Sampling system

Abstract

A sampling system for obtaining a sample of particulate contamination on a surface of an object. The sampling system comprises a sampling device and an applicator. The sampling device comprises a sampling plate having a tacky sampling surface on a first side of the sampling plate, and at least one mechanical connector on an opposite, second side of the sampling plate. The applicator comprises a handle portion, and an engagement portion configured to releasably couple to the at least one mechanical connector. The sampling system is configured to allow the tacky sampling surface to be pressed against the surface of the object and then removed.

Description

[0001]P137813PC00 Title: Sampling system FIELD OF THE INVENTION The invention relates to a method and system for gathering a sample for, e.g. automated, detection of particles on a surface of an object. BACKGROUND TO THE INVENTION It is known to inspect a flat object surface for the presence of particles by observing the surface with a digital camera while the surface is illuminated under a grazing angle. This produces a dark field image, wherein the only observed light is due to scattering of the grazing light from particles on the surface and / or other irregularities. If the particles are scarcely distributed, this makes it possible to spot individual particles even if the particles individually cannot be optically resolved. Instead of direct measurements on the surface of the object, it is also known to perform indirect measurements. In such indirect measurement, a Particle Measurement Card, PMC, can be used. The PMC generally comprises a tacky surface, such as of polyurethane elastomer, e.g. carried by a carrier. The tacky surface can be pressed against the surface of the object. When lifting the PMC off the object, the particles tend to stick to the surface of the PMC, rather than to the surface of the object. In this way, particulate surface contamination of the object can be determined by determining the presence of particles on the PMC. This allows off-line measurements. An example of an indirect measurement is described in WO2013 / 149961A1. The PMC in practice usually comprises a carrier formed by a flat substrate having a hole, the tacky layer being accessible through the hole. A flexible sheet may be provided on an opposite side of the tacky layer from the hole. Obtaining a sample then comprises placing the carrier on a portion of the object, and pressing, usually with a finger of the user, the flexible sheet to press the tacky layer against the surface of the object. Next, the PMC is removed from the surface of the object by peeling off the sheet. It has been found that the practice of obtaining samples with the PMC can be cumbersome, and results may depend on the skill of the user. Therefore, a simpler and more uniform way of obtaining samples is desired. SUMMARY OF THE INVENTION It is an object to provide a system and / or method for obtaining samples for, e.g. automated, inspection of particles on a surface of an object, such that obtaining the samples can be less cumbersome and more user-independent. According to an aspect is provided a sampling system for obtaining a sample of particulate contamination on a surface of an object. The sampling system comprising a sampling device and an applicator. The sampling device comprises a sampling plate having a tacky sampling surface on a first side of the sampling plate. The sampling system is configured to allow the tacky sampling surface to be pressed against the surface of the object and then removed. Hence, the tacky sampling surface is configured to be pressed against the surface of the object. This can e.g. be done by pulling the sampling device in a direction substantially perpendicular to the surface of the object. Removing the tacky sampling surface from the surface of the object in the direction substantially perpendicular to the surface of the object, allows the particulate contamination to be transferred to the tacky sampling surface while maintaining a mutual position of individual particles of the particulate contamination. Thus, a concentration of contamination particles per unit area, and / or positional information of the contamination can accurately be determined. It will be clear that alternative sampling methods, which e.g. rely on swiping a sampling device across the surface of the object, or sucking (e.g. by vacuum) contamination from the surface of the object, do not allow accurate determination of concentration of contamination particles per unit area, and / or positional information of the contamination. The tacky sampling surface can comprise a polyurethane elastomer surface. The sampling device comprises at least one mechanical connector on an opposite, second side of the sampling plate. The protrusion extending from the second side of the sampling plate can allow the sampling surface to be removed from the surface of the object in a direction substantially perpendicular to the surface of the object. The applicator comprises a handle portion. The applicator comprises an engagement portion configured to releasably couple to the at least one mechanical connector. Hence, the sampling device can be connected to the applicator and released from the applicator with little effort. The handle portion allows easy manipulation of the sampling device. After the sampling device has been removed from the surface of the object, and particulate contamination on the surface of the object has been transferred to the tacky layer. The particulate contamination on the tacky layer can be examined with an inspection device. The examination can be performed off- line. In the sampling system, the sampling device can be a consumable. The sampling device can be a single-use sampling device. Hence, after the sampling device has been examined it can be discarded. The at least one mechanical connector can be integral with or, e.g. permanently, attached (such as affixed) to the sampling plate. The mechanical connector can e.g. glued, welded, co-moulded, to the sampling plate. As such, the at least one mechanical connector can be immobile relative to the sampling plate. Optionally, the at least one mechanical connector comprises at least one protrusion and / or at least one recess. Optionally, the at least one mechanical connector is formed by at least one protrusion and / or at least one recess. Optionally, the at least one mechanical connector is formed by at least one protrusion. Optionally, the at least one mechanical connector is formed by at least one recess. The engagement portion of the applicator can be configured to releasably hold the at least one protrusion, and / or the engagement portion of the applicator can be configured to releasably engage the at least one recess. The engagement portion can include locking features configured such that in a locked state the at least one mechanical connector (e.g. the at least one protrusion and / or at least one recess) is locked in engagement with the engagement portion. This allows the mechanical connector and engagement portion to transfer forces (e.g. pushing, pulling) from the handle portion to the sampling device. The locking features can also be configured such that in an unlocked state the at least one mechanical connector (e.g. the at least one protrusion and / or at least one recess) can freely be moved out of engagement with the engagement portion. The locking features can include a snap feature causing the at least one protrusion and / or recess to automatically engage with the engagement portion in the locked state upon engagement of the protrusion with the engagement portion. Optionally, the at least one mechanical connector (e.g. the at least one protrusion and / or recess) is positioned at or near an outer perimeter of the sampling plate. The at least one mechanical connector can e.g. be positioned at 0%- 50%, e.g. 0%-25%, of a distance from an outer edge of the sampling plate to the center of the sampling plate. This can aid in removing the sampling surface from the surface of the object. This can also aid in pressing the sampling to the surface of the object across the entire surface of the sampling plate. Optionally, the sampling plate comprises a tacky layer having the tacky sampling surface on a first side of the tacky layer, and a carrier mounted to an opposite, second side of the tacky layer. The carrier can be affixed (such as glued, welded, bonded) to the second side of the tacky layer. As such, the carrier can be immobile relative to the portion of the tacky layer to which it is affixed. Preferably, the tacky layer is flexible. The tacky layer can e.g. be a layer of tacky elastomer, e.g. being or comprising polyurethane elastomer. The tacky layer can e.g. be 0.3-2.5 mm thick. Preferably, the carrier is more rigid than the tacky layer. Preferably, the carrier is made of a material that is more rigid than the tacky layer. The carrier can e.g. comprise, or be made of, a polymer material, such as PC, PE, PP, ABS, PVC, PLA, or the like. The carrier can e.g. be manufactured using 3D printing or injection moulding. Optionally, the at least one mechanical connector is present on the carrier. Optionally, the at least one protrusion extends from the carrier and / or the at least one recess extends into the carrier. The at least one protrusion can be formed integrally with the carrier. Thus, the tacky sampling surface can e.g. be formed from a planar sheet of material. The tacky layer can e.g. be formed by cutting, such as laser cutting, from sheet material. The tacky layer can e.g. be formed by injection moulding. The sampling device can e.g. be formed by co- injection moulding or in-mould labeling. For instance, the tacky layer and the at least one mechanical connector can be co-injection moulded or in-mould labeled. For instance, the tacky layer and the carrier can be co-injection moulded or in- mould labeled. Optionally, the carrier comprises an aperture allowing access to the tacky layer at the second side. This allows access to the tacky layer from the back side, i.e. from the side opposite to the tacky sampling surface. Thus, the tacky sampling surface can be pushed against the surface of the object through the aperture in the carrier. Optionally, the sampling device comprises a cover sheet covering the tacky layer at the second side, within the aperture. The cover sheet can cover a potentially tacky second side of the tacky layer. Thus, pushing the tacky sampling surface against the surface of the object can be more convenient. Optionally, the applicator comprises a pusher, movable relative to the engagement portion, for pushing a portion of the sampling surface outwardly, i.e. in a direction away from the applicator. Pushing a part of the sampling surface outwardly, relative to other parts of the sampling surface that are retained by the engagement portion engaging the at least one protrusion, allows to deform the sampling surface to bulge outwardly. The sampling surface that bulges outwardly, can be pushed against the surface of the object with the portion of the sampling surface that projects away most from the applicator. Preferably, the sampling system is configured such that the sampling surface deforms to be double curved under influence of the pusher. Subsequently allowing the sampling surface to return to its planar state again, allows the sampling surface to contact the surface of the object with a minimal risk of trapping air pockets between the sampling surface and the surface of the object. The applicator may comprise a resilient element, such as a spring, biasing the pusher in a direction away from the sampling plate. Thus, the pusher may be actuated against the biasing force to deform the sampling surface to bulge outwardly, while releasing the pusher will allow the sampling surface to relax to its planar state. The sampling system may comprise a force distribution element, such as a flexible element, e.g. a foam element, positioned between the sampling plate, e.g. the second side of the tacky layer, and the pusher. The force distribution element may extend through the aperture. The force distribution element may be attached to the pusher. The force distribution element may be a foam element, such as a closed cell foam element, attached to a surface of the pusher facing the sampling plate. The force distribution element may be attached to the sampling plate. The force distribution element may be a foam element, such as a closed cell foam element, attached to a surface of the sampling plate facing the pusher. The force distribution element can e.g. be about 1-12 mm thick, e.g.2-12 mm, or 2-6 mm. The force distribution element can aid in the sampling plate conforming to a non-planar surface of the object. The force distribution element can also aid in the sampling plate bulging outwardly in a smooth manner. Optionally, the pusher is configured to engage the sampling plate at or near a center of the sampling plate. This may allow to deform the sampling surface to bulge in a symmetrical way. Optionally, the pusher is configured to engage the sampling plate within the aperture. Thus, the pusher can conveniently deform the sampling surface by extending through the aperture in the carrier. Optionally, the at least one protrusion comprises a plurality of, such as three, legs configured to be engaged by the engagement portion. The legs provide a convenient way to connect the sampling device to the applicator. Optionally, the at least one recess comprises a plurality of, such as three, recesses configured to be engaged by the engagement portion. Optionally, the sampling device includes a human-readable and / or machine-readable identification. The machine-readable identification can e.g. comprise a barcode, QR code, RFID chip, NFID chip, or the like. The identification can assist in managing multiple samples taken in succession. Optionally, the sampling system further comprises a cover. The cover is configured to be releasably attached to the sampling device for covering the tacky sampling surface. Prior to taking a sample, the tacky sampling surface can be covered by the cover to prevent contamination of the sampling surface by particles not present on the surface of the object. The cover may be removed from the sampling device immediately prior to placing the sampling device on the surface of the object. The cover may e.g. be removed by a snap action or twisting action. The cover may be repositioned on the sampling device immediately after taking removing the sampling device from the surface of the object. Optionally, the sampling system further comprises a lid. The lid and the cover can be configured to, together, form a closed enclosure around the sampling device. Thus, contamination of the sample can be prevented. The lid may be closed to the cover, e.g. by a screw or bayonet connection. The lid may be removed from the cover immediately prior to engaging the sampling device with the applicator. The lid may be reconnected to the cover immediately after releasing the sampling device from the applicator. According to a further aspect, is provided a sampling device, for instance as describe hereinabove. According to a further aspect is provided an applicator, for instance as described hereinabove. According to a further aspect is provided a method for obtaining a sample of particulate contamination on a surface of an object. The method includes providing a sampling system as described hereinabove. The method includes engaging the at least one mechanical connector of the sampling device to the engagement portion of the applicator. The method can include locking the at least one mechanical connector in engagement with the engagement portion. The method includes pressing the tacky sampling surface against the surface of the object. The method includes removing the tacky sampling surface from the surface of the object. The method includes releasing the at least one mechanical connector of the sampling device from the engagement portion of the applicator. The method can include unlocking the at least one mechanical connector from the engagement portion. Preferably, the tacky sampling surface is removed from the surface of the object in a direction substantially perpendicular to the surface of the object. This can e.g. be done by pulling the sampling device in a direction substantially perpendicular to the surface of the object. Optionally, the method includes actuating the pusher of the applicator for bulging the tacky sampling surface outwardly prior to pressing the tacky sampling surface against the surface of the object. Optionally, the method includes releasing the pusher of the applicator while pressing the tacky sampling surface against the surface of the object. Optionally, the method includes removing the cover from the sampling device prior to pressing the tacky sampling surface against the surface of the object. Optionally, the method includes repositioning the cover on the sampling device after removing the tacky sampling surface from the surface of the object. Optionally, the method includes removing the lid from the cover prior to engaging the at least one protrusion of sampling device to the engagement portion of the applicator. Optionally, the method includes repositioning the lid on the cover after releasing the at least one protrusion of the sampling device from the engagement portion of the applicator. It will be appreciated that any one or more of the above aspects, features and options can be combined. It will be appreciated that any one of the options described in view of the system can be applied equally to the sampling device, applicator, and / or method, and vice versa. BRIEF DESCRIPTION OF THE DRAWING The invention will further be elucidated on the basis of exemplary embodiments which are represented in a drawing. The exemplary embodiments are given by way of non-limitative illustration. It is noted that the figures are only schematic representations of embodiments of the invention that are given by way of non-limiting example. In the drawing: Fig. 1 shows a cross sectional view of an example of a sampling system; Fig. 2 shows an example of a sampling device; Figures 3A and 3B show examples of detail; Fig. 4 shows a cross sectional view of an example of a sampling system; Fig. 5 shows a cross sectional view of an example of a sampling device in a container; Fig. 6 shows an example of a method; and Fig. 7 shows a cross sectional view of an example of a sampling system. DETAILED DESCRIPTION Figure 1 shows a cross sectional view of an example of a sampling system 1 for obtaining a sample 2 of particulate contamination on a surface 3 of an object 4. The sampling system 1 comprises a sampling device 10 and an applicator 20. Figure 2 shows an isometric view of a sampling device 10. The sampling device 10 comprises a sampling plate 11 having a tacky sampling surface 12 on a first side 11A of the sampling plate 11. The tacky sampling surface 12 can comprise a tacky elastomer surface, such as a polyurethane elastomer surface. The sampling device 10 comprises at least one mechanical connector 13 on an opposite, second side 11B of the sampling plate 11. The sampling plate 11 and the at least one mechanical connector are affixed to each other in this example. In this example, the at least one mechanical connector is embodied as at least one protrusion 13. Hence, here the sampling device 10 comprises at least one protrusion 13 extending from an opposite, second side 11B of the sampling plate 11. In the example of figure 2, the sampling device 10 comprises three protrusions 13. The protrusion in figure 1 are embodied as legs extending from the sampling plate 11. Here, the mechanical connectors, here the protrusions, 13 are positioned at an outer perimeter 11C of the sampling plate 11. It will be appreciated that it is also possible that the at least one mechanical connector 13 is positioned near the outer perimeter 11C of the sampling plate 11, e.g. at 0%-50%, e.g.0%-25%, of a distance from the outer perimeter 11C of the sampling plate 11 to the center 11D of the sampling plate 11. In the example of figure 1, the sampling plate 11 comprises a tacky layer 14 having the tacky sampling surface 12 on a first side 14A of the tacky layer 14. Preferably, the tacky layer 14 is flexible. The tacky layer 14 can e.g. be a layer of a tacky elastomer, such as of polyurethane elastomer. The tacky layer 14 can e.g. be 0.3-2.5 mm thick. The tacky layer 14 can e.g. be formed from a planar sheet of material. The tacky layer 14 can e.g. be formed by cutting, such as laser cutting, from sheet material. The tacky layer 14 can e.g. be formed by injection moulding. Here, a carrier 15 is mounted to an opposite, second side 14B of the tacky layer 14. Hence, the tacky layer 14 is affixed to the carrier 15. Here, the protrusions 13 extend from the carrier 15. In particular, the protrusions 13 are formed integrally with the carrier 15. In this example, the carrier 15 is made of a material that is more rigid than the material of the tacky layer 14. The carrier 15 can e.g. comprise, or be made of, a plastics material, such as PC, PE, PP, ABS, PVC, PLA, or the like. The carrier can e.g. be manufactured using 3D printing or injection moulding. In the example of figure 1, the carrier 15 comprises an aperture 16 allowing access to the tacky layer 14 at the second side 14B. This allows access to the tacky layer 14 from the back side, i.e. from the side opposite to the tacky sampling surface 12. Here, a cover sheet 17 is provided covering the tacky layer 14 at the second side 14B, within the aperture. It will be appreciated that the cover sheet 17 may extend only within the aperture 16, or also outside the aperture 16, such as across the entire second side 14B of the tacky layer 14. The cover sheet 17 can cover a potentially tacky second side 14B of the tacky layer. The applicator 20 comprises a handle portion 21. The applicator 20 comprises an engagement portion 22 configured to releasably couple to the at least one mechanical connector 13. Here, the engagement portion 22 is configured to releasably hold the protrusions 13. In this example, the engagement portion 22 includes locking features 23. The locking features 23 are configured to selectively be in a locked state or an unlocked state. In the locked state, the mechanical connectors, here the protrusions, 13 are locked in engagement with the engagement portion 22. This allows the mechanical connectors 13 and engagement portion 22 to transfer forces (e.g. pushing, pulling) from the handle portion 21 to the sampling device 10. In the unlocked state, the mechanical connectors, here the protrusions, 13 can freely be moved out of engagement with the engagement portion 22. The locking features 23 can include a snap feature causing the at least one protrusion 13 to automatically engage with the engagement portion 22 in the locked state upon engagement of the protrusion with the engagement portion. Figures 3A and 3B show an example of the locking features 23. In this example, the locking features 23 includes a locking disc, here rotatable about a longitudinal axis of the applicator 20. Here the protrusions 13 comprise retainers 13A, such as enlargements of hooks. In the locked state, shown in figure 3A, the retainers 13A are locked behind the locking feature 23. In the unlocked state, shown in figure 3B, the locking features are moved, here the locking disc is rotated, relative to the locked state, and the retainers 13A are free to pass the locking feature 23. Hence, the sampling device 10 can be selectively locked to and released from the applicator 20. In this example, the locking feature rotates about an axis, particularly the longitudinal axis of the applicator 20. It will be clear that it is also possible that the locking feature rotates about a different axis, e.g. orthogonal to the longitudinal axis, or e.g. translates, such as in a direction perpendicular to the longitudinal axis, parallel to the longitudinal axis, and / or tangential relative to the longitudinal axis. Returning to figures 1 and 2, in this example, the applicator 20 comprises a pusher 24. The pusher 24 is movable relative to the engagement portion 22. Here, the pusher is movable in a towards and away from the sampling device 10. Here, the movement direction of the pusher 22 is substantially perpendicular to a plane in which the sampling surface 12 extends. In this example, the pusher extends substantially along a center line of the applicator. In this example, the pusher 22 extends substantially along a line through the center 11D of the sampling plate 11. Here, the applicator 20 comprises a resilient element 25, such as a spring, biasing the pusher 24 in a direction away from the sampling plate 11. Here, a force distribution element 26 is positioned between the sampling plate 11, e.g. the second side 14B of the tacky layer 14, and the pusher 24. The force distribution element 26 can be a flexible element, such as a foam element, such as a closed cell foam element. In this example the force distribution element 26 is attached to the pusher 24. It will be appreciated that alternatively, or additionally, a force distribution element may be attached to the sampling plate 11, e.g. on top of, or instead of the cover sheet 17. In this example, the force distribution element 26 extends through the aperture 16. Figure 4 shows a cross sectional view of another example of a sampling system 1 for obtaining a sample 2 of particulate contamination on a surface 3 of an object 4. The sampling system of figure 4 is highly similar to the sampling system 1 described in view of figure 1. Therefore, only the differences with the sampling system 1 of figure 1 are described. In the example of figure 4, the at least one mechanical connector 13 is embodied as at least one recess 13. Hence, here the sampling device 10 comprises at least one recess 13 on the second side 11B of the sampling plate 11. The sampling device 10 can e.g. comprise three recesses 13. The recesses 13 in figure 4 are embodied as recesses having a widening cross section in a direction towards the sampling surface 12. Here, the recesses 13 are positioned at an outer perimeter 11C of the sampling plate 11. It will be appreciated that it is also possible that the at least one recess 13 is positioned near the outer perimeter 11C of the sampling plate 11, e.g. at 0%-50%, e.g. 0%-25%, of a distance from the outer perimeter 11C of the sampling plate 11 to the center 11D of the sampling plate 11. Here, the recesses 13 extend into carrier 15. In this example, the carrier 15 can also be made of a material that is more rigid than the material of the tacky layer 14. The carrier 15 can e.g. comprise, or be made of, a plastics material, such as PC, PE, PP, ABS, PVC, PLA, or the like. The carrier can e.g. be manufactured using 3D printing or injection moulding. The applicator 20 in figure 4 also comprises an engagement portion 22 configured to releasably couple to the at least one mechanical connector 13. Here, the engagement portion 22 is configured to releasably engage the recesses 13. In this example, the engagement portion 22 also includes locking features 23. The locking features 23 are configured to selectively be in a locked state or an unlocked state. In the locked state, the engagement portions 22 are locked in engagement with the recesses 13. This allows the mechanical connectors 13 and engagement portion 22 to transfer forces (e.g. pushing, pulling) from the handle portion 21 to the sampling device 10. In the unlocked state, the engagement portions 22 can freely be moved out of engagement with the recesses 13. Here too, the locking features 23 can include a snap feature causing the at least one recess 13 to automatically engage with the engagement portion 22 in the locked state upon engagement of the protrusion with the engagement portion. Figure 5 shows a cross sectional view of an example of the sampling device 10 of figure 1 in combination with a container 30. It will be appreciated that the sampling device 10 of figure 4 can also be provided in combination with the same, or similar, container 30. The container 30 comprises a cover 31 and a lid 32. In this example, the cover 31 comprises an insert 33. The insert 33 is attached to the cover 31 in this example. The insert 33 is configured to releasably couple to the sampling device 10. In this example, the insert 33 comprises snap features 34 cooperating with detents 18 of the sampling device 10. Here, the detents 18 are provided in the carrier 15. It will be appreciated that the insert 33 may configured to releasably couple to the sampling device 10 in different manners, e.g. using a bayonet coupling, friction coupling, or the like. It will also be appreciated that the insert 33 may be integral with the cover 31. In the example of figure 5, the cover 31 extends across the entire sampling surface 12 of the sampling device 10. Hence, the cover 31 can protect the sampling surface from inadvertently touching any other surface that the surface 3 of the object 4. The lid 32 and the cover 31 are adapted to each other to form a closed enclosure around the sampling device 10. The lid 32 may e.g. be closed to the cover 31 via an interface 35, such as a screw connection, bayonet connection, or the like. The lid 32 and the cover 31 can be adapted to each other to form a hermetically sealed enclosure around the sampling device 10. Hence, the sampling device can be shielded from contamination while inside the container 30. It will be appreciated, however, that the container 30 can be optional. Referring to figure 6, the sampling system 1 as described in view of figures 1, 2, 3A, 3B, 4 and 5 can be used in a method 100 for obtaining a sample 2 of particulate contamination on the surface 3 of the object 4. The method 100 is described in terms of an optional preparatory stage 110, a sampling stage 120, and an optional closing stage 130. In the optional preparatory stage 110, in a first step 111 the sampling device 10 is provided contained in the container 30. The lid 32 is removed 112 from the cover 31. Next, the engagement portion 22 of the applicator 20 is coupled 113 to the protrusions 13 of the sampling device 10. The locking feature 23 can then be brought to the locked state. The cover 31 (and insert 33, if present) is removed 114 from the sampling device 10. Next, the sampling device 10 is coupled to the applicator 20, ready for obtaining a sample 2 of particulate contamination on the surface 3 of the object 4. Removing the lid 31 and cover 32 from the sampling device 10 just prior to performing the sampling stage 120 can reduce the risk of contamination of the sample. In the sampling stage 120, in an optional first step 121 the pusher 24 is actuated. Actuating the pusher 24 to move relative to the engagement portion 22 allows to push a portion 12A of the sampling surface 12 outwardly, i.e. in a direction away from the applicator 20, as shown in figure 7. In this example, actuating the pusher 22 causes the pusher, at least the force distribution element 26, to extend through the aperture 16 in the carrier 15. Pushing a portion 12A of the sampling surface 12 outwardly, relative to other portions 12B of the sampling surface 12 that are retained by the engagement portion 22 engaging the protrusions 13, allows to deform the sampling surface 12 to bulge outwardly. In the example of figure 2, the sampling system 1 is configured such that the sampling surface 12 deforms to be double curved under influence of the pusher 24. In this example, the sampling surface 12 can deform to be approximately part-spherical or parabolical. In this example, the pusher 24 extends though the aperture 16, such that the pusher, here via the force distribution element 26 and the cover sheet 17, pushes the second side 14B of the tacky layer 14. In a next step 122, the sampling surface 12, that e.g. bulges outwardly, is pushed against the surface 3 of the object 4 with the portion 12A of the sampling surface 12 that projects away most from the applicator 20. Subsequently, the sampling surface 12 is allowed 123 to return to its planar state, allowing the sampling surface 12 to contact the surface 3 of the object 4 with a minimal risk of trapping air pockets between the sampling surface 12 and the surface 3 of the object 4. It will be appreciated that it is also possible to use the sampling system 1 for obtaining a sample of a non-planar surface of an object. In that case, particularly, the bulging of the sampling surface 12 allows making proper initial contact with the surface of the object. Next, the sampling surface can be manipulated to follow the contours of the surface of the object. Thereto, the sampling surface 12 can be pressed against the non-planar surface of the object by pressing the handle portion 21, and / or relaxing, or partially relaxing the pusher 24. When the sampling surface 12 makes contact with the surface 3 of the object 4 according to the wishes of the user, the sampling device 10 can be removed 124 from the surface 3 of the object 4 again. This can e.g. be done by pulling the sampling device 10 in a direction substantially perpendicular to the surface 3 of the object 4. This is made possible by the protrusions 13 being locked in engagement with the engagement portion 22 of the applicator 20. This can provide the advantage that particles are accurately retained by the tacky sampling surface 12. It will be appreciated that it is also possible to remove the sampling surface 12 from the surface 3 of the object 4 by tilting the applicator 20, such that the sampling surface 12 is ‘peeled’ off the surface 23 of the object 4. In the optional closing stage 130, in a first step 131 the cover is reattached to the sampling device 10. Next, the engagement portion 22 of the applicator 20 is releases 132 from the protrusions 13 of the sampling device 10. The locking feature 23 can then be brought to the unlocked state. Now, the lid 32 is reattached to the cover 31, such that the sampling device 10 is completely encased in the container 30. Reattaching the lid 31 and cover 32 to the sampling device 10 immediately after performing the sampling stage 120 can reduce the risk of contamination of the sample. Optionally, the sampling device 10 includes a human-readable and / or machine-readable identification. The machine-readable identification can e.g. comprise a barcode, QR code, RFID chip, NFID chip, or the like. The identification can assist in managing multiple samples taken in succession. The human-readable or machine-readable identification can be provided on the sampling plate 11. The human-readable or machine-readable identification can be provided on the cover sheet 17. The human-readable or machine-readable identification can be provided on the carrier 1. Herein, the invention is described with reference to specific examples of embodiments of the invention. It will, however, be evident that various modifications, variations, alternatives and changes may be made therein, without departing from the essence of the invention. In the examples of figures 1, 2,, 3A, 3B, 5 and 7, the protrusions extend from the carrier, the carrier being attached to the tacky layer. It will be appreciated that it is also possible that the protrusions extend from the tacky layer. In the example of figure 4, the recesses extend into the carrier, the carrier being attached to the tacky layer. It will be appreciated that it is also possible that the recesses extend into the tacky layer. In the example of figure 2 the sampling device comprises three protrusions, in particular three legs. It will be clear that also different numbers of protrusions are possible, such as one, two, four, five, six, or more. In case a single protrusion is used, this may be an annular protrusion. The annular protrusion may extend from the sampling plate at or near an outer perimeter thereof. It will be clear that the sampling device can comprise any number of recesses, such as one, two, three, four, five, six, or more. In case a single recess is used, this may be an annular recess. The annular recess may extend into the sampling plate at or near an outer perimeter thereof. In the example of figures 1, 2, 3A, 3B, 5 and 7, the mechanical connectors are formed by protrusions. In the example of figure 4, the mechanical connectors are formed by recesses. It will be appreciated that also embodiments can be conceiver in which one or more mechanical connectors are formed by protrusions and one or more mechanical connectors are formed by recesses. For the purpose of clarity and a concise description features are described herein as part of the same or separate embodiments, however, alternative embodiments having combinations of all or some of the features described in these separate embodiments are also envisaged and understood to fall within the framework of the invention as outlined by the claims. The specifications, figures and examples are, accordingly, to be regarded in an illustrative sense rather than in a restrictive sense. The invention is intended to embrace all alternatives, modifications and variations which fall within the spirit and scope of the appended claims. Further, many of the elements that are described are functional entities that may be implemented as discrete or distributed components or in conjunction with other components, in any suitable combination and location. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word ‘comprising’ does not exclude the presence of other features or steps than those listed in a claim. Furthermore, the words ‘a’ and ‘an’ shall not be construed as limited to ‘only one’, but instead are used to mean ‘at least one’, and do not exclude a plurality. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to an advantage.

Claims

Claims 1. A sampling system for obtaining a sample of particulate contamination on a surface of an object, the sampling system comprising: - a sampling device comprising: a sampling plate having a tacky sampling surface configured to be pressed against the surface of the object on a first side of the sampling plate; at least one mechanical connector on an opposite, second side of the sampling plate; and - an applicator comprising: a handle portion; and an engagement portion configured to releasably couple to the at least one mechanical connector; wherein the sampling system is configured to allow the tacky sampling surface to be pressed against the surface of the object and then removed.

2. The sampling system of claim 1, wherein the at least one mechanical connector is integral with, or affixed to, the sampling plate.

3. The sampling system of claim 1 or 2, wherein the at least one mechanical connector comprises at least one protrusion and / or at least one recess.

4. The sampling system of claim 3, wherein the at least one protrusion and / or at least one recess is positioned at or near an outer perimeter of the sampling plate.

5. The sampling system of any of claims 1-4, wherein the sampling plate comprises a tacky layer having the tacky sampling surface on a first side of the tacky layer, and a carrier mounted to an opposite, second side of the tacky layer.

6. The sampling system of claim 5, wherein the carrier is affixed to the second side of the tacky layer.

7. The sampling system of claim 5 or 6, wherein the at least one protrusion extends from the carrier and / or wherein the at least one recess extends into the carrier.

8. The sampling system of claim 5, 6 or 7, wherein the carrier comprises an aperture allowing access to the tacky layer at the second side.

9. The sampling system of claim 8, comprising a cover sheet covering the tacky layer at the second side, within the aperture.

10. The sampling system of any of claims 1-9, wherein the applicator comprises a pusher, movable relative to the engagement portion, for pushing a portion of the sampling surface outwardly.

11. The sampling system of claim 10, wherein the pusher is configured to engage the sampling plate at or near a center of the sampling plate.

12. The sampling system of claim 10 or 11, when dependent from claim 8 or 9, wherein the pusher is configured to engage the sampling plate within the aperture.

13. The sampling system of any of claims 10-12, comprising a force distribution element, such as a flexible element, e.g. a foam element, positioned between the sampling plate and the pusher.

14. The sampling system of any of claims 1-13, wherein the at least one protrusion comprises a plurality of legs configured to be engaged by the engagement portion.

15. The sampling system of any of claims 1-14, wherein the sampling device includes a human-readable and / or machine-readable identification.

16. The sampling system of any of claims 1-15, further comprising a cover, wherein the cover is configured to be releasably attached to the sampling device for covering the tacky sampling surface.

17. The sampling system of claim 16, further comprising a lid, wherein the lid and the cover are configured to, together, form a closed enclosure around the sampling device.

18. The sampling device of the system of any of claims 1-17.

19. The applicator of the system of any of claims 1-17.

20. A sampling device comprising: a sampling plate having a tacky sampling surface configured to be pressed against the surface of the object on a first side of the sampling plate; at least one mechanical connector on an opposite, second side of the sampling plate; wherein the sampling system is configured to allow the tacky sampling surface to be pressed against the surface of the object and then removed.

21. The sampling device of claim 20, wherein the at least one mechanical connector is integral with, or affixed to, the sampling plate.

22. The sampling device of claim 20 or 21, wherein the at least one mechanical connector comprises at least one protrusion and / or at least one recess.

23. The sampling device of claim 22, wherein the at least one protrusion and / or at least one recess is positioned at or near an outer perimeter of the sampling plate.

24. The sampling device of any of claims 20-23, wherein the sampling plate comprises a tacky layer having the tacky sampling surface on a first side of the tacky layer, and a carrier mounted to an opposite, second side of the tacky layer.

25. The sampling device of claim 24, wherein the carrier is affixed to the second side of the tacky layer.

26. The sampling device of claim 24 or 25, wherein the at least one protrusion extends from the carrier and / or wherein the at least one recess extends into the carrier.

27. The sampling device of claim 24, 25 or 26, wherein the carrier comprises an aperture allowing access to the tacky layer at the second side.

28. The sampling device of claim 27, comprising a cover sheet covering the tacky layer at the second side, within the aperture.

29. The sampling device of any of claims 20-28, comprising a force distribution element, such as a flexible element, e.g. a foam element, positioned on the second side of the sampling plate.

30. The sampling device of any of claims 20-29, wherein the at least one protrusion comprises a plurality of legs configured to be engaged by the engagement portion.

31. The sampling device of any of claims 20-30, including a human-readable and / or machine-readable identification.

32. The sampling device of any of claims 20-31, in combination with a cover, wherein the cover is configured to be releasably attached to the sampling device for covering the tacky sampling surface.

33. The combination of claim 32, further comprising a lid, wherein the lid and the cover are configured to, together, form a closed enclosure around the sampling device.

34. An applicator for a sampling device comprising a sampling plate having a tacky sampling surface on a first side of the sampling plate, and at least onemechanical connector on an opposite, second side of the sampling plate, the applicator comprising: a handle portion; and an engagement portion configured to releasably couple to the at least one mechanical connector.

35. The applicator of claim 34, wherein the at least one mechanical connector comprises at least one protrusion and / or at least one recess, and wherein the engagement portion is configured to releasably hold the at least one protrusion and / or recess.

36. The applicator of claim 34 or 35, comprising a pusher, movable relative to the engagement portion, for pushing a portion of the sampling surface outwardly.

37. The applicator of claim 36, wherein the pusher is configured to engage the sampling plate at or near a center of the sampling plate.

38. The applicator of claim 36 or 37, comprising a force distribution element, such as a flexible element, e.g. a foam element, positioned on the pusher.

39. A method for obtaining a sample of particulate contamination on a surface of an object, the method comprising: - providing a sampling system according to any of claims 1-17; - engaging the at least one mechanical connector of the sampling device to the engagement portion of the applicator; - pressing the tacky sampling surface against the surface of the object; - removing the tacky sampling surface from the surface of the object; and - releasing the at least one mechanical connector of the sampling device from the engagement portion of the applicator.

40. The method of claim 39, further comprising: - actuating the pusher of the applicator for bulging the tacky sampling surface outwardly prior to pressing the tacky sampling surface against the surface of the object; and- releasing the pusher of the applicator while pressing the tacky sampling surface against the surface of the object.

41. The method of claim 39 or 40, further comprising: - removing the cover from the sampling device prior to pressing the tacky sampling surface against the surface of the object; and - repositioning the cover on the sampling device after removing the tacky sampling surface from the surface of the object.

42. The method of claim 39, 40 or 41, further comprising: - removing the lid from the cover prior to engaging the at least one protrusion of sampling device to the engagement portion of the applicator; and - repositioning the lid on the cover after releasing the at least one protrusion of the sampling device from the engagement portion of the applicator.

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