JP2008500542A - Airborne particulate collection method and apparatus - Google Patents

Abstract

An embodiment of an apparatus for collecting biological suspended dust from an air sample includes a hollow tube adapted to pump liquid through an internal volume to an outer surface, and an ambient air sample disposed on the outer surface. And a collection surface adapted to collect airborne particulates from. Collection efficiency is enhanced by a charging mechanism that applies a charge to the airborne particulate so that the airborne particulate is refracted toward the collection surface. Embodiments of the apparatus operation include supplying an air sample, directing the air sample to a hollow tube, and charging the airborne particulate so that the airborne particulate is deposited on the collection / outside surface of the hollow tube. Adding.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of US patent application Ser. No. 10 / 603,119, filed Jun. 24, 2003 (named “Method And Apparatus For Concentrated Airborne Particle Collection”), The entire contents of which are incorporated herein by reference. This application also includes US Provisional Patent Application No. 60/574803 (named “Electrostatic Particle Collection System”) filed May 27, 2004, and “Spinning Disc Electrostatic” filed March 7, 2005. Claims priority of US Provisional Patent Application No. 60 / 659,362 (named “Collection System”), the entire contents of both of which are hereby incorporated by reference.

REFERENCE TO GOVERNMENT FINANCIAL SUPPORT This invention relates to contract numbers DAAD13-03-C-0041 and U.S.A. awarded by the Defense Advanced Research Projects Agency. S. Made with government support under contract number W911SR-04-C-0025 awarded by Army Robert Morris Acquisition Center. The government has certain rights in this invention.

  The present invention relates generally to air sampling, and more particularly to the collection of pathogens and aerosol particles from air samples.

There is an increasing demand for military, civilian or personal air sampling systems that can collect airborne and pathogenic microparticles or spores. Although current air sampling systems have been proven to function reliably, they are often very large and therefore not only consume large amounts of power but also generate a lot of noise. These systems also tend to produce very large liquid samples and their analysis can take days or even weeks. Thus, current air sampling systems are not practical for civilian or personal use, or for environments or situations where air sample analysis must be done quickly.
US Patent Application No. 10/603119 US Provisional Application No. 60/574803 US Provisional Application No. 60/659362

  Accordingly, there is a need in the art for a compact and highly efficient bio-aerosol collector that can produce a relatively small volume of liquid sample for rapid analysis.

  An embodiment of an apparatus for collecting biologically suspended dust particles from an air sample is disposed on the outer surface, with a hollow tube adapted to pump liquid through the inner volume of the hollow tube to the outer surface, A collection surface adapted to collect airborne particulates from an ambient air sample. Collection efficiency is enhanced by a charging mechanism that imparts charge to the airborne particulates such that the airborne particulates are refracted toward the collection surface. Embodiments of the apparatus operation include supplying an air sample, directing the air sample to a hollow tube, and charging the airborne particulate so that the airborne particulate is deposited on the collection / outside surface of the hollow tube. Including the step of imparting.

  In order that the above-described embodiment of the invention may be achieved and understood in detail, a further specific description of the invention briefly summarized above will be made by reference to that embodiment illustrated in the accompanying drawings. Do it. However, the attached drawings show only typical embodiments of the present invention, and therefore the present invention can tolerate other equally effective embodiments and should not be considered as limiting its scope. Please be careful.

  To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.

  Embodiments of the present invention generally provide a compact, lightweight, low power and low noise device that can collect respiratory inhalable airborne particulates and focus or concentrate them in a small liquid volume. In one embodiment, the device can achieve a concentration of particulates of about 1 to 10 microns and can achieve a sampling rate of up to about 1000 liters per minute (lpm).

  FIG. 1 is a cutaway view of one embodiment of a particulate collection device 100 according to the present invention. In the illustrated embodiment, the device 100 is configured in a substantially cylindrical shape. However, those skilled in the art will appreciate that embodiments of the invention may be configured in any alternative form and shape without departing from the scope of the invention. The device 100 includes a housing 102 containing an air inhalation assembly 104 therein, a sample separation zone 106, and a particulate collection zone 108.

  The air intake assembly 104 is adapted to draw an air flow into the collection device 100 and includes a motor 110, first and second fans 112 A, 112 B, and an air duct 114. The first fan 112 </ b> A is disposed adjacent to the first end 101 of the collecting device 100 and is connected to the fan motor 110. An optional second fan 112B is disposed inwardly of the first fan 112A along the longitudinal axis of the device 100, and in one embodiment, the second fan 112B is smaller than the first fan 112A. The air duct 114 begins at the opening 116 at the second end 103 of the device 100 and extends at least partially therethrough to provide an inlet passage for air that is inhaled by the fans 112A, 112B during operation. In one embodiment, this duct 114 is disposed through the central portion 105 of the housing 102. Optionally, the air intake assembly 104 can further comprise an impactor 150 disposed between the duct 114 and the fans 112A, 112B and adapted to act as a prefilter. That is, the impactor 150 includes a plurality of tubes or channels 152 for filtering large particles out of the primary flow as it is drawn into the device 100.

  The sample separation zone 106 is substantially annular in the cyclone 118 located radially outward of the central portion 105 of the device 100 (ie, in the radial direction of the air duct 114 in the embodiment shown in FIG. 1). An arrangement and a vortex breaker 120 (shown in FIGS. 2 and 4) are provided. FIG. 3 is a top view of the cyclone arrangement shown in FIG. Although FIG. 3 shows an array of eight cyclones 118, those skilled in the art will appreciate that a greater or lesser number of cyclones can be used to advantage. Referring to FIGS. 1 and 3 simultaneously, each cyclone 118 in the array is coupled to the air duct 114 via a tangential inlet 124. This inlet 124 is adapted to carry incoming air from the duct 114 to the sample separation zone 106. Each cyclone 118 is adapted to separate airborne particulates from the primary air stream. A plurality of vortex finders 154 disposed proximate to the first end 107 of the cyclone 118 project into the cyclone 118 to form a first outlet hole (port) 122 for primary flow. The short flow path is provided. That is, the first outlet holes 122 at the first end 107 of each cyclone 118 parallelize and guide the primary flow exiting the cyclone 118 so that the primary flow can be discharged from the separation zone 106. It is made like that. A second outlet hole (port) 126 located proximate to the second end 109 of each cyclone 118 carries the separated particulate stream to the vortex shelter 120.

  With reference to FIGS. 1, 2, and 4, the vortex breaker 120 is disposed proximate the second end 109 of the cyclone 118 and in one embodiment comprises a series of chambers 128. One chamber 128 is positioned adjacent to the second end 109 of each cyclone 118 and has an internal volume adapted to concentrate the particulate stream carried from the cyclone 118 into a relatively dense, low velocity stream. Have. Alternatively, one chamber (not shown) can be substantially annular in shape and can receive a flow of suspended dust from all cyclones 118. A tangential slot 136 in the wall 138 of the vortex chamber 128 draws a flow of suspended dust from the chamber 128 and directs it toward the capture area 108.

  This vortex breaker 120 is separated from the capture zone 108 by a controllable air / fluid interface 130. The air / fluid interface 130 is disposed adjacent to the outside of the vortex chamber 128, and in one embodiment the mechanism comprises a liquid plate 132 having a highly porous hydrophobic membrane 134 disposed thereon. . The hydrophobic membrane 134 includes a vortex chamber 128 adapted to contain air or particulate flow (ie, a gaseous medium) and a capture zone 108 adapted to contain a liquid as further described herein. To form a liquid seal or boundary. In one embodiment, the membrane 134 comprises a nylon mesh that is thermally embedded on at least a portion of the capture zone 108. This nylon network is optionally treated with polytetrafluoroethylene (PTFE) or an equivalent material to increase its hydrophobic properties.

  Referring to FIGS. 1 and 5, the capture zone 108 has at least one microfluidic (microfluidic) in which a small volume of liquid for carrying suspended dust or other particulates directed and focused therein is contained. ) Or nanofluidic channel 140. In one embodiment, a nylon mesh as described above is thermally embedded on at least one flow path 140. The capture zone 108 is a means for collecting a liquid stream (including particulates guided and converged therein) or, alternatively, transporting the stream to another analysis or collection device (not shown). A liquid collection chamber 142 that can be coupled may further be provided.

  The air / fluid interface 130 described above provides an electrostatic induction focusing mechanism such as a corona charging area 500 for electrostatic handling of particulates to enhance the guidance or convergence of the particulates into the liquid. Optionally included in at least one flow path 140. One embodiment of a corona charging zone 500 is shown schematically in FIG. The corona charging area 500 includes a corona array 602 and a ground electrode 604. Corona array 602 includes a plurality of corona tips (tips) 606 disposed proximate to at least one flow path 140 of capture zone 108. The electrode 604 is positioned some distance away from the array, and in one embodiment is positioned across the flow path 140 from the array 602. Thereby, an electrostatic field 608 is generated between the array 602 and the electrode 604. This electrostatic field 608 charges the particulates in the liquid stream and drives them towards the center of the flow path 140. Thereby, the corona charging zone 500 is adapted to enhance the operability of the microparticles into the liquid by forcing the microparticles into the center of the liquid for faster and more efficient transport. The electrostatic field generated by the corona charging zone 500 also ensures a substantially uniformly charged particulate flow.

  FIG. 7 is a schematic diagram of a second embodiment of a collection area 700 that includes a corona charging area 702. In this embodiment, collection area 700 includes corona array 704 and electrodes 706, moving particulate-collecting material such as tape 708, sump 710, and particulate removal device 712. In one embodiment, the collection tape 708 has a first surface 701 and a second surface 703 that are adapted to move in a closed loop around several (eg, three or more) bearings 714. . In one embodiment, this closed loop resembles a triangle. The corona array 704 and the electrode 706 generate an electrostatic field 716 that drives the particulates through the opening 722 of the flow path 740 and onto the adjacent first surface 701 of the collection tape 708. A liquid reservoir 710 is positioned adjacent to the lower bearing or bearings 714 to wick a thin layer 718 of liquid onto the first surface 701 of the tape 708 as the tape moves past or through the liquid reservoir 710. It is made like that. This liquid layer 718 enhances the collection of suspended dust on the tape surface 701. The particulate removal device 712 is arranged to remove particulates from the tape 708 after the particulates are deposited but before the tape 708 moves past the sump 710. This collection device 712 includes a squeegee (rubber plate), blade, vacuum device or any device that can remove the liquid layer 718 from the tape 708 so that the liquid and particulates in the liquid layer are transferred to the collection chamber 720. can do. Optionally, the first surface 701 of the tape 708 is treated to be hydrophilic and the second surface 703 is treated to be hydrophobic. The area of this collection tape 708 is very small to allow higher concentration of particles.

  FIG. 9 is a schematic view of a third embodiment of a capture zone 900 according to the present invention. The capture area 900 includes a flow path 902, a hydrophobic membrane 904, an electrostatic focusing electrode 906, and an electrophoresis electrode 908. This hydrophobic membrane 904 is generally similar to that previously described herein, but is made to be more conductive and a portion of the flow path 902 adjacent to the vortex shelter area (not shown). Embedded on top. The electrophoresis electrode 908 is disposed across the flow path 902 from the hydrophobic film 904. The electrostatic focusing electrode 906 is disposed outside the flow path 902 and close to the side surface on which the electrophoresis electrode 908 is disposed. A differential voltage V is applied across the channel 902 between the hydrophobic membrane 904 and the electrophoresis electrode 908 to create an electrophoretic pumping cell in the channel 902. The electrostatic effect created by the electrostatic focusing electrode 906 enhances the operability of the fine particles entering the liquid flow through the hydrophobic film 904. The electrophoretic effect created by the pumping cell charges the particulates in the liquid stream and drives them towards the center of the liquid stream for faster and more efficient transport. If there is an interference between electrostatic and electrophoretic effects, the two competing effects allow for effective electrostatic transport in the microparticle stream and also for electrophoretic transport of the microparticle in the liquid stream It can be operated in a cyclic manner at the established optimum frequency.

  FIG. 8 illustrates another embodiment of the present invention in which the collection device 800 also includes an electrostatic precipitator area 802. In one embodiment, electrostatic precipitator section 802 includes a plurality of precipitator plates 804 and at least one corona electrode 806, both proximate to inlet 801 (ie, the first end) of cyclone 810. Be placed. This electrostatic precipitator area 802 exits rather than passing small charged particles that escape the cyclone 810 (ie, charged in the cyclone 810 by at least one corona electrode 806) to the capture area 808. It is made to attract with the going primary stream.

  Referring back to FIG. 1, in operation, the inhalation assembly 104 is activated to draw air into the device 100 via the air duct 114. Air passes through the duct 114 and reaches a tangential inlet 124 that carries the airflow to the cyclone 118.

  Cyclone 118 separates particulates from the primary air stream. As the flow field is rapidly rotated within the cyclone 118, centrifugal force forces the suspended dust particles to drive toward the walls of the cyclone 118 where they can be triboelectrically charged by friction contacting the wall surface. As the flow continues to spiral through the cyclone 118 toward the second end 109, additional particulates are separated from the flow. The suspended dust particulate stream exits the cyclone 118 through the second end 109 and enters the chamber 128 of the vortex breaker 120 where it is concentrated to a more concentrated, slower stream.

  The primary flow reverses direction and flows back through the center of the cyclone 118 where it passes out of the first end 107 of the cyclone 118 and is carried through the fans 112A, 112B, and the first of the housing 102 1 exits the collection device 100 through an exhaust hole (port) 144 at one end 101. When a dust collector area such as that shown in FIG. 8 is incorporated, small charged particulates that have not been separated from the primary flow rate by the cyclone 118 will be collected by the dust collector plate in the middle of the primary flow to the exhaust hole 144. Will be attracted to the dust collector plate as it passes through. Using an array of small cyclones 118 (eg, rather than a single large cyclone) to separate airborne dust and primary flow allows for improved separation efficiency at low pressure drops, and thus more A quieter and more compact device 100 that consumes less power is provided. For example, in one embodiment, the entire device 100 is only 6 inches in diameter.

  The concentrated airborne dust stream is drawn through a tangential slot 136 in the wall 138 of the vortex breaker chamber 128. As the microparticles flow outward from the chamber 128, the microparticles are electrostatically guided and converged into the capillary array formed by the hydrophobic network 134. Particulates are drawn through the capillaries of the mesh 134 into the liquid in the collection area 108 where a continuous liquid flow through the microfluidic channel 140 carries the captured particulates into the collection chamber 142. Alternatively, the capture zone 108 can be connected to a hole or line (not shown) adapted to transport liquid exiting the collection device 100, for example, into another collection container or analysis device.

  As the particulate flow arrives at the air / fluid interface (ie, the hydrophobic membrane 134), the particulates remain in the boundary layer where the liquid flow rate approaches zero. Particle transport in the liquid is enhanced by placing a corona electrode (604 in FIG. 6) adjacent to the collection chamber 142 but insulated from the collection liquid. In this way, the electrostatic field 608 continues to act on the microparticles after they have entered the collection liquid in the microfluidic channel 140 in the capture area 108 so that the microparticles can be carried away quickly. The fine particles are forced into the higher velocity flow in the central portion of the flow path 140. This arrangement of the electrode 604 also reduces the need to bias the liquid in the flow path 140 to a high voltage to attract the suspended dust particles. Other means for enhancing particulate transport in the liquid include, but are not limited to, electrokinetic pumping, pulse pumping, ultrasonic technology and incremental pumping.

  During the course of operation, the hydrophobic mesh membrane 134 can become clogged with large particles, dust or debris. In such a case, the water in the flow path 140 can be pressurized to a level that exceeds the holding pressure of the mesh membrane 134. As a result, the boundary formed by the membrane 134 will be broken and water will flow out of the mesh 134 and carry dust and debris along with the flow. The water pressure is then lowered and the mesh membrane 134 can recreate the liquid seal. Thus, the hydrophobic membrane 134 can be easily cleaned without disassembling the collection device 100.

  Although the collection device according to the present invention has been described so far as a device having a substantially cylindrical configuration, those skilled in the art will appreciate that the collection device can be configured in alternative shapes or configurations without departing from the scope of the present invention. Will do. For example, FIGS. 10A-10B illustrate an embodiment of a collection device 1000 having a substantially box-shaped housing 1002.

  The collection device 1000 is configured as a box having an air inlet side 1004 for inhalation of an air sample and an outlet side 1006 for the removal of separated primary flow air opposite the inlet side 1004. The inlet and outlet sides 1004, 1006 have a plurality of openings 1010 for inhaling and excluding air. Further, at least one capture liquid outlet 1008 can be connected to the housing 1002 for transporting the liquid and the particulates trapped therein to a collection or analysis device (not shown).

  As shown in FIG. 10B, the collection device 1000 includes an air suction area 1018, a separation area 1012, a vortex shelter area 1014, and a capture area 1016. The air suction area includes a plurality of flow paths 1020 connected to openings 1010 formed in the inlet side surface 1004 of the housing 1002. Each flow path 1020 has a tangential inlet 1022 connected to the separation zone 1012 for conveying an air sample to the separation zone 1012.

  As in the previous embodiment, the separation zone 1012 comprises at least one cyclone 1024 connected to an inlet 1022 for receiving an air sample and separating airborne particulates in the sample from the primary stream. The at least one cyclone discharges a clean primary flow through the first outlet hole 1040 and discharges the separated fine particles through the second outlet hole 1026.

  This second outlet hole 1026 conveys the separated particulates to the chamber 1028 of the vortex breaker section 1014 where the particulate stream is concentrated for passage through the capture section 1016.

  The capture zone 1016 is connected to the vortex breaker zone 1014. The concentrated particulate stream passes through the exit hole 1030 of the vortex chamber 1028 and reaches the capture zone channel 1032. The flow path 1032 contains a liquid for transporting the particulate to a collection or analysis device (ie, via the capture liquid outlet 1008 shown in FIG. 10A). An electrostatic focusing mechanism, such as the hydrophobic mesh and / or corona biasing assembly discussed herein, can be used to enhance the fine particle operability in the flow path 1032.

  FIG. 11 shows a fourth embodiment according to the present invention. The collection device 1100 is generally similar to the device 800 shown in FIG. 8, but instead of an electrostatic deposition zone, the device 1100 includes a condensation zone 1102. In one embodiment, the condensing section 1102 includes an exhaust volume 1104 adapted to cool and condense small airborne particulates that escaped with the primary flow exiting the cyclone 1106. This condensation zone 1102 can be adapted to connect to an analysis or extraction device (not shown), for example by a hole or connection that carries condensed particulates out of the device 1100. Optionally, apparatus 1100, or any alternative embodiment described herein, retains an apparatus (not shown) for analyzing collected and condensed particulates in capture zone 1110. A detector area 1108 disposed adjacent to the capture area 1110 can be included. The analyzer can be formed integrally with the device 1100, or the detector area 1108 can be manufactured to interface with a number of other compatible analyzers.

  FIG. 14 is a schematic diagram showing a fifth embodiment of a particulate collection device 1400 for depositing suspended dust particulates in a liquid according to the present invention. This particulate collection system 1400 can be implemented, for example, instead of the previously disclosed mechanism (eg, sample separation and particulate capture zone) for collecting and concentrating airborne particulates in a liquid medium. However, the particulate collection system 1400 can be similarly implemented with other forms of collection devices (eg, devices without an initial separator front end).

  The particulate collection system 1400 includes a hollow tube 1402 that is coaxially disposed within an air duct 1404 that accommodates a flow of suspended dust. The hollow tube 1402 is open at both the first end 1406 and the opposing second end 1408. In one embodiment, the hollow tube 1402 is composed of at least one of sintered metal, sintered glass, and sintered polymer.

  In one embodiment of operation, liquid is received near the first end 1406 of the hollow tube 1402 (eg, via at least one inlet 1412 connected to a reservoir or other liquid source not shown); Pumped through the internal volume of the hollow tube 1402 toward the open second end 1408 of the hollow tube 1402. As the liquid approaches the open second end 1408 of the hollow tube 1402, the liquid exits the hollow tube 1402 and spills over the second end 1408 of the hollow tube 1402 and along the outer surface of the hollow tube 1402. . As a result, additional liquid is automatically supplied to the surface of the hollow tube 1402 as evaporation occurs at the outer surface of the hollow tube 1402. Airborne particulates from the incoming air sample in the air duct 1404 accumulate in the liquid on the outer surface of the hollow tube 1402. The liquid containing the deposited particulate flows along the outer surface of the hollow tube 1402 to the particulate collection or analysis device (eg, via an outlet 1414 disposed near the outer surface of the hollow tube 1402).

  In another embodiment of operation, airborne particulates from the incoming air sample in the air duct 1404 are deposited on the dry outer surface of the hollow tube 1402. This deposited particulate is then “rinsed” from the outer surface of the hollow tube 1402 by pumping liquid through the hollow tube 1402 as described above.

  Another embodiment of the particulate collection system 1400 includes a first electrode 1418 at the surface of the hollow tube and at least one of the second electrodes proximate to an area that receives an incoming air sample that includes a particulate stream. This can be enhanced by providing a charged area with two arrays 1420 (ie, corona tips). In one embodiment, the first electrode 1418 is disposed on the outer surface of the hollow tube 1402 (eg, such as tin, titanium, etc., such that the outer surface of the hollow tube 1402 functions as a ground electrode). A thin (e.g., 0.0005-0.002 inch thick) layer of conductive material (deposited for a sputtered metal). In another embodiment, the material comprising the hollow tube 1402 is a sintered metal (eg, stainless steel, titanium, etc.) such that the hollow tube 1402 itself functions as the first electrode 1418 (ie, without a coating). Alternatively, a conductive or semiconductive material such as a mixture of a sintered polymer and a sintered metal (for example, conductive plastic) can be used. In one embodiment, the corona tip array 1420 is disposed radially around the inner periphery of the air duct 1404, for example.

  Corona tip array 1420 cooperates with first electrode 1418 to generate an electrostatic field therebetween. When the array of corona chips 1420 is energized to a voltage sufficient to create a corona discharge, the particulate passing through this electrostatic field will charge due to electric field charging (ie, according to Pauthenier's equation). get. As a result, the trajectory of the charged particulates has a high probability that each particulate is deposited in the liquid on the outer surface of the hollow tube 1402 (eg, the particulate is refracted toward the first electrode 1418). Affected. In one embodiment, charging efficiency of about 99 percent or more for microparticles of about 2μ size is achieved by charging the incoming microparticles. Here, collection efficiency is defined as the number of particulates collected on first electrode 1418 divided by the total number of particulates entering (eg, measured at the inlet of air duct 1404). In another embodiment, an additional array of corona tips is provided along the length of the air duct 1404 to the length of the hollow tube 1402 to increase the refraction of the particulates along substantially the entire length of the hollow tube 1402. Further, it can be mounted at a near point (eg, closer to the first end 1406 of the hollow tube 1402).

  Thus, the particulate collection system 1400 may incorporate a charging mechanism (eg, an array of corona chips 1420 that operate in conjunction with the first electrode 1418) to achieve a more efficient collection of airborne particulates. For example, it is combined with a hollow tube 1402). Thereby, the particulates are charged and collected in a single stage process (eg, as opposed to the standard method of charging particulates in a first stage and depositing the particulates on a collection surface in a second stage). The The adoption of a single stage charging and collection mechanism substantially increases the amount of airborne particulate trapped on the outer surface of the hollow tube 1402 and thus more than is currently achieved by existing collection devices. Provide good sample concentration for analysis.

  FIG. 12 is a schematic diagram illustrating a sixth embodiment of a particulate collection system 1200 for depositing suspended dust in a liquid according to the present invention. Similar to particulate collection system 1400, this particulate collection system 1200 may be implemented, for example, instead of the previously disclosed mechanism (eg, sample separation and particulate capture zone) for collecting and concentrating airborne particulates in a liquid medium. can do.

  The particulate collection system 1200 is generally similar to the particulate collection system 1400 and includes a hollow tube 1202 disposed coaxially within the air duct 1204 of the particulate collection device. The hollow tube 1202 opens at a first end 1206 and closes at an opposing second end 1208. The hollow tube 1202 is constructed of a porous material that can draw liquid onto its surface. For that purpose, the hollow tube 1202 includes a plurality of holes 1210. For example, in one embodiment, the hollow tube 1202 is comprised of at least one of sintered glass or sintered polymer.

  In one embodiment of operation, liquid is received near the open first end 1206 of the hollow tube 1202 (eg, via at least one inlet 1212 connected to a reservoir or other liquid source not shown). And pumped through the internal volume of the hollow tube 1202 toward the closed second end 1208 of the hollow tube 1202. As liquid is pumped through the hollow tube 1202, the liquid is drawn by capillary action through the hole 1210 of the hollow tube 1202 and onto the outer surface of the hollow tube 1202. As a result, additional liquid is automatically supplied to the surface of the hollow tube 1202 as evaporation occurs at the outer surface of the hollow tube 1202. Airborne particulates from the incoming air sample in the air duct 1204 accumulate in the liquid on the outer surface of the hollow tube 1202. The liquid containing the deposited particulate flows along the outer surface of the hollow tube 1202 (eg, via an outlet 1214 located near the outer surface of the hollow tube 1202) to the particulate collection or analysis device.

  In another embodiment of operation, airborne particulates from the incoming air sample in the air duct 1204 are deposited on the dry outer surface of the hollow tube 1202. The deposited particulate is then “rinsed” from the outer surface of the hollow tube 1202 to the outlet 1214 by pumping liquid through the hollow tube 1202 and through the hole 1210 as described above.

  Similar to particulate collection system 1400, another embodiment of particulate collection system 1200 can be enhanced by generating an electrostatic field that refracts incoming particulate into the liquid on the outer surface of hollow tube 1202. In one embodiment, this electrostatic field is generated by providing at least one array 1220 of corona tips proximate to an area that receives an incoming air sample containing a particulate stream. This corona tip array 1220 is formed on the outer surface of the incoming particulate hollow tube 1202 with the first electrode 1218 deposited on the outer surface of the hollow tube 1202, as described above with reference to FIG. Works to refract into the liquid above. In one embodiment, the array of corona tips 1220 is disposed radially around the inner periphery of the air duct 1204, for example. In another embodiment, an additional array of corona tips is placed at a closer point further along the length of the hollow tube 1202 (eg, hollow to enhance refraction of the particulate along substantially the entire length of the hollow tube 1202. (Closer to the first end 1206 of the tube 1202). In another embodiment, the porous material comprising the hollow tube 1202 may be a sintered metal (eg, stainless steel, titanium, etc.) such that the hollow tube 1202 itself functions as the first electrode 1218 (ie, without a coating). Or a conductive or semiconductive material such as a mixture of sintered polymer and sintered metal (eg, conductive plastic).

  In another embodiment, the hollow tube 1202 further comprises an electrokinetic pump to enhance the flow of liquid through the hole 1210 of the hollow tube 1202. In this electrokinetic pump, the third electrode is formed of an insulator from the first electrode (eg, the hollow tube 1202 itself, in this embodiment it is made of, for example, sintered glass or sintered polymer, The first electrode 1218 is deposited as a coating on the hollow tube 1202 so as to be spaced apart. The third electrode 1216 and the first electrode 1218 are at different potentials, and when the electric field between the third electrode 1216 and the first electrode 1218 is energized, the electrokinetically induced pressure is The liquid meniscus is refracted outward at the hole 1210 of the hollow tube 1202.

  13A and 13B are schematic diagrams illustrating a typical hole 1210 of the hollow tube 1202. Specifically, FIG. 13A shows holes 1210 without electrokinetic pumping effects, while FIG. 13B shows the electrokinetic pumping effects described above applied to the same holes 1210. As shown, the effect of electrokinetic pumping is to allow liquid meniscus 1300B to pass through hole 1210 and outward so that the outer surface of hollow tube 1202 is substantially covered with at least a thin layer of liquid. Push towards you. In some embodiments, this is the ability of the particulate collection system 1200 to collect particulates from an incoming air sample compared to embodiments where electrokinetic pumping is not applied (see, eg, meniscus 1300A). Can be increased.

  The proximity of the electrokinetic pump to the particulate collection surface (eg, the outer surface of the hollow tube 1202) provides several advantages. For example, such an arrangement facilitates liquid distribution in a multi-unit configuration. Furthermore, this electrokinetic pump uses space that would normally remain unoccupied, and therefore does not require any additional volume to achieve enhanced particulate collection capacity. Moreover, the configuration of the particulate collection system 1200 including the electrokinetic pump is substantially independent of orientation and requires only a minimal volume of liquid to collect particulates.

  FIG. 15 is an isometric view illustrating a seventh embodiment of a particulate collection system 1500 for depositing suspended dust in a liquid according to the present invention. Similar to particulate collection systems 1200 and 1400, particulate collection system 1500 is an alternative to previously disclosed mechanisms (eg, sample separation and particulate capture zones) for collecting and concentrating airborne particulates in a liquid medium, for example. Can be implemented.

  The particulate collection system 1500 is similar in many ways to particulate collection systems 1200 and 1400 and includes a hollow tube 1502 adapted to be coaxially disposed within the air duct of the particulate collection device. The hollow tube 1502 is open at both the first end 1506 and the opposing second end 1508.

  The particulate collection system 1500 further includes a rotatable disk 1504 that is disposed at the second end 1508 of the hollow tube 1502. The rotatable disk 1504 is positioned such that the axis of rotation of the rotatable disk 1504 is substantially coaxial with the longitudinal axis of the hollow tube 1502, and thus the rotatable disk 1504 is disposed on the longitudinal axis of the hollow tube 1502. Can rotate around.

This rotatable disk 1504 comprises a flat surface 1510 having a hole 1514 disposed substantially at its center and a first radius r ₁ . This first radius r ₁ is smaller than the radius r _{2 of the} entire rotatable disk 1504 such that a groove 1512 is formed between the flat surface 1510 of the rotatable disk 1504 and the outer circumference of the rotatable disk 1504. .

  In one embodiment of operation, liquid is received near the first end 1506 of the hollow tube 1502 (eg, via at least one inlet connected to a reservoir or other liquid source not shown) and hollow. Pumped through the internal volume of the tube 1502 toward the second end 1508 of the hollow tube 1502. As the liquid approaches the second end 1508 of the hollow tube 1502, the liquid exits the hollow tube 15021502 through the rotatable disk hole 1514 and spills over the flat surface 1510 of the rotatable disk 1504. As a result, additional liquid is automatically supplied to the flat surface 1510 of the rotatable disk 1504 as evaporation occurs at the flat surface 1510 of the rotatable disk 1504. Airborne particulates from the incoming air sample in the air duct accumulate on the liquid on the flat surface 1510 of the rotatable disk 1504. As the rotatable disk 1504 rotates, the liquid containing the deposited particulate is pulled away from the hole 1514 and is pumped centrifugally toward the groove 1512 where the liquid is collected. The collected liquid containing the deposited particulate is then siphoned, pumped, or otherwise (eg, via an outlet (not shown) located near the outer surface of the groove 1512 or hollow tube 1502). Delivered to a particle collection or analysis device.

  In another embodiment of operation, airborne particulate from an incoming air sample in the air duct is deposited on the dry surface 1510 of the rotatable disk 1504. The deposited particulate is then “rinsed” from the flat surface 1510 of the rotatable disk 1504 by pumping liquid through the hollow tube 1502 and rotating the rotatable disk 1504 as described above.

  Similar to particulate collection systems 1200 and 1400, another embodiment of particulate collection system 1500 is by providing at least one array of corona chips proximate to an area receiving an incoming air sample containing particulate streams. Can be increased. This arrangement of corona tips allows the incoming particulate to be flattened on the rotatable disk 1504 with the first electrode 1218 deposited on the outer surface of the hollow tube 1502, as described above with reference to FIG. Acts to refract into the liquid on the surface 1510. In one embodiment, the corona tip array is arranged radially, for example, around the inner periphery of the air duct.

  In one embodiment, the rotatable disk 1504 rotates at a high enough speed that gravity is substantially unimportant. In such an embodiment, the particle collection system 1500 can be oriented to a greater degree by the particle collection device incorporating the particle collection system 1500 because it does not rely on gravity to carry the liquid on which the particles are deposited. become.

  In another embodiment, the rotatable disk 1504 replaces different mechanisms such as moving tape or wire collecting means that move in and out of the air duct in a direction of motion substantially perpendicular to the air flow through the duct. can do.

  The present invention thus represents an important advantage in the field of biofloating dust collection. An apparatus is provided that achieves highly efficient collection of airborne particulates in a small liquid volume that can be easily analyzed for the detection of pathogens, airborne dust or other undesirable particulates. The efficiency of this device is incompatible with the compact size of this device that allows it to be easily incorporated into a portable particulate collection device. Furthermore, configurations that are independent of the orientation of the device make it suitable for use in a variety of environments and devices.

  While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the appended claims.

It is a cutaway view of one embodiment of the airborne particulate collection device of the present invention. It is an exploded view of the airborne particulate collection device shown in FIG. It is a top view of the cyclone arrangement | sequence shown in FIG. FIG. 2 is a top view of the vortex breaker area shown in FIG. 1. FIG. 2 is an exploded view of the capture area shown in FIG. 1. FIG. 6 is a schematic view of a corona charging zone adapted for use with the capture zone shown in FIGS. FIG. 6 shows a second embodiment of a capture area and a corona charging area. FIG. 4 is a diagram of a second embodiment of a collection device according to the present invention. FIG. 6 is a schematic view of a third embodiment of a capture zone according to the present invention. FIG. 6 is a plan view of a third embodiment of a collection device according to the present invention. FIG. 10B is a cutaway view of the collection device shown in FIG. 10A. FIG. 6 is a cutaway view of a fourth embodiment of a collection device according to the present invention. FIG. 6 is a schematic diagram showing a fifth embodiment of a particulate collection system for depositing suspended dust particulates in a liquid according to the present invention. It is a schematic diagram which shows the typical hole of the microparticles | fine-particles collection apparatus of FIG. It is a schematic diagram which shows the typical hole of the microparticles | fine-particles collection apparatus of FIG. It is a schematic diagram which shows 6th Embodiment of the particulate collection system which deposits suspended dust particulates in a liquid by this invention. FIG. 9 is an isometric view illustrating a seventh embodiment of a particulate collection system for depositing suspended dust particulates in a liquid according to the present invention.

Claims (10)

A hollow tube adapted to pump liquid through the internal volume of the hollow tube to the outer surface of the hollow tube;
A collection surface disposed on the outer surface and adapted to collect airborne particulates from an air sample;
An apparatus for collecting airborne particulates from an air sample, comprising: a charging mechanism configured to charge the airborne particulates so that the airborne particulates are deflected toward the collection surface.   The hollow tube is formed from a porous material comprising a plurality of the holes adapted to draw the liquid from the internal volume through the holes through the capillary action onto the collection surface. The device described in 1.   The apparatus of claim 1, wherein the hollow tube is formed from a conductive or semiconductive material.   The apparatus of claim 1, wherein the hollow tube comprises the open end adapted to draw the liquid from the internal volume through the open end onto the collection surface.   The apparatus of claim 1, wherein the collection surface comprises a layer of conductive material. A first electrode in which the charging mechanism is formed by the layer of conductive material;
6. The apparatus of claim 5, comprising a second electrode adapted to cooperate with the first electrode to create an electrostatic field therebetween.   When the first electrode and the second electrode are separated by a dielectric material, the layer of conductive material is adapted to cooperate with the second electrode to create an electrokinetic pump. 6. An apparatus according to claim 5, forming one electrode.   The apparatus of claim 1, wherein the collection surface is a rotatable disk disposed at one end of the hollow tube. An air inhalation assembly for aspirating an air sample into the system;
A hollow tube adapted to pump liquid through the internal volume of the hollow tube to the outer surface of the hollow tube, further disposed on the outer surface and removing the airborne particulates from the air sample. Comprising a collecting surface adapted to collect;
A charging mechanism configured to charge the airborne particulates such that the airborne particulates are deflected toward the collection surface;
A system for analyzing airborne particulates in an air sample comprising an outlet adapted to carry the liquid from the collection surface. Supplying air sample,
Directing the air sample to a hollow tube having a first end and a second end, and charging the airborne particulate to deflect the airborne particulate toward an outer surface of the hollow tube. In addition, charging and collecting airborne particles in a single stage,
A method of collecting airborne particulates from an air sample characterized by comprising:

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