Microfluidic channel impactor for aerosol capture

Abstract

An aerosol capture assembly includes a body and a body conduit, extending between a body inlet and a body outlet, configured to direct a flow of air containing aerosol particles. An aerosol capture device is disposed in the body conduit and includes a microfluidic channel impactor (MCI). The MCI has an air conduit with an air inlet in fluid communication with the body inlet and an air outlet in fluid communication with the body outlet. The air conduit of the MCI includes a flow diverter configured for separating aerosol particles from the air. A microfluidic conduit extends between a fluid inlet and a fluid outlet of the MCI. The microfluidic conduit is in fluid communication with the air conduit for extraction of the separated aerosol particles.

Description

MICROFLUIDIC CHANNEL IMPACTOR FOR AEROSOL CAPTURECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority on United States Patent Application No. 63 / 706,376 filed on October 11, 2024, the entire content of which is incorporated herein by reference.TECHNICAL FIELD

[0002] The present disclosure relates generally to an aerosol capture device which may be used, for example, to help diagnose infectious respiratory diseases.BACKGROUND

[0003] Bio-aerosols are a core vector for the transmission of many pathogens that cause respiratory diseases. For instance, aerosol transmission can contribute to the spread of pathogens such as SARS-CoV-2, tuberculosis, and influenza. In such cases, accurate and rapid testing of exhaled aerosols could provide valuable insight regarding the societal risk of each individual infected patient. However, due to the lack of availability of aerosol-based tests, standard sampling methods such as throat and nasopharyngeal (NP) swabs and blood drawing are commonly used. The discrepancy between the transmission vector and the sampling location can cause patients to test positive while no longer posing a risk to society. The opposite can also occur, where patients who were falsely testing negative on NP swabs still posed a risk to those around them through the exhalation of virus laden aerosols. Measuring the exhaled viral load at the source is thus the most effective way to determine the pathogenic risk an individual poses to their surroundings. A patient’s respiratory tract lining fluid (RTLF) can be sampled through the semi-invasive procedure of bronchiolar lavage. Alternatively, exhaled aerosols can be sequestered and their contents analyzed to non-invasively sample the patients RTLF.

[0004] Aerosol capture devices (ACDs) are emerging as valuable tools in the rapid and accurate diagnosis of infectious respiratory diseases, particularly those transmitted through exhaled aerosolized particles. Rather than measuring a secondary sample type such as blood or nasopharyngeal swab, ACDs allow for direct measurement of the pathogenic output of an individual. However, existing ACDs are fraught with challenges, facing trade-offs betweenvolumetric airflow, capture efficiency, device size and captured sample dilution. Improvements are thus desired.SUMMARY

[0005] In one aspect, there is provided an aerosol capture assembly, comprising: a body having a body inlet, a body outlet, and a body conduit extending between the body inlet and the body outlet, the body conduit being configured to direct a flow of air therethrough, the flow of air containing aerosol particles; an aerosol capture device disposed in the body conduit, the aerosol capture device being a microfluidic channel impactor (MCI) including: an air conduit having an air inlet in fluid communication with the body inlet and an air outlet in fluid communication with the body outlet, the air conduit of the MCI including a flow diverter configured for separating aerosol particles from the air; and a microfluidic conduit extending between a fluid inlet and a fluid outlet of the MCI, the microfluidic conduit being in fluid communication with the air conduit for extraction of the aerosol particles separated from the air.

[0006] The aerosol capture assembly defined above and described herein also includes, in certain embodiments, any one or more of the following features, in whole or in part, and in any combination.

[0007] In some embodiments, the flow diverter includes an array of microbeams disposed in the air conduit, the array of microbeams configured for diverting the flow of air and impacting the aerosol particles.

[0008] In some embodiments, the microbeams form a ninety-degree bend in the air conduit.

[0009] In some embodiments, the microbeams each include a microchannel extending along an upper surface thereof for capturing the impacted aerosol particles.

[0010] In some embodiments, each microchannel includes a capture surface aligned with the air inlet of the air conduit.

[0011] In some embodiments, the aerosol capture assembly further includes an array of micro-slits upstream of the microbeams, the air configured to flow through the micro-slits before reaching the microbeams.

[0012] In some embodiments, the MCI includes a capillary pump for extraction of a buffer solution from the microfluidic conduit.

[0013] In some embodiments, the aerosol capture assembly further includes outlets wells in the microfluidic conduit upstream of the capillary pump for preventing overflow in the microfluidic conduit.

[0014] In some embodiments, the outlet wells are penetrated by pillars of the capillary pump for fluid communication therebetween.

[0015] In some embodiments, the microbeams have an at least partially triangular cross- sectional shape.

[0016] In some embodiments, at least a portion of the microbeams have a rectangular cross-sectional shape.

[0017] In some embodiments, the aerosol capture assembly further includes a plurality of dividers separating the microbeams in multiple cells.

[0018] In another aspect, there is provided a method for capturing aerosol particles with an aerosol capture device, comprising: receiving a flow of air through the aerosol capture device; directing the flow of air through an air conduit of the aerosol capture device towards microbeams in the air conduit; impacting the aerosol particles against the microbeams while the flow of air flows around the microbeams; flowing a buffer fluid through a microfluidic conduit of the aerosol capture device, the microfluidic conduit intersecting the air conduit at the microbeams, the buffer fluid suspending the aerosol particles; and extracting the buffer liquid containing the aerosol particles from the aerosol capture device.

[0019] The method defined above and described herein also includes, in certain embodiments, any one or more of the following features and / or steps, in whole or in part, and in any combination.

[0020] In some embodiments, impacting the flow of air against the microbeams includes diverting the air in a ninety-degree direction around the microbeams.

[0021] In some embodiments, impacting the flow of air against the microbeams includes impacting the flow of air in microchannels formed on upper surfaces of the microbeams.

[0022] In some embodiments, flowing the flow of air through the air conduit of the aerosol capture device includes flowing the flow of air through an array of slits formed in an upper wall of the aerosol capture device.

[0023] In some embodiments, extracting the buffer liquid includes extracting the buffer liquid via a capillary pump downstream of the microbeams.

[0024] In some embodiments, the method further includes flowing the buffer liquid through outlet wells upstream of the capillary pump.

[0025] In a further aspect, there is provided a microfluidic channel impactor (MCI) for capturing aerosol particles in a flow of air, comprising: an upper plate including an array of upper micro-slits; a lower plate including an array of microbeams, with an array of lower microslits disposed between adjacent microbeams; an air conduit receiving the flow of air, the air conduit extending through the upper micro-slits, around the microbeams and through the lower micro-slits, the aerosol particles configured for impacting against the microbeams; and a microfluidic conduit extending between a fluid inlet and a fluid outlet, the microfluidic conduit being in fluid communication with the air conduit for extraction of the impacted aerosol particles.

[0026] The microfluidic channel impactor defined above and described herein also includes, in certain embodiments, any one or more of the following features, in whole or in part, and in any combination.

[0027] In some embodiments, the microbeams have an at least partially triangular cross- sectional shape.

[0028] In some embodiments, at least a portion of the microbeams have a rectangular cross-sectional shape.

[0029] In some embodiments, the microbeams each include an open microchannel extending through an upper surface thereof.

[0030] In some embodiments, each microchannel includes a capture surface aligned with an air inlet of the air conduit.

[0031] In some embodiments, the MCI further includes a capillary pump for extraction of a buffer solution from the microfluidic conduit.

[0032] In some embodiments, the MCI further includes outlets wells in the microfluidic conduit upstream of the capillary pump for preventing overflow in the microfluidic conduit.

[0033] In some embodiments, the outlet wells are penetrated by pillars of the capillary pump for fluid communication therebetween.

[0034] In some embodiments, a gap formed between the upper plate and the lower plate is between 20-300 pm.

[0035] In some embodiments, the MCI further includes a plurality of dividers separating the microbeams in multiple cells.

[0036] Many further features and combinations thereof concerning the present improvements will appear to those skilled in the art following a reading of the instant disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG. 1 is a schematic view of an aerosol capture assembly in accordance with the present disclosure;

[0038] FIG. 2 is a schematic view of a microfluidic channel impactor (MCI) for the aerosol capture assembly of FIG. 1;

[0039] FIG. 3 is a schematic view of an exemplary aerosol particle capture procedure using the aerosol capture assembly of FIG. 1 ;

[0040] FIG. 4 is a schematic cross-sectional view of the aerosol capture assembly of FIG. 1 during the exemplary capture procedure of FIG. 3;

[0041] FIGS. 5A-5C are schematic cross-sectional views showing an exemplary aerosol particle capture procedure using the MCI of FIG. 2;

[0042] FIG. 6 is an enhanced cross-sectional view of an array for the MCI of FIG. 2;

[0043] FIG. 7 shows schematic and graphical views of the MCI of FIG. 2 and the fluid flowing therethrough;

[0044] FIG. 8 shows enhanced top views of the MCI of FIG. 2 during the exemplary capture procedure of FIG. 3;

[0045] FIG. 9 shows enhanced perspective views of the MCI of FIG. 2 during the exemplary capture procedure of FIG. 3;

[0046] FIG. 10 shows further graphical depictions of the performance of various MCI geometries;

[0047] FIG. 11 is a table comparing the performance of an exemplary MCI versus other capture devices;

[0048] FIG. 12 is an image depicting an exemplary MCI testing procedure;

[0049] FIG. 13 are images depicting obstructed and unobstructed MCI conditions;

[0050] FIG. 14 shows schematic views of various exemplary MCI embodiments;

[0051] FIG. 15 shows schematic views of an exemplary large scale MCI;

[0052] FIG. 16 shows schematic views of another exemplary MCI channel geometry;

[0053] FIG. 17 shows schematic views of another exemplary MCI channel geometry;

[0054] FIG. 18 shows graphical depictions of the performance of an exemplary MCI geometry;

[0055] FIG. 19 shows schematic and graphical depictions of of MCI performance testing;

[0056] FIG. 20 shows another graphical depiction of MCI performance testing;

[0057] FIG. 21 shows another graphical depiction of MCI performance testing;

[0058] FIG. 22 shows another graphical depiction of MCI performance testing;

[0059] FIG. 23 is a schematic top view of MCI for the aerosol capture assembly of FIG. 1 , according to another embodiment;

[0060] FIG. 24 shows perspective and cross-sectional views of the MCI of FIG. 23;

[0061] FIG. 25 shows schematic and cross-sectional views of a flow diverter for the MCI ofFIG. 23;

[0062] FIG. 26 shows images depicting exemplary performance results of the MCI geometry shown in FIG. 23;

[0063] FIG. 27 shows a graphical depiction of exemplary performance results of the MCI geometry shown in FIG. 23;

[0064] FIG. 28 shows an exemplary capture procedure using the MCI of FIG. 23;

[0065] FIG. 29 shows an exemplary sample extraction and storage procedure using the aerosol capture assembly of FIG. 1;

[0066] FIG. 30 shows images depicting steps of the exemplary sample extraction and storage procedure of FIG. 29; and

[0067] FIG. 31 shows another exemplary sample collection procedure using the aerosol capture assembly of FIG. 1.DETAILED DESCRIPTION

[0068] According to the present disclosure, there is provided an aerosol capture device (ACD), in particular a microfluidic channel impactor (MCI), that leverages capillary microfluidics and 3D printing to address at least some of the above-described challenges. The MCI improves upon previous attempts, for instance, through the incorporation of microfluidic channels to allow for sample extraction in a much (~10x) smaller volume of liquid, improving the sample concentration compared to known devices. The disclosed MCI is provided with a compact footprint and configured for high volumetric airflow for capture of exhaled bioaerosols and minimal dilution. The microfluidic channel impactor (MCI) may also be referred to as a Microfluidic Comb Impinger (MCI).

[0069] In various embodiments, the MCI includes an array of triangular microbeams (concurrently forming an array of micro-slits between the microbeams), positioned facing an array of micro-slits on top, and with a critical gap between the two arrays, each microbeam further includes an open microchannel on top running over its length. In use, air flowing through the narrow top slits is sped up, and abruptly redirected around the microbeams into the critical gap and to the bottom of the MCI, while aerosol particles, carried by their inertia, impact the microchannel floor. In a particular embodiment, the MCI includes a capillary circuit that connects to each of the open channels on the microbeams allowing for the extraction of capturedaerosols by capillary flow. In an alternate embodiment, fluid is circulated in a fluidic circuit of the MCI using a liquid pump, rather than by capillary flow.

[0070] Referring to FIG. 1, there is shown an exemplary aerosol capture assembly 10 receiving an aerosol capture device (ACD) 20’ for detecting the presence of pathogens in aerosol particles 30 in an exhaled sample of air 40. The depicted aerosol capture assembly 10 includes a body 11 having a body inlet 12, a body outlet 13, and a body conduit 14 extending between the body inlet 12 and the body inlet 13. Other aerosol capture assemblies may be contemplated, for instance having one or more tubes directing air to and from the ACD 20’. In other cases, the body 11 of the aerosol capture assembly 10 is omitted, and the ACD 20’ is configured to directly capture airflow from a user or patient. For instance, in an embodiment, the ACD 20’ is placed in a mask of a user or patient to capture the expelled airflow. In the shown case, the ACD 20’ is disposed in the body conduit 14, illustratively at a midpoint between the body inlet 12 and the body outlet 13. Other positions for the ACD 20’ in the body conduit 14 may be contemplated. In the shown case, the ACD 20’ is removably received in the body conduit 14, illustratively by way of a removable portion 15 of the body 11. In the shown case, the body conduit 14 has a converging-diverging cross-sectional profile, for instance to increase the pressure and concentration of the pathogens (aerosol particles 30) in the flowing air 40 towards the ACD 20’, thereby promoting a laminar flow of the air 40. Other body conduit 13 profiles may be contemplated.

[0071] Referring additionally to FIGS. 2-5C, in the shown case, the ACD 20’ is a microfluidic channel impactor (MCI) 20. The MCI 20 disposed in the body conduit 14 includes a chip body 21 having an air inlet 22 in fluid communication with the body inlet 12 and an air outlet 23 in fluid communication with the body outlet 13. The MCI 20 includes an upper plate 20a spaced apart from a lower plate 20b, with an air conduit 24 extending through the plates 20a, 20b to fluidly connect the air inlet 22 and the air outlet 23. The air 40 is flowed through the air conduit 24 for the capture of aerosol particles 30, as will be discussed in further detail below. Illustratively, the flowing air 40 is a laminar air flow. The air conduit 24 includes a flow diverter 25 configured for separating the aerosol particles 30 from the flowing air 40. As the air 40 flows through the air conduit 24, the aerosol particles 30 impact the flow diverter 25, causing separation from the air 40, while the air 40 continues to flow around the flow diverter 25 and towards the air outlet 23. Stated differently, the air 40 is diverted (i.e., flows) around the flow diverter 25 towards the air outlet 23 while the inertia of the aerosol particles 30 causes them to impact the flow diverter 25. As shown in FIG. 4, in some embodiments, the flow diverter 25 includes a plurality of recessesor cavities for capturing the impacted aerosol particles 30. In the shown embodiment, the flow diverter 25 is formed of an array of microbeams 25a in the lower plate 20b, illustratively triangular microbeams 25a (concurrently forming an array of micro-slits 25b between the microbeams 25a). The microbeams 25a are positioned facing an array of micro-slits 24a in the upper plate 20a, and with a critical gap X3 (see FIG. 6) between the plates 20a, 20b. The air conduit 24 thus extends through the slits 24a, 25b in the plates 20a, 20b. Each microbeam 25a further includes an open microchannel 25c on top running over its length. The microchannels 25c are configured for capturing or trapping the inertia-driven aerosol particles 30 while the airflow 40 flows around the microbeams 25a. Other geometries may be contemplated. An exemplary scale of the microfluidic channel 26 is shown relative to a person’s finger in FIG. 4.

[0072] Still referring to FIGS. 1-5C, the MCI 20 further includes a microfluidic conduit 26 extending between a fluid inlet 27 and a fluid outlet 28. The microfluidic conduit 26 is in fluid communication with the air conduit 24 adjacent the flow diverter 25, illustratively meeting the air conduit 24 transversely. As shown in FIG. 4, the microfluidic channel 26 includes an embedded inlet 26a upstream of the flow diverter 25 and an embedded outlet 26b downstream of the flow diverter 25. The microchannels 25c illustratively form part of the microfluidic channel 26. As such, a buffer 50 (or other like extraction fluid) is flowed through the microfluidic conduit 26 to extract the separated aerosol particles 30. In the shown case, the fluid outlet 28 includes outlet wells 28a and a capillary pump 28b at the downstream end of the microfluidic conduit 26, the outlet wells 28a being penetrated by pillars of the capillary pump 28b for fluid communication therebetween. The buffer 50 is thus introduced into the microfluidic conduit 26 via the fluid inlet 27, circulated through the microfluidic conduit 26 to recover the captured aerosol particles 30, and exits via the fluid outlet 28 (illustratively via fluid wells 28a and capillary pump 28b). The captured aerosol particles 30 are suspended in the extracted buffer 50 for subsequent testing to confirm the presence of pathogens in the exhaled air 40 and thus in a patient.

[0073] Referring to FIG. 3, an exemplary capture and extraction procedure is shown at 300, with reference to the aerosol capture assembly 10 and MCI 20 shown in FIGS. 1-2. A user 60, also referred to as a patient, expels air 40 into the aerosol capture assembly 10. The air 40 flows through the body conduit 14 towards the MCI 20. As the air 40 flows into the body inlet 12 and through the air conduit 24 in the MCI 20, aerosol particles 30 are impacted at the flow diverter 25 and thus separated from the air 40, which flows out of the MCI 20 and out of the aerosol capture assembly 10 through the body outlet 13. The MCI 20 is then removed from theaerosol capture assembly 10 for extraction. In other cases, the aerosol capture assembly 10 may be configured for extraction without removal of the MCI 20.

[0074] The buffer 50 is introduced to the microfluidic conduit 26 via the fluid inlet 27, flowed through the microfluidic conduit 26 to capture the separated aerosol particles 30, and extracted from the MCI 20 via the fluid outlet 28. The extracted buffer 50 containing the captured and suspended aerosol particles 30 (also referred to as a sample to be tested) is isolated, for instance via centrifuge, and then tested or analyzed to detect the presence of one or more pathogens.

[0075] In an exemplary embodiment, the MCI 20 is configured for sequestering aerosol particles 30 from the flow of air 40 passing through it, illustratively by depositing (via impact) the sample containing particles into the internal microfluidic channels. Following capture, the buffer 50 or other like extraction liquid is added to the microfluidic conduit 26, illustratively a capillary microfluidic network, to resuspend the captured aerosol particles. Capillary flow propels the buffer 50 towards the capillary pump 28b where the finer cross sectional feature size draws further fluid through the channels. This flow washes the impact surface and extracts the sample from the MCI 20 array into the capillary pump 28b. Once extracted, the sample can then undergo pathogen analysis, for instance ELISA, LAMP, PCR or other similar analyses. Advantageously, the MCI 20 facilitates direct sample extraction and minimizes sample loss while retaining the sample in a small volume to increase concentration. By maximizing the concentration of the sample, prior concerns regarding low sample quantity prevalent in aerosol sampling can be addressed to improve assay performance.

[0076] Various manufacturing procedures may be contemplated. As noted above, various components of the aerosol capture assembly 10 are manufactured via 3D printing. For instance, the MCI 20 and capillary pump 28b are 3D printed. In a particular embodiment, the MCI 20 and capillary pump 28b are printed on a ASIGA Max X27 385 nm DLP 3D printer. Parts were sliced into 20 pm layers in Z with 27pm pixels in XY. A base exposure time of 5.5 seconds and a layer exposure time of 0.65 seconds with a power of 4.95 mW / cm2. Resin was filtered between printing sessions to preserve print quality. The parts were washed repeatedly with isopropyl alcohol (I PA) and blow dried clean with compressed air. Finally, a 30 second UV post cure is applied. Other 3D printing procedures may be contemplated. The resin is, for instance a photopolymer resin composed of Poly (ethylene glycol) diacrylate (PEGDA)-250, diphenyl(2,4,6- trimethylbenzoyl)phosphine oxide (TPO), 2-isopropylthioxanthone (ITX). The three componentswere mixed at a ratio of 98.7% PEGDA, 0.8% ITX, and 0.5% TPO at room temperature for 24 hours prior to printing. Resins were stored in light impermeable containers. Other resin compositions may be contemplated.

[0077] In an embodiment, the MCI 20 geometry is a complex 3D structure enabled by advances in high resolution 3D printing of internal voids and -100 pm feature sizes. While traditional subtractive manufacturing could possibly be used to create a similar geometry, this would be prohibitively complex and expensive. Additionally, the ability to rapidly iterate and change the internal geometry to influence the airflow allows for modification of the MCI 20 geometry to fit the needs of specific applications. In embodiments, the entire chip is 3D printed using a custom photopolymer resin termed.

[0078] Referring to FIG. 6, an enhanced cross sectional view of the MCI array 20a is shown. Various dimensions for the various components are contemplated. For instance, a width X1 of the dividers 24b between micro-slits 24a is between 300-800 pm, a width X2 of the micro-slits is between 50-200 pm, the critical gap X3 between top and bottom arrays is between 20-300 pm, a depth X4 of the micro-channels 25c is between 20-200 pm, a width X5 of the micro-channels 25c is between 50-200 pm, a distance X6 from an upper edge of a micro-channel 25c to an adjacent upper edge of the micro-beam 25a is between 50-300 pm, an overall thickness X7 of the MCI array 20a is 700-2,000 pm, and a center-to-center distance X8 between micro-beams 25a is between 400-2,000 pm. Other dimensions may be contemplated.

[0079] Referring to FIG. 7, images and graphs are shown at 700 to highlight various features enabled by high resolution additive manufacturing in the formation of MCI 20, according to various embodiments. The fluid wells 28a, also referred to as outlet wells, act as stop valves, preventing the overflow or escape of the buffer 50 from the MCI 20 array until the capillary pump 28b is positioned properly. As noted above, the fluid wells 28a are penetrated by the pillars present on the capillary pump 28b. Once this fluidic connection is made between the fluid wells 28a and the pillars of the capillary pump 28b, the extraction can begin and fluid flows from the fluid inlet 27 through the MCI 20 array and into the capillary pump 28b. In some embodiments, sub 10 pm dimensional accuracy of key geometrical parameters.

[0080] Referring to FIGS. 8 and 9, images of fluid flow through the MCI 20 are shown at 800 and 900. In particular, FIG. 8 shows at 800 an enhanced top view of the MCI 20, while FIG. 9 shows at 900 an enhanced perspective view of the MCI 20, with images (i)-(iv) in FIG. 8corresponding to images (i)-(iv) in FIG. 9. As discussed above, a critical gap is formed between the top layer of slits and the bottom layer of capillary channel carrying struts, for instance < 40 pm. The depth of the capillary channel may also vary. The critical gap mainly influences the airflow while the channel depth impacts the dead-volume of the chip, the flow rate during extraction and theoretically the capture rate. In some embodiments, a feature-less zone is provided around the edge of the open channels to maintain the containment of liquid in the open-faced capillary channels and prevent leakage.

[0081] Referring to FIG. 10, graphical depictions of pressure-related results are shown at 1000. In various embodiments, a reduced pressure drop across the MCI 20 improves patient comfort and capture performance. If the required pressure drop were too high, a patient with a reduced expiratory pressure would not be capable of generating a sufficient flow rate for high capture flow. A reduction in the required pressure drop allows for sampling from a wide variety of patients and maximize device performance.

[0082] Referring to FIG. 11, table 1100 is provided to compare the performance of an exemplary MCI 20 versus other capture devices. In particular, the airflow, capture rate, pressure drop, extraction volume, footprint, and fabrication are compared.

[0083] Referring to FIG. 12, an image 1200 of an exemplary characterization platform with PDA operational is shown. Other platforms may be contemplated.

[0084] Referring to FIG. 13, images 1300 depicting obstructed and unobstructed MCI conditions are shown. Such obstruction may result, for instance, from the occlusion of air slits during fabrication. This occlusion can be caused, for instance, by higher base cure times. Such occlusion may be avoided, for instance, by changing the design geometry to widen channels to prevent over-exposed mediated polymerization expansion.

[0085] Referring to FIG. 14, schematic views of various exemplary MCI embodiments at 1400. Various features in each embodiment are disclosed, depicting different slit and pore designs, channel geometry, and monolithic or two-part chip designs. Other variations may be contemplated.

[0086] Referring to FIG. 15, schematic views of an exemplary large scale MCI are shown at 1500. In an embodiment, a large scale MCI is provided for high throughput air processing rather than patient sampling. For instance, such a device may be used for environmental monitoringwith longer collection times. In embodiments, the large scale MCI is configured for 100-500 LPM of airflow while maintaining the above-noted capture rates demonstrated above.

[0087] Other embodiments of the above-described MCI 20 may be contemplated. For instance, a two component device may be contemplated, for instance with different surface coatings to the different components to further influence the fluidic behavior. In addition, a cartridge system for the extraction and storage of samples obtained from MCI or similar aerosol capture devices may be provided to utilize the principles of capillary flow to confine and draw liquid into its geometry. In addition, in situ MCI analysis may be contemplated wherein the sample can be resuspended in gel in the channels for further analysis and or staining and imaging.

[0088] Referring to FIGS. 16 and 17, other embodiments of MCI channel geometry are shown at 1600 and 1700. As discussed above, leakage is a concern in MCI design, as such failure can lead to a wasted sample. In the embodiment shown in FIG. 16, the single array design discussed above is replaced with single cell geometry-based design in which physical barriers separate each cell from one another. Stated differently, internal divisions along a vertical axis of the MCI prevent leaked fluid from spreading in that direction, as shown in FIG.16. Alternatively, divisions along both the vertical and lateral axes of the MCI, as shown in FIG.17, may be provided to further isolate any leaked fluid from the other cells. Other cell designs may be contemplated.

[0089] Referring to FIG. 18, graphical depictions of the performance of an exemplary MCI geometry are shown at 1800. At A, the geometry of an exemplary MCI is shown in crosssection. The depicted MCI was tested via phase doppler anemometry, although this is only exemplary. At B, the pressure drop across the MCI is shown for varied airflow rates. At C and D, the effect of geometrical parameters on pressure drop is shown. At E, the capture rate of different MCI geometries for different sized particles is shown. At F, the effect of air flow rate on capture rate is shown. At G and H, the effect of geometrical parameters on capture rate, illustratively taken at, from dark to light shaded lines, 2 pm, 1.5 pm, 1 pm, 0.75 pm, 0.5 pm, and 0.25 pm.

[0090] Referring to FIG. 19, another exemplary testing procedure is shown at 1900, demonstrating that the sample was captured in the channel beds of the MCI rather than in off- target areas. In the testing procedure, fluorescent AF647 tagged BSA protein was aerosolized inartificial saliva into the airflow passing through the chip. The chip was then imaged using confocal Z stack microscopy and reconstructed in 3D to demonstrate the deposition patterns and locations of the fluorescence within the internal geometry. The “on-target” fraction of fluorescence can be quantified to shown a relationship to the flow rate, similarly to what was observed for the total capture rate in the previous testing procedures described above. The image shown in FIG. 19 a projection of the 3D reconstructed image into a 2D plane so that the off-target fluorescence and on target fluorescence can both be seen together the same image.

[0091] Referring now to FIG. 20, another exemplary testing procedure is shown at 2000, demonstrating the robustness of sample accumulation. In this testing procedure, aerosolization, capture, extraction and sample measurement were with FITC as the sample, and a nanodrop spectrofluorometer as the measurement tool. The results shown in FIG. 20 depict a robust and predictable accumulation of sample in the extract.

[0092] Referring now to FIG. 21, another exemplary testing procedure is shown at 2100, depicting reproducibility experiments. In particular, the testing aimed to verify if similar concentration in the extract could be detected across ten replicates. This testing procedure was conducted similarly to the previous experiments, but with AF647 labelled BSA as the sample instead of FITC.

[0093] Referring now to FIG. 22, another exemplary testing procedure is shown at 2200. In these experiments, a bacteriophage virus PR772 is used as a model for influenza. Samples were aerosolized, captured, and extracted from an airstream containing this phage. The samples were then put through PCR to verify the presence of the genetic material of the PR772 phage. FIG. 22 depicts a cutout of the PCR gel depicting a positive signal in the four minute capture conditions, the positive control condition, and a lack of signal in the negative control condition.

[0094] Referring now to FIGS. 23 and 24, another embodiment of an MCI 120 for the aerosol capture assembly 10 of FIG. 1 is shown. Referring to FIG. 25, an exemplary flow diverter 125 for the MCI 120 of FIGS. 23-24 is shown. As was the case in the above-described embodiments, the flow diverter 125 configured for separating the aerosol particles 130 from the flowing air 140. As the air 140 flows through the air conduit 124, the aerosol particles 130 impact the flow diverter 125, causing separation from the air 140, while the air 140 continues to flow around the flow diverter 125 and towards the air outlet. Stated differently, the air 140 isdiverted (i.e. , flows) around the flow diverter 125 towards the air outlet while the inertia of the aerosol particles 130 causes them to impact the flow diverter 125. As shown in FIG. 25, the flow diverter 125 includes a plurality of recesses or cavities for capturing the impacted aerosol particles 130. In the shown embodiment, the flow diverter 25 is formed of an array of microbeams 125a in the lower plate, illustratively microbeams 125a having at least a portion with a rectangular cross-sectional shape. These at least partially cross-sectional microbeams 125a concurrently form an array of micro-slits 125b between the microbeams 125a. Each microbeam 125a further includes an open microchannel 125c on top running over its length. The microchannels 125c are configured for capturing or trapping the inertia-driven aerosol particles 130 while the airflow 140 flows around the microbeams 125a. Other geometries may be contemplated. As was the case in the above-described embodiments, a buffer 150 flowing through the microchannels 125 to recover the captured aerosol particles 130. The captured aerosol particles 130 are suspended in the extracted buffer 150 for subsequent testing to confirm the presence of pathogens in the exhaled air 140 and thus in a patient. In the shown embodiment, the microchannels 125 are persistently embedded channels which contact an elevated capture surface for sample re-solubilization in the areas aligned with the air conduits 124. As shown in FIG. 25, the step-like cross-sectional shape of the microchannels 125 allow for this capture surface alignment, although other cross-sectional shapes are contemplated.

[0095] Referring now to FIGS. 26 and 27, exemplary performance testing results for the MCI geometry of FIG. 23 are shown at 2600 and 2700. In the tests represented at 2600, fluorescent protein was aerosolized and captured within the chip under different flow conditions and then extracted. Devices were imaged with confocal microscopy to visualize the localization of the protein deposition and confirm its extraction. In addition, as represented at 2700, this MCI geometry was tested for its overall capture rate vs particle size.

[0096] Referring now to FIG. 28, an exemplary capture sequence using the MCI 120 of FIG. 23 is shown. At a), an empty chip is provided. At b), 20 pL of buffer is added to the inlet reservoir. At c), the buffer starts to fill through the inlet channels, travelling down the extraction channels sequentially. At d), as the extraction channels have all filled and paused at the stop valves, the timing channel is filling at a slight delay relative to the extraction channels. At e), the timing channel is filled and the fluid reaches the stop valves at the ends of the extraction channels. When the fluid reaches these locations, it breaks the edge pinning condition holding the liquid back in the channels. At e), once all the stop valves are broken, the main reservoir is drained into the capillary pump through all of the extraction channels evenly. The above-described sequence can allow for evenly captured samples, thereby accounting for different flow rates through the various channels. As such, fluid flow is controlled, while the formation of clogs due to air bubbles is prevented.

[0097] Referring now to FIGS. 29 and 30, an exemplary sample extraction and storage procedure using the aerosol capture assembly of FIG. 1 is shown at 2900 and 3000. A user dips the system into a well of extraction buffer to draw liquid up into the extraction channels through capillary flow. The user then brings the tip of the device into contact with an adsorbent sample storage card. Capillary wicking leads to the unloading of the sample into the storage card for further processing, storage or standardization. In particular, and with reference to FIGG. 29, at a), a diagram of the dip design of the MCI geometry. At b), a diagram of MCI carrier and patient exhalation is shown. At c), buffer loading and sample re-solubilization steps are shown. At d), the sample is shown to be transferred to the adsorbent pad storage card.

[0098] Referring now to FIG. 31, there is shown at 3100 another exemplary sample collection procedure using the aerosol capture assembly of FIG. 1. In the shown embodiment, the channels are filled with a hydrogel or similar porous and diffusive matrix containing reagents or signal generation molecules which can interact with potential targets in the captured analyte. For instance, the channels are prefilled with the hydrogel containing all required reagents for pathogen viability, activity and signal generation. For instance, the above-described process can be used via l_AM activated fluorescent reaction, pH mediated reaction, or other cellular metabolic activity based reaction depending on the target.

[0099] Still referring to FIG. 31, at a), there is shown a capillary filling process of liquid gel precursor into channels. At b), there is shown gelation, which leads to the solidification of the gel in channel beds. At c), the capture of samples proceeds as described above with reference to previous embodiments. At d), a chemical reaction (e.g., LAM assay or similar) happens locally around the impacted sample, based its contents, to generate a signal. At e), a top-down image of each capture area is shown, for instance depicting what would be seen via a microscope. At f), an image of the entire array of capture surfaces enables obtainment of a quantification of reactive aerosol impaction points.

[0100] According to an embodiment, there is provided a method for capturing aerosol particles with an aerosol capture device. A flow of air is received through the aerosol capture device. The flow of air is flowed through an air conduit of the aerosol capture device. The flow ofair is impacted against a wall in the air conduit to separate the aerosol particles from the flow of air. A buffer liquid is flowed through a microfluidic conduit of the aerosol capture device, the microfluidic conduit intersecting the air conduit at the wall, the buffer fluid suspending the separated aerosol particles. The buffer liquid containing the separated aerosol particles is extracted from the aerosol capture device.

[0101] The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure.

[0102] Various aspects of the systems and methods described herein may be used alone, in combination, or in a variety of arrangements not specifically discussed in the embodiments described in the foregoing and is therefore not limited in its application to the details and arrangement of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments. Although particular embodiments have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects. The scope of the following claims should not be limited by the embodiments set forth in the examples, but should be given the broadest reasonable interpretation consistent with the description as a whole.

Claims

WHAT IS CLAIMED IS:

1. An aerosol capture assembly, comprising: a body having a body inlet, a body outlet, and a body conduit extending between the body inlet and the body outlet, the body conduit being configured to direct a flow of air therethrough, the flow of air containing aerosol particles; an aerosol capture device disposed in the body conduit, the aerosol capture device being a microfluidic channel impactor (MCI) including: an air conduit having an air inlet in fluid communication with the body inlet and an air outlet in fluid communication with the body outlet, the air conduit of the MCI including a flow diverter configured for separating aerosol particles from the air; and a microfluidic conduit extending between a fluid inlet and a fluid outlet of the MCI, the microfluidic conduit being in fluid communication with the air conduit for extraction of the aerosol particles separated from the air.

2. The aerosol capture assembly as defined in claim 1, wherein the flow diverter includes an array of microbeams disposed in the air conduit, the array of microbeams configured for diverting the flow of air and impacting the aerosol particles.

3. The aerosol capture assembly as defined in claim 2, wherein the microbeams form a ninety-degree bend in the air conduit.

4. The aerosol capture assembly as defined in claim 2 or 3, wherein the microbeams each include a microchannel extending along an upper surface thereof for capturing the aerosol particles.

5. The aerosol capture assembly as defined in claim 4, wherein each microchannel includes a capture surface aligned with the air inlet of the air conduit.

6. The aerosol capture assembly as defined in any one of claims 1 to 5, further comprising an array of micro-slits upstream of the microbeams, the air configured to flow through the microslits before reaching the microbeams.

7. The aerosol capture assembly as defined in any one of claims 1 to 6, wherein the MCI includes a capillary pump for extraction of a buffer solution from the microfluidic conduit.

8. The aerosol capture assembly as defined in claim 7, further comprising outlets wells in the microfluidic conduit, upstream of the capillary pump, for preventing overflow in the microfluidic conduit.

9. The aerosol capture assembly as defined in claim 8, wherein the outlet wells are penetrated by pillars of the capillary pump for fluid communication therebetween.

10. The aerosol capture assembly as defined in any one of claims 2 to 9, wherein the microbeams have an at least partially triangular cross-sectional shape.

11. The aerosol capture assembly as defined in any one of claims 2 to 9, wherein at least a portion of the microbeams have a rectangular cross-sectional shape.

12. The aerosol capture assembly as defined in claim 10 or 11 , further comprising a plurality of dividers separating the microbeams in multiple cells.

13. A method for capturing aerosol particles with an aerosol capture device, comprising: receiving a flow of air through the aerosol capture device; directing the flow of air through an air conduit of the aerosol capture device towards microbeams in the air conduit; impacting the aerosol particles against the microbeams while the flow of air flows around the microbeams; flowing a buffer fluid through a microfluidic conduit of the aerosol capture device, the microfluidic conduit intersecting the air conduit at the microbeams, the buffer fluid suspending the aerosol particles; and extracting the buffer fluid containing the aerosol particles from the aerosol capture device.

14. The method as defined in claim 13, wherein impacting the flow of air against the microbeams includes diverting the air in a ninety-degree direction around the microbeams.

15. The method as defined in claim 13, wherein impacting the flow of air against the microbeams includes impacting the flow of air in microchannels formed on upper surfaces of the microbeams.

16. The method as defined in any one of claims 13 to 15, wherein flowing the flow of air through the air conduit of the aerosol capture device includes flowing the flow of air through an array of slits formed in an upper wall of the aerosol capture device.

17. The method as defined in any one of claims 13 to 16, wherein extracting the buffer fluid includes extracting the buffer fluid via a capillary pump downstream of the microbeams.

18. The method as defined in claim 17, further comprising flowing the buffer fluid through outlet wells upstream of the capillary pump.

19. A microfluidic channel impactor (MCI) for capturing aerosol particles in a flow of air, comprising: an upper plate including an array of upper micro-slits; a lower plate including an array of microbeams, with an array of lower micro-slits disposed between adjacent microbeams; an air conduit receiving the flow of air, the air conduit extending through the upper microslits, around the microbeams and through the lower micro-slits, the aerosol particles configured for impacting against the microbeams; and a microfluidic conduit extending between a fluid inlet and a fluid outlet, the microfluidic conduit being in fluid communication with the air conduit for extraction of the aerosol particles.

20. The microfluidic channel impactor as defined in claim 19, wherein the microbeams have an at least partially triangular cross-sectional shape.

21. The microfluidic channel impactor as defined in claim 19, wherein at least a portion of the microbeams have a rectangular cross-sectional shape.

22. The microfluidic channel impactor as defined in claim 19 or 20, wherein the microbeams each include an open microchannel extending through an upper surface thereof.

23. The microfluidic channel impactor as defined in claim 22, wherein each microchannel includes a capture surface aligned with an air inlet of the air conduit.

24. The microfluidic channel impactor as defined in any one of claims 19 to 23, further comprising a capillary pump for extraction of a buffer solution from the microfluidic conduit.

25. The microfluidic channel impactor as defined in claim 24, further comprising outlets wells in the microfluidic conduit, upstream of the capillary pump, for preventing overflow in the microfluidic conduit.

26. The microfluidic channel impactor as defined in claim 25, wherein the outlet wells are penetrated by pillars of the capillary pump for fluid communication therebetween.

27. The microfluidic channel impactor as defined in any one of claims 19-26, wherein a gap formed between the upper plate and the lower plate is between 20-300 pm.

28. The microfluidic channel impactor as defined in any one of claims 19-27, further comprising a plurality of dividers separating the microbeams in multiple cells.

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