Airborne particle collection membrane

Abstract

The invention relates to an airborne particle collection membrane (M), the membrane being in the form of a strip composed of: a matrix (40) formed from a mixture of a polymer material and a filler (41) made of an electrically conductive material; a hydrophilic particle collection layer (3) on which said matrix is ​​deposited so as to form at least one layer of composite material (400); said membrane comprising at least one area obtained by a surface treatment of said hydrophilic layer (3). Figure to be published with the abbreviation: Figure 3

Description

Title of the invention: Airborne particle collection membrane Technical field of the invention

[0001] The present invention relates to a membrane for collecting airborne particles. State of the art

[0002] Several solutions have already been proposed in the prior art for collecting particles present in an aerosol, for the purpose of analyzing these particles.

[0003] A known and particularly advantageous separation method is of the electrostatic type. It is implemented in electrostatic collectors, also called electrostatic precipitators or electrostatic filters (ESP for "electrostatic pre-cipitator" in English) or also called electrofilters.

[0004] There are several categories of electrostatic collectors, including:

[0005] - So-called dry electrostatic collectors, for example described in patent application WO2015 / 197747A1, - So-called wet electrostatic collectors, for example those described in patent application WO2004 / 041440A1, - Electrostatic collectors known as semi-wet, for example described in WO2007 / 012447A1.

[0006] In all these categories, the collectors comprise a chamber into which an airflow containing the particles is injected or drawn, generating an electric field between two electrodes: a discharge electrode and a counter-electrode, known as the collecting electrode, which is generally connected to ground. The electric field created between the two electrodes generates a flow of ions from a pocket of ionized gas surrounding the discharge electrode. The airflow containing the particles is injected through this ion flow. In the presence of ions, the particles acquire electrical charges and thus become sensitive to the electric field generated between the two electrodes, and are drawn by the electric force toward the counter-electrode.

[0007] In the first category of so-called dry electrostatic collectors, the collected particles are detached from the collection electrodes by a dry process, for example by vibrating the electrodes or by the mechanical friction of brushes on their surface.

[0008] In the second category of electrostatic collectors, known as wet collectors, the particles captured on the collection electrodes are removed by water flowing over them.

[0009] In the third category of electrostatic collectors, known as semi-wet collectors, water vapor is introduced into the chamber containing the discharge electrode or upstream of it. Airborne particles then grow by heterogeneous nucleation to form droplets, and these droplets are precipitated onto the counter-electrode by the electrical force. The introduced vapor can also condense on the walls, thus leading to runoff onto the collecting electrode, which contributes to the removal of the captured particles.

[0010] The referenced publication "Hyeong Rae Kim, Sanggwon An, and Jungho Hwang, Aerosol-to-Hydrosol Sampling and Simultaneous Enrichment of Airborne Bacteria for Rapid Biosensing, ACS Sens. 2020, 5, 2763-2771" describes a wet electrostatic collector for collecting bioparticles in an airflow. The airflow is injected into a channel and passes between two electrodes. The particles are attracted to the collection electrode. A liquid is continuously injected to elute the particles captured on the collection electrode. This solution, which falls into the category of so-called wet electrostatic precipitators, requires, in particular, a continuous flow of liquid to elute the particles present on the collection electrode, which makes the solution poorly suited for easy implementation in a wearable or deployed instrument, for example, on a drone.Indeed, during operation, there is a risk that the eluting liquid will disperse and flow into the air channel if the device is tilted or if there are vibrations. The liquid could also form a bridge between the electrodes if the device were inverted, potentially causing a short circuit between the two electrodes. The same problem is generally posed by wet and semi-wet electrostatic precipitators, such as those described in the aforementioned patents WO2004 / 041440A1 and WO2007 / 012447A1.

[0011] In the unpublished patent application FR2013772, the use of a hydrophilic collection membrane was proposed. Due to its hydrophilic nature, the membrane is capable of draining a liquid by capillary action, thus preventing the risk of liquid dispersion if the device is tilted or subjected to shocks during operation. The membrane is in the form of a flexible strip of material. It is made of a fibrous or honeycomb material capable of draining a liquid. In this patent application, the membrane is made of a cellulose-based material (e.g., filter paper or equivalent), a hydrophilic fabric-type material, a foam (sponge) type material, or a fiberglass type material. However, this membrane was not designed to also serve as a collection electrode.

[0012] Patent EP1112124B1 describes a collection membrane intended for use in an electrostatic collector that can be dry or wet.

[0013] Patent EP1112124B1 describes an electrostatic collector based on the use The original design consists of a membrane made of interwoven fibers, which can be ceramic, metal, metal alloys, or carbon. The technical solution is interesting, but its implementation in an aerosol collector for biological analysis presents several challenges. Indeed, all materials used must meet compatibility criteria with the various biological analysis techniques, making their selection complex.

[0014] Many patents, such as EP1112124B1, describe the use of metallic or metal alloy materials. However, many metals inhibit biomolecular analyses. Aluminum, for example, is an inhibitor of these reactions. Furthermore, it is necessary to be able to preserve culturable microorganisms for analysis by culture, but metals such as copper or silver have disinfectant properties. An interesting solution is the use of non-metallic conductive materials such as carbon or polymers, provided that they are conductive and that their components do not interact with the biological analysis reactions. PEDOT-based materials, for example, are interesting conductive polymer materials, often described in the literature, but their use for biological analyses is not straightforward.Indeed, the solvents used in their preparation must be removed by specific processes so that they can be used in a collection container intended for biological analysis. Furthermore, carbon-based materials and conductive polymers are hydrophobic and do not meet the hydrophilicity criterion necessary for the membrane rinsing solution to penetrate it properly. The silicone matrix described in patent EP1112124B1 is also inherently hydrophobic. While rinsing with water is always possible to clean the membrane regardless of whether its material is hydrophilic or not, a problem arises from the quantity of water required for biological analysis. In this context, the volumes used must be minimized and, if possible, less than 5 ml, with a preferred volume of less than 300 lp / cm².Furthermore, if the membrane is hydrophobic, rinsing will be less effective due to surface interactions between the hydrophobic layer and the collected particles. A surface treatment of these materials must therefore be undertaken, which must also be compatible with subsequent analyses that may be performed on the collected sample.

[0015] An additional problem arises with the processes described in patents US20040083790A1, US20080295687A1, US20100000540A1 which rely on wet or semi-wet electrostatic precipitators, the oxidizing molecules formed by the electrical discharges used for the collection process leading, in the presence of water, to the formation of dissolved hydrogen peroxide (JM. Roux, A. Rongier, D. Jary, Importance of the substrate nature to preserved microorganisms' cultivability in electrostatic air samplers, Journal of Physics: (Sériés Conference, 646(1), (2015), 012039). Hydrogen peroxide is indeed a powerful oxidant that kills all collected microorganisms, preventing their analysis by culture, including bacterial spores, which are among the most resistant microorganisms. Furthermore, it is a relatively stable compound that risks inhibiting the biochemical reactions used for analysis.

[0016] The object of the invention is to provide a membrane-type solution capable of acting both as an electrode for collecting airborne particles and as an elution support, without inhibiting the biochemical reactions that can be carried out for the analysis of bioaerosols. The solution would be able to contribute to the collection of particles and their elution for analysis with a recovery rate greater than 50% and a high concentration of particles in the eluted liquid.

[0017] In the context of electrostatic collection and elution integrated within the same component, such a membrane must indeed ensure the key step of air / liquid passage of particles in order to guarantee a good operation of the rest of the analytical chain. Description of the invention

[0018] This objective is achieved by means of an airborne particle collection membrane, said membrane being in the form of a strip composed of:

[0019] - A matrix formed from a mixture of a polymer material and a filler made of an electrically conductive material, - A hydrophilic particle collection layer on which said matrix is ​​deposited so as to form at least one layer of composite material, - Said membrane comprising at least one zone obtained by a surface treatment of said hydrophilic layer.

[0020] According to a particular embodiment, the hydrophilic layer is made from cellulose.

[0021] According to another particular embodiment, the hydrophilic layer is made from a woven material.

[0022] According to one particular feature, the hydrophilic layer is made from a material which retains by capillarity a volume less than 30pl / cm2.

[0023] According to one particular feature, the matrix is ​​made of a silicone-based material.

[0024] According to a particular embodiment, the charge is in the form of a powder of carbon, mixed with said matrix.

[0025] According to another particular embodiment, the filler is in the form of a carbon powder in its graphite form.

[0026] According to a particular embodiment, the hydrophilic layer has a total surface area and comprises at least a first so-called collection zone obtained by said surface treatment on a first part of its total surface and at least a second zone made on a second part of its total surface, the first layer having a first thickness on its collection zone and a second thickness on its second zone, said first thickness being less than the second thickness.

[0027] According to one particular feature, the hydrophilic layer is treated to form an electrical contact resumption zone with a surface area less than its total surface area, obtained by said surface treatment of said hydrophilic layer over a thickness equal to its total thickness.

[0028] According to another characteristic, the second zone is a so-called wetting zone, more hydrophilic than the first collection zone.

[0029] According to another feature, the wetting zone is made without surface treatment of said hydrophilic layer.

[0030] According to another feature, the membrane includes a hydrophobic barrier zone formed between the contact zone and the wetting zone.

[0031] According to another feature, the hydrophobic barrier zone is made in the form of a paraffin deposit.

[0032] According to another feature, the membrane has a water-soluble layer deposited on the hydrophilic layer.

[0033] The invention also relates to a method for manufacturing the collection membrane as defined above, the method comprising the steps of:

[0034] - Formation of a support formed from said hydrophilic layer, - Deposition onto said support of the matrix formed from a mixture of the polymer material and the filler produced in the electrically conductive material, - Polymerization of the polymer material, - Surface treatment of the hydrophilic material layer, in order to form said zone.

[0035] The invention also relates to an electrostatic airborne particle collector, comprising a collection unit, collection means configured to force said airborne particles towards said collection unit, the collection unit incorporating a collection membrane such as that defined above.

[0036] According to one particular feature, the electrostatic collector includes a fluidic circuit for eluting airborne particles collected by the collection membrane, said fluidic elution circuit comprising at least one fluidic channel opening onto said collection membrane.

[0037] In the invention, the absence of water during the capture of airborne particles ensures the absence of persistent chemical compounds (H2O2, etc.) that could inhibit the biological analysis reactions that could be carried out. It is therefore preferable to employ a dry collection process, while finding a solution for efficiently detaching the collected particles from the collection medium. Electrostatic collection causes the particles to adhere strongly to the collection electrodes, and therefore, in the absence of continuous water flow, the electrodes must be mechanically rubbed or scraped as described in patent EP1112124B1. This rubbing or scraping step is difficult to integrate. Brief description of the figures

[0038] Other features and advantages will become apparent in the detailed description that follows, given in relation to the accompanying drawings in which:

[0039] - Fig. 1 illustrates the operating principle of an electrostatic collector using a collection membrane according to the invention; - Fig. 2 illustrates the manufacturing principle of the collection membrane of the invention; - Fig. 3 shows a top view of the collection membrane, according to a preferred embodiment variant;

[0040] Detailed description of at least one embodiment

[0041] The invention relates to a collection membrane M intended for use in an electrostatic collector 1 of airborne particles P.

[0042] P particles can be micro-particles or nano-particles present in the air in the form of aerosols.

[0043] By way of exception, the collection of P particles can notably be carried out in ambient air or in the air exhaled by a living being. In the remainder of this description, it will be assumed that the collection of particles is carried out in ambient air.

[0044] One of the objectives is to analyze the P particles in order to detect the presence of a pathogen or a trace of its presence, by analyzing the collected particles.

[0045] The pathogens sought may be, among others, microorganisms such as viruses, bacteria, fungal spores, or toxins, mycotoxins, allergens, or any other harmful agent.

[0046] The particles are advantageously collected for the purpose of analysis. The analysis may consist of detecting the presence of DNA, RNA, proteins, components of the pathogen, such as lipids or carbohydrates, or one or more pathogens present in the collected particles. The analysis may also consist of detecting molecules such as ATP or sugars such as mannitol, arabitol, and glucose, which indicate the presence of microorganisms. The analysis may also involve the detection of molecules such as allergens and mycotoxins.

[0047] By way of example, the analytical method may be of the biomolecular amplification type (for example, LAMP, RPA, PCR, etc.) or of the immunoenzymatic type (for example, ELISA type).

[0048] The collector can notably be used in the form of a monitoring beacon. For this purpose, it must then have a certain degree of operational autonomy, that is to say, be able to collect and analyze the particles with minimal external intervention and in particular without any manipulation between the collection and analysis phases.

[0049] Fig. 1 illustrates the operating principle of an electrostatic collector 1 employing a collection membrane such as that of the invention.

[0050] The collector can integrate a particle collection unit U1 and a particle analysis unit U2. The architecture described below and shown in [Fig. 1] is to be considered in a non-limiting manner.

[0051] The particle collection unit U1 comprises a main collection component 10.

[0052] By way of example, the collection component 10 can be made of a material of Type COP / COC (Cyclo Olefin Polymer / Cyclo Olefin Copolymer), polycarbonate, or PMMA (Polymethyl Methacrylate). It may, in particular, exhibit transparency characteristics sufficient for optical reading when the analysis is carried out directly in the U2 analysis unit of component 10.

[0053] Component 10 operates by electrostatic effect. It comprises two electrodes, a discharge electrode and a counter electrode, known as a collecting electrode, which is generally connected to ground. The two electrodes are each connected to a separate terminal of a power supply and are spaced apart to create an electrostatic field sufficient to attract airborne particles towards the collecting electrode, where they are captured and trapped. The collecting electrode is formed by the collecting membrane M of the invention.

[0054] The collection unit U1 is arranged on a dedicated wall of the component 10 and carries the collection membrane M of the invention, in order to collect the particles P.

[0055] The component 10 may include a chamber into which an airflow containing the particles is injected or drawn. Collection means 2, which may generate the airflow, are configured to direct the particles present in the air towards the collection membrane M. The component 10 may include an internal collection channel through which the air to be analyzed flows. The airflow through the channel may be forced (for example, by means of a fan) or not.

[0056] The component 10 can advantageously incorporate a fluidic circuit, called an elution fluidic circuit. This elution fluidic circuit advantageously comprises a first fluidic channel 11 opening towards the collection membrane M, in order to be able to discharge the elution liquid L onto the membrane.

[0057] The fluidic elution circuit may also include a receptacle for receive the elution liquid L drained by the membrane M and transporting the particles P.

[0058] The elution liquid L is, for example, water.

[0059] By capillarity, the liquid L ensures the wetting of the entire surface of the membrane M and carries with it the previously collected particles.

[0060] The U2 analysis unit for the collected particles P can be integrated into the component 10 used for collection, as shown in [Fig. 1], or be separate from it. It is advantageously integrated into the component 10 to reduce the equipment that an operator would have to handle and to allow for automation of the process. The U2 analysis unit may include a detection chamber made within the component 10 and intended to receive the sample collected after elution. This detection chamber may be formed directly from the receptacle for recovering the liquid L after elution. This detection chamber may contain reagents necessary for the analysis, for example, to carry out a biomolecular amplification reaction.

[0061] As mentioned previously, the analysis can be carried out by biomolecular amplification or be of the immuno-enzymatic type (ELISA type) or even of the immuno-chromatographic type (LFA type).

[0062] Biomolecular amplification analysis of microorganisms requires the extraction of genomic material from the microorganisms. Three technical solutions can be implemented:

[0063] - Train the microorganisms with a first liquid solution which wets the collection membrane, recover this solution containing the particles in a reservoir or a receptacle chamber and then lyse them mechanically or thermally or chemically in this or in another chamber of the device. - Wet the membrane with a chemically lysed liquid solution that extracts the genetic material from the microorganisms. This liquid solution will also carry away the genetic material of interest, which will then be collected in a reservoir or receptacle chamber. - Heat the membrane to a temperature suitable for the lysis of the target microorganisms (for example, 65°C for 5 minutes). The elution of the genetic material can then be carried out in a second step, into a reservoir or a receptacle chamber.

[0064] According to the invention, the collection membrane M is designed to ensure:

[0065] - The role of the collection electrode; - The role of support for collecting airborne particles P and trapping airborne particles; - The role of elution support to facilitate the recovery of collected P particles for analysis without risk of liquid dispersion if the device is tilted, shaken, or vibrates;

[0066] The membrane M is also designed with materials compatible with the analytical reactions that can be implemented and listed above.

[0067] According to the invention, the membrane M is in a composite form, from:

[0068] - A hydrophilic layer 3 for collecting particles; - A matrix 40 made from a mixture of a polymer material and a charge 41 made in an electrically conductive material;

[0069] By hydrophilic character, we mean that the hydrophilic layer 3 is capable of draining a liquid L, for example a liquid such as water, by capillary action. As a reminder, the wettability of a material is defined by observing the contact angle (most often denoted α) that the material has with a drop of water:

[0070] • When this angle (also called contact angle, or connection angle) is less than 90°, the surface is said to be more or less hydrophilic (the contact surface between the water and the material is high); • When it is greater than 90°, the surface is said to be more or less hydrophobic (the contact surface between the water and the material is small);

[0071] In the context of the invention, hydrophilic character means that the hydrophilic layer advantageously exhibits a contact angle of less than 75° after a very short period of less than a few seconds, for example, 5 seconds. Furthermore, in the membrane's collection zone, this contact angle then decreases very rapidly to less than 50°, as water penetrates the material very quickly. It therefore exhibits a highly hydrophilic character.

[0072] Without limitation, the different manufacturing stages of the membrane are illustrated by [Fig.2] and described below.

[0073] Step El: The hydrophilic layer 3 is used as a support for the matrix 40 in the manufacturing process.

[0074] The hydrophilic layer 3 advantageously comprises interlaced fibers, said fibers defining interstices through which the liquid can flow during elution.

[0075] Advantageously, the hydrophilic layer 3 can be made of a fibrous or cellular material capable of draining a liquid such as water. For example, it can be made of a cellulose-based material (e.g., filter paper or equivalent), a hydrophilic fabric-type material, a foam (sponge) type material, or a fiberglass type material.

[0076] As an example, the hydrophilic layer 3 is, for example, composed of Whatman type paper (registered trademark).

[0077] In order to minimize the volumes used and thus increase the concentration in solution of the collected and eluted particles, the thickness of the membrane is chosen so as to retain by capillarity a volume less than 30 pl / cm2.

[0078] Step E2: A second layer 4 is fabricated. This second layer 4 is composed of a mixture of a matrix 40 made of polymer material and a filler 41 made of an electrically conductive material. The filler 41 is added to the matrix to give the membrane its conductive character.

[0079] By way of exception, the matrix 40 can be made of silicone and the filler 41 can be carbon powder. Carbon and silicone, as well as the carbon / silicone combination, have the advantage of being inert with respect to biochemical reactions. The resulting composite material is therefore not likely to inhibit these reactions. Of course, other materials exhibiting such properties with respect to biochemical reactions could be considered.

[0080] Advantageously, carbon in the form of graphite is added to the silicone matrix in a mass percentage of between 30% and 50%. The concentration of the filler must be chosen to be sufficient to obtain good electrical conductivity, without reducing the mechanical strength of the resulting material and in particular the trapping of the powder incorporated by the matrix (for example, silicone-based).

[0081] This second layer has a liquid, pasty and viscous form, facilitating its shaping and deposition before polymerization.

[0082] Step E3: The second layer 4 is deposited on the hydrophilic layer 3, for example made of paper (see above). It should be noted that the hydrophilic layer 3 is advantageously chosen with a sufficiently rough and / or porous surface, in order to better adhere the mixture.

[0083] Advantageously, the second layer 4 is deposited on the first layer 3 at a constant thickness over the whole of the first layer 3.

[0084] Step E4: The multilayer assembly is then placed under conditions for polymerization of the matrix (T°). For example, in the case of a silicone-based membrane, the multilayer assembly can be heated to 60°C for 3 hours.

[0085] During polymerization, the second layer 4 impregnates the hydrophilic layer 3, forming the composite material 400. As can be seen in [Fig.2], a thin hydrophilic layer 3 remains on the surface.

[0086] If the thickness of the remaining first hydrophilic layer 3 is sufficiently small, typically less than 100 µm, the membrane M can be used as is in a collector. The hydrophilic layer 3 is placed in the collector in contact with the air and in the path of the airflow, and therefore in the path of the particles P to be collected. The particles will be attracted by the polarized conductive layer 4 and deposited on the hydrophilic layer 3 of the membrane M, where they will captured, possibly inside the first layer if it has sufficient porosity.

[0087] If the hydrophilic layer 3 has a three-dimensional structure (thus forming cells and a sufficiently porous layer), such as paper, the elution liquid L for the collected particles P will penetrate the entire thickness of the hydrophilic layer 3. This "volume capillarity" is much more effective at guiding the liquid L throughout the entire support. All the captured particles P are then carried along by the elution liquid L, increasing the elution yield. The liquid carrying the particles can be collected in a dedicated receptacle located downstream.

[0088] The elution liquid L is advantageously water. It may advantageously contain a surfactant such as, for example, TritonXIOO and proteins such as, for example, BSA or casein to increase membrane wetting, block protein / surface interactions and increase the recovery yield of collected particles.

[0089] It is also possible that the remaining layer 3 has too high a thickness, thus limiting the collection efficiency. In this case, advantageously, a manufacturing step of membrane M consists of creating one or more zones on the membrane by treating the hydrophilic layer.

[0090] Step E5: The surface treatment may consist of etching the remaining hydrophilic layer 3 (etching means 5), for example by laser etching, milling, or by creating zones using barriers made, for example, of paraffin. The etching operations may be carried out over a greater or lesser thickness than the total thickness of the hydrophilic layer, in order to define one or more zones.

[0091] Step E6: The membrane M is obtained with, for example, different distinct zones.

[0092] These different zones obtained are shown for example in [Fig.3]:

[0093] - A so-called collection zone ZI where the hydrophilic layer 3 is partially etched; - A so-called wetting zone Z2 at which the hydrophilic layer 3 is not etched, or is etched to a thickness less than that of the collection zone ZI;

[0094] Advantageously, it is also possible to create on the membrane M:

[0095] - A contact resumption zone Z3, in which the hydrophilic layer 3 is removed over its entire thickness, so as to create access to the second layer 4 located below; - One or more barrier zones Z4, arranged between the wetting zone Z2 and the contact re-establishment zone Z3 to guide the elution liquid F and prevent it from migrating to the Z3 contact zone.

[0096] The different zones can be made on the same membrane M and occupy all or part of the total surface of the membrane M. The collection zone ZI can in particular be more or less extensive.

[0097] The collection zone ZI is obtained by etching a thickness of the hydrophilic layer 3, less than its total thickness, in order to obtain a zone having a compromise between wettability characteristics and quality of capture of particles P by electrostatic forces.

[0098] The wetting zone Z2 is the zone through which the elution liquid L is introduced for the recovery of the collected particles P. It ensures the distribution of the elution front over the entire width of the membrane, preventing preferential flow paths, and a consistent flow of the elution liquid L. By capillary action, the liquid L introduced through the wetting zone Z2 wets the entire surface of the membrane M, at least at its collection zone Z1, and carries away the previously collected particles. The liquid L carries the particles P and is advantageously recovered in a dedicated receptacle.

[0099] The contact resumption zone Z3 can also be used as a containment zone for the elution liquid L, the second layer 4 being hydrophobic.

[0100] Each barrier zone Z4 can be formed by depositing a layer of paraffin on the surface of the membrane M. A barrier zone is configured to form a barrier to the liquid L between two distinct zones of the membrane.

[0101] It is also possible to add a water-soluble agent to the hydrophilic layer 3, whether etched or not, to promote the elution of the collected particles. For example, the hydrophilic layer, at its collection zone Zl, can be treated with a solution composed of a sugar such as lactose, trehalose, or sucrose, which, by dissolving during elution, facilitates the entrainment of the collected particles by the elution liquid L.

[0102] The final membrane M obtained can be cut to the desired dimensions, in order to adapt to the geometry of the electrostatic collector.

[0103] It should be noted that inhibition tests were conducted to confirm the compatibility of the invention with biomolecular reactions. For this purpose, samples of membranes made of Whatman paper, carbon powder in its graphite form, and silicone were placed in the presence of a reaction mix. This mix was then extracted, and a biomolecular amplification reaction was performed. The results show a slight delay in onset compared to the controls but excellent reproducibility of the results, regardless of the membrane's aging state. The proposed membrane type therefore does not appear to inhibit the biomolecular reaction.

[0104] The membrane M of the invention is thus suitable for collecting airborne particles P and eluting them. It also has the following characteristics and advantages:

[0105] - It allows a high recovery efficiency of P particles after elution, thanks in particular to a high degree of wettability and the presence of low dead volumes; - It is compatible with biological reagents, thus enabling the implementation of biochemical type reactions (for example PCR for "Polymerase Chain Reaction", LAMP or equivalent). - The M membrane has a size comparable to the characteristic dimensions of the air vein, ensuring efficient collection without the need for added flow or a complex geometry electrode; - The M membrane is suitable for the implementation of a dry collection system; - It has good mechanical strength; - It is flexible enough to fit into electrostatic collectors of various shapes; - It is easy to make and shape, with edges designed to avoid creating a pointed effect;

Claims

Demands

1. Airborne particle collection membrane (M), characterized in that it is in the form of a strip composed of: - A matrix (40) formed of a mixture of a polymer material and a filler (41) made of an electrically conductive material, - A hydrophilic particle collection layer (3) on which said matrix is ​​deposited so as to form at least one layer of composite material (400), - Said membrane comprising at least one zone obtained by a surface treatment of said hydrophilic layer (3).

2. Membrane according to claim 1, characterized in that the hydrophilic layer (3) is made of cellulose.

3. Membrane according to claim 1, characterized in that the hydrophilic layer (3) is made from a woven material.

4. Membrane according to any one of claims 1 to 3, characterized in that the hydrophilic layer (3) is made from a material which retains by capillarity a volume of less than 30pl / cm2.

5. Membrane according to any one of claims 1 to 4, characterized in that the matrix (40) is made of a silicone-based material.

6. Membrane according to any one of claims 1 to 5, characterized in that the filler (41) is in the form of a carbon powder, mixed with said matrix (40).

7. Membrane according to any one of claims 1 to 6, characterized in that the filler (41) is in the form of a carbon powder in its graphite form.

8. Membrane according to any one of claims 1 to 7, characterized in that the hydrophilic layer (3) has a total surface area and comprises at least a first so-called collection zone (Z1) obtained by said surface treatment on a first part of its total surface area and at least a second zone (Z2) made on a second part of its total surface area, the first layer having a first thickness on its collection zone and a second thickness on its second zone, said first thickness being less than the second thickness.

9. Membrane according to claim 8, characterized in that the hy- layer drophile (3) is treated to form an electrical contact resumption zone (Z3) with a surface area less than its total surface area, obtained by said surface treatment of said hydrophilic layer (3) over a thickness equal to its total thickness.

10. Membrane according to claim 9, characterized in that the second zone (Z2) is a so-called wetting zone, more hydrophilic than the first collection zone (Z1).

11. Membrane according to claim 10, characterized in that the wetting zone (Z2) is made without surface treatment of said hydrophilic layer (3).

12. Membrane according to claim 10 or 11, characterized in that it comprises a hydrophobic barrier zone (Z4) made between the contact zone (Z3) and the wetting zone (Z2).

13. Membrane according to claim 12, characterized in that the hydrophobic barrier zone is made in the form of a paraffin deposit.

14. Membrane according to any one of claims 1 to 13, characterized in that it comprises a water-soluble layer deposited on the hydrophilic layer (3).

15. A method for manufacturing the collection membrane (M) as defined in any one of claims 1 to 14, characterized in that it comprises the steps of: - Forming a support formed of said hydrophilic layer (3), - Deposition on said support of the matrix (40) formed of a mixture of the polymer material and the filler made in the electrically conductive material, - Polymerization of the polymer material, - Surface treatment of the hydrophilic material layer, in order to form said zone.

16. Electrostatic airborne particle collector, comprising a collection unit (Ul), collection means (2) configured to force said airborne particles towards said collection unit (Ul), characterized in that the collection unit (Ul) incorporates a collection membrane such as that defined in any one of claims 1 to 14.

17. Electrostatic collector according to claim 16, characterized in that it comprises a fluidic circuit for eluting airborne particles collected by the collection membrane, said fluidic elution circuit comprising at least one fluidic channel (11) opening onto said collection membrane (M).

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