Device for collecting particles contained in the environment on a transparent adhesive tape by impact and associated method

Description

Domaine technique de l'invention

[0001] The present invention relates to the field of devices for collecting particles contained in ambient air by impaction. Arrière-plan technique

[0002] Impaction is a widely used principle for collecting particles from ambient air. It involves sucking ambient air into a home at a controlled, fixed flow rate to collect particles on a support. After a collection campaign, the support can be recovered and analyzed afterward.

[0003] In the field considered, many devices are already known.

[0004] Thus, we find in the literature, impaction devices operating in "cascade".

[0005] A detailed example of the design of such a device is presented in the article by Misra et al., “Development and evaluation of a personal cascade impactor sampler (PCIS),” Aerosol Science 33 (2002), 1027–1047. The device consists of several impaction stages arranged in series along the airflow. The largest particles, namely those with the highest mass, in the ambient air impact the first stage. The other particles pass through this first stage, and the remaining largest particles then impact the second stage, and so on. The different stages, which define the “cascade” principle, therefore make it possible to collect particles of various sizes. Such a device therefore makes it possible to determine the size of the particles impacted at each stage.To obtain more information, for example the shape of the particles or their chemical nature, it is then necessary, a posteriori and in the laboratory, to carry out dedicated analyses.

[0006] Thus, we also find in the literature "continuous" impaction devices otherwise called "HIRST type".

[0007] Such a device uses a single roller around which is a ribbon with an adhesive impaction face. The roller, set in motion by a motor, allows the ribbon to be moved and consequently, to be able to make a collection over time, most often over one or a few days, and thus to follow the evolution of the particle concentration in a second stage, in this case with a two-hourly time step associated with a significant margin of error. This is not possible with a "cascade impactor" type device which collects a set of particles over a predefined period, without it being possible to make a detailed temporal evolution analysis over this period. On the other hand, a device operating "continuously" comprising only a single stage, can only detect particles in a restricted size range predefined by the device's implementation parameters.In practice, it is used solely for the detection of pollen (size defined in a restricted range) and aims to monitor these pollens over time. At the end of the acquisition campaign, the ribbon can be recovered and analyzed in the laboratory, a posteriori, to determine a change in the concentration of pollens (allergens) in the ambient air and thus warn the health authorities of a possible future allergen crisis.

[0008] It would therefore be interesting to be able to propose a device for collecting particles contained in the ambient air by impaction, making it possible to collect a wide range of particle sizes, which would involve particles of different natures, while being able to monitor the evolution of the concentration of these particles over time.

[0009] In addition to a collection of a wide range of particle sizes, it would be interesting to be able to access their physicochemical nature.

[0010] Furthermore, it would also be interesting to carry out precise monitoring over time, particularly with a time step smaller than the two-hourly step of a HIRST-type device, reducing errors in the concentration measurements carried out.

[0011] Furthermore, it would also be interesting to be able to obtain this data in real time because known impaction collection systems do not currently allow this. Certainly, there are devices for real-time analysis of particles contained in ambient air. These are, however, based on principles radically different from that of impaction. For example, the company PLAIR offers the device called RAPID-E allowing real-time analysis, but based on fluorescence induced by particles subjected to a laser beam. For more information, reference may be made to documents US 2019 / 033191 A1 and US 2019 / 331601 A1. Document US 2016 / 116405 A1 discloses the preamble of claim 1. Résumé de l'invention

[0012] The invention therefore aims mainly to propose a device for collecting by impaction particles contained in the ambient air making it possible to collect a wide range of particle sizes while being able to monitor over time the evolution of the concentration of these particles.

[0013] In addition, the invention also aims to obtain at least one of the other aforementioned needs.

[0014] To this end, the invention proposes a device for collecting by impaction particles contained in the ambient air on an adhesive tape according to claim 1.

[0015] The device according to the invention may include at least one of the following characteristics, taken alone or in combination: the device comprises a light source arranged to illuminate the transparent adhesive tape from its edge; alternatively, the light source is arranged to illuminate the impaction face with an angle strictly greater than 0° and less than or equal to 90°; the housing comprises a support for the transparent adhesive tape, said support being intended to be in contact with a rear face of the transparent adhesive tape, said rear face being the face parallel and opposite to the impaction face; the device comprises a nozzle, one end of which, of smaller section, defines the air inlet orifice in the housing; the device comprises an additional particle collection support, which is capable of collecting the non-impacted particles on the transparent adhesive tape; the camera is located at a distance of between 10 µm and 100 µm from the rear face of the transparent adhesive tape;the housing comprises guides for the transparent adhesive tape, said guides being located between the rollers.;

[0016] For this purpose also, the invention proposes a method of collecting by impaction particles contained in the ambient air on a transparent adhesive tape according to claim 7.

[0017] The method according to the invention may comprise at least one of the following characteristics, taken alone or in combination: a step during which the filmed data are transmitted remotely, for example wirelessly; a step during which light is emitted, for example in the visible range, towards a slice of the transparent adhesive tape; as a variant, a step during which light is emitted, for example in the visible range, towards the impaction face with an angle strictly greater than 0° and less than or equal to 90°; a step during which the speed of the ambient air sucked into the housing is accelerated, upstream of the air inlet orifice of the housing, with reference to the direction of air flow, preferably so as to generate a turbulent flow in the space formed between said air inlet orifice and the impaction face; a step during which the particles contained in the air which have not impacted on the impaction face of the transparent adhesive tape are collected;a step during which the speed of travel of the transparent adhesive tape is varied between the two rollers; a step during which, from a constant speed of travel, the speed of travel is reduced to zero.; Brève description des figures

[0018] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which one will refer to the attached drawings and for which: [ Fig. 1 ] There figure 1 is a sectional diagram of a device according to the invention; [ Fig. 2 ] There figure 2 is a diagram according to another sectional view of the device shown in the figure 1 ; [ Fig. 3 ] There figure 3 is an enlarged view of the device according to the invention as shown in the figure 1 , at the level of an impaction zone; [ Fig. 4 ] there figure 4 is a perspective view of a component of the device shown in the figure 1 ; [ Fig. 5 ] There figure 5 is a perspective view of an alternative embodiment of the component shown in the figure 4 ; [ Fig. 6 ] There figure 6 is a sectional diagram of another device according to the invention; [ Fig. 7 ] There figure 7 is a diagram representing the steps of a method according to the invention; [ Fig. 8 ] There figure 8 is an alternative embodiment of the device shown in the figures 1 Or 6 , according to a sectional view; [ Fig. 9 ] There figure 9 represents the variant of the figure 8 , according to a top view; [ Fig. 10 ] There figure 10 illustrates an image captured by a camera of the device according to the invention, in real time, with lighting at 0° relative to the impaction face (edge ​​lighting) during an episode of circulation of Saharan dust; [ Fig. 11 ] There figure 11 illustrates an image captured by the camera of the device according to the invention, in real time, with lighting at 0° relative to the impaction face (edge ​​lighting); [ Fig. 12 ] There figure 12 illustrates an image captured by the camera of the device according to the invention, in real time, with lighting at 60° relative to the impaction face; [ Fig. 13 ] There figure 13 illustrates an image captured by the camera of the device according to the invention, in real time, with lighting at 60° relative to the impaction face and a light intensity different from that of the Fig. 13 ; [ Fig. 14 ] There figure 14 is a schematic representation of the device according to the invention on which the arrangement of the camera and the lighting source can be observed. Description détaillée de l'invention

[0019] Throughout the following description, the (O; X, Y, Z) frame defines a direct orthogonal frame.

[0020] A first embodiment of the invention is shown in support of the figures 1 à 4 .

[0021] There figure 1 represents a device 100 for collecting by impaction particles contained in the ambient air on a transparent adhesive tape 14, in accordance with the invention.

[0022] The transparent adhesive tape 14 can be various. For example, it can be silicone-coated cellophane. Alternatively, it can be a commercial tape, called "crystal", for example offered by the company 3M under the reference XA004830560. The latter is preferred, due to its good mechanical and optical properties (transparency).

[0023] The device 100 comprises a housing 10 provided with an air inlet orifice 11. The section of the orifice 11 may have various shapes. By way of non-limiting example, this section may be elliptical, circular or even rectangular, i.e. in the form of a slot. For example, a circular orifice 11 may be visualized on the figure 4 (the orifice appears elliptical there because the figure 4 is in perspective) and an orifice 11 in the form of a slot on the figure 5 . On the figures 4 And 5 , the arrows indicate the direction of air flow when the device 100 is in operation. If we consider for example a circular slot, its diameter is typically between 0.3 cm and 1 cm. In the case of the device 100 shown in the figure 1 , the section of the orifice has a predetermined, constant value.

[0024] The housing 10 comprises a first roller 12, a second roller 13 and the transparent adhesive tape 14 intended to run between the first roller 12 and the second roller 13. The direction of travel of the transparent adhesive tape is indicated by the arrow F. The rollers 12, 13 are arranged so that an adhesive face 14a of the transparent adhesive tape 14, called the impaction face, located between the rollers, is located opposite the orifice 11. By this means, the ambient air (external to the device 100) enters the housing 10 through the section of the orifice 11 and impacts the impaction face 14a of the transparent adhesive tape 14 with a flow substantially perpendicular to the impaction face 14a. It will be noted that the distance d (taken along the main direction of air flow, Y axis) between the air inlet orifice 11 and the impaction face 14a is typically between 0.5 mm and 1 mm.

[0025] The housing 10 also comprises a motor 20 for rotating the rollers 12, 13. The motor 20 is controlled by a controller 50, the latter therefore being configured to send a command to the motor 20 and thus run the transparent adhesive tape 14 between the rollers 12, 13.

[0026] From a practical point of view, the motor 20 can be connected to the second roller 13, then intended to receive the transparent adhesive tape 14, the first roller 12 then being the one which, at the start of a measurement campaign, contains the transparent adhesive tape 14. The driving of the second roller 13 by the motor 20 involves in this case, the unwinding of the transparent adhesive tape 14 from the first roller 12. Alternatively, it is also possible to arrange for the motor 20 to drive the two rollers 12, 13. Such a drive, in fact synchronized for the two rollers 12, 13, limits the risk of deformation of the part P of transparent adhesive tape 14 included between the rollers 12, 13, which can only be beneficial for the quality of the collection, by impaction, of the particles that the air is likely to contain.

[0027] The advantage of scrolling the transparent adhesive tape 14 lies in the fact that the evolution of the number of particles collected by impaction can be monitored during the test campaign. If, for example, a test campaign is planned for a total duration of one week, to detect pollen in particular, the impaction at a given moment provides information on the situation at that given moment, information which can then be monitored over time. In particular, if an increasingly large quantity of collected pollen is detected with a constant scrolling speed of the transparent adhesive tape 14, then a probable upcoming allergic crisis can be deduced in real time.

[0028] Advantageously, a removable counter-roller CR is provided to exert pressure on the transparent adhesive tape 14 against the roller 13 receiving the tape 14. This facilitates the correct winding of the transparent adhesive tape 14 around the roller 13. Also advantageously, the counter-roller CR may comprise a printing tool (not visible) for time-stamping the transparent adhesive tape 14. Thus, when the transparent adhesive tape 14 is recovered after a measurement campaign, a precise date and time of collection may be associated with the particles collected at a location on the impaction face 14a. As an alternative to the printing tool, other means may be provided fulfilling the same time-stamping function, for example a laser arranged to allow engraving of the impaction face 14a of the transparent adhesive tape 14. The counter-roller CR may also be connected to the motor 20, but this is not obligatory.

[0029] The housing 10 also comprises a pump 30 for generating, through the air inlet orifice 11, a controlled air inlet flow towards the impaction face 14a of the transparent adhesive tape 14. E air is the air intake outside the housing 10 and S air is the air outlet outside the housing 10.

[0030] In an impaction method, the section of the air inlet orifice 11 being known, the control of the pump 30 makes it possible to control the air flow through the section of the orifice 11, and therefore the speed of the air flow through the orifice 11, which corresponds substantially to the impaction speed on the impaction face 14a of the transparent adhesive tape 14.

[0031] The control of the pump 30 is provided by the controller 50. The controller 50 is therefore configured to control the pump 30 so that the pump 30 generates a controlled air inlet flow.

[0032] The controller 50 is further configured so that the pump 30 generates a variable air flow.

[0033] This provides great advantages.

[0034] Indeed, when the pump 30 is operating, the air flow from the orifice 11 is directed towards the impaction face 14a. However, this impaction face 14 constitutes an obstacle in the path of the air flow, imposing certain boundary conditions on this air flow. A portion of the air flow approaching the impaction face 14a is therefore deflected and with it, certain particles that the air contains. Thus, for a given air flow rate (flow rate 1), the particles with the highest mass, due to their inertia, are less likely to be deflected. They therefore impact more easily. On the contrary, the particles with the lowest mass, due to their lower inertia, are more deflected so that some of them may not impact on the impaction face 14a. Thus, if one wishes to collect only the particles with the highest mass, it is advantageous to implement a low air flow rate. In this case, the lowest mass particles are not collected.It is thus possible, for a given period of time during the measurement campaign, to focus more particularly on this type of particle (the highest in mass), it being recalled in particular that the transparent adhesive tape 14 can pass between the rollers 12, 13 during this period of time.

[0035] On the contrary, if one wishes to collect the particles with the lowest mass, it is then appropriate to increase the air flow rate (flow rate 2). Of course, in the latter case, the particles with the highest mass will also impact, but the variation in air flow rate then applied (changing from flow rate 1 to flow rate 2, which is higher) then makes it possible to collect the particles with the highest mass in the center of the impaction face 14a and to collect the particles with the lowest mass on the edges of the impaction face 14a. It is thus possible to collect, in a manner that can be used for the analysis to be carried out, particles of different masses (and therefore in practice of very different nature and sizes: pollen, soot, etc.) on distinct areas of the adhesive face 14a.

[0036] Furthermore, by further increasing the air flow rate (flow rate 3), it is even possible to carry out a usable collection for analysis of only the lowest mass particles. Indeed, it is possible to adjust the air flow rate to ensure that several families of particles, among the highest mass particles, impact in the center, without any differentiation being possible between them, while allowing the impaction of the lowest mass particles on the edges of the transparent adhesive tape. This thus ensures good differentiation among the different families of particles contained in the sampled ambient air which are among the lowest mass particles. In this case, it is also possible to collect, in an usable manner and for a given period of time, only the lowest mass particles.

[0037] Ultimately, the fact that the air flow rate passing through the air inlet orifice 11 can be modified, under the control of the controller 50, makes it possible, in particular in combination with the fact that the transparent adhesive tape 14 runs between the rollers 12, 13, to collect a wide range of particles in an exploitable manner. Indeed, the control of the air flow rate makes it possible to control the speed at the air inlet orifice (the section is constant), this speed being a characteristic parameter of the impaction.

[0038] The variation of the air flow by a command from the controller 50 on the pump 30 is particularly simple to implement.

[0039] However, in an alternative embodiment, it would be possible to ensure that the air inlet orifice 11 has a variable cross-section. This can be achieved with a device D configured to vary the cross-section of the inlet orifice 11, connected to a motor 20'. In this case, the controller 50 acts on the motor 20' to vary the cross-section of the air inlet orifice 11, and therefore for a given air flow rate, the speed through the air inlet orifice 11. This alternative is shown, in a sectional view, on the figure 8 and according to a top view, on the figure 9 in the case of a circular orifice 11. Here, the device D may in particular be in the form of an iris. What is shown in these figures then fits perfectly into the device 100. The precise shape of the device D will depend in particular on the shape of the orifice. Thus, in the case of a rectangular slot, it can be provided that the device D is in the form of two sliding plates each from one of two opposite sides of the slot. In all cases, this solution, involving a moving mechanical part, is not the most advantageous, in particular due to an increased risk of clogging, or even the singular pressure losses implied by this design.

[0040] According to another variant, corresponding to an association of the two variants described previously, a solution may be provided in which both the device D and its motor 20' are implemented, with a controller configured to control both the pump 30 and the motor 20'.

[0041] The motor 20 can be configured to ensure constant speed movement (starting and stopping of the motor 20 at the beginning and end of the measurement campaign aside) of the transparent adhesive tape 14, under the control of the controller 50. The speed of movement of the tape will depend greatly on the observed particle concentration. However, and typically, this will generally be a few millimeters per hour, and will rarely exceed 10 mm / h, or even 8 mm / h.

[0042] However, it can be provided that the controller 50 sends a stop command to the motor 20 during the measurement campaign (for example, with information of the ramp type, from the scrolling speed to the zero value). Once the motor 20 has stopped, the transparent adhesive tape 14 no longer scrolls, during the time that the motor 20 is stopped. This makes it possible to obtain information on the concentration of particles in the ambient air, in an easy manner since an optical measurement of absorbance through the transparent adhesive tape 14 is sufficient. It will be noted, however, that this information can also be obtained when the transparent adhesive tape 14 scrolls, but not as directly.

[0043] Indeed, knowing the air flow printed by the pump 30 through the air inlet orifice 11, and the time period during which the motor 20 is stopped, the volume of air sampled (VAP) is easily determined. A count (N) of the impacted particles can also be carried out, either after the measurement campaign or, in real time, during the measurement campaign. The concentration of impacted particles can then be easily obtained by calculating the ratio of the count (N) carried out to the volume of air sampled (VAP).

[0044] The controller 50 can then send a new command to the motor 20 so that it starts rotating again (for example, with ramp-type information, from the zero value to the desired scrolling speed).

[0045] It is possible to provide a flat support 17 for the part P of the transparent adhesive tape 14 which is located between the rollers 12, 13. The support 17 prevents the part P of the transparent adhesive tape 14 present between the two rollers 12, 13 from becoming deformed. This can only improve the quality of the collection of particles which is carried out on the impaction face 14a of the transparent adhesive tape 14. Indeed, if the rollers 12, 13 already fulfill a function of tensioning the part P of the transparent adhesive tape located between the rollers 12, 13, the flat support 17 makes it possible to further limit the risks of having a non-flat impaction face 14a. In this case, it is advantageous to provide a support 17 made of a material with non-electrostatic or low electrostatic properties, for example glass or plexiglass ®< . This avoids or at least limits the risk of the transparent adhesive tape 14 adhering to the support 17.As a result, the risk of the part P of transparent adhesive tape 14 present between the two rollers 12, 13 becoming deformed is avoided or limited, which can only improve the quality of the collection of particles which is carried out at the impaction face 14a.

[0046] The device 100 advantageously comprises a nozzle 70, one end of which, of smaller section, defines the air inlet orifice 11 in the housing 10. Such a nozzle 70 makes it possible in particular to accelerate the air sucked in from the exterior E air of the device 100, by the pump 30, up to the level of the impaction face 14a of the transparent adhesive tape 14. Reference may in particular be made to the figure 4 representing the nozzle 70 implemented in the device 100 of the figures 1 à 3 , at the end of which is located a circular orifice 11.

[0047] As shown in the attached figures, the device 100 may also include an additional particle collection support 80. The additional collection support 80 has the function of collecting the particles not impacted on the transparent adhesive tape 14. For this purpose, a membrane may be used that is removably mounted downstream of the transparent adhesive tape 14, with reference to the path of the air in the housing 10. This membrane 80 may then be analyzed a posteriori. This membrane 80 may be installed in several locations, for example at the EP inlet of the pump 30, as shown in the figure 1 . It is also possible, at the outlet of the SP pump, to provide a bypass (case not shown in the attached figures) leading to the membrane.

[0048] The device 100 further comprises a camera 40 for filming a rear face 14b of the transparent adhesive tape 14, said rear face 14b being the face parallel and opposite to the impaction face 14a. In this case, and in the presence of the support 17, it is understood that the support 17 must also be transparent. Indeed, the camera 40 is then located behind the support 17, opposite the impaction face 14a.

[0049] Such a configuration makes it possible to collect the particles without loss on the adhesive and transparent tape 14 in comparison with a configuration where the camera 40 would be arranged to film the impaction face 14a of the transparent adhesive tape 14. Indeed, in this latter configuration, the camera 40 would necessarily be an obstacle for the flow of the air flow and the latter would be obliged to bypass it. However, the bypassing of the camera 40 necessarily filters the particles collected on the impaction face 14a since only the lightest particles are then capable of reaching said impaction face 14a. By arranging the camera 40 so that it films the rear face 14b, it is possible to collect particles of all sizes, and therefore to collect without loss.

[0050] Such a configuration also makes it possible to film and therefore detect the particles deposited on the tape 14 in real time. This makes it possible to calculate a saturation index, corresponding to the total concentration, which makes it possible to control the input flow rate generated by the pump 30 and / or the unwinding speed of the transparent adhesive tape 14 and improve the separation and identification of the collected particles. figure 10 illustrates an image captured by camera 40 showing the significant number of Saharan dust particles detected in the boundary layer in Grenoble at a given time. We can clearly understand the importance of using real-time detection to monitor the number of particles deposited on strip 14 in real time.

[0051] The 40 camera can feature autofocus.

[0052] It may, in addition or alternatively, be mounted on rails (not shown). The rails are then arranged to allow movement of the camera 40 in a direction perpendicular to the plane defined by the rear face 14b (or the impaction face 14, which amounts to the same thing) of the transparent adhesive tape 14. The movement of the camera 40 on rails makes it possible to perform a function similar to, or additional to, that of an autofocus.

[0053] Advantageously, when the camera 40 films the rear face 14b, opposite and parallel to the impaction face 14a, the camera 40 is located at a distance of between 10 µm and 100 µm from the adhesive and transparent tape 14. This makes it possible to improve the sharpness of the acquired images, independently of any autofocus, without hindering the collection of particles on the adhesive and transparent tape 14.

[0054] When the camera 40 is provided, the controller 50 is then configured to analyze and process the data provided by the camera 40, to perform real-time analyses. The camera 40 is more generally controlled by the controller 50 and furthermore, the controller 50 controls, as a function of the data provided by the camera 40, the motor 20 (and / or as the case may be the motor 20' to vary the section of the air inlet orifice) and the pump 30 to respectively adapt the running speed of the transparent adhesive tape 14 and the air flow sucked in by the air inlet orifice 11.

[0055] It is also possible, as a variant, to provide for the images provided by the camera 40 to be transmitted remotely (for example by wireless means), so that an analysis of this data can be carried out by a remote computer (not shown), also in real time.

[0056] It is also possible to provide that the images from the camera 40 are stored in a memory 51 of the device 100. The data from the memory 51 can then be recovered, a posteriori, namely after the measurement campaign, either to carry out an a posteriori analysis, or to verify, still a posteriori, an analysis which would have been carried out in real time by the controller 50 of the device or, as the case may be, by the aforementioned remote computer.

[0057] In reference to the figure 2 , it is noted that the housing 10 can also comprise a light source 60 arranged so as to illuminate the transparent adhesive tape 14 via its edge 14c (the edge 14c is referenced in figure 3 ). The edge 14c defines a side face of the transparent adhesive tape 14, substantially flat and both substantially perpendicular to the impaction face 14a and to the rear face 14b of the transparent adhesive tape 14. The illumination of the edge 14c of the transparent adhesive tape 14 makes it possible to capture images on a black background with the camera 40. Indeed, as mentioned previously, the camera 40 films the rear face 14b which is opposite and parallel to the impaction face 14a. The illumination of the edge 14c is therefore carried out with an angle of 0° (zero angle) relative to the impaction face 14a. The presence of a black background in the captured images derives from this 0° illumination by the light source 60. Such a configuration makes it possible to highlight absorbent or reflective luminous objects and therefore makes it easier to recognize biological particles, which are absorbent by nature, and non-biological particles, which are more reflective.In addition, it also makes it possible to highlight the volumes and internal structures of the collected particles, for example the existence of spheres or even conductive lines.

[0058] There figure 11 illustrates an image captured by the camera 40 in the aforementioned configuration. Among the collected particles, pollens of different sizes can be observed. The sizes are determined by calibration using inorganic spheres of known sizes (1µm, 10µm, 30µm, 40µm) and pixel / size conversions.

[0059] Alternatively, the light source 60 is arranged so as to illuminate the impaction face 14a with an angle strictly greater than 0° (non-zero angle) and less than or equal to 90°. This is for example illustrated in figure 14 , where the angle is 60° relative to the impaction face. In other words, in this configuration, the light source 60 is positioned so as to illuminate the adhesive and transparent tape 14 with an angle strictly greater than 90° and less than or equal to 180° relative to a detection axis of the camera, the camera 40 filming the rear face 14b which is opposite and parallel to the impaction face 14a. Such a configuration makes it easier to recognize dark objects and therefore makes it possible to highlight highly absorbent objects such as soot and crustal dust. In addition, this makes it possible to highlight transparent objects such as sea salts and silicates while accentuating the contours of internal and external shapes.

[0060] THE figures 12 And 13illustrate images captured by the camera 40 in a configuration where the illumination is carried out at an angle of 60° relative to the impaction face 14a. It should be noted that the figure 13 differs from the figure 12 by the light intensity of the source 60. In these two figures, it is possible to distinguish the presence of well-defined molds, strings of soot (black) and the internal structure of pollens.

[0061] In the configuration of the figure 11 as in that of the figures 12 And 13 , it is possible to highlight the intrinsic optical properties of the particles such as absorption, diffusion, reflection, granularity, external and internal structures, degree of transparency, edge effects, etc. When implementing the method according to the invention, care will be taken not to modify the color of the support 17 between the measurements so that they are comparable.

[0062] The light source 60 may be a white light source (visible range), therefore polychromatic. The light beam FL coming from the diode 60 has been shown when it is in operation. It will also be noted in passing that the air flow not impacting on the transparent adhesive tape 14 and therefore passing around it has been shown on the figure 2 .

[0063] An example of a suitable light source 60 is a diode, such as that shown, in section, in the figure 2 . Alternatively, another type of light source could be provided, for example, instead of the diode 60, an incandescent lamp or a Xenon lamp, advantageously fibered. A Xenon lamp is particularly powerful, which makes it possible, particularly in the presence of biological particles, to take advantage of, namely to amplify, the fluorescence that they generate.

[0064] A monochromatic light source can also be used, capable of operating in the visible, near-infrared or ultraviolet ranges when targeting certain types of particles. For example, in the visible range, if one wishes to better visualize pollens that have been collected, a light source operating at around 520nm (green) is particularly useful, because this wavelength is not or only slightly absorbed by pollens. The natural fluorescence of bioparticles can also be used to distinguish those that contain chloroplasts or not. Similarly, if one wishes to better visualize carbon particles (notably those resulting from fuel or wood fire combustion products), a light source operating at 880nm is particularly well suited (near-infrared).According to a final example, if we wish to better visualize dust which would have been collected by the transparent adhesive tape 14, their typical dimensions imply operation at a wavelength generally at most 320nm (to benefit as much as possible from the diffusion involved by this dust).

[0065] The transparency of the transparent adhesive tape 14 will depend greatly on the intended application. However, it is understood that generally the transparent adhesive tape 14 will be transparent in the visible range, and advantageously also in the near infrared and / or near ultraviolet.

[0066] A second embodiment of the invention is shown in the figure 6 .

[0067] On this figure 6 , the device 100' comprises, in addition to the rollers 12', 13', guides 15, 16 for the transparent adhesive tape 14, advantageously each with a section that is both rounded and smaller than the section of a roller 12', 13'. The guides 15, 16 are located between the rollers 12', 13'.

[0068] It is indeed useful to provide, in order to carry out a long-term test campaign, a relatively large length of transparent adhesive tape 14. Therefore, a roll 12', 13' around which the majority of the adhesive is wound has a certain diameter and therefore a significant size. In such a case, it is useful to arrange the rolls 12', 13', not near the impaction face 14a of the transparent adhesive tape 14 (as is the case on the figure 1 ), but further away, for reasons of space. The guides 15, 16 are then positioned in place of the rollers 12, 13 of the variant described previously in support of the figure 1 .

[0069] These guides 15, 16 then make it possible to ensure good mechanical strength of the transparent adhesive tape 14 by ensuring a certain tension along the longitudinal axis of the tape 14. Indeed, in this case, the transparent adhesive tape 14 and therefore the impaction face 14a remain taut and flat.

[0070] Advantageously, the guides 15, 16 are made of a material with non- or low-electrostatic properties, for example glass or Plexiglas ®<. This avoids or at least limits the risk of the transparent adhesive tape 14 adhering to the guides 15, 16. As a result, the risk of the portion of transparent adhesive tape 14 present between the two guides 15, 16 becoming deformed is avoided or limited, which can only improve the quality of the particle collection that is carried out.

[0071] It should also be noted that the guides can be mounted on bearings (not shown) to better support the movement of the transparent adhesive tape 14.

[0072] Everything else, for the 100' device shown on the figure 6 , is identical to what was previously described in support of the figures 1 à 4 , being also mentioned as the component illustrated on the figure 5 can also be implemented in place of the nozzle 70 in the device 100'.

[0073] Obtaining the data can be done in real time, thanks to the presence of the camera 40. Indeed, it can film the transparent adhesive tape 14, in particular under the effect of the light provided by the light source 60 to obtain a lot of information.

[0074] Thus, it is possible to know, in real time, the size of the particles having impacted (overall dimensions, form factors). To do this, it is sufficient to inject into the air flow, for example, upstream of the air inlet orifice 11, balls (often made of latex) of calibrated and known dimensions. These balls then impact on the impaction face 14a of the transparent adhesive tape 14 and their detection by the camera 40 allows a comparison with the other particles having impacted and coming from the ambient air. From a practical point of view, the controller 50 then collects the images provided by the camera 40, counts the number of pixels of an image representing a calibrated ball, which makes it possible to make a link between the dimension of a pixel and the actual size of a calibrated ball. Then, counting pixels, on the image considered, for all the other particles allows access to the size and form factor of these other particles.

[0075] Once this information is known, we can then calculate concentrations for each type of particle, as explained previously.

[0076] It is also possible to know, in real time, the color of the particles that have impacted. This information, added to that of the size of the particles, makes it possible to determine the nature of the particles visualized (biological, non-biological and their more precise nature in these two classes).

[0077] Furthermore, this real-time analysis is of interest for, for example, adapting the running speed of the transparent adhesive tape 4. Thus, if we observe an excessively high concentration (or even saturation) of certain particles on the impaction face 14a, we may have an interest in increasing the running speed of the transparent adhesive tape 14.

[0078] In the context of the invention, it should be noted that the size of the particles and their chemical nature can also be obtained a posteriori, namely after the measurement campaign. Nevertheless, as will have been understood, the analysis of this data in real time, by the controller 50, is particularly advantageous.

[0079] The invention also relates to a method for collecting particles contained in the ambient air by impaction onto a transparent adhesive tape 14. This method can be implemented regardless of the embodiment variant of the device 100, 100' considered and the advantages described above of course apply to the method steps that can be implemented.

[0080] We can refer to the figure 7 .

[0081] Thus, the process includes the following steps: sucking (ETP1), through the air inlet orifice 11 of the housing 10, the ambient air at a controlled air inlet flow rate; running (ETP2) the transparent adhesive tape 14 between the two rollers 12, 12'; 13, 13' belonging to the housing 10, so that the impaction face 14a of the transparent adhesive tape 14 runs in front of the orifice 11, the air thus being directed towards the impaction face of the transparent adhesive tape; varying (ETP3), in a controlled manner, the air inlet flow rate through the air inlet orifice 11.

[0082] This method may in particular take advantage of the fact that the controlled variation of the air flow rate is achieved by means of a controller configured to control the pump 30 so that the latter produces a variable flow rate. The variation of the flow rate implies a variation of the speed (constant orifice section), which, as previously stated, is a characteristic parameter of the impaction. Thus, for example, the more this speed increases, the more light, small particles there will be on the impaction face.

[0083] This method may, in addition or as a variant, make use of a motor 20' acting on a device D capable of varying the section of the air inlet orifice 11. Thus for a flow rate supplied by the pump 30 which is constant, the air inlet speed, which is considered at the level of the air inlet orifice 11, may vary due to the change in section of the orifice.

[0084] Another way of doing this would be to vary, still in a controlled manner, the distance between the air inlet and the impaction face of the ribbon (another impaction parameter, by applying the similarity criteria). The effect would be equivalent to that of varying the speed at the air inlet.

[0085] The method comprises a step during which the transparent adhesive tape is filmed by a rear face 14b of said transparent adhesive tape 14, said rear face 14b being the face parallel and opposite to the impaction face 14a. When a support 17 is provided between the rear face 14b and the camera 40, the support 17 is then transparent.

[0086] The method comprises a step during which the filmed data is analyzed in real time using a controller. The controller 50 may in particular be the one provided in the device 100, 100'. This step may in particular be followed by a step of controlling the speed of movement of the transparent adhesive tape 14.

[0087] The method may include a step during which the filmed data is transmitted remotely, for example wirelessly. In this case, the analysis of the data provided by the camera 40 may be carried out by a remote computer.

[0088] During the method, a step may be provided during which light is emitted, for example in the visible range, towards a slice 14c of the transparent adhesive tape 14. This illumination by the slice 14 of the transparent adhesive tape 14 has the effect of allowing better diffusion of the light within the tape 14 and therefore ensuring better visibility by the camera 40.

[0089] A step may be provided during which the speed of the ambient air drawn into the housing is accelerated, upstream of the air inlet orifice 11 of the housing 10, with reference to the direction of air flow, preferably so as to generate a turbulent flow in the space formed between said air inlet orifice 11 and the impaction face 14.

[0090] It is also possible to provide a step during which the particles contained in the air that have not impacted the impaction face 14a of the transparent adhesive tape 14 are collected. Indeed, the areas located on either side of the tape, with reference to the width of the transparent adhesive tape, form free spaces through which the air flow is able to circulate. The particles that have not impacted can then be collected by the pump 3, if the latter is for example equipped with a recovery tank, or any suitable collection device. It should be noted in particular that when the camera 40 is very close to the rear face 14b, i.e. at a distance of between 10 µm and 100 µm, the space formed between the camera 40 and the rear face 14b does not constitute a natural circulation path for the air flow which, after having bypassed the transparent adhesive tape 14, bypasses the camera 40. The camera 40 is therefore not a source of particle losses.

[0091] It is also possible to vary the running speed of the transparent adhesive tape 14 between the two rollers 12, 12', 13, 13'. In particular, from a constant running speed, the running speed can be reduced to zero. When the tape is stopped, it is then possible to carry out particularly easy concentration measurements of certain particles. This can in fact be carried out by an absorbance measurement. Example of application:

[0092] With any of the devices 100, 100' described above, the following parameters can be provided: Circular air inlet orifice 11, with a cross-section of 14mm 2< (i.e. an orifice diameter slightly greater than 0.4cm); Distance d between the air inlet orifice 11 and the impaction face 14a of 0.7mm; The air inlet flow rate, through the cross-section of the orifice 11, is 10 l / min; In this case, particles between 1 micron and 100 microns in size are collected by impaction.

[0093] By taking the same parameters, and only doubling the flow rate (i.e. going to 20 l / min), we can then also collect particles whose dimensions are between 800 nm and 1 micron.

Claims

1. A device (100, 100') for collecting by impaction particles contained in ambient air on a transparent adhesive strip (14), the device comprising: - a housing (10) provided with an air inlet orifice (11), said housing (10) comprising a first roller (12, 12') and a second roller (13, 13') and the transparent adhesive strip (14) mounted between the rollers (12, 12'; 13, 13'), said rollers (12, 12'; 13, 13') also being arranged so that an adhesive face (14a) of the transparent adhesive strip (14), known as the impaction face, can pass in front of the orifice (11); - a first motor (20) for rotating the rollers (12, 12'; 13, 13'); - at least one pump (30) for generating, through the air inlet orifice (11), an air inlet flow rate toward the impaction face (14a) of the transparent adhesive strip (14), and / or a device (D) configured to vary, in a controlled way, a section of the air inlet orifice (11), said device (D) being connected to a second motor (20'); - a controller (50) for controlling the first motor (20) to rotate the rollers and thus feed the transparent adhesive strip (14) between said rollers and for controlling, as appropriate, at least one of the pump (30) so that the pump generates a controlled and variable air inlet flow or the second motor (20') connected to the device (D) configured to vary, in a controlled way, the section of the air inlet orifice (11); and - a camera (40) for filming a rear face (14b) of the transparent adhesive strip (14), said rear face (14b) being the face parallel and opposite to the impaction face (14a), wherein the controller (50) is configured to analyze and process the data provided by the camera (40) to perform real-time analyses, the camera (40) being controlled by the controller (50), characterized in that the controller (50) is configured, based on the data provided by the camera (40), to control the first motor (20) and / or, as appropriate, the second motor (20') or at least one of the pump (30) to respectively adapt the speed of the transparent adhesive strip (14) and the air flow rate sucked in through the air inlet orifice (11).

2. The device (100, 100') according to claim 1, characterized in that it comprises a light source (60) arranged so as to illuminate the transparent adhesive strip (14) through its edge (14c).

3. The device (100, 100') according to one of the preceding claims, characterized in that the housing (10) comprises a support (17) for the transparent adhesive strip (14), said support (17) being intended to be in contact with a rear face (14b) of the transparent adhesive strip (14), said rear face (14b) being the face parallel and opposite to the impaction face (14a).

4. The device (100, 100') according to one of the preceding claims, characterized in that it comprises a nozzle (70), one end of which, of smaller cross-section, defines the air inlet orifice (11) in the housing (10).

5. The device (100, 100') according to one of the preceding claims, characterized in that it comprises an additional particle collection support (80) which is capable of collecting particles that have not impacted on the transparent adhesive strip (14).

6. The device (100') according to one of the preceding claims, characterized in that the housing (10) comprises guides (15, 16) for the transparent adhesive strip (14), said guides (15, 16) being located between the rollers (12', 13').

7. A method for collecting by impaction particles contained in ambient air on a transparent adhesive strip (14), using the device (100, 100') according to one of the preceding claims, said method comprising the following steps of: - suctioning ambient air through the air inlet orifice (11) of the housing (10) at a controlled air inlet flow rate; - passing the transparent adhesive strip (14) between the two rollers (12, 12'; 13, 13') belonging to the housing (10) so that the impaction face (14a) passes in front of the orifice, the air thus being directed towards the impaction face of the transparent adhesive strip; - varying, in a controlled way, the air inlet flow rate through the air inlet orifice (11) and / or varying, in a controlled way, the section of the air inlet orifice (11), - filming the transparent adhesive strip with a rear face (14b) of said transparent adhesive strip (14), said rear face (14b) being the face parallel and opposite to the impaction face (14a), - analyzing, in real time, the data filmed with the controller, and - adjusting the speed of the transparent adhesive strip and / or the air flow rate sucked in through the air inlet orifice.

8. The method according to claim 7, characterized in that it comprises a step in which the filmed data is transmitted remotely, for example by wireless means.

9. The method according to one of claims 7 or 8, characterized in that it comprises a step in which light, for example in the visible range, is emitted toward a section (14c) of the transparent adhesive strip (14).

10. The method according to one of claims 7 to 9, characterized in that it comprises a step in which, upstream of the air inlet orifice (11) of the housing (10), with reference to the direction of air flow, the speed of the ambient air sucked into the housing, preferably so as to generate a turbulent flow in the space formed between said air inlet orifice (11) and the impaction face (14).

11. The method according to one of claims 7 to 10, characterized in that it comprises a step in which the particles contained in the air that have not impacted the impaction face (14a) of the transparent adhesive strip (14) are collected.

12. The method according to one of claims 7 to 11, characterized in that it comprises a step in which, starting from a constant frame rate, the frame rate is reduced to zero.