Protective respirator using far UV-C radiation

Abstract

A protective respirator inactivates pathogens within a kill zone in front of a user's mouth and nose by emitting far UV-C radiation (e.g., having a wavelength centered around 222 nanometers). In some embodiments, the controller uses a mathematical model to determine the intensity or duration of emission required to provide a threshold probability of killing a microorganism (e.g., a virus such as SARS-CoV-2). The required intensity or duration may be determined based on atmospheric conditions and / or the user's physiological condition. The far UV-C radiation may be emitted in a direction through the kill zone that does not intersect with the user's skin or eyes (e.g., away from the user or across the front of the user's face). Alternatively, the controller may estimate the fluence of the far UV-C radiation at the user's skin or eyes over time and adjust the emitted far UV-C radiation.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 124,437, filed December 11, 2020, and U.S. Provisional Patent Application No. 63 / 265,336, filed December 13, 2021, which are incorporated herein by reference. [Background technology]

[0002] Over the past decade, natural pandemics of influenza, Zika, and coronaviruses have caused economic destruction and morbidity and mortality worldwide. Natural pandemics have the potential to recur based on the proven zoonotic disease epidemics of the past decade (e.g., H1N1, SARS, MERS, Zika, Ebola, Marburg) as well as increasing vulnerable populations, new vulnerable birth cohorts each year, and older adults experiencing immunosenescence. COVID-19 has demonstrated the seriousness of biological threats, particularly to the United States, given its inadequate preparedness and response measures.

[0003] By definition, novel biological threats do not have proven vaccines or medicines and must rely solely on public health measures such as personal hygiene, physical separation, decontamination of surfaces and air, and wearing personal protective equipment (PPE) such as masks, gloves, and goggles. During the COVID-19 pandemic, stockpiling and supplying disposable PPE, hand sanitizer, and air filters proved extremely challenging. However, the dramatic increase in the use of PPE (various qualities, from high-filtration N-95 and KN-95 masks to household cotton cloth masks) likely contributed to the significant decline in seasonal influenza incidence and morbidity during the 2020–2021 and early 2021–2022 seasons.

[0004] Highly effective PPE, such as N95 respirators, are often disposable and worn for short periods of time. However, N95 respirators are often underused due to discomfort and poor fit. Additionally, disposable respirators are an expensive solution when scaled to meet global demand. Therefore, effective, reusable, and scalable PPE are needed to address respiratory pathogens, such as influenza, coronavirus, respiratory syncytial virus (RSV), and human metapneumovirus (HMPV). These respiratory viruses are the leading cause of illness and death from contagious respiratory diseases.

[0005] Ultraviolet (UV) radiation with wavelengths between approximately 200 nanometers (nm) and 320 nm causes photochemical damage to important biomolecules such as deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Therefore, 200-320 nm UV radiation, sometimes referred to as "germicidal UV," can be used to disinfect surfaces and air volumes. UV radiation with wavelengths less than approximately 240 nm also damages proteins, which can also result in the inactivation of microorganisms and viruses. However, prolonged exposure to radiation from parts of the UV spectrum can cause damage to human skin and eyes. Therefore, to take advantage of the disinfecting properties of germicidal UV irradiation, it is necessary to protect human tissue from prolonged exposure to radiation with wavelengths in parts of the spectrum where radiation can damage human tissue. Summary of the Invention

[0006] A protective respirator provides "near-field" protection to a user by emitting Far UV-C radiation (e.g., having a wavelength centered around 222 nanometers) through a kill zone in front of the user's mouth and nose. In an embodiment, the protective respirator includes a power source, one or more Far UV-C radiation sources that emit the Far UV-C radiation, and a controller that uses a mathematical model to determine the required intensity of the Far UV-C radiation or the time required to emit the Far UV-C radiation and provide a threshold probability of killing a microorganism (e.g., a virus such as SARS-CoV-2) traveling through the kill zone. The mathematical model is developed by using computational fluid dynamics to combine the velocity field in a simulated environment, the fluence of the Far UV-C radiation emitted by the Far UV-C radiation source, and the intrinsic dynamics of the inactivation response of microorganisms identified using laboratory experiments.

[0007] Because the required intensity or duration may depend on atmospheric conditions, in some embodiments the controller receives data indicative of one or more atmospheric conditions. In some embodiments, the data is determined by one or more atmospheric sensors. In some embodiments, the data is received from a server, a personal electronic device, or a location beacon.

[0008] Because these atmospheric conditions may depend on one or more physiological conditions of the user, in some embodiments the controller receives data indicative of the one or more physiological conditions of the user. In some embodiments, the data is determined by an inertial measurement unit, a geolocation module, or one or more physiological sensors. In some embodiments, the data is received from a personal electronic device or a fitness tracker.

[0009] In some embodiments, the Far UV-C radiation source emits the Far UV-C radiation away from the user. In some embodiments, the Far UV-C radiation source emits the Far UV-C radiation through a kill zone in a direction that does not intersect the user's skin or eyes. In other embodiments, the controller estimates the fluence of the Far UV-C radiation at the user's skin or eyes over time and, in response to the determination, adjusts the Far UV-C radiation emitted by the one or more Far UV-C radiation sources.

[0010] In some embodiments, the controller monitors the charge level of the power source over time and, in response to the determination, adjusts the Far UV-C radiation emitted by the one or more Far UV-C radiation sources.

[0011] Aspects of the exemplary embodiments may be better understood with reference to the accompanying drawings, in which the components are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the exemplary embodiments. [Brief explanation of the drawings]

[0012] [Figure 1A] 1 is a diagram of ultraviolet (UV) penetration into human skin. [Figure 1B] 1 is a diagram of UV penetration into the human eye. [Figure 2A] 1 is a graph of the relative spectral effectiveness of UV radiation as a function of wavelength. [Figure 2B] 1 is a graph of threshold limits as a function of wavelength. [Figure 3] FIG. 1 is a block diagram of a protective respirator according to an exemplary embodiment. [Figure 4A] 1 is a diagram of a Far UV-C radiation source according to an exemplary embodiment. [Figure 4B] 1 is a diagram of a Far UV-C radiation source according to an exemplary embodiment. [Figure 4C] 1 is a graph of the normalized output of two exemplary Far UV-C radiation sources. [Figure 5A]1 illustrates a protective respirator according to a wearable embodiment. [Figure 5B] 10A-10C illustrate protective respirators according to alternative wearable embodiments. [Figure 5C] 10A-10C illustrate protective respirators according to alternative wearable embodiments. [Figure 5D] 10A-10C illustrate protective respirators according to alternative wearable embodiments. [Figure 5E] 10A-10C illustrate protective respirators according to alternative wearable embodiments. [Figure 5F] 10A-10C illustrate protective respirators according to alternative wearable embodiments. [Figure 5G] 10A-10C illustrate protective respirators according to alternative wearable embodiments. [Figure 6] 6A-6B are diagrams illustrating kill zones according to an exemplary embodiment. [Figure 6C] FIG. 10 illustrates a kill zone in accordance with another illustrative embodiment. [Figure 6D] FIG. 10 illustrates a kill zone in accordance with another illustrative embodiment. [Figure 7A] FIG. 1 illustrates an exemplary laboratory experiment. [Figure 7B] FIG. 7B shows a computer simulation of the inactivation response during the experiment of FIG. 7A. [Figure 8] 8A-8C illustrate simulations using computational fluid dynamics in accordance with an illustrative embodiment. [Figure 9] FIG. 1 is an illustration of a network environment in accordance with an illustrative embodiment. [Figure 10] 1 is a flowchart illustrating a process for inactivating microorganisms (e.g., microorganisms such as bacteria, spores, viruses, protozoa, and / or fungi and / or viral particles) according to an exemplary embodiment. [Figure 11] 1 illustrates a protective respirator according to a portable embodiment. [Figure 12] 1 shows a protective respirator according to a stationary embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Reference is now made to the drawings, which illustrate various views of exemplary embodiments. In the drawings and description of the drawings herein, specific terminology is used for convenience only and is not to be construed as limiting the embodiments of the invention. Moreover, in the drawings and the following description, like numbers refer to like elements throughout.

[0014] Although some ultraviolet (UV) radiation causes damage to human tissue, recent studies have shown that UV radiation with wavelengths between approximately 200 nanometers (nm) and 230 nm (informally referred to as "Far UV-C" radiation) causes minimal damage to vital mammalian tissues, including the skin and eyes.

[0015] 1A is a diagram of UV penetration into human skin 170, including the stratum corneum (dead layer) 171, stratum lucidum 173, stratum granulosum (granular layer) 175, stratum spinosum (post-spinous layer) 177, stratum basale (basal layer) 178, and dermis 179. As shown in FIG. 1A, radiation from a 254 nm source 154 can penetrate the stratum corneum 171, stratum lucidum 173, and stratum granulosum 175 before being absorbed by the stratum spinosum 177. In contrast, however, radiation from a 222 nm source 400 is almost completely absorbed by the stratum corneum, which is the outer layer of dead cells in human skin 170.

[0016] FIG. 1B is a diagram of UV penetration into a human eye 190, including the iris 192, aqueous humor 194, lens 196, and cornea 198. As shown in FIG. 1B, 222 nm radiation does not penetrate beyond the layer of dead cells on the outer surface of the cornea 198. Far UV-C radiation is absorbed only by dead cells in human skin and the eye, causing little to no damage to those tissues. Recent experiments involving mammalian models (hairless mice) and human tissue support these conclusions.

[0017] To protect humans, organizations including the American Conference of Governmental Industrial Hygienists (ACGIH) and the International Commission on Non-Ionizing Radiation Protection (ICNIRP) have established threshold limit values ​​(TLVs), which are recommended limits of exposure to each hazardous substance or object to which a person can be exposed without adverse health effects. Recent studies demonstrating the safety of far UV-C radiation have prompted a reevaluation of exposure limits for far UV-C radiation.

[0018] Figure 2A is a graph of the relative spectral efficacy of UV radiation as a function of wavelength (on the horizontal axis). As shown in Figure 2A, the potential for UV irradiation to cause damage to human tissue peaks at approximately 270 nm. At longer wavelengths, the radiation has insufficient energy to cause damage. At shorter wavelengths, it cannot penetrate the germinal layer, which gives rise to new cells. These spectral efficacy values ​​are then used to identify daily (8-hour) exposure limits (for a worker's typical workday).

[0019] Figure 2B shows millijoules per square centimeter (mJ / cm) as a function of wavelength. 2 ) is a graph of threshold limit values ​​in units of 1000 mJ / cm². Line 201 is the current guidance provided by ACGIH and ICNIRP. Lines 202 and 203 provide proposed updated guidance for threshold limit values ​​(TLVs) for human skin (line 203) and eye (line 202) exposure, taking into account recent research findings. These proposed changes to the 8-hour exposure limit result in a seven-fold increase in the permissible eye exposure (23 mJ / cm²). 2 to 161 mJ / cm 2 ), and a more than 20-fold increase in the permissible skin exposure (23 mJ / cm 2 to 479 mJ / cm 2 (To).

[0020] As discussed above, exposure to far UV-C radiation has been shown to be significantly safer for human tissue than previously assumed. Meanwhile, disinfection with far UV-C irradiation remains effective. Indeed, respiratory viruses (including SARS-CoV-2, HuCoV-229E, and influenza A) are among the pathogens most sensitive to far UV-C radiation, so very low doses of far UV-C radiation are required to inactivate respiratory viruses. Because exposure limits recently proposed by the ACGIH far exceed the doses of far UV-C radiation likely required for disinfection applications, far UV-C irradiation can be safely used to inactivate pathogens in air, aerosols, on surfaces, or in water. Therefore, protective respirators and devices are disclosed that utilize the safety and effectiveness of far UV-C radiation to provide effective, reusable, and scalable personal protection for individuals and groups of individuals.

[0021] 3 is a block diagram of a protective respirator 300 according to an exemplary embodiment. As shown in FIG. 3, the protective respirator 300 includes one or more Far UV-C radiation sources 400, a controller 310, and a power source 390. In some embodiments, the protective respirator 300 may also include a proximity sensor 320, a communications module 320, an air temperature sensor 340, an inertial measurement unit 350, a geolocation module 360, a microphone 370, and / or a physiological sensor 380.

[0022] The far UV-C radiation source 400 may include any UV radiation source having a wavelength between about 200 nm and about 230 nm. As described below with reference to Figure 4, the far UV-C radiation source 400 may be an optically filtered krypton chloride (KrCl*) excimer lamp that outputs far UV-C radiation having a wavelength centered around 222 nm.

[0023] Controller 310 may be any suitable computing device capable of performing the functions described herein. In the embodiment of Figure 3, controller 310 includes a non-transitory computer-readable storage medium (memory 318) and a hardware computer processor 314. In other embodiments, controller 310 may be, for example, a finite state machine.

[0024] The communications module 320 may be any hardware device that enables the protective respirator 300 to communicate with other electronic devices directly and / or over a network. For example, the communications module 320 may provide the functionality for the respirator 300 to communicate with other respirators 300 and / or personal electronic devices (e.g., smartphones, activity monitors, fitness trackers, etc.) using direct, short-range, wireless communications (e.g., Bluetooth).

[0025] Distance sensor 330 may be any device suitably configured to detect the presence of a nearby object without any physical contact and to sense data indicative of the distance between protective respirator 300 and the nearby object.

[0026] Air temperature sensor 340 may include any electronic device used to collect data indicative of the atmosphere surrounding protective respirator 300. Air temperature sensor 340 may include temperature sensor 322, relative humidity sensor 324, barometer 326, and / or wind speed sensor 328.

[0027] The inertial measurement unit 350 may include any hardware device that measures and reports the movement and / or orientation of the protective respirator 300. The internal measurement unit 350 may include an accelerometer 352, a gyroscope 354, and / or a magnetometer 356.

[0028] Geolocation module 360 ​​may include any hardware device that determines or estimates the geographic location of protective respirator 300 using, for example, satellite navigation, network identification, communication with location beacons, or the like.

[0029] Microphone 370 may be any hardware device that senses audible noise. Power source 390 may be any hardware device that provides power to protective respirator 300. In the wearable embodiments described below, power source 390 may be a rechargeable battery. In other embodiments, power source 390 may be a wired connection to an external power source.

[0030] Physiological sensors 380 may include any hardware device that senses data indicative of the physiological condition of a user wearing protective respirator 300. Physiological sensors 380 may include a photoplethysmogram (PPG) sensor 382, ​​which uses a light source and photodetector on the surface of the skin to measure volumetric changes in blood circulation, and / or a galvanic skin response (GSR) sensor 384, which detects changes in electrical (ionic) activity resulting from changes in sweat gland activity. Data from PPG sensor 382 may be used, for example, to estimate the frequency, strength, and amplitude of the user's breathing.

[0031] Movement of the protective respirator 300 can affect the data captured by the physiological sensors 380, the atmospheric sensors 340, etc. Thus, in some embodiments, the controller 310 can determine movement of the protective respirator 300 and use digital signal processing algorithms (e.g., stored in memory 318) to remove motion artifacts affected by the movement from the data received by the sensors.

[0032] 4A and 4B are diagrams of a Far UV-C radiation source 400 according to an example embodiment.

[0033] 4A and 4B, the far UV-C radiation source 400 includes a plurality of microcavities 440, each of which accumulates a low-temperature plasma. The far UV-C radiation source 400 also includes a plurality of anodes 420 and cathodes 430 electrically connected to a power source 390. In response to power supplied by the anodes 420 and cathodes 430, the plasma within the microcavities 440 generates excimers 460, which emit far UV-C radiation 450. In the embodiment of FIGS. 4A and 4B, the excimers 460 are krypton chloride.

[0034] 4C is a graph 490 of the normalized power output (logarithmic scale) of two exemplary Far UV-C radiation sources 400 across the UV spectrum. Line 491 represents the normalized power output of the first exemplary Far UV-C radiation source 400 (unfiltered), and line 492 represents the normalized power output of the second exemplary Far UV-C radiation source 400 (unfiltered). As shown in FIG. 4C, the krypton-chloride (KrCl*) excimer lamp has a major primary peak centered around 222 nm and is therefore well suited for inactivating aerosolized viruses, as described below.

[0035] Additionally, krypton-chloride excimer lamps have a secondary peak near 258 nm. Because radiation with the wavelength of the secondary peak can be damaging to human tissue, the far UV-C radiation source 400 of Figures 4A and 4B also includes an optical filter 480 to attenuate transmission outside the far UV-C spectrum. In graph 490, line 495 represents the optically filtered output of the first exemplary far UV-C radiation source 400 with optical filter 480, and line 492 represents the normalized output of the second exemplary far UV-C radiation source 400 with optical filter 480. As shown in graph 490, when optical filter 480 is applied, it can reduce the potentially harmful secondary peak by approximately 100 times.

[0036] These exemplary Far UV-C radiation sources 400, known as microcavity plasmas (or simply microplasmas), are characterized by continuous operation at pressures up to and above 1 atmosphere, low gas temperatures, and plasma volumes in the nanoliter range. The confinement of the plasma by the cavity allows for electron temperatures of a few eV and plasma volumes in the 10 13 ~10 16 cubic centimeter (cm 3 ), resulting in the generation of a stable, diffuse, and uniform glow discharge with an electron density of 1000 kJ / cm. These values ​​are unprecedented for a continuous wave (CW), high-pressure glow and are ideally suited for efficient excitation of light emitters in the gas phase. Due to the unique properties of plasma confined in a microcavity structure 440, the exemplary Far UV-C radiation source 400 of FIGS. 4A and 4B is a thin, lightweight UV radiation source that provides instant illumination and extinction over a long lifetime.

[0037] Unbalanced photon flux (dose) can result in inconsistent kill rates over space or time. Conventional UV lamps have a cylindrical shape and therefore cannot provide uniform treatment over a large area without specific equipment. In contrast, the exemplary Far UV-C radiation source 400 of FIGS. 4A and 4B efficiently utilizes Far UV-C photons in a flat form factor and provides a uniform distribution of emitted photons over a large surface or space to effectively kill microorganisms and viruses across a target space (air, aerosols, particles, droplets, surfaces, water, etc.).

[0038] 4A and 4B, in some embodiments, the Far UV-C radiation source 400 may be a microplasma krypton-chloride excimer lamp. However, in other embodiments, the protective respirator 300 may include other Far UV-C radiation sources 400, including excimer lasers, light emitting diodes (LEDs), laser diodes, etc.

[0039] 5A-5G show various wearable embodiments of a protective respirator 300. In the embodiment of FIG. 5A, the protective respirator 300a incorporates a Far UV-C radiation source 400 into a pendant 500a that can be worn around a user's neck to emit Far UV-C radiation 450 through a volume in front of the user's nose and mouth, effectively covering the individual's breathing volume.

[0040] In the embodiments of Figures 5B-5D, protective respirators 300b-300d are realized as headwear 500b, 500c, and 500d, respectively, including a boom 510 that extends in front of the user's face. In these embodiments, a far UV-C radiation source 400 can be incorporated into the boom 510 to emit far UV-C radiation 450 over an area in front of the user's nose and mouth. In some of these embodiments, the far UV-C radiation source 400 can emit far UV-C radiation 450 toward the user's face. In Figure 5E, protective respirator 300e is realized as a hat 500d having a brim 520. In these embodiments, the far UV-C radiation source 400 can be attached to the bottom of the brim 520 to emit far UV-C radiation 450 over an area in front of the user's nose and mouth. In Figure 5F, protective respirator 300f is realized as a helmet 500f with a Far UV-C radiation source 400 extending from the front to emit Far UV-C radiation 450 over the area in front of the user's nose and mouth. In the embodiment of Figure 5G, protective respirator 300g is realized such that Far UV-C radiation source 400 is incorporated into eyewear 500g.

[0041] In wearable embodiments, protective respirator 300 emits far UV-C radiation 450 through a kill zone 600 in front of the user's nose and mouth. Figures 6A-6D illustrate kill zone 600 according to various exemplary embodiments.

[0042] In some wearable embodiments, such as pendant 500a and eyeglasses 500g, protective respirator 300 is configured such that far UV-C radiation source 400 emits far UV-C radiation 450 away from the user's skin and eyes. As shown in Figures 6A and 6B, kill zone 600a is the volume of air that includes a plane (e.g., approximately 10 cm x 10 cm) in front of the user's mouth and nose. In the embodiment of Figure 6C, kill zone 600b includes a cone-shaped volume of air with an apex in front of the user's mouth.

[0043] In other embodiments, protective respirator 300 may be configured so that some Far UV-C radiation is absorbed by the user's skin or eyes. In the embodiment of Figure 6D, kill zone 600d is a volume that includes the user's mouth, nose, and, in some embodiments, the user's eyes.

[0044] As described above, protective respirator 300 is configured to inactivate microorganisms (including microorganisms such as bacteria, spores, viruses, protozoa, and / or fungi and / or viral particles) by emitting Far UV-C radiation 450. In some embodiments, protective respirator 300 is configured to provide a threshold probability (e.g., 90 percent, 99 percent, 99.9 percent, etc.) of killing a particular microorganism traveling through kill zone 600. The probability p of killing a particular microorganism during irradiation (or the percentage of those microorganisms killed) depends on the fluence D of Far UV-C irradiation 450 and the susceptibility constant k of the particular microorganism. p=1-e -D*k On the other hand, the fluence D of the far UV-C radiation 450 depends on the intensity I of the far UV-C radiation 450 along the path of the microorganism and the time t that the microorganism is exposed to the far UV-C radiation 450. D=∫I(t) dt

[0045] Returning briefly to FIG. 5A , in embodiments where the far UV-C radiation source 400 is a point source, the intensity I of the far UV-C radiation 450 decreases with the inverse square of the distance from the far UV-C radiation source 400. Meanwhile, the time t that a microorganism is exposed depends on the microorganism's speed and the distance d through the far UV-C radiation 450. The longer a particle's path through the far UV-C radiation 450, the greater the absorbed radiation or fluence, resulting in a higher rate of microorganism death within the particle. Particles passing a longer relative distance (e.g., distance d3 in FIG. 5A ) may experience a longer exposure to the far UV-C radiation 450 than particles passing a shorter relative distance (e.g., distance d1 in FIG. 5A ), resulting in a higher level of received fluence D.

[0046] 3 , in some embodiments, the controller 310 determines the intensity I required to emit the far UV-C radiation 450 to achieve a predetermined probability p (e.g., 90 percent, 99 percent, etc.) of killing a selected microorganism (e.g., the SARS-CoV-2 virus). In other embodiments, the intensity I of the UV-C radiation 450 emitted by the UV-C radiation source 400 may be constant. In some of these embodiments, the controller 310 may determine the time t required to emit the far UV-C radiation 450 to achieve the predetermined probability p of killing the selected microorganism.

[0047] In addition to the distance from the Far UV-C radiation source 400 and the distance d that the microorganism travels through the Far UV-C radiation 450, the intensity I and / or time t required to achieve the probability p of killing a particular microorganism depends on the velocity of the microorganism, which in turn depends on the aerosol particle size distribution and atmospheric conditions (humidity, wind speed, or local ventilation) in the kill zone 600. Thus, in some embodiments, the protective respirator 300 collects data indicative of the atmospheric conditions within the kill zone 600.

[0048] For example, in some embodiments, protective respirator 300 may receive data indicative of the air temperature within kill zone 600 (e.g., from temperature sensor 322), the relative humidity within kill zone 600 (e.g., from relative humidity sensor 324), the absolute air pressure and / or changes in air pressure within kill zone 600 (e.g., using air pressure measurements from barometer 326), and / or the wind speed or ventilation within kill zone 600 (e.g., using data from wind speed sensor 328).

[0049] In wearable embodiments, kill zone 600 includes the area in front of the user's nose and mouth. Thus, in these wearable embodiments, the atmospheric conditions within kill zone 600 may be highly dependent on the user's behavior (e.g., the frequency, intensity, and amplitude of the user's breathing). Accordingly, in some embodiments, protective respirator 300 may collect data indicative of the user's physiological condition. In some embodiments, for example, protective respirator 300 may receive data indicative of the user's activity level (e.g., from geolocation module 360 ​​and / or inertial measurement unit 350). In these embodiments, controller 210 may store information indicative of the user's physiological condition (e.g., gender, weight, height, smoking status, pulmonary health, etc.). Together, the user's activity level and the user's physiological condition are highly correlated with the user's breathing frequency, intensity, and amplitude.

[0050] In other embodiments, the protective respirator 300 can receive data indicative of the user's physiological condition (e.g., data indicative of volumetric changes in blood circulation from the PPG sensor 382, ​​data indicative of galvanic skin response from the GSR sensor 384, etc.), which is also highly correlated with the frequency, strength, and amplitude of the user's breathing.

[0051] In yet other embodiments, protective respirator 300 can receive sound data (e.g., from microphone 370) and execute a mathematical model (e.g., stored in memory 318) to isolate sounds indicative of the user's breathing.

[0052] In some wearable embodiments, the protective respirator 300 may be worn on a user's body in a position uniquely suited to collecting data indicative of respiration. In embodiments in which the Far UV-C radiation source 400 is incorporated into the pendant 500a of FIG. 5A, for example, the protective respirator 300b-300d may include an inertial measurement unit 350 that collects data indicative of the user's chest movement, which is highly correlated with the frequency, intensity, and amplitude of the user's breathing. In embodiments in which the Far UV-C radiation source 400 is incorporated into the headwear 500b of FIG. 5B or the headsets 500c or 500d of FIG. 5C or 5D, the protective respirator 300b-300d may include a PPG sensor 382 on the user's temple to measure data indicative of volumetric fluctuations in blood circulation.

[0053] To determine the required intensity I of Far UV-C radiation 450 (and / or the required amount of time t for emitting Far UV-C radiation 450) to achieve a predetermined probability p of killing a selected microorganism, controller 310 uses a mathematical model (e.g., stored in memory 318) developed based on laboratory experiments and computational fluid dynamics.

[0054] FIG. 7A shows an exemplary laboratory experiment 700 for measuring the intrinsic kinetics of the inactivation response of aerosolized viruses.

[0055] In the exemplary laboratory experiment 700, aerosolized virus is introduced into a quartz channel 750 using a nebulizer 710. The quartz channel 750 contains multiple Far UV-C radiation sources 400 that emit Far UV-C radiation 450. The aerosolized virus is exposed to the Far UV-C radiation 450 as it passes through the quartz channel 750. Samples are collected at the output of the quartz channel 750 using a bioaerosol sampler 790. These samples are then analyzed to determine the inactivation response of the aerosolized virus exposed to the Far UV-C radiation 450.

[0056] To determine the inactivation response of known viruses, laboratory experiments are performed using biological surrogates of these pathogens. For example, experiments are performed using phages that have the ability to infect bacteria but not affect human tissue. To determine the inactivation response of coronaviruses, for example, phages are selected that have a response to UV radiation similar to that of those coronaviruses. For example, T1 and T1UV phages, Φ6 phages, Qβ phages, and mouse hepatitis virus (MHV) all have similar log-linear (first-order) behavior, all of which are slightly conservative relative to coronaviruses.

[0057] These laboratory experiments are used to measure the intrinsic kinetics of the inactivation response of known pathogens, and then computer models using computational fluid dynamics simulate the inactivation response of these known pathogens.

[0058] 7B shows a computer simulation of the inactivation response during experiment 700. Heat map 740 is a map of the velocity vector field through quartz channel 750. Image 760 is a map of the fluence rate contour of one of the Far UV-C radiation sources 400. By integrating the velocity field and fluence rate of the Far UV-C radiation source 400 with the inactivation kinetics of a specific pathogen, the system can develop a mathematical model that predicts the inactivation response of a specific pathogen as it passes through channel 750, as shown in image 780.

[0059] 8A-8C further illustrate a simulation using computational fluid dynamics to inform a model executed by the controller 310 of the protective respirator 300 to determine the required intensity I of the Far UV-C radiation 450 (and / or the required amount of time t for emitting the Far UV-C radiation 450) to achieve a predetermined probability p of killing a selected microorganism.

[0060] 8A is a simulation of airflow 810 in a room containing a user 820 wearing a protective respirator 300 and a person 860 (not shown) who is emitting viruses toward the user 820 (e.g., by coughing or breathing). FIG. 8B shows a heat map 840 of the simulated fluence rate of Far UV-C radiation 450 emitted by the Far UV-C radiation source 400 of the protective respirator 300 worn by the user 820. Using computational fluid dynamics, the system combines the velocity field in the user's 820's environment (shown in FIG. 8A), the fluence rate of Far UV-C radiation 450 emitted by the Far UV-C radiation source 400 of the protective respirator 300 (shown in FIG. 8B), and the specific kinetics of inactivation of specific pathogens (e.g., identified using laboratory experiments, as shown in FIG. 7A) to develop a mathematical model of the inactivation response of specific pathogens through the kill zone 600 of the protective respirator 300. 8A and 8B , as determined by a mathematical model. Using that mathematical model (and, in some embodiments, data indicative of atmospheric conditions within kill zone 600), controller 310 determines the required intensity I of Far UV-C radiation 450 (and / or the required amount of time t for emitting Far UV-C radiation 450) to deliver the fluence D required to achieve a predetermined probability p of killing a particular microorganism (e.g., SARS-CoV-2) upon passing through kill zone 600.

[0061] As described above, in wearable embodiments, protective respirator 300 protects the user (and reduces the likelihood of the user infecting others nearby) by emitting Far UV-C radiation 450 through kill zone 600 in front of the user's mouth and nose. In some embodiments, protective respirator 300 also protects the user from exposure to unsafe amounts of Far UV-C radiation.

[0062] In some wearable embodiments, the protective respirator 300 is implemented such that the Far UV-C radiation source 400 emits Far UV-C radiation 450 through a kill zone 600 in front of the user's mouth and nose (e.g., as shown in FIG. 5C ) and away from the user (e.g., as shown in FIGS. 6A-6C ). In other wearable embodiments, the protective respirator 300 is implemented such that the Far UV-C radiation source 400 emits Far UV-C radiation 450 across a kill zone 600 in front of the user's nose and mouth (e.g., as shown in FIGS. 6A-6B ) without emitting the Far UV-C radiation 450 toward the user's skin or eyes (e.g., as shown in FIG. 5A ). However, in some embodiments, some of the Far UV-C radiation 450 emitted by one or more Far UV-C radiation sources 400 may be absorbed by the user's skin or eyes. Thus, in some of these embodiments, the controller 310 may be configured to limit the amount of Far UV-C radiation 450 emitted towards the user.

[0063] 3 , in some embodiments, controller 310 receives data (e.g., from distance sensor 330) indicating the distance between one or more of Far UV-C radiation sources 400 and a user. Using that distance and the intensity I of Far UV-C radiation 450 emitted toward the user, controller 310 can determine the fluence of Far UV-C radiation 450 at the user's skin or eyes. In some of these embodiments, controller 310 can determine the total dose of Far UV-C radiation 450 over time and adjust the intensity I of Far UV-C radiation 450 emitted toward the user (or the time t over which Far UV-C radiation 450 is emitted toward the user) to limit the dose of Far UV-C radiation 450 absorbed by the user's skin and / or eyes. For example, the controller 310 may reduce the intensity I of the Far UV-C radiation 450 (or the time t over which the Far UV-C radiation 450 is emitted) to prevent the protective respirator 300 from emitting more than a threshold limit of Far UV-C radiation 450 toward the user for a predetermined period of time (e.g., 8 hours) or for a period of time specified by the user that the user is expected to wear the protective respirator 300.

[0064] In embodiments in which the protective respirator 300 includes two or more Far UV-C radiation sources 400, the controller 310 can use data from the distance sensors 330 to determine which of the Far UV-C radiation sources 400 are emitting Far UV-C radiation 450 toward the user's skin or eyes (and the distance between each of those Far UV-C radiation sources 400) and limit the intensity I of the Far UV-C radiation 450 (and / or the time t over which the Far UV-C radiation 450 is emitted) for a predetermined or user-specified time.

[0065] In embodiments in which the power source 390 is a rechargeable battery, the controller 310 may also monitor the amount of charge accumulated by the battery over time and limit the intensity I of the Far UV-C radiation 450 (and / or the time t over which the Far UV-C radiation 450 is emitted) so that the protective respirator 300 emits Far UV-C radiation 450 for a predetermined period of time, or for a period of time specified by the user, that the user is expected to wear the protective respirator 300.

[0066] 9 is a diagram of a network environment 900 according to an exemplary embodiment. As shown in FIG. 9, protective respirator 300 may communicate with server 920 (e.g., using communication module 320) over one or more wide area networks 950, such as the Internet. Additionally or alternatively, protective respirator 300 may be paired with personal electronic device 940 (e.g., a smartphone) using a direct wireless communication protocol (e.g., Bluetooth). In these embodiments, protective respirator 300 may communicate with server 920 via personal electronic device 940. In some of these embodiments, personal electronic device 940 may also be paired with activity tracker 960 (e.g., a fitness tracker, wristband, smartwatch, etc.).

[0067] By communicating with server 920, protective respirator 300 can receive a mathematical model (developed using computational fluid dynamics and the specific kinetics of inactivation identified in laboratory experiments, as described above) used by controller 310 to determine the required intensity I of Far UV-C radiation 450 (and / or the required amount of time t to emit Far UV-C radiation 450) to deliver the fluence D necessary to achieve a predetermined probability p of killing a particular microorganism (e.g., SARS-CoV-2) as it passes through kill zone 600.

[0068] As described above with reference to FIG. 3 , in some embodiments, the required intensity I of Far UV-C radiation 450 (and / or the required amount of time t for emitting Far UV-C radiation 450) is determined using data indicative of the atmospheric conditions surrounding protective respirator 300 and / or the user's physiological condition (e.g., breathing). In the embodiment of FIG. 3 , protective respirator 300 includes atmospheric sensor 340, inertial measurement unit 350, geolocation module 360, microphone 370, and / or physiological sensor 380. However, in other embodiments, personal electronic device 940 and / or activity tracker 960 may include some or all of these sensors. In some of these embodiments, protective respirator 300 may receive data indicative of the atmospheric conditions and / or the user's physiological condition from personal electronic device 940 and / or activity tracker 960.

[0069] 9, in some embodiments, protective respirator 300 may receive data indicative of atmospheric conditions from other sources. For example, protective respirator 300 may receive data indicative of atmospheric conditions from a location beacon 980 (e.g., indicating that protective respirator 300 is located in a building having a particular ventilation system that provides a particular rate of air exchange).

[0070] In some embodiments, each protective respirator 300 is configured to communicate with other protective respirators 300 (e.g., via Bluetooth, a mesh network, a local area network, a cell network, etc.). In some of these embodiments, each protective respirator 300 can determine the required intensity I of Far UV-C radiation 450 (and / or the required amount of time t to emit Far UV-C radiation 450) as dictated by a mathematical model so that the protective respirators 300 collectively achieve a predetermined probability p of killing a specified microorganism in each user's kill zone 600.

[0071] In some embodiments, protective respirator 300 may receive data indicative of atmospheric conditions from server 920. For example, one atmospheric condition that may be relevant to determining the required intensity I of Far UV-C radiation 450 (and / or the required amount of time t to emit Far UV-C radiation 450) is whether protective respirator 300 is indoors or outdoors. Accordingly, in some embodiments, controller 310 may output the geographic location of protective respirator 300 (e.g., as determined by geolocation module 360), and server 920 may determine whether protective respirator 300 is indoors or outdoors based on that location. To determine whether protective respirator 300 is indoors or outdoors, server 920 may store a two-dimensional map of building locations and determine whether the location of protective respirator 300 is within one of the buildings. Additionally, the server 920 may store a terrain map and determine whether the elevation of the protective respirator 300 is above or below ground level (indicating that the user is on an upper floor or underground).

[0072] FIG. 10 is a flowchart illustrating a process 1000 performed by protective respirator 300 to inactivate microorganisms (e.g., microorganisms such as bacteria, spores, viruses, protozoa, and / or fungi, and / or viral particles), according to an exemplary embodiment. As described in detail above, protective respirator 300 inactivates microorganisms by emitting Far UV-C radiation 450. In some embodiments, protective respirator 300 is configured to emit Far UV-C radiation 450 with sufficient intensity / for a time t sufficient to provide a threshold probability (e.g., 90 percent, 99 percent) of killing a particular microorganism (e.g., SARS-CoV-2 virus) traveling through kill zone 600.

[0073] To determine the required intensity I and / or required time t of Far UV-C radiation 450 to achieve a threshold probability of killing a selected microorganism, protective respirator 300 stores a mathematical model in memory 318 in step 1002. As described above, the mathematical model may be developed by using computational fluid dynamics to combine the velocity fields in various simulated environments, the fluence rate of Far UV-C radiation 450 emitted by Far UV-C radiation source 400, and the specific kinetics of the inactivation response of the selected microorganism (identified in laboratory experiments). As described above with reference to FIG. 9, in some networked embodiments, the mathematical model may be received from server 920. In other embodiments, the mathematical model may be stored in memory 318 at the time of manufacture.

[0074] As discussed above, the intensity I (and / or the required time t) required to achieve a threshold probability p of killing a particular microorganism depends on the velocity of the microorganism, which may depend on the atmospheric conditions within the kill zone 600. Thus, in some embodiments, the protective respirator 300 receives data indicative of the atmospheric conditions in the environment surrounding the protective respirator 300, in step 1004. As discussed above with reference to FIG. 9, the data indicative of the atmospheric conditions may be received from a server 920, a personal electronic device 940, a location beacon 980, etc. As discussed above with reference to FIG. 3, the data indicative of the atmospheric conditions may be received from one or more atmospheric sensors 340 (integrated with the protective respirator 300, the personal electronic device 940, etc.).

[0075] As discussed above, the atmospheric conditions within the kill zone 600 may depend on the physiological condition of the user. Accordingly, in some embodiments, the protective respirator 300 receives data indicative of the user's physiological condition in step 1006. As discussed above with reference to FIG. 9, the data indicative of the user's physiological condition may be received from a personal electronic device 940, an activity tracker 960, etc. As discussed above with reference to FIG. 3, the data indicative of the user's physiological condition may be received from an inertial measurement unit 350, a geolocation module 360, one or more physiological sensors 380, etc. (integrated with the protective respirator 300, the personal electronic device 940, the activity tracker 960, etc.).

[0076] The controller 310 determines, in step 1008, the intensity I (and / or the time t required) required to achieve a threshold probability p of killing a particular microorganism.

[0077] In some embodiments, the protective respirator 300 is configured such that one or more of the Far UV-C radiation sources 400 emit Far UV-C radiation 450 toward the skin and / or eyes of a user. Thus, in some embodiments, the controller 310 determines, in step 1010, a fluence rate D of the Far UV-C radiation 450 absorbed by the user, and, in step 1012, adjusts the intensity I of the Far UV-C radiation 450 emitted by one or more of the Far UV-C radiation sources 400 and / or the time t over which one or more of the Far UV-C radiation sources 400 emit Far UV-C radiation 450 to prevent the fluence of the Far UV-C radiation 450 absorbed by the user's skin or eyes from exceeding a threshold limit value over a predetermined period of time (e.g., 8 hours) or over a user-specified period of time during which the user is expected to wear the protective respirator 300.

[0078] In some embodiments, the power source 390 of the protective respirator 300 is a rechargeable battery. Thus, in some embodiments, the controller 310, in step 1014, determines the amount of charge remaining in the power source 390 and adjusts the intensity I of the Far UV-C radiation 450 (and / or the time t over which the Far UV-C radiation 450 is emitted) so that the protective respirator 300 emits Far UV-C radiation 450 for the entire predetermined period (e.g., 8 hours) or for a period of time specified by the user that the user is expected to wear the protective respirator 300.

[0079] As mentioned above, in some embodiments, the protective respirator 300 may be wearable. However, the protective respirator 300 is not so limited.

[0080] 11 illustrates a portable embodiment of a protective respirator 300. In the portable embodiment of FIG. 11, the protective respirator 300 is implemented as a wand 1100 that includes one or more Far UV-C radiation sources 400 that emit Far UV-C radiation 450.

[0081] 12 illustrates a stationary embodiment of a protective respirator 300. In the embodiment of FIG. 12, the protective respirator 300 is realized as an object 1200 (in this example, a table tamp) that includes one or more Far UV-C radiation sources 400 that emit Far UV-C radiation 450.

[0082] While preferred embodiments have been described above, those skilled in the art who have reviewed this disclosure will readily appreciate that other embodiments may be realized within the scope of the invention. Accordingly, it is intended that the invention be construed as limited only by any accompanying patent claims.

Claims

1. 1. A protective respirator that utilizes ultraviolet (UV) radiation to inactivate pathogens in a kill zone in front of a user's mouth and nose, the protective respirator comprising: Power supply, one or more UV-C radiation sources that emit UV-C radiation through the kill zone; a controller that determines a required intensity of the UV-C radiation, or a required time to emit the UV-C radiation, based at least in part on data indicative of one or more physiological conditions of the user, and provides a predetermined probability of killing a microorganism traveling through the kill zone; Including, The one or more UV-C radiation sources emit the UV-C radiation through the kill zone at a required intensity or for a required time as determined by the controller.

2. 10. The protective respirator of claim 1, wherein the UV-C radiation has a wavelength centered around 222 nanometers (nm).

3. 10. The protective respirator of claim 1, wherein the microorganism is a virus.

4. The protective respirator of claim 1, wherein the one or more UV-C radiation sources emit Far UV-C radiation.

5. the required intensity or duration is further determined based on one or more atmospheric conditions; the controller receiving data indicative of the one or more atmospheric conditions; 10. The protective respirator of claim 1.

6. 6. The protective respirator of claim 5, wherein the data indicative of the one or more atmospheric conditions is received from a server, a personal electronic device, or a location beacon.

7. 6. The protective respirator of claim 5, wherein the data indicative of the one or more atmospheric conditions is determined by one or more atmospheric sensors.

8. The method of claim 7, further comprising: a communications module for communicating with additional protective respirators having associated kill zones in front of additional users; the controller determines a required intensity or time for each of the protective respirator and the additional protective respirator, collectively providing a predetermined probability of killing microorganisms in the kill zone of the protective respirator and each of the associated kill zones of the additional protective respirators; 10. The protective respirator of claim 1.

9. The protective respirator of claim 1 , wherein the data indicative of the one or more physiological conditions is received from a personal electronic device or a fitness tracker.

10. 10. The protective respirator of claim 1, wherein the data indicative of the one or more physiological conditions is determined by an inertial measurement unit, a geolocation module, or one or more physiological sensors.

11. 10. The protective respirator of claim 1, wherein the one or more UV-C radiation sources emit UV-C radiation away from the user.

12. 10. The protective respirator of claim 1, wherein the one or more UV-C radiation sources emit the UV-C radiation through the kill zone in a direction that does not intersect the skin or eyes of the user.

13. The controller: Estimating the fluence of UV-C radiation at the user's skin or eye over time; adjusting the UV-C radiation emitted by the one or more UV-C radiation sources in response to the estimated fluence.

10. The protective respirator of claim 1.

14. The controller: monitoring the charge level of said power source over time; adjusting the UV-C radiation emitted by the one or more UV-C radiation sources in response to the monitored charge level.

10. The protective respirator of claim 1.

15. 1. A method of inactivating pathogens in a kill zone in front of a user's mouth and nose using ultraviolet (UV) radiation with a protective respirator, the protective respirator including a power source, a controller, and one or more sources of UV-C radiation, the method comprising: receiving, by the controller, data indicative of one or more physiological conditions of the user; determining, by the controller, a required intensity of UV-C radiation or a time required to emit the UV-C radiation based at least in part on the one or more physiological conditions of the user to provide a predetermined probability of killing microorganisms traveling through the kill zone; emitting UV-C radiation by the one or more UV-C radiation sources through the kill zone in front of the user's mouth and nose at the determined intensity or for the determined time necessary to provide a predetermined probability of killing microorganisms traveling through the kill zone; The method includes:

16. receiving data indicative of the one or more atmospheric conditions; the required intensity or duration is further determined based on the data indicative of the one or more atmospheric conditions. The method of claim 15.

17. The method of claim 16 , wherein the data indicative of the one or more atmospheric conditions is determined by one or more atmospheric sensors.

18. The method of claim 15, wherein determining the required intensity or time includes determining the required intensity or time for each of a plurality of protective respirators to collectively provide a predetermined probability of killing microorganisms in each of a plurality of kill zones in front of the mouths and noses of a plurality of users.

19. The method of claim 15 , wherein the data indicative of the one or more physiological conditions is received from a personal electronic device or a fitness tracker.

20. The method of claim 15 , wherein the data indicative of the one or more physiological conditions is determined by an inertial measurement unit, a geolocation module, or one or more physiological sensors.

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