <NUM> negatively charged, or vice versa. Particles such as microorganisms <NUM> inherently carry a residual surface charge. As such, electrically biasing anti-microbial filter <NUM> facilitates attracting microorganisms <NUM> to anti-microbial filter <NUM> to enhance the lysis thereof. Alternatively or additionally, power source <NUM> may provide an electrical discharge from anti-microbial filter <NUM>. The electrical discharge is for lysing at least some of microorganisms <NUM> entrained in the flow of filtered air <NUM>, such as those that are in close proximity to, but that may not come into contact with, filtration surface <NUM>.

In one implementation, sensor <NUM> monitors a capacitance across anti-microbial filter <NUM>. Monitoring the capacitance and/or changes in the capacitance facilitates providing an indication of a potential buildup of contamination on the electrically conductive filtration surface <NUM>. When the capacitance and/or the change in capacitance reaches or exceeds a threshold level, controller <NUM> causes power source <NUM> to provide a surge charge to anti-microbial filter <NUM>. The surge charge is for removing contamination from anti-microbial filter <NUM>. Accordingly, power source <NUM> facilitates periodically cleaning anti-microbial filter <NUM>.

The movement of airflow channeled through conduit <NUM> and recirculation duct <NUM> can be effectuated by one or more air moving devices (not shown), such as a pump, a fan, or the like. The one or more air moving devices may accelerate the airflow to a first velocity, for example. In the example implementation, air supply system <NUM> also includes an auxiliary air mover <NUM> and an airflow sensor <NUM> in communication with each other, and also both in flow communication with first conduit section <NUM>. Auxiliary air mover <NUM> can be a pump, a fan, or the like. Airflow sensor <NUM> monitors the airflow velocity of the flow of filtered air <NUM> channeled through first conduit section <NUM>, and provides airflow velocity data to auxiliary air mover <NUM>. Auxiliary air mover <NUM> is selectively operable to facilitate accelerating the flow of filtered air <NUM> from the first velocity to a greater second velocity. As described above, anti-microbial filter <NUM> facilitates purifying filtered air <NUM> by mechanically damaging or lysing microorganisms <NUM> (shown in <FIG> and <FIG>) entrained therein by causing microorganisms <NUM> to impact atomically sharp surface features <NUM> (shown in <FIG> and <FIG>). In general, microorganisms <NUM> must contact surface features <NUM> with a predetermined amount of force to facilitate piercing and/or damaging membrane <NUM> (shown in <FIG> and <FIG>) with atomically sharp edge <NUM> (shown in <FIG> and <FIG>). In one implementation, the mass or average mass of microorganisms <NUM> entrained in filtered air <NUM> may be a known or estimatable value. Accordingly, based on the mass of microorganisms <NUM>, auxiliary air mover <NUM> facilitates selectively accelerating the flow of filtered air <NUM> to the second velocity to cause microorganisms <NUM> to contact surface features <NUM> with sufficient lysing force.

Claim 1:
An aircraft comprising:
a confined space (<NUM>); and
an air supply system (<NUM>) configured to provide a flow of purified air to the confined space (<NUM>), the air supply system (<NUM>) comprising:
a conduit (<NUM>) for channeling a flow of air therethrough, wherein the flow of air has microorganisms (<NUM>) entrained therein; and
an anti-microbial filter (<NUM>) in flow communication with the flow of air, wherein the anti-microbial filter (<NUM>) comprises a plurality of atomically sharp surface features (<NUM>) for non-selective lysing of at least some of the microorganisms (<NUM>) that contact the anti-microbial filter (<NUM>) such that the flow of purified air is discharged from the anti-microbial filter (<NUM>).