DEVICE AND METHOD FOR DETECTING A CONCENTRATION OF PREDETERMINED PARTICLES BASED ON THEIR MORPHOLOGICAL PROPERTIES IN AIR

Abstract

The present disclosure relates to a device for detecting a concentration of predetermined particles, in particular viruses, in air, which comprises organic and/or inorganic aerosol particles, wherein the device has a supply unit for binding the aerosol particles as particles in a fluid, an imaging unit for producing an enlarged image of the particles contained in the fluid, an image capture unit for capturing and transmitting the image, and an evaluation unit for evaluating the particles depicted in the image, wherein the evaluation unit is designed to automatically detect morphological properties of the particles depicted in the image, to compare the detected morphological properties with morphological properties of the predetermined particles, and by the comparison to determine a proportion of predetermined particles in the image and the concentration of the predetermined particles in the air.

Claims

1. Device for detecting a concentration of predetermined particles, including viruses, in air, which comprises organic and/or inorganic aerosol particles, the device comprising: a supply unit, an imaging unit, an image capture unit, and an evaluation unit; wherein the supply unit is configured to bind the aerosol particles contained in the air in a fluid such that that the fluid contains the aerosol particles previously contained in the air as particles, and is configured to provide a steady or uniformly timed fluid flow along a predetermined flow path, wherein the imaging unit has a sample channel through which the fluid flow can flow, which determines the predetermined flow path within the imaging unit, and wherein the imaging unit is configured to produce an enlarged image of the particles contained in the fluid flowing through the sample channel, wherein the image capture unit is configured to capture the image and transmit it to the evaluation unit, wherein the evaluation unit is configured to automatically detect morphological properties of the particles depicted in the image, and configured to compare the morphological properties detected with morphological properties of the predetermined particles, and by the comparison to determine a proportion of predetermined particles in the image and the concentration of the predetermined particles in the air.

2. Device according to claim 1, wherein the supply unit is configured to bind the aerosol particles contained in a predetermined volume of the air in a predetermined volume of the fluid, so that the concentration of the predetermined particles in the predetermined volume of the fluid can be determined from the proportion of predetermined particles in the predetermined volume of air.

3. Device according to claim 1, wherein the fluid is an electrolyte solution, and wherein the supply unit and/or the imaging unit comprises an electric field generating isotachiophoresis device which is configured to separate the particles bound in the electrolyte solution from one another in sections by their different ionic mobilities, so that the fluid flowing through the sample channel is separated in sections in which particles with the same ionic mobility are concentrated.

4. Device according to claim 1, further comprising a pump configured to drive the fluid flow along the flow path and to pump the fluid from the supply unit through the imaging unit at a steady volumetric flow or timed in a continuous cycle.

5. Device according to claim 1, wherein the supply unit is configured to admix a contrast medium to the fluid.

6. Device according to claim 1, wherein the supply unit has a prefilter on an inlet side, which is configured to filter air flowing into the supply unit on the inlet side, so that organic and/or inorganic aerosol particles contained in the air, which are not the predetermined particles, are filtered out before the aerosol particles are bound in the fluid.

7. Device according to claim 1, wherein the supply unit comprises a condenser for binding the aerosol particles contained in the air in the fluid by condensation.

8. Device according to claim 1, wherein the imaging unit is a transmission electron microscope comprising an electron source generating an electron beam, a plurality of magnets directing the electron beam and acting as a lens for the electron beam, and a vacuum chamber through which the electron beam passes, and wherein the sample channel passes through the vacuum chamber orthogonally to the electron beam and the electron beam passes through the sample channel and the fluid flowing through the sample channel.

9. Device according to claim 8, wherein the sample channel is formed of a material permeable to the electron beam.

10. Device according to claim 8, wherein the magnets are configured as permanent magnets or are configured as electromagnets and are supplied with a constant voltage so that the electron beam is directed by the magnets in a single predetermined manner and is focused on the fluid flowing through the sample channel, and/or wherein the sample channel is permanently connected to the vacuum chamber, and/or wherein the vacuum chamber is completely sealed in a pressure-tight manner and is configured to permanently maintain a vacuum prevailing therein, so that a pressure reduction determining the vacuum only has to be carried out once.

11. Device according to claim 1, wherein the image capture unit is a CCD sensor or a camera which is configured to capture the image produced by the imaging unit.

12. Device according to claim 1, wherein the evaluation unit has a data memory in which the morphological properties and an appearance of the predetermined particles are stored, and the evaluation unit is configured to determine, by image processing and object recognition, how many of the particles depicted in the image have morphological properties and an appearance corresponding to the morphological properties and the appearance of the predetermined particles and are thus predetermined particles.

13. Method for detecting a concentration of predetermined particles, including viruses, in air, which comprises organic and/or inorganic aerosol particles, using a device according to claim 1.

14. System for detecting a movement and concentration of predetermined particles in a space comprising a central evaluation unit and a plurality of devices according to claim 1, wherein the devices are distributed in the space according to a predetermined pattern having a predetermined grid, wherein the central evaluation unit is configured to determine and/or predict a concentration of the particles in the space and/or a distribution of the predetermined particles in the space and/or a movement of the predetermined particles in the space from the concentrations determined in each case by the devices.

15. Device according to claim 8, wherein the sample channel is formed of silicon nitride.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Other advantageous developments of the disclosure are indicated in the subclaims or are illustrated in more detail below together with the description of the preferred embodiment of the disclosure with reference to the figures. Shown are:

[0048] FIG. 1 a device with a TEM as imaging unit.

DETAILED DESCRIPTION OF THE DRAWINGS

[0049] The figure is exemplary schematic and shows a device 1 that uses a transmission electron microscope (TEM) as imaging unit 20.

[0050] The basic principle of the device 1 is to draw in or take in air 3 and, for example, room air at an air inlet 2, to bind the particles contained in the air 3 in the supply unit 10 in a liquid 4 as a fluid, and to provide a continuous liquid or fluid flow by the imaging unit 20, so that an “in situ analysis” of the particles bound in the liquid 4 is made possible, in which the sample to be analyzed, which is the liquid 4 or, more precisely, the liquid 4 flowing through the imaging unit 20, changes constantly. Together with the liquid 4, a continuous flow of particles is thus provided by the TEM or by the imaging unit 20, through which the particles are imaged enlarged so that the particles contained in the sample or in the liquid 4 can subsequently be analyzed.

[0051] In the present case, the supply unit 10 has a prefilter 11 through which particles are filtered out of the air 3 which, due to their size, charge or other factors, cannot be the predetermined particles. The prefilter 11 can have several filter stages for this purpose and use different filter principles.

[0052] The air 3 filtered by the prefilter 11 is then condensed by a condenser 12 to form a condensate as a liquid 4 in which the particles previously contained in the filtered air 3 are bound.

[0053] The condensate or liquid 4 is then pumped along a predetermined flow path from the supply unit 10 into or through the imaging unit 20, using a pump 60 arranged on the outlet side of the imaging unit 20.

[0054] In the liquid 4, the predetermined particles as well as all particles contained therein are initially relatively evenly distributed, so that the searched or predetermined particles, whose concentration is to be determined in the air, are evenly distributed over a section of the liquid 4 and are difficult or costly to find. To improve and simplify the analysis, the imaging unit 20 has an isotachiophoresis device with a first voltage clamp 25 and a second voltage clamp 25′. The first voltage clamp 25 is arranged fluidically on the inlet side of the imaging unit 20 or of the sample channel 29, and the second voltage clamp 25′ is arranged fluidically on the outlet side of the imaging unit 20 or of the sample channel 29, respectively, wherein these establish an electric field in the sample channel 29, so that several sections are formed in the liquid 4 flowing through the sample channel 29, which each have particles with the same or approximately the same ion mobility. In one of these sections, therefore, essentially all particles with an ion mobility equal to the ion mobility of the predetermined particles and thus essentially all predetermined particles are present, so that it is sufficient to image only this section with the imaging unit 20, to detect it with the image capture unit 40 or to evaluate it with the evaluation unit 50.

[0055] The imaging unit 20 realized as a TEM in the present case does not have to be designed for different measuring methods or an exchange of sample carriers or the like, so that the TEM is specialized for the present application. For this purpose, the TEM has a completely and permanently sealed vacuum chamber 31 in which a vacuum (high vacuum) has been generated once and is maintained permanently. An electron beam 30 is emitted into the vacuum chamber, which can also be referred to as a measuring column, by an electron source 21 and passes through the vacuum chamber 31 lengthwise. The electron beam 30 is invariably adjusted in its beam strength by a Wehnelt cylinder 22 and is directed or focused by a fixed and non-adjustable aperture 23 and several magnets 24, 26, 27 onto the sample channel 29 and the luminescent screen 32. A first magnet 24 or a first magnet system, which can also consist of a plurality of magnets, serves as a condenser magnet system, a second magnet 26 or a second magnet system, serves as an object magnet system and a third magnet 27 or a third magnet system, respectively, serves as a projection magnet system, wherein these are each designed as permanent magnets and thus invariable.

[0056] The liquid 4 flowing through the sample channel 29 is thus always struck by the electron beam 30 in a single predetermined manner and an image of the particles present in the liquid 4 is projected onto the illuminated screen 32 so that an analogous image is visible there, which can also be viewed through the control window 28.

[0057] The image projected onto the illuminated screen 32 is captured by the image capture unit 40, which in the present case is essentially formed by a camera 41, and the image is thereby digitized and subsequently transmitted to the evaluation unit 50.

[0058] As an example, a section 5 of an image captured by the camera 41 is shown, in which a large number of particles are visible. In particular, four predetermined particles 42, 42′, 42″ are shown there by way of example, which are only partially visible or hidden. These can also be overlaid by other particles 43, 44. Further, the external appearance 52 of a predetermined particle is stored in the evaluation unit 50 or its data memory 51 as a comparative image 6 or as a morphological property of the predetermined particle. With the aid of image processing, the particles in the section 5 of the image are now compared with the external appearance 52 of the target particle or the predetermined particle. If the match with the comparison image 6 is sufficiently high, the respective analyzed particle in the cutout 5 is recognized and counted as a predetermined particle. The predetermined particles or viruses can thus be distinguished from other particles by their external appearance or form. For example, although the particle 43 has an approximately identical size, so that it would be incorrectly identified as a virus or predetermined particle if it were determined on the basis of size, it has a completely different contour or surface shape, so that it can be correctly classified as not being a predetermined particle or virus with the presently proposed device.