Full-particle-size respiratory droplet sampling system

Abstract

A full-particle-size respiratory droplet sampling system. Airflow exhaled from a human body directly enters a droplet collection device (1); the droplet collection device (1) is communicated with a sampling flow rate adjustment device (5) by means of a droplet bent collection device (2) and a droplet particle size screening device (3); the droplet collection device (1) is communicated with a droplet particle size measurement device (6); the droplet collection device (1), the droplet bent collection device (2) and the droplet particle size screening device (3) are all arranged in a sampling chamber air supply and filtering device (4); under the action of the sampling flow rate adjustment device (5), the airflow passes through a metal shell (12), an impact guide member (21), a bent redirection member (23) and a vertical transition pipeline (24) and then enters an impactor (31); a laser component (63) and a camera (62) are used in cooperation; and a droplet particle size distribution is obtained by means of processing of a computer (65).

Description

A full-size respiratory droplet sampling system Technical Field

[0001] The present invention relates to a droplet sampling system in the technical field of virus sampling, and in particular to a full-particle-size respiratory droplet sampling system. Background Art

[0002] Respiratory droplets are the most important carriers of respiratory pathogens. In the study of various respiratory infectious diseases, their transmission routes can be divided into large droplet splash transmission, close / long-range air transmission, and direct / indirect surface contact transmission, etc., according to the exposure mechanism of susceptible people's respiratory droplets. The particle size of respiratory droplets not only affects its kinetic characteristics during the transmission process, but also affects its virus carrying capacity and the deposition site in the respiratory tract of susceptible people. It plays an important role in the prevention and control of respiratory infectious diseases. However, at present, the relative importance of droplets of different particle sizes in the transmission process of pathogens is still controversial. Therefore, a system that can be used for live virus sampling and particle size measurement in the entire particle size range of human respiratory droplets is developed, which can be used to study the particle size effect of respiratory droplets and provide direct evidence for the transmission risk assessment of respiratory pathogens.

[0003] At present, some respiratory droplet sampling systems have been developed abroad, but the sampling efficiency of droplets larger than 10 μm is low or cannot provide effective collection data, and they fail to provide droplet particle size distribution data.

[0004] The G-II sampling system developed by Harvard University operates at a flow rate of 130 L / min. Its main components consist of a conical inlet, a large-droplet slit impactor, a condensation growth unit, and a small-droplet slit impactor. It includes two sampling locations: a first-stage slit impactor located in the middle of a horizontal transition duct, and a second-stage slit impactor located after the bottom outlet of the saturator. The first-stage slit impactor is designed to collect all droplets larger than 5 μm, while the second-stage slit impactor is designed to collect all droplets smaller than 5 μm. However, the inlet design of this system is relatively large relative to the human head, and its regular shape and beveled end face do not conform to the ergonomic design of human respiratory activities such as breathing and speaking. This makes it difficult to position and orient the volunteer's head in actual sampling scenarios. When the head enters the inlet, the mouth is still a short distance from the lower edge of the inlet, making it difficult to accurately control the position and direction of the exhaled airflow. This can easily cause large droplets to escape or be lost at the inlet, preventing them from being effectively transmitted to the slit. Therefore, its actual sampling range is only 0.05 μm-10 μm, and there is a lack of test data on droplets with larger particle sizes. The impact of different respiratory airflow rates on the system sampling performance is not considered. The overall size of the system is large, and the components cannot be separated and disassembled.

[0005] The two-stage cyclonic aerosol sampler developed by the U.S. National Institute for Occupational Safety and Health (NIOSH) operates at a flow rate of 3.5 L / min and can collect aerosols into three categories: above 4 μm, 1-4 μm, and below 1 μm. However, its sampling range is generally between 10 nm and 10 μm, making it unable to sample droplets larger than 10 μm. Furthermore, the sample collection efficiency is low due to significant physical damage during impact. In experiments using it to sample H1N1 influenza virus aerosols, the bio-efficiency was only approximately 34%. Summary of the Invention

[0006] In order to solve the problems existing in the background technology, the purpose of the present invention is to design a full-particle size respiratory droplet sampling system.

[0007] The technical solutions of the present invention are as follows:

[0008] The system includes a droplet collection device, a droplet bend collection device, a droplet particle size screening device, a sampling chamber air supply filter device, a sampling flow rate regulating device and a droplet particle size measuring device; the gas exhaled by the human body enters the droplet collection device, the droplet collection device is connected to the inlet of the droplet particle size screening device through the droplet bend collection device, the outlet of the droplet particle size screening device is connected to the inlet of the sampling flow rate regulating device, a port is opened on the droplet collection device, the port of the droplet collection device is connected to the droplet particle size measuring device, and the droplet collection device, the droplet bend collection device and the droplet particle size screening device are all arranged in the sampling chamber air supply filter device.

[0009] The droplet collection device includes a human-sampler flexible interface with openings at both ends and a metal shell with openings at both ends. The human-sampler flexible interface is mounted on the metal shell. The inlet of the metal shell is connected to the outlet of the human-sampler flexible interface. The outlet of the metal shell is connected to the inlet of the droplet curve collection device. The exhaled gas of the human body enters the metal shell through the human-sampler flexible interface. The upper and lower sides of the human-sampler flexible interface are respectively provided with a nose wing positioning groove and a mandibular positioning groove, which respectively contact the nose wing and mandibular positioning groove of the human body.

[0010] A particle size spectrometer interface and a laser transmission slit are provided on the side wall of the metal shell. The light emitted by the droplet particle size measuring device is incident on the cavity inside the metal shell through the laser transmission slit. The particle size spectrometer interface is connected to the droplet particle size measuring device through a pipe. A first sampling film is attached to the inner bottom surface of the metal shell. A transparent visual window is provided on the side wall of the metal shell. A semicircular baffle is installed at the outlet of the metal shell, and a second sampling film is attached to the inner wall of the semicircular baffle.

[0011] The droplet curve collection device includes an impact guide component, an impact collection component, a curve turning component and a vertical transition pipe; the inlet of the impact guide component is connected to the outlet of the metal shell, the outlet of the impact guide component is connected to the inlet of the curve turning component, the two outlets of the curve turning component are respectively connected to the inlet of the impact collection component and the vertical transition pipe, and the outlet of the vertical transition pipe is connected to the inlet of the droplet particle size screening device; a third sampling membrane is provided in the impact collection component;

[0012] The droplet particle size screening device includes an impactor and a first filter; the inlet of the impactor is connected to the outlet of the vertical transition pipe, and the outlet of the impactor is connected to the inlet of the sampling flow rate regulating device through the first filter. The impactor lifting bracket is placed on the ground, and the impactor is fixedly mounted on the impactor lifting bracket;

[0013] The impactor includes an impact shell, an impact plate, a sampling plate and a fourth sampling membrane; the three impact plates are evenly spaced from top to bottom in the cavity of the impact shell along the height direction of the impact shell, and the three impact plates divide the cavity of the impact shell from top to bottom into an inlet cavity, a first filter cavity, a second filter cavity and an outlet cavity. A sampling plate is provided in each of the first filter cavity, the second filter cavity and the outlet cavity, and a fourth sampling membrane is attached to the upper surface of each sampling plate. The inlet cavity is connected to the outlet of the vertical transition pipe, and the outlet cavity is connected to the inlet of the sampling flow rate regulating device through the first filter.

[0014] The droplet collection device collects droplets with a particle size of 50 μm and above, the droplet curve collection device collects droplets with a particle size of 10-50 μm, and the three impact plates from top to bottom filter droplets with a particle size of 10 μm or above, droplets with a particle size of 5-10 μm, and droplets with a particle size of 2.5-5 μm respectively. The first filter filters droplets with a particle size of 2.5 μm and above.

[0015] The sampling chamber air supply filter device includes a positive pressure chamber, a positive pressure chamber bracket, a humidity adjustment unit and a filter assembly; the positive pressure chamber is a cavity mainly constructed of transparent plastic cloth, the positive pressure chamber bracket is placed on the ground, the positive pressure chamber is fixed on the positive pressure chamber bracket, and the filter assembly is installed on the top of the positive pressure chamber; the droplet collection device, the droplet bend collection device and the droplet particle size screening device are arranged in the positive pressure chamber;

[0016] The humidity adjustment unit includes a humidifier, a humidity sensor, a solenoid valve, a second filter and a humidifying nozzle. The outlet of the humidifier is connected to the humidifying nozzle through a pipe. The solenoid valve and the second filter are sequentially arranged on the pipe from the humidifier to the humidifying nozzle. The humidifying nozzle and the humidity sensor are both arranged inside the positive pressure chamber; the humidity sensor and the solenoid valve are both connected to the droplet particle size measuring device.

[0017] The droplet particle size measuring device includes an aerodynamic particle size spectrometer, a camera, a laser assembly, a camera bracket, and a computer; the aerodynamic particle size spectrometer is connected to the particle size spectrometer interface through a pipeline, the camera bracket is fixed to the ground, the camera is mounted on the camera bracket, and the camera is located on a side of the metal housing with a visual window, the light emitted by the laser assembly is incident on the interior of the metal housing through a laser transmission slit, and the aerodynamic particle size spectrometer, the camera, and the laser assembly are all electrically connected to the computer;

[0018] The humidity sensor and the solenoid valve of the humidity adjustment unit are both electrically connected to the computer.

[0019] The sampling flow rate regulating device includes a mass flow meter, a sampling pump and a fourth filter; the inlet of the fourth filter is connected to the outlet of the first filter, the outlet of the fourth filter is connected to the inlet of the sampling pump via a pipeline, and a mass flow meter is provided on the pipeline from the fourth filter to the sampling pump.

[0020] The impact collection component includes an impact cavity and a sample collector. The outlet of the impact cavity and the inlet of the sample collector are connected by a flange. A third sampling membrane is attached to the inner wall of the sample collector. The outlet of the curve steering component is connected to the inlet of the impact cavity.

[0021] The laser assembly includes a laser, a spatial filter, a plane mirror and a beam expander lens. The spatial filter is fixedly installed at the front end of the laser, the beam expander lens is located in front of the spatial filter, and the plane mirror is located in front of the beam expander lens and directly above the laser transmission slit. The light emitted by the laser is filtered by the spatial filter, transmitted by the beam expander lens, and reflected by the plane mirror, and then incident on the inside of the metal shell through the laser transmission slit.

[0022] This system offers the advantages of large droplet sampling and measurement, multi-level particle size screening, and a high degree of sampling freedom. The use of a water-soluble, viscous semisolid gelatin membrane (i.e., sampling membrane) to collect samples reduces droplet loss during collection and transfer while effectively preserving viral bioactivity. This system enables direct, efficient, quantitative sampling and analysis of live viruses and particle size measurement across the full range of respiratory droplet sizes, particularly virus-containing droplets larger than 10 μm. Virus concentrations in respiratory droplets of various sizes can be determined, providing direct evidence for studies of respiratory droplet size effects and transmission risk assessments.

[0023] The high-efficiency filter at the top of the plenum chamber is a HEPA filter. Because ambient air dust may interfere with the system's collection of droplet samples in the airflow and affect particle size measurements and aerodynamic spectrometer counts, air filtration is required to prevent interference with the sampling system. The velocity near the face of the flexible interface flow field between the person and the sampler is kept between 0.2 m / s and 0.3 m / s, meeting the volunteers' thermal comfort requirements. The humidity control unit is designed based on the negative feedback principle. Because the humidity of exhaled air is typically higher than that of ambient air, and the plenum chamber fan continuously introduces relatively dry air into the chamber, the humidity control unit controls the humidity of the flow field around the head to align the sampling airflow with the humidity of respiratory droplets and the activity requirements of the viruses they contain. This prevents evaporation of droplets during transport due to humidity differences between the respiratory and ambient airflows, which could interfere with droplet deposition, count measurements, and the bioefficiency of the sampling process. A humidity sensor transmits humidity data from the airflow around the head to a computer. Based on the difference between this humidity data and the set humidity range, the computer adjusts the opening of the solenoid valve, thereby regulating the humidifier's humidification output. Water vapor from the humidifier flows through the pipe, the solenoid valve, and a second filter into the positive pressure chamber, maintaining a stable airflow around the head within a defined humidity range. The droplet collection device, designed based on particle gravity deposition theory and sheath flow theory, is designed to sample particles 50 μm and larger. It features a conical structure with an oblique angled lower wall to intercept large droplets. The cone expands at the cheeks to draw air into the positive pressure chamber, entraining droplets and preventing excessive localized airflow near the face. The total length of the flexible interface between the person and the sampler and the metal housing is designed to be 100 mm, sufficient to deposit all droplets larger than 100 μm at the preset location. Horseshoe-shaped nose and chin positioning slots are designed on the upper and lower sides of the interface to facilitate conformity to the volunteer's face and ensure that the sampling flow direction remains within the designed range in various sampling positions, such as sitting and lying.

[0024] Because respiratory airflow undergoes entrainment when carried by ambient air, which can easily lead to sampling flow instability, a sheath flow guide component is installed at the inlet of the droplet collection device. Under the suction of the flow pump at the sampling system's outlet, this component guides the positive pressure chamber airflow toward the lower wall of the flexible interface body and spreads it. When the ratio of the sampling flow velocity to the sheath flow velocity is within a certain range, it can protect the sampling airflow entrained with respiratory droplets, enriching medium- and small-sized droplets in the sampling flow and reducing the deposition loss of droplets smaller than 50 μm at the sampling system interface. In addition, to meet the mechanical comfort requirements of volunteers and the cleanliness requirements of the sampling device, the flexible interface between the human and the sampler of the large droplet collection device is manufactured using 3D-printed silicone mold technology. The material has a hardness of 70 Shore A, which is quite soft and can be deformed appropriately with different volunteers' facial differences without causing collapse. It can also be quickly disassembled and replaced. The device body is made of metal to reduce static electricity adsorption on droplets and facilitate cleaning and disinfection.

[0025] Since the direction of the airflow is approximately horizontal when the volunteers perform respiratory activities in a natural sitting position, and the impactor used for small-particle droplet screening usually works vertically, it is necessary to design a flow channel steering component. In order to make the system as simple and portable as possible, the flow channel steering function is integrated with the medium-particle droplet collection function, and the droplet curve collection device is designed based on the particle curve deposition theory and the throat jet principle. The sampling particle size is designed to be 10-50 μm. In order to ensure the portability of the system and prevent it from containing too many or too small parts, the various components of the medium-particle droplet curve collection device are designed to be integrated. After the sampling airflow flows through the large-particle droplet collection device, it flows through the impact guide component, the impact collection component and the vertical transition pipe in sequence. A flange connection is provided at the inlet of the impact guide component to facilitate assembly and disassembly of the large-particle droplet collection device and sampling. The impact guide component forms a curved, tapered conduit that slopes upward. The outlet diameter is designed to be 14 mm, smaller than the inlet diameter, based on a three-dimensional model of the human respiratory tract. Due to mass conservation across the inlet and outlet cross-sections, secondary acceleration of the sample flow is achieved within the tapered conduit, guiding the airflow upward. The curve turning component mimics the structure of the human respiratory tract, forming a branched, high-curvature curve. The two branch outlets are connected to the impact collection component and the vertical transition conduit, respectively. To minimize the impact of the impact chamber on the flow field within the curve, the impact collection component is positioned outside the curve turning component along the streamline. In the embodiment of the present invention, droplets of 10-50 μm are collected by a third sampling membrane in the sample collector and a second sampling membrane attached to the metal shell outlet baffle. A flange connection is used between the impact chamber and the sample collector to facilitate multiple sampling, assembly, and disassembly for cleaning.

[0026] The primary function of the droplet particle size screening device is to screen droplets smaller than 10 μm. The impactor utilizes the principle of inertial impact during the curvilinear motion of droplets. As droplets pass through the slit nozzles on each impactor plate, the airflow is organized into a 90° deflection along the streamline. Droplets larger than the cutoff size are prevented from following the streamline due to inertia and instead impact directly onto the collection medium. To prevent droplet loss during subsequent sample transfer, a groove is provided on the sampling plate and a water-soluble, sticky semi-solid gelatin membrane is attached as the droplet collection medium. This prevents the gelatin membrane from slipping or falling when the device is not operating horizontally. Droplets impinging on the membrane adhere to the membrane, while droplets smaller than the cutoff size are carried by the airflow around the sampling plate and into the next stage. The cutoff sizes for each stage follow Stokes' law and include 10 μm, 5 μm, and 2.5 μm, which can be freely combined to suit specific sampling needs. The impactor bracket is used to support the impactor and the medium-particle droplet collection device and large-particle droplet collection device connected to the impactor, and can be raised and lowered to make the sampling system adaptable to volunteers of different heights.

[0027] The particle size spectrometer operates based on aerodynamics and dual-beam laser particle size measurement principles, measuring the size distribution of particles ranging from 0.5 to 20 μm and is unaffected by factors such as the inherent properties of aerosol particles. Large droplet size distribution is measured based on the Mie scattering principle. A high-speed camera directly records the scattering of raw respiratory droplets under laser irradiation through a viewing window in the metal casing. The droplet size distribution is determined based on their varying scattering characteristics, minimizing the effects of evaporation, sampling loss, and environmental interference on droplet size measurement.

[0028] The laser assembly and high-speed camera work together to perform particle size analysis. Droplets of different particle sizes produce different numbers of interference fringes under laser irradiation. The fringes information is recorded by the high-speed camera and can be transmitted to the connected computer for software analysis.

[0029] Considering the requirements of multiple sampling and easy portability and assembly, the system is designed to be compact, with all connections made with screws, nuts, or flanges. For sample recovery, a semi-solid, soluble gelatin membrane is preferred, as it is easily removable. Because the gelatin membrane is soluble in body-temperature water, Universal Viral Transport Medium (UTM), and saline, virus-containing droplets deposited on it dissolve and are completely transferred to the subsequent analysis medium, effectively preserving viral activity. Furthermore, due to the device's small size, alternative methods for collecting droplet samples, such as swabbing or flushing with buffer, are also possible.

[0030] The beneficial effects of the present invention are:

[0031] 1. This system can realize the direct separation and sampling of respiratory droplets in the entire particle size range. Sampling membranes are attached to the droplet collection device, the droplet curve collection device, and the droplet particle size screening device respectively. Droplets of different particle sizes in the respiratory airflow are separated and collected with 2.5 μm, 5 μm, 10 μm and 50 μm as critical diameters. The particle size screening device below 10 μm can be freely combined according to actual sampling needs, which has the advantage of high sampling freedom.

[0032] 2. This system can achieve efficient sampling of live viruses, using a water-soluble viscous semi-solid gelatin membrane to collect virus-containing droplet samples. During the sampling process, the sampling area can be kept flat and moist, reducing the rebound or drying inactivation of virus-containing droplets. After sampling, it can be directly dissolved in water at body temperature, reducing the loss of droplets during the collection and transfer process and effectively maintaining the biological activity of the virus.

[0033] 3. This system can measure viral concentrations in respiratory droplets of various particle sizes. By performing PCR analysis / viral culture on collected virus-containing droplet samples and combining them with particle size distribution measurement data, the viral content in droplets of different particle sizes can be determined. This facilitates in-depth research on the particle size effect of respiratory droplets and provides direct evidence for respiratory pathogen transmission risk assessment. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is a schematic diagram of the system of the present invention;

[0035] Figure 2 is a schematic diagram of a droplet collection device;

[0036] Figure 3 is a schematic diagram of a droplet collection device;

[0037] FIG4 is a schematic diagram of a droplet particle size screening device;

[0038] Figure 5 is a schematic diagram of the sampling chamber air supply filter device;

[0039] FIG6 is a schematic diagram of a sampling flow rate regulating device;

[0040] Figure 7 is a schematic diagram of the droplet particle size measuring device.

[0041] In the figure: 1. Droplet collection device; 11. Human-sampler flexible interface; 111. Nose wing positioning slot; 112. Mandibular positioning slot; 12. Metal housing; 121. First sampling membrane; 122. Particle size spectrometer interface; 123. Particle size spectrometer interface sealing plug; 124. Sheath flow guide component; 125. Laser transmission slit; 126. Visual window; 127. Baffle; 128. Second sampling membrane; 2. Droplet curve collection device; 21. Impact guide component; 22. Impact collection component; 221. Impact cavity; 222. Sample collector; 223. Third sampling membrane; 23. Curve steering component; 24. Vertical transition duct; 3. Droplet particle size screening device; 31. Slit impactor; 311. Impact plate; 312. Sampling plate; 317. Fourth sampling membrane; 32. First filter; 33. Impactor lifting bracket; 4. Sampling chamber air supply and filtration device; 41. Positive pressure chamber; 42. Positive pressure chamber bracket; 43. Humidity adjustment unit; 431. Humidifier; 432. Humidity sensor; 433. Solenoid valve; 434. Second filter; 435. Humidification nozzle; 44. Filter assembly; 441. Third filter; 442. Fan; 5. Sampling flow rate adjustment device; 51. Mass flow meter; 52. Sampling pump; 53. Fourth filter; 6. Droplet particle size measuring device; 61. Aerodynamic particle size spectrometer; 62. Camera; 63. Laser assembly; 631. Laser; 632. Spatial filter; 633. Plane mirror; 634. Beam expander lens; 64. Camera bracket; 65. Computer. Implementation Method

[0042] The present invention will be further described below with reference to the accompanying drawings and examples.

[0043] As shown in Figure 1, it includes a droplet collecting device 1, a droplet bend collecting device 2, a droplet particle size screening device 3, a sampling chamber air supply filter device 4, a sampling flow rate regulating device 5 and a droplet particle size measuring device 6; the gas exhaled by the human body enters the droplet collecting device 1, the droplet collecting device 1 is connected to the inlet of the droplet particle size screening device 3 through the droplet bend collecting device 2, the outlet of the droplet particle size screening device 3 is connected to the inlet of the sampling flow rate regulating device 5, a port is opened on the droplet collecting device 1, the port of the droplet collecting device 1 is connected to the droplet particle size measuring device 6, and the droplet collecting device 1, the droplet bend collecting device 2 and the droplet particle size screening device 3 are all arranged in the sampling chamber air supply filter device 4.

[0044] As shown in Figure 2, the droplet collection device 1 includes a human-sampler flexible interface 11 with openings at both ends and a metal shell 12 with openings at both ends. The human-sampler flexible interface 11 is installed on the metal shell 12, and the inlet of the metal shell 12 is connected to the outlet of the human-sampler flexible interface 11. The outlet of the metal shell 12 is connected to the inlet of the droplet bend collection device 2, and the gas exhaled by the human body enters the metal shell 12 through the human-sampler flexible interface 11; the upper and lower sides of the human-sampler flexible interface 11 are respectively provided with a nose wing positioning groove 111 and a mandibular positioning groove 112, which are in contact with the nose wing and mandibular positioning groove of the human body respectively;

[0045] A particle size spectrometer interface 122 and a laser transmission slit 125 are provided on the side wall of the metal shell 12, and an interface sealing plug 123 is installed on the particle size spectrometer interface 122. The light emitted by the droplet particle size measuring device 6 is incident on the cavity inside the metal shell 12 through the laser transmission slit 125. The particle size spectrometer interface 122 is connected to the droplet particle size measuring device 6 through a pipe. A first sampling membrane 121 is attached to the inner bottom surface of the metal shell 12, a sheath flow guide component 124 is provided on the inner side wall of the metal shell 12, and a transparent visual window 126 is provided on the side wall of the metal shell 12. A semicircular baffle 127 is installed at the outlet of the metal shell 12, and a second sampling membrane 128 is attached to the inner wall of the semicircular baffle 127.

[0046] As shown in Figure 3, the droplet bend collection device 2 includes an impact guide component 21, an impact collection component 22, a bend turning component 23 and a vertical transition pipe 24; the inlet of the impact guide component 21 is connected to the outlet of the metal shell 12, the outlet of the impact guide component 21 is connected to the inlet of the bend turning component 23, the two outlets of the bend turning component 23 are respectively connected to the inlet of the impact collection component 22 and the vertical transition pipe 24, and the outlet of the vertical transition pipe 24 is connected to the inlet of the droplet particle size screening device 3; a third sampling membrane 223 is provided in the impact collection component 22;

[0047] As shown in FIG4 , the droplet particle size screening device 3 includes a vertically placed impactor 31 and a first filter 32 ; the inlet of the impactor 31 is connected to the outlet of the vertical transition pipe 24 , and the outlet of the impactor 31 is connected to the inlet of the sampling flow rate regulating device 5 through the first filter 32 ; the impactor lifting bracket 33 is placed on the ground, and the impactor 31 is fixedly mounted on the impactor lifting bracket 33 ;

[0048] The impactor 31 includes an impact shell, an impact plate 311, a sampling plate 312 and a fourth sampling membrane 317; the three impact plates 311 are evenly spaced from top to bottom in the cavity of the impact shell along the height direction of the impact shell, and the three impact plates 311 divide the cavity of the impact shell from top to bottom into an inlet cavity, a first filter cavity, a second filter cavity and an outlet cavity. A sampling plate 312 is provided in the first filter cavity, the second filter cavity and the outlet cavity, and a fourth sampling membrane 317 is attached to the upper surface of each sampling plate 312. The inlet cavity is connected to the outlet of the vertical transition pipe 24, and the outlet cavity is connected to the inlet of the sampling flow rate regulating device 5 through the first filter 32.

[0049] The droplet collection device 1 collects droplets with a particle size of 50 μm and above, the droplet curve collection device 2 collects droplets with a particle size of 10-50 μm, and the three impact plates 311 from top to bottom filter droplets with a particle size of more than 10 μm, droplets with a particle size of 5-10 μm, and droplets with a particle size of 2.5-5 μm respectively. The first filter 32 filters droplets with a particle size of 2.5 μm and above.

[0050] As shown in Figure 5, the sampling chamber air supply filter device 4 includes a positive pressure chamber 41, a positive pressure chamber bracket 42, a humidity adjustment unit 43 and a filter assembly 44; the positive pressure chamber 41 is a cavity mainly constructed of transparent plastic cloth, the positive pressure chamber bracket 42 is placed on the ground, the positive pressure chamber 41 is fixed on the positive pressure chamber bracket 42, and the filter assembly 44 is installed on the top of the positive pressure chamber 41; the droplet collection device 1, the droplet bend collection device 2 and the droplet particle size screening device 3 are arranged in the positive pressure chamber 41;

[0051] A lifting chair is also provided in the middle of the positive pressure chamber bracket 42. The volunteer sits on the lifting chair. By adjusting the height of the lifting chair, the volunteer's nose and mandible are respectively restricted on the nose wing positioning groove 111 and mandible positioning groove 112 of the human-sampler flexible interface.

[0052] The humidity adjustment unit 43 includes a humidifier 431, a humidity sensor 432, a solenoid valve 433, a second filter 434 and a humidifying nozzle 435. The humidifier 431 is placed on the ground, and the outlet of the humidifier 431 is connected to the humidifying nozzle 435 through a pipe. The solenoid valve 433 and the second filter 434 are sequentially arranged on the pipe from the humidifier 431 to the humidifying nozzle 435. The humidifying nozzle 435 and the humidity sensor 432 are both arranged inside the positive pressure chamber 41; the humidity sensor 432 and the solenoid valve 433 are both connected to the droplet particle size measuring device 6.

[0053] As shown in FIG7 , the droplet particle size measuring device 6 includes an aerodynamic particle size spectrometer 61, a camera 62, a laser assembly 63, a camera bracket 64, and a computer 65. The aerodynamic particle size spectrometer 61 is connected to the particle size spectrometer interface 122 via a pipe. The camera bracket 64 is fixed to the ground. The camera 62 is mounted on the camera bracket 64. The camera 62 is located on a side of the metal housing 12 where a visual window 126 is provided. The light emitted by the laser assembly 63 is incident on the interior of the metal housing 12 through the laser transmission slit 125. The aerodynamic particle size spectrometer 61, the camera 62, and the laser assembly 63 are all electrically connected to the computer 65.

[0054] The humidity sensor 432 and the electromagnetic valve 433 of the humidity adjustment unit 43 are both electrically connected to the computer 65. The camera 62 is a high-speed camera.

[0055] As shown in Figure 6, the sampling flow rate regulating device 5 includes a mass flowmeter 51, a sampling pump 52 and a fourth filter 53; the inlet of the fourth filter 53 is connected to the outlet of the first filter 32, and the outlet of the fourth filter 53 is connected to the inlet of the sampling pump 52 via a pipeline. A mass flowmeter 51 is provided on the pipeline from the fourth filter 53 to the sampling pump 52.

[0056] The impact collection component 22 includes an impact cavity 221 and a sample collector 222. The outlet of the impact cavity 221 and the inlet of the sample collector 222 are connected by a flange. A third sampling membrane 223 is attached to the inner wall of the sample collector 222. The outlet of the curve turning component 23 is connected to the inlet of the impact cavity 221.

[0057] The laser assembly 63 includes a laser 631, a spatial filter 632, a plane mirror 633 and a beam expander lens 634. The spatial filter 632 is fixedly mounted at the front end of the laser 631, the beam expander lens 634 is located in front of the spatial filter 632, and the plane mirror 633 is located in front of the beam expander lens 634 and directly above the laser transmission slit 125. The light emitted by the laser 631 is filtered by the spatial filter 632, transmitted by the beam expander lens 634, and reflected by the plane mirror 633, and then incident on the interior of the metal shell 12 through the laser transmission slit 125.

[0058] The first sampling membrane 121 is attached to the lower wall of the metal housing 12. The first sampling membrane 121 is made of a water-soluble viscous semi-solid gelatin membrane and is used to collect large droplets of 50 μm and above. The particle size spectrometer interface 122 can be used to connect to the aerodynamic particle size spectrometer 61 to measure the particle size distribution of exhaled droplets of 20 μm and below. The outer diameter of the particle size spectrometer interface 122 is much smaller than the size of the metal housing 12 so as not to affect the flow field within the system. The interface sealing plug 123 can seal the particle size spectrometer interface 122 when the system is only used for sampling, further ensuring the stability of the flow field within the system during sampling.

[0059] The sheath flow guide component 124 guides the clean air in the positive pressure chamber to impact and spread toward the lower wall of the human-sampler flexible interface 11, which can protect the sampling flow pattern, reduce the loss of medium and small particle size droplets below 100 μm in the droplet collection device 1, and ensure the stability of the performance of the droplet collection device 1 within the range of respiratory activity airflow fluctuations; the laser transmission slit 125 is a glass slit, located at the top of the droplet collection device 1, which can ensure that the parallel laser passes through without affecting the flow field in the system; the visual window 126 is a glass window, located on the side of the droplet collection device 1 and in front of the particle size spectrometer interface 122. The high-speed camera can capture the particle size distribution image of the exhaled droplets through the visual window 126, and is not affected by the local flow field changes of the particle size spectrometer interface 122, ensuring that the measured particle size distribution is as close as possible to the original particle size distribution of the exhaled droplets.

[0060] The flexible human-sampler interface 11 can be quickly removed from the metal housing 12, facilitating cleaning, disinfection, and repeated sampling. Designed as an asymmetric cone, the flexible human-sampler interface 11 covers only the face below the nose. The lower wall of the cone is beveled and flared at the cheeks, meeting the thermal and mechanical comfort requirements of volunteers. Both the nose wing positioning slot 111 and the mandibular positioning slot 112 are horseshoe-shaped, allowing for easy positioning and adaptation for different volunteers, reducing sampling errors caused by individual differences.

[0061] The droplet collection device 2 combines flow channel diversion and guidance with the collection of droplets with a medium particle size of 10-50 μm. After passing through the droplet collection device 1, the sampled airflow sequentially flows through the impact guide component 21, the curved diversion component 23, and the vertical transition duct 24, and is separated at the entrance of the impact collection component 22. The impact guide component 21, the impact collection component 22, the curved diversion component 23, and the vertical transition duct 24 are integrally formed. The impact guide component 21 forms a contracting duct. In the embodiment of the present invention, the inlet and outlet duct diameters of the impact guide component 21 are designed to be 32 mm and 14 mm, respectively.

[0062] The impact guide component 21 forms a contraction pipe, and the sampling airflow undergoes secondary acceleration in the contraction pipe, increasing the inertia of 10-50 μm droplets and entering the bend turning component 23. The bend turning component 23 imitates the structure and size of the human respiratory tract to form a large curvature bend with branches, and is connected to the vertical transition pipe 24. The impact collection component 22 is set along the streamline on the outer wall of the bend turning component 23. The airflow is separated when it flows through the inlet of the impact collection component 221. Most of the medium-sized droplets of 10-50 μm enter the impact cavity 221 along the streamline under the action of inertia, while the small-sized droplets follow the airflow and continue to flow along the bend turning component 23 until they enter the droplet particle size screening device 3.

[0063] The impact chamber 221 is connected to the sample collector 222 via a flange, facilitating disassembly, cleaning, and multiple sampling. A third sampling membrane 223 is located within the sample collector 222. This membrane, specifically a water-soluble, viscous semisolid gelatin membrane, works in conjunction with the second sampling membrane 128 to collect droplets with a medium diameter of 10-50 μm.

[0064] The impactor 31 is a single-stage or multi-stage, freely combinable slit-type inertial impactor. It comprises an impactor housing, an impactor plate 311, a sampling plate 312, and a fourth sampling membrane 317. The impactor 31 and the vertical transition duct 24 are connected by a pagoda or hose, allowing airflow to enter vertically from the top of the impactor. Each impactor plate 311, located within the impactor housing, is equipped with a slit-shaped nozzle whose length is less than the diameter of the impactor plate. Below each impactor plate 311 is a sampling plate 312. As the sampled airflow passes through the impactor plates 311, droplets of varying sizes are separated based on the cutoff diameter of the slit-shaped nozzle. Droplets larger than the cutoff diameter are unable to follow the streamline due to inertia and will impact the sampling plate 312. Droplets smaller than the cutoff diameter are carried by the airflow around the sampling plate and enter the next stage. The sampling plate 312 has a groove in which a fourth sampling membrane 317 is affixed. The fourth sampling membrane 317 is a water-soluble, viscous semi-solid gelatin membrane that adheres to the droplets. The cut-off particle size of the impact plate 311 includes 10 μm, 5 μm, 2.5 μm, and the like.

[0065] The inlet of the first filter 32 is connected to the outlet of the impactor, and the outlet of the first filter 32 is connected to the inlet of the fourth filter 53, which can filter droplets smaller than 2.5 μm.

[0066] The impactor lifting bracket 33 can be adjusted to meet the height differences of different volunteers. When the volunteer is in a sitting position, the impactor lifting bracket 33 is placed on the ground, and the impactor 31 is fixed to the impactor lifting bracket 33. When the volunteer is in a semi-reclining or side-lying position, the impactor 31 can be placed flat on a table or any flat surface.

[0067] The positive pressure chamber 41 is of moderate size, bottomless at the bottom, and constructed of transparent plastic cloth. Volunteers will not feel cramped or claustrophobic when sitting in it, and the airflow samples collected by the system can be prevented from being disturbed by ambient air dust.

[0068] The humidity regulating unit 43 is connected to the positive pressure chamber 41 and is located on the back of the human head. The humidifier 431 can ensure that the relative humidity of the sampled airflow is controlled within a stable range, preventing the evaporation of droplets during transmission, which may cause the virus to be inactivated or change the droplet collection site, so as to ensure the collection of live viruses. The humidity sensor 432 monitors the air humidity near the head in real time and feeds the results back to the computer 65. After receiving the feedback, the computer 65 adjusts the opening of the humidification solenoid valve 433 to control the humidification amount supplied by the humidifier 431 to the humidification nozzle 435. The second filter 434 filters the airflow generated by the humidifier 431 to prevent the clean gas in the positive pressure chamber from being disturbed by particulate matter in the air. The filter assembly 44 includes a third filter 441 and a stepless speed regulation fan 442. Both third filter 441 and steplessly variable speed blower 442 are connected to the top of plenum chamber 41. Third filter 441 filters the air entering plenum chamber 41, preventing dust particles in the air from affecting measurement results. Steplessly variable speed blower 442 effectively controls the flow of clean air within the plenum chamber, ensuring a constant positive pressure within plenum chamber 41. Plenum chamber 41 and plenum chamber support 42 can also be fully enclosed or replaced by a room containing humidity control and filtering components.

[0069] In the experimental test, the maximum flow rate was 65 m 3 The stepless speed adjustment fan was turned on at 442°C / h. After approximately one minute, a handheld laser particle counter measured the concentrations of particles of all sizes in the sitting breathing area of ​​the positive pressure chamber. In particular, the concentration of particles larger than 5 μm decreased by an order of magnitude. This indicates that the filter assembly is effectively providing clean air to the positive pressure chamber.

[0070] The fourth filter 53 is connected to the airflow outlet of the impactor 31 through a pipeline to prevent residual particles from entering the sampling pump. The aerodynamic particle size spectrometer 61 can measure the particle size distribution of exhaled droplets of 20 μm and below.

[0071] A high-speed camera 62 with a microscope lens, used in conjunction with a laser assembly 63, can clearly record the light scattering of exhaled droplets through a visual window 126 located on the side of the metal housing 12. A laser 631 is located on one side of the positive pressure chamber 41. The light beam emitted by laser 631 passes through a spatial filter 632 and a beam expander lens 634, becoming a parallel beam of light with a specific wavelength. The resulting beam plane passes through the laser transmission slit 125, scattering the exhaled droplets. A plane mirror 633 reflects the horizontal laser light emitted by laser 631 into a vertical laser beam.

[0072] The camera bracket 64 is used to support and adjust the position of the camera with a microscope lens 62. The laser assembly 63 is located on the top of the positive pressure chamber to avoid interfering with the flow field around the head and prevent the laser from directly hitting the volunteer's face.

[0073] The computer 65 can automatically convert the droplet image obtained by the microscope camera 62 into particle size distribution data through image processing software.

[0074] The first sampling membrane 121, the second sampling membrane 128, the third sampling membrane 253, and the fourth sampling membrane 317 are all viscous semi-solid gelatin membranes that are soluble in water and can efficiently recover droplets within the designed particle size range. After sampling, the gelatin membrane is dissolved in warm water / hot water, universal virus transport medium UTM, or normal saline, and the droplets deposited on the semi-solid viscous gelatin membrane can be completely transferred to the subsequent analysis medium, facilitating subsequent virus culture and PCR analysis. In actual use, since the common low-cost gelatin sheets on the market can only be dissolved in water or hot water at body temperature and cannot be completely dissolved in water at room temperature, when it is necessary to recover viruses that are very sensitive to temperature during the sampling process, an alternative solution can also be adopted, that is, using a swab to smear or flushing the sampling points at each level with buffer to recover the sample.

Claims

1. A full-size respiratory droplet sampling system, characterized in that: The invention comprises a droplet collecting device (1), a droplet curved channel collecting device (2), a droplet particle size screening device (3), a sampling chamber air supply filtering device (4), a sampling flow rate regulating device (5) and a droplet particle size measuring device (6); gas exhaled by a human body enters the droplet collecting device (1); the droplet collecting device (1) is connected to the inlet of the droplet particle size screening device (3) via the droplet curved channel collecting device (2); the outlet of the droplet particle size screening device (3) is connected to the inlet of the sampling flow rate regulating device (5); a port is provided on the droplet collecting device (1); the port of the droplet collecting device (1) is connected to the droplet particle size measuring device (6); the droplet collecting device (1), the droplet curved channel collecting device (2) and the droplet particle size screening device (3) are all arranged in the sampling chamber air supply filtering device (4).

2. A full-size respiratory droplet sampling system according to claim 1, characterized in that: The droplet collection device (1) comprises a human-sampler flexible interface (11) with openings at both ends and a metal shell (12) with openings at both ends. The human-sampler flexible interface (11) is mounted on the metal shell (12). The inlet of the metal shell (12) is connected to the outlet of the human-sampler flexible interface (11). The outlet of the metal shell (12) is connected to the inlet of the droplet curve collection device (2). The gas exhaled by the human body enters the metal shell (12) through the human-sampler flexible interface (11). The upper and lower sides of the human-sampler flexible interface (11) are respectively provided with a nose wing positioning groove (111) and a mandibular positioning groove (112), and the nose wing positioning groove (111) and the mandibular positioning groove (112) are respectively in contact with the nose wing and the mandibular of the human body; The side wall of the metal shell (12) is provided with a particle size spectrometer interface (122) and a laser transmission slit (125); light emitted by the droplet particle size measuring device (6) is incident on the cavity inside the metal shell (12) through the laser transmission slit (125); the particle size spectrometer interface (122) is connected to the droplet particle size measuring device (6) through a pipeline; a first sampling film (121) is attached to the inner bottom surface of the metal shell (12); a transparent visual window (126) is provided on the side wall of the metal shell (12); a semicircular baffle (127) is installed at the outlet of the metal shell (12); and a second sampling film (128) is attached to the inner wall of the semicircular baffle (127).

3. A full-size respiratory droplet sampling system according to claim 2, characterized in that: The droplet bend collection device (2) comprises an impact guide component (21), an impact collection component (22), a bend steering component (23) and a vertical transition pipe (24); the inlet of the impact guide component (21) is connected to the outlet of the metal shell (12), the outlet of the impact guide component (21) is connected to the inlet of the bend steering component (23), the two outlets of the bend steering component (23) are respectively connected to the inlet of the impact collection component (22) and the vertical transition pipe (24), and the outlet of the vertical transition pipe (24) is connected to the inlet of the droplet particle size screening device (3); a third sampling membrane (223) is provided in the impact collection component (22); The droplet particle size screening device (3) comprises an impactor (31) and a first filter (32); the inlet of the impactor (31) is connected to the outlet of the vertical transition pipe (24), and the outlet of the impactor (31) is connected to the inlet of the sampling flow rate regulating device (5) via the first filter (32); The impactor (31) comprises an impact shell, an impact plate (311), a sampling plate (312) and a fourth sampling membrane (317); the three impact plates (311) are evenly spaced from top to bottom in the cavity of the impact shell along the height direction of the impact shell, and the three impact plates (311) divide the cavity of the impact shell from top to bottom into an inlet cavity, a first filter cavity, a second filter cavity and an outlet cavity, and each of the first filter cavity, the second filter cavity and the outlet cavity is provided with a sampling plate (312), and a fourth sampling membrane (317) is attached to the upper surface of each sampling plate (312); the inlet cavity is connected to the outlet of the vertical transition pipe (24), and the outlet cavity is connected to the inlet of the sampling flow rate regulating device (5) via the first filter (32).

4. A full-size respiratory droplet sampling system according to claim 3, characterized in that: The droplet collection device (1) collects droplets with a particle size of 50 μm or more, the droplet curve collection device (2) collects droplets with a particle size of 10-50 μm, the three impact plates (311) from top to bottom filter droplets with a particle size of more than 10 μm, filter droplets with a particle size of 5-10 μm, and filter droplets with a particle size of 2.5-5 μm, respectively, and the first filter (32) filters droplets with a particle size of 2.5 μm or more.

5. A full-particle respiratory droplet sampling system according to claim 2, characterized in that: The sampling chamber air supply filter device (4) comprises a positive pressure chamber (41), a positive pressure chamber bracket (42), a humidity adjustment unit (43) and a filter assembly (44); the positive pressure chamber (41) is a cavity mainly constructed of transparent plastic cloth, the positive pressure chamber bracket (42) is placed on the ground, the positive pressure chamber (41) is fixed on the positive pressure chamber bracket (42), and the filter assembly (44) is installed on the top of the positive pressure chamber (41); the droplet collection device (1), the droplet bend collection device (2) and the droplet particle size screening device (3) are arranged in the positive pressure chamber (41); The humidity adjustment unit (43) comprises a humidifier (431), a humidity sensor (432), a solenoid valve (433), a second filter (434) and a humidifying nozzle (435); the outlet of the humidifier (431) is connected to the humidifying nozzle (435) via a pipeline; the solenoid valve (433) and the second filter (434) are sequentially arranged on the pipeline from the humidifier (431) to the humidifying nozzle (435); the humidifying nozzle (435) and the humidity sensor (432) are both arranged inside the positive pressure chamber (41); and the humidity sensor (432) and the solenoid valve (433) are both connected to the droplet particle size measuring device (6).

6. A full-size respiratory droplet sampling system according to claim 5, characterized in that: The droplet particle size measuring device (6) comprises an aerodynamic particle size spectrometer (61), a camera (62), a laser assembly (63), a camera bracket (64) and a computer (65); the aerodynamic particle size spectrometer (61) is connected to the particle size spectrometer interface (122) through a pipeline, the camera bracket (64) is fixed on the ground, the camera (62) is mounted on the camera bracket (64), and the camera (62) is located on a side of the metal shell (12) where a visible window (126) is provided, the light emitted by the laser assembly (63) is incident on the inside of the metal shell (12) through the laser transmission slit (125), the aerodynamic particle size spectrometer (61), the camera (62) and the laser assembly (63) are all electrically connected to the computer (65); the humidity sensor (432) and the solenoid valve (433) of the humidity adjustment unit (43) are all electrically connected to the computer (65).

7. A full-size respiratory droplet sampling system according to claim 3, characterized in that: The sampling flow rate regulating device (5) comprises a mass flow meter (51), a sampling pump (52) and a fourth filter (53); the inlet of the fourth filter (53) is connected to the outlet of the first filter (32), the outlet of the fourth filter (53) is connected to the inlet of the sampling pump (52) via a pipeline, and the mass flow meter (51) is provided on the pipeline from the fourth filter (53) to the sampling pump (52).

8. A full-size respiratory droplet sampling system according to claim 3, characterized in that: The impact collection component (22) comprises an impact cavity (221) and a sample collector (222); the outlet of the impact cavity (221) and the inlet of the sample collector (222) are connected via a flange; a third sampling membrane (223) is attached to the inner wall of the sample collector (222); and the outlet of the curve steering component (23) is connected to the inlet of the impact cavity (221).

9. A full-size respiratory droplet sampling system according to claim 6, characterized in that: The laser assembly (63) comprises a laser (631), a spatial filter (632), a plane mirror (633) and a beam expander lens (634); the spatial filter (632) is fixedly mounted at the front end of the laser (631); the beam expander lens (634) is located in front of the spatial filter (632); the plane mirror (633) is located in front of the beam expander lens (634) and directly above the laser transmission slit (125); the light emitted by the laser (631) is filtered by the spatial filter (632), transmitted by the beam expander lens (634), and reflected by the plane mirror (633) in sequence, and then incident from the laser transmission slit (125) into the interior of the metal housing (12).

Images