Device for collecting particles in an exhaled air flow

Abstract

A device for collecting aerosol particles in an exhaled air flow. The particles may be aerosol particles such as biomarkers or particles related to drugs or other substances formed or found in the alveoli of the lungs. The device comprises an elongate housing with an inner wall and at least four first type partition walls extending substantially perpendicularly from opposite sides of the inner wall to partly cover the cross-section of the housing. The first type partition walls create a labyrinth shaped flow path to divert air flowing from the inlet towards the outlet of the housing in a direction towards opposite inner walls of the housing so that the particles separate from the air flow and attach on the device. The distance between two opposite first type partition walls is smaller than the transverse width of the housing and increases in the flow direction.

Claims

1. A device for collecting aerosol particles in an exhaled airflow, the device comprising: a housing having an extension length in a direction between a first end with an inlet arranged to receive an exhaled airflow and a second end with an outlet arranged to transmit the exhaled airflow, and an inner cross-section defined by one or more inner walls of the housing, wherein the cross-section exhibits a transverse width, and wherein the housing has an elongated shape; and at least four first type partition walls, arranged at a distance from each other and extending in a direction substantially perpendicular to the inner wall, partly covering the inner cross-section of the housing, wherein the first type partition walls protrude from opposite sides of the one or more inner walls of the housing creating opposite openings with an opening area between the first type partition walls and the respective opposite inner wall of the housing, whereby the first type partition walls are arranged to create a labyrinth shaped flow path from the inlet to the outlet which is arranged to divert the air flowing from the inlet towards the outlet in a direction towards the opposite inner wall of the housing so that the aerosol particles separate from the airflow and attach on the device; wherein the distance between two opposite first type partition walls is smaller than the transverse width of the cross section; and wherein the distance between opposite first type partition walls increases in the extension direction of the housing from the inlet.

2. The device according to claim 1, wherein each first type partition wall has a partition area substantially perpendicular to the extension direction of the housing, covering 50-95% of the inner cross-section area of the housing.

3. The device according to claim 1, wherein the inner cross-section area is between 20 mm.sup.2 and 615 mm.sup.2.

4. The device according to claim 1, wherein the opening area is within the interval of 10 mm-25 mm.sup.2, the extension length between 10 and 70 mm and the number of first type partition walls between 4 and 14.

5. The device according to claim 1, wherein the housing has the shape of an elongated cylinder with a circular cross-section.

6. The device according to claim 5, wherein the housing has a diameter between 8 and 30 mm.

7. The device according to claim 1, wherein the housing has a rectangular cross-section.

8. The device according to claim 1, wherein the device is made of a non-absorbent material.

9. The device according to claim 1, wherein at least one of the following parts has a rough surface structure in order to increase surface area: housing, first type partition walls.

10. The device according to claim 1, wherein the housing comprises a first and a second housing half which are adapted to be joined.

11. The device according to claim 10, wherein each housing half comprises at least two first type partition walls extending further than half of the total cross-section of the housing.

12. The device according to claim 11, wherein each housing half comprises at least one second type partition wall arranged substantially parallel to the extension direction of the housing extending a maximum of half of the total cross-section of the housing.

13. The device according to claim 12, wherein the at least one second type partition wall has at least two recesses in which the at least two first type partition walls are arranged to be inserted.

14. The device according to claim 12, wherein the at least one second type partition wall has a rough surface structure in order to increase surface area.

15. The device according to claim 1, wherein the opening area between the first type partition walls and the respective opposite inner wall of the housing gradually increases in the extension direction of the housing from the inlet.

16. The device according to claim 1, wherein the opening area defines a first cross-sectional flow area, and the first type partition walls and the transverse width of the cross-section of the housing defines a second cross-sectional flow area, wherein the relation between the first cross-sectional flow area and the second cross-sectional flow area is kept essentially constant throughout the entire length of the device.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The invention is now described, by way of example, with reference to the accompanying drawings, in which:

(2) FIG. 1a show a cut view of one embodiment of the invention.

(3) FIG. 1b show a plane view of the embodiment shown in FIG. 1a.

(4) FIG. 1c visualizes the different areas defining the invention

(5) FIG. 1d shown a different embodiment of the invention having a different cut section geometry.

(6) FIG. 2a show a cut view of one embodiment of the invention.

(7) FIG. 2b show a plane view of the embodiment shown in FIG. 2a.

(8) FIG. 3 show a plane view of another embodiment of the invention.

(9) FIG. 4 show a cut view of yet another embodiment of the invention.

(10) FIG. 5a-5d show yet another embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

(11) In the following, a detailed description of device according to the invention is presented. In the drawing figures, like reference numerals designate identical or corresponding elements throughout the several figures. It will be appreciated that these figures are for illustration only and are not in any way restricting the scope of the invention.

(12) FIGS. 1a and 1b disclose an embodiment of the device 1 for collection particles in exhaled breath. FIG. 1a is a cut view taken at cut B-B in FIG. 1b and show the inside of the device 1. FIG. 1c visualizes the different cross-section areas of the invention. FIG. 1d is another cut view of another embodiment of the device.

(13) The device 1 comprises a housing 2 having an extension direction between a first end 2a with an inlet and a second end 2b with an outlet. The inlet is arranged to receive an exhaled airflow Q.sub.in comprising aerosol particles P from a subject, such as for example a person, and the outlet is arranged to transmit the exhaled airflow Q.sub.out from the device 1. Thus, the exhaled air is arranged to flow in a direction from the inlet to the outlet. The housing 2 has an inner cross-section area A1 defined by inner walls 2c of the housing 2. In the embodiment shown in FIG. 1a-1c the housing has an elongated cylindrical shape with a length L and a circular cross-section, i.e. the cross-section area A1 has an area defined by the inner diameter d1 of the housing 2. FIG. 1d disclose another embodiment of the invention where the housing has a rectangular cross-section and the cross-section area A1 is defined by the height and width of the housing. Other cross-section area shapes are also possible, but the cross-section area is always defined by the distance d between the inner walls 2c of the housing.

(14) The outer diameter of the housing is in one embodiment of such a dimension that it can easily be fitted into a standard size test tube. I.e. it has a diameter between 8 and 30 mm, preferably between 10 and 20 mm. The inner cross-section area A1 is therefore slightly less than the above-mentioned area, depending on the thickness of the housing walls. Therefore, the cross-section area A1 may be between 20 mm.sup.2 and 615 mm.sup.2, preferably between 50 and 250 mm.sup.2, most preferably between 70 and 90 mm.sup.2. Comparably, the distance d between the inner walls 2c of the housing may be between 5 and 28 mm, preferably between 8 and 18 mm, most preferably between 9.5 and 10.5 mm.

(15) At least four partition walls of a first type 3 are arranged to extend in a direction substantially perpendicular to the inner walls 2c, thus substantially perpendicular to the initial direction of the exhaled airflow when exiting the subject's mouth. Each first type partition wall 3 has a first surface 3a facing the air flow, an opposite second surface 3b and a peripheral edge 3c. The first and second surface 3a and 3b each have a surface area A2 smaller than the cross-section area A1. Thus, the first type partition walls have a surface area A2 partly covering the inner cross-section area A1 of the housing 2. In different embodiments the first type partitions walls have a surface area A2 covering 50-95%, preferably 60-85%, more preferably 65-80% of the cross-section area A1.

(16) The first type partition walls 3 protrude from opposite sides of the inner wall 2c of the housing 2. Thus, the walls are creating opposite openings 4a, 4b between the first type partition walls 3 and the housing inner wall 2c having an opening area A3=A1−A2.

(17) The first type partition walls 3 are arranged to create a labyrinth shaped flow path having a cross-sectional flow area from the inlet to the outlet. When the airflow collides with a surface substantially perpendicular to the air flow, the flow is diverted in a direction parallel to the surface. The diversion of the airflow separates the heavier particles P in the exhaled air from the air itself. The heavier particles P continue in the original flow direction and collide with the partition walls 3 or the housing inner wall 2a, while the air changes direction and follow the labyrinth shaped flow path. The longer distance the air flows and the more and larger direction changes the airflow is forced to do, the larger number of particles are separated from the air and collected in the device 1. Further, a direction change also creates a turbulent flow during which the particles are more easily separated from the air. A turbulent air also increases the impact frequency between the particles and the surfaces of the walls of the device 1, thus increasing the amount of airborne particles P attaching to the surfaces. Thus, the outflow Q.sub.out out of the device comprises less particles P than the inflow Q.sub.in into the device.

(18) A person is only able to exhale with a certain maximum flow rate Q.sub.in. At a certain counter pressure from the device the velum of the person closes, and exhalation is impossible. The pressure difference over the device must therefore not be too high. However, a certain inflow Q.sub.in and pressure difference is necessary to create the certain conditions with a high enough flow velocity to separate the particles from the air flow. It is therefore important to design the device to have a certain flow path cross-sectional flow area which is defined by a first cross-sectional flow area, defined by the opening area A3 between the first type partition walls 3 and the inner walls of the housing and a second cross-sectional flow area circumscribed by the first type partition walls and the inner diameter d1 of the housing. I.e. the parameters defining the second cross-sectional flow area are the specific extension length L of the housing, the distance d between the inner walls 2c of the housing or inner diameter d1 of the housing and the number of first type partition walls 3 of the device 1, i.e. the distance x between the first type partition walls 3. The opening area A3 is preferably within the interval of 10 mm.sup.2-25 mm.sup.2, the extension length L between 10 and 70 mm and the number of first type partition walls 3 between 4 and 14. The first cross-sectional flow area is in one embodiment smaller than the second cross-sectional flow area. This relationship increases the acceleration of the air flowing pass the peripheral edge 3c of the first type partition wall 3.

(19) In the preferred embodiment shown for example in FIG. 2a the number of first type partition walls 3 are 8, the length L approximately 22 mm and the area A3 is approximately 20 mm.sup.2. Thus, in this embodiment the wall surface area A2 cover approximately 75% of the total inner cross-section area A1.

(20) In order to increase the flow area, it is in one embodiment of the invention possible to arrange more than one device parallel to each other in an additional outer housing (not shown) thus decreasing the total flow resistance.

(21) The first type partition walls 3 may be separated from each other with a certain distance x depending on the maximum allowed pressure difference over the device. The distance x depends on the length L of the device and the number of first type walls 3. However, in order to create the certain conditions with a high enough flow velocity to separate the aerosol particles from the air flow, the distance x between at least two opposite first type partition walls 3 is always smaller than the distance d between the inner walls of the housing. In one embodiment, shown in FIGS. 1a and 2a the distance x is constant. In another embodiment, show in FIG. 4, the distance between the first type partition walls 3 is increasing in the distance from the first end 2a of the device 1. I.e. the distance x.sub.1 between the two opposite partition walls 3 closest to the inlet 2a is smaller than the distance x.sub.n between the two opposite partition walls 3 closest to the outlet 2b. With an increasing distance between the first type partition walls 3 the flow velocity through the device 1 can be substantially maintained. In the embodiment shown in FIG. 4, the second flow path cross-sectional flow area is increasing towards the outlet 2b due to the increasing distance between the first type partition walls and the constant kept opening area A3. However, it is also possible to gradually increase the opening area A3 closer to the outlet 2b. This will further decrease the flow resistance in the device and contribute to a maintained flow velocity. In one embodiment, the relation between the first flow path cross-sectional flow area and the second flow path cross-sectional flow area is kept substantially constant throughout the entire length L of the device.

(22) In one embodiment, see FIG. 1b, the openings 4a, 4b have the shape of circle segments, wherein the cord delimiting the circle segment is defined by the peripheral edge 3c of the first type partition wall. The peripheral edge 3c may be arranged as a straight line, see FIG. 1d, or may be have an arc shape, see FIGS. 1b, 1c, 2b and 3.

(23) The device is in one embodiment made of a non-absorbent material, for example polymer materials such as for example polypropylene (PP), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP) or other non-absorbent, preferably, polymer materials. On a non-absorbent material the particles may attach but are easily washed off when a later analyzing step is performed. The washing off may be performed in a test tube filled with an amount of test fluid enough to cover the entire length L of the housing.

(24) In order to increase the surface area on which the particles P are collected, the housing inner wall have in one embodiment a rough surface structure. The rough structure is in one embodiment adapted to the size of the particles to be collected. I.e. if the aerosol particles to be collected have a diameter of 0.1 and 2.0 μm the inner walls may preferably be provided or covered with cavities of approximately the same size. The surface may also be machined to have protrusions distanced by approximately the same distance as the diameter of the particles. The rough structure may also for example be a spark or electro eroded surface with a surface roughness Ra from 0.1 micron to up to 12.5 micron. The possible surface roughness value also depend on the draft angle on the surface to be eroded in relation to the tool producing the eroded surface. With a larger draft angle, a larger surface roughness is possible to create.

(25) It is also possible to further increase the surface area by providing all surfaces of the device, both inner and outer with a rough structure. Different surface roughness values are possible on different surfaces of the device 1.

(26) In one embodiment the first surface 3a and second surface 3b of the first type partition walls 3 are directed at an angle in relation to each other such that the edge 3c of the respective first type wall 3 is narrower than the base of the first type wall. However, the first surface 3a and second surface 3b of the first type partition walls 3 may also be parallel or substantially parallel to each other, as can been seen in FIG. 3. They may also be produced having only a small draft angle.

(27) FIGS. 2b and 2c and FIGS. 4a-e show another embodiment where the housing further comprises at least one second type partition wall 5. The second type partition wall 5 is arranged substantially parallel to the extension direction of the housing 2. The at least one second type partition wall 5 extend from the first end 2a to the second end 2b of the housing creating at least two flow channels 6a-6d leading the airflow from the inlet to the outlet. In the embodiment according to FIGS. 2b, 2c and FIGS. 4a-e three second type parallel partition walls 5 are shown thus four flow channels 6a-6d are created. The flow channels 6a-6d have, in the embodiment shown in FIGS. 2b and 2c, different flow areas A6a-A6d. Thus, a pressure change may occur in the different channels creating different flow velocities through the different channels.

(28) In FIG. 3 another embodiment is show where the second type partition wall or walls 5 are divided into two wall parts 5a, 5b protruding from opposite sides of the inner wall 2c of the housing 2 so that a small gap 7 is arranged between the two wall parts 5a, 5b. The small gap 7 compensate for the pressure changes which may occur in the channels 6a-6d. The gap also contributes to a turbulent airflow in the channels.

(29) According to one embodiment, shown in FIGS. 5a-5d, the device 1 comprises two device halves 1a, 1b which are adapted to be joined. When the device part 1a and 1b according to FIG. 4a-4d are joined they together form an elongated cylinder with a total cross-section area A1. Each device half 1a, 1b comprises at least two first type partition walls 3 extending further than half of the total cross-section A1 of the housing 2. In one embodiment the first type partition walls 3 extend between 10% and 60% further than half of the total cross-section A1 of the housing 2.

(30) Each housing half 1a, 1b comprises at least one partition wall of a second type 5 arranged substantially parallel to the extension direction of the housing 1 extending a maximum of half the total cross-section of the housing 1. In order for the first type partition walls 3 to be able to extend further than half of the total cross-section A1 of the housing 2 the second type partition walls 5 have cuttings 8 which are adapted to receive the outer ends 3c of the first type partition walls. The first type partition walls 3 are in one embodiment arranged to be inserted by press fitting into the cuttings 8.

(31) A preferred embodiment of a device 1 for collecting particles according to the invention has been described. However, the person skilled in the art realizes that this can be varied within the scope of the appended claims without departing from the inventive idea.

(32) All the described alternative embodiments above or parts of an embodiment can be freely combined without departing from the inventive idea as long as the combination is not contradictory.