WO2017174726A1 - Sensor for measuring the concentration of particles in the atmosphere - Google Patents

Sensor for measuring the concentration of particles in the atmosphere Download PDF

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Publication number
WO2017174726A1
WO2017174726A1 PCT/EP2017/058261 EP2017058261W WO2017174726A1 WO 2017174726 A1 WO2017174726 A1 WO 2017174726A1 EP 2017058261 W EP2017058261 W EP 2017058261W WO 2017174726 A1 WO2017174726 A1 WO 2017174726A1
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WO
WIPO (PCT)
Prior art keywords
particles
diameter
stages
concentration
stage
Prior art date
Application number
PCT/EP2017/058261
Other languages
French (fr)
Inventor
Laurent FERTIER
Lyes DJOUMI
Virginie Blondeau-Patissier
Meddy VANOTTI
Etienne QUIVET
Original Assignee
Eco Logic Sense Sas
Universite D'aix Marseille
Universite De Franche Comte
Ecole Nationale Superieure De Mecanique Et Des Microtechniques
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Application filed by Eco Logic Sense Sas, Universite D'aix Marseille, Universite De Franche Comte, Ecole Nationale Superieure De Mecanique Et Des Microtechniques filed Critical Eco Logic Sense Sas
Publication of WO2017174726A1 publication Critical patent/WO2017174726A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/02—Analysing fluids
    • G01N29/022—Fluid sensors based on microsensors, e.g. quartz crystal-microbalance [QCM], surface acoustic wave [SAW] devices, tuning forks, cantilevers, flexural plate wave [FPW] devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
    • G01N15/02—Investigating particle size or size distribution
    • G01N15/0255—Investigating particle size or size distribution with mechanical, e.g. inertial, classification, and investigation of sorted collections
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
    • G01N15/06—Investigating concentration of particle suspensions
    • G01N15/0606—Investigating concentration of particle suspensions by collecting particles on a support
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/22—Details, e.g. general constructional or apparatus details
    • G01N29/223—Supports, positioning or alignment in fixed situation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/22—Details, e.g. general constructional or apparatus details
    • G01N29/24—Probes
    • G01N29/2462—Probes with waveguides, e.g. SAW devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
    • G01N2015/0042—Investigating dispersion of solids
    • G01N2015/0046—Investigating dispersion of solids in gas, e.g. smoke
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
    • G01N15/02—Investigating particle size or size distribution
    • G01N15/0255—Investigating particle size or size distribution with mechanical, e.g. inertial, classification, and investigation of sorted collections
    • G01N2015/0261—Investigating particle size or size distribution with mechanical, e.g. inertial, classification, and investigation of sorted collections using impactors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/024—Mixtures
    • G01N2291/02408—Solids in gases, e.g. particle suspensions
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/025—Change of phase or condition
    • G01N2291/0256—Adsorption, desorption, surface mass change, e.g. on biosensors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/028—Material parameters
    • G01N2291/02809—Concentration of a compound, e.g. measured by a surface mass change
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/04—Wave modes and trajectories
    • G01N2291/042—Wave modes
    • G01N2291/0423—Surface waves, e.g. Rayleigh waves, Love waves

Definitions

  • the invention relates to the field of air pollution sensors and more specifically to the field of instruments for the real-time measurement of the concentration of polluting particles present in the atmosphere.
  • Air quality is an essential parameter for ensuring a good quality of life, especially in cities and urban areas.
  • particles of a few ⁇ in diameter are particularly dangerous for human health. These particles are produced largely by human activities related to industry and transportation. They are responsible for health risks such as impaired lung function and can lead to decreased life expectancy.
  • Fine particles (PM or "Particulate Matter” in English) are often classified according to their size.
  • the PM10 name is used for particles having an aerodynamic diameter of less than 10 ⁇ and PM2.5 for particles with a diameter of less than 2.5 ⁇ .
  • the aerodynamic diameter of a particle is defined as the diameter of a sphere, of unit density (1 g / cm 3 ), having the same limit speed of fall as a particle in a fluid. It describes the aeraulic behavior of the particles in the airflow.
  • Devices employing optical techniques have high realization costs and, even if they are quite compact and portable, they generally have a low particle size selectivity.
  • the simplest gravimetric devices operate by impaction of the particles on a filter which is then weighed. Although these devices have good size selectivity and relatively low costs, they do not allow real-time monitoring of the particle concentration.
  • the beta gauge systems rely on an electron absorption technique. These systems have the advantage of being very reliable but, in addition to their high cost, they require the presence of a radioactive source, which can reduce the portability.
  • TEOM ® gravimetric systems (Tapered Element Oscillating Microbalance) are based on the use of a microbalance and are used for regulatory monitoring in some countries. These systems allow real-time monitoring of the particle concentration but they do not allow good selectivity while keeping costs relatively high.
  • the present invention relates to a device capable in particular of real-time monitoring of the concentration of particles in the atmosphere while ensuring good portability of the system, limited costs and the possibility of creating sensor networks.
  • the invention relates to a sensor for real-time measurement of the atmospheric concentration of particles comprising:
  • An air inlet adapted to receive a flow of air whose atmospheric concentration of particles is to be measured
  • At least two stages cascaded and configured to separate the particles according to their size, said air inlet being connected to at least one of the two stages; At least one of said stages comprising means for real-time measurement of the concentration of the particles;
  • said real-time particle concentration measurement means comprising at least one Surface Acoustic Wave (SAW) transducer.
  • SAW Surface Acoustic Wave
  • air inlet is meant an inlet known to those skilled in the art such as a cannula adapted to the suction of air for which it is desired to measure the concentration of particles.
  • floor means a stack of parts adapted so that the air can flow through the stage and adapted to filter the particles according to their size.
  • one or more parts of the floor may have one or more holes of diameter adapted to the size of the particles to be retained and the air flow used.
  • Real-time measurement means means one or more components adapted, for example, to provide a signal proportional to the mass of particles present in the air flow passing through the device.
  • the senor according to the invention uses as measuring means surface acoustic wave transducers (or SAW transducer in English). These transducers are used as a microbalance that can measure the mass of particles deposited on their surface.
  • the sensor according to the invention therefore allows a selective measurement of the particles by differentiating PM10 and PM2.5.
  • An advantage of the invention is to provide a sensor for real-time monitoring of the concentration of atmospheric particles, said sensor being of reduced size and therefore having a high portability.
  • the useful volume is for example of the order of 750 cm 3 .
  • Another advantage of the invention is the use of SAW type transducers. These transducers have a greater sensitivity compared to other types of microbalances such as conventional quartz microbalances. Using the SAW transducers, we can estimate a gain of a factor of 5 to 10 in sensitivity by compared to a quartz microbalance. In addition, the device according to the invention makes it possible to achieve a very high resolution of the order of a few ng / cm 2 .
  • the response time of this system is very fast and less than 10 minutes.
  • the senor requires low maintenance and can operate up to six months without intervention.
  • the sensor according to the invention may have one or more of the following characteristics considered individually or in any technically possible combination:
  • the air intake comprises a protection element, said protection element being intended to prevent the penetration of water droplets or macroscopic particles inside the cascade structure while allowing the circulation of air ;
  • the protection element is a hollow cone frustum having an open face
  • the sensor comprises means for controlling the flow of air through the stages connected in cascade;
  • the air flow inside the cascade stages is set to have a flow rate between 0.45 and 5.5 l / min;
  • the sensor has three stages cascaded and configured to retain particles of diameter greater than 10 ⁇ respectively, those with a diameter between 10 ⁇ and 2.5 ⁇ and those with a diameter less than 2.5 ⁇ ;
  • the first filtering plate comprises at least one hole having a diameter of between 3 mm and 8 mm, the second filtering plate at least one hole having a diameter of between 1 mm and 3 mm and the third filtering plate at least one hole of diameter between 0.7 and 0.9 mm;
  • the sensor comprises support plates for said means for measuring the concentration of the particles
  • Said support plates comprise openings arranged so as to allow the circulation of air and the separation of the particles according to their size; said support plates comprise connectors and printed circuits for supplying the SAW transducer and recovering the signals corresponding to the measurement of the concentration of the particles;
  • the SAW transducers have a mechanical and chemical functionalization of their surface to facilitate the adhesion of the particles to the surface of the transducer;
  • SAW transducers exhibit mechanical and chemical surface functionalization with a Teflon TM layer to facilitate adhesion of particles to the surface of the transducer;
  • the vibration frequency of the SAW transducers is between 100 and 270 MHz;
  • the vibration frequency of the SAW transducers is preferably between 1 and 130 MHz;
  • the senor comprises a plurality of SAW transducers.
  • said support plates and said SAW transducers are located at the second and third stages cascaded.
  • Figure 1 shows a sectional view of the sensor according to the invention
  • Figure 2 shows a sectional view of the sensor according to the invention, the section plane being normal to the sectional plane of Figure 1;
  • Figure 3a shows the air intake of the sensor according to the invention
  • Figure 3b shows a protection element of the air inlet in a sensor according to the invention
  • FIG. 4a shows an airflow acceleration plate used to sort the particles according to their size in a sensor according to the invention
  • FIG. 4b shows an impaction plate for the collection of particles larger than 10 ⁇ m in a sensor according to the invention
  • FIG. 4c shows an airflow acceleration plate used for sorting the particles according to their size in a sensor according to the invention
  • FIG. 4d shows an airflow acceleration plate used for sorting the particles according to their size in a sensor according to the invention
  • FIG. 5 shows a support plate of a SAW transducer in a sensor according to the invention.
  • FIG. 1 shows a sectional view of the sensor 100.
  • the sensor 100 according to the invention comprises:
  • a stage 10 comprising a plate 102 called an airflow acceleration plate or filtering plate and an impaction plate 101, said impaction plate intended to retain particles with a diameter greater than 10 ⁇ m;
  • a stage 20 comprising a plate 203 called an airflow acceleration plate or filtering plate, an element 202 intended to bind the plate 203 to a plate 201, said plate 201 being a support plate of an element for real-time measurement of particle concentration, including a SAW transducer;
  • a stage 30 comprising a plate 303 called an airflow acceleration plate or filtering plate, an element 302 intended to bind the plate 303 to a plate 301, said plate 301 being a support plate of an element for real-time measurement of particle concentration, including a SAW transducer;
  • the air inlet 40 brings air to measure the concentration of particles inside the sensor. It is protected by the protection element 50 having the open face 501, the role of the opening 501 being to let the air to be analyzed.
  • An advantage of the presence of the element 50 is to prevent the arrival of macroscopic particles or water droplets inside the sensor, elements that could disturb the measurement operation.
  • the element 50 has the shape of a hollow truncated cone.
  • An advantage of this embodiment is to facilitate the flow of rain around the air inlet cannula 40 while preventing water from entering the interior of the device.
  • the device comprises a plurality of stages 10, 20, 30 cascaded and configured to retain particles of different diameters.
  • An advantage of this embodiment is that it is possible to separately measure the particle concentrations of different size.
  • the device comprises three stages (10, 20, 30) cascaded and configured to retain particles of diameter greater than 10 ⁇ respectively, those with a diameter of between 10 ⁇ and 2.5 ⁇ and those with a diameter of less than 2.5 ⁇ .
  • An advantage of this embodiment is to selectively measure the concentrations of PM10 and PM 2.5 particles, which are particularly important for the control of air quality.
  • the device 100 of FIG. 1 is equipped with three stages 10, 20, 30. Each of these stages has the double role of selecting the particles according to their size and of measuring the quantity of particles having a given size.
  • the stage 10 connected to the air inlet, comprises the plate 102 for acceleration of the air flow. This plate makes it possible to stop the particles of diameter greater than 10 ⁇ .
  • the stage 10 also comprises the impaction plate 101 intended to accommodate particles with a diameter greater than 10 ⁇ m.
  • Stages 20 and 30 allow real-time tracking of particle concentration by accommodating SAW transducers.
  • the stage 20 includes the plate 203 for acceleration of the air flow and for stopping particles of diameter between 10 ⁇ and 2,5 ⁇ . These particles are measured at the stage 20.
  • the stage 20 also comprises the element 202 linking the element 203 and the support plate 201 of the SAW transducer.
  • An advantage of this embodiment is that it allows the measurement in real time of the concentration of particles having a diameter of between 10 ⁇ and 2,5 ⁇ . These PM10 particles are particularly important for the verification of air quality.
  • the stage 30 comprises an acceleration plate 303 of the air flow and stopping particles with a diameter of less than 2.5 ⁇ m.
  • the stage 30 also comprises a connecting element 302 between the element 303 and the support plate 301 of the SAW transducer.
  • An advantage of this embodiment is that it allows the measurement in real time of the concentration of particles having a diameter of less than 2.5 ⁇ , also called PM2.5.
  • PM2.5 particles are particularly important for the verification of air quality.
  • it is possible to measure the concentration of PM10 particles.
  • the cables are connected through the connectors 60.
  • the cables and the connectors 60 are of the SMA type.
  • the connection cables are used to feed the SAW transducers and to recover the signals relating to the measured concentration of particles.
  • Element 70 is the air outlet whose particle concentration has been measured. This element makes it possible to connect the sensor 100 to the pump which circulates the flow of air inside the device.
  • the flow of air inside the cascade stages is set to have a flow rate of between 0.45 and 5.5 l / min. According to a preferred embodiment of the invention the air flow is set to have a flow rate of 3 l / min.
  • An advantage of this embodiment is to have a low energy consumption, the flow rate being relatively low.
  • the holes in the acceleration plates 102, 203 and 303 must be sized correctly with respect to the selected airflow.
  • the first acceleration plate 102 comprises at least one hole of diameter comprised between 3 mm and 8 mm
  • the second accelerating plate 203 at least one hole of diameter between 1 mm and 3 mm.
  • the third acceleration plate 303 at least one hole of diameter between 0.7 and 0.9 mm.
  • An advantage of this embodiment is to size the number and size of the holes at each stage so that the filtration and size selection of the particles is effective for a given airflow.
  • FIG. 2 shows a sectional view of the sensor 100, the section plane being normal to the sectional plane of FIG. 1.
  • Figure 3a shows the air inlet 40 of the sensor 100.
  • the air inlet holes 401 allow air to enter the interior of the device.
  • Figure 3b shows the protective element 50 having an open face 501, said protective element adapted to prevent the entry of droplets or macroscopic particles within the device.
  • Figure 4a shows the acceleration plate 102 of the air flow positioned at the stage 10 or first acceleration plate.
  • the plate 102 has a central hole 105 and lateral holes 106.
  • the central hole 105 accelerates the flow of air when it passes through this element.
  • the particles of greater inertia are deviated from the path of the airflow. More particularly, the particles of diameter greater than 10 ⁇ are stopped at the level of the impaction plate 101.
  • the lateral holes 106 can accommodate means for holding the sensor, for example to fix the different plates that form the sensor.
  • the size of holes in each floor must be sized according to the air flow used.
  • the hole on the plate 102 has a diameter of (7 ⁇ 1) mm.
  • the hole has a diameter of respectively (3.0 ⁇ 0.3) and (8 ⁇ 1) ) mm.
  • FIG. 4b shows the second part of the stage 10 composed by an impaction plate 101.
  • the plate 101 comprises openings 108 and holes 107.
  • Particles with a diameter greater than 10 ⁇ are deposited on this plate.
  • the openings 108 allow the flow of air containing the particles of diameter less than 10 ⁇ to flow to the stage 20.
  • the lateral holes 107 can accommodate means for holding the sensor, for example to fix the different plates that form the sensor.
  • the impaction plate 101 can be covered with a Teflon ® layer to facilitate the adhesion of the particles on the surface of the plate 101 even.
  • FIG. 4c shows the acceleration plate 203 of the air flow at the level of the stage 20 of the sensor 100.
  • the plate 203 comprises a central hole 205 and lateral holes 206.
  • the central hole 205 accelerates the flow of air as it passes through this element.
  • the particles of greater inertia are deviated from the path of the air flow. More particularly, particles with a diameter greater than 2.5 ⁇ are stopped at the level of the support plate 201 of the SAW transducer.
  • the lateral holes 206 can accommodate means for holding the sensor, for example to fix the different plates that form the sensor.
  • the size of the holes must be chosen as a function of the air flow so that the particle filtering according to their size is effective.
  • the hole on the plate 203 has a diameter of (3.0 ⁇ 0.5) mm. If a flow rate of (0.50 ⁇ 0.05) l / min is chosen, the hole must have a diameter of (1.0 ⁇ 0.3) mm.
  • the plate 203 must have two holes each of diameter equal to (2.0 ⁇ 0.3) mm.
  • Figure 4d shows the plate 303 of acceleration of the air flow.
  • the plate 303 has two central holes 305 and side holes 306.
  • the two central holes 305 make it possible to accelerate the flow of air as it passes through this element.
  • the particles of greater inertia are deviated from the path of the air flow. More particularly, the particles with a diameter of between 2.5 and 0 ⁇ 3 ⁇ are stopped at the level of the support plate 301 of the SAW transducer.
  • the lateral holes 306 can accommodate means for holding the sensor, for example to fix the different plates that form the sensor.
  • the plate 303 has two holes, each of diameter equal to (0.8 ⁇ 0.1) mm.
  • the plate 303 has a single hole of diameter equal to (0.7 ⁇ 0.1) mm.
  • the plate 303 comprises 2 holes each of diameter equal to (0.9 ⁇ 0.1) mm.
  • the device has a reduced energy consumption, which allows to have an extended autonomy.
  • a high throughput even if more expensive in terms of operating energy, allows faster and more precise acquisitions.
  • the senor comprises at least one support plate (201, 301) for the means for measuring the concentration of the particles.
  • FIG. 5 shows one of the support plates 201, 301 of the SAW 600 transducers. These plates have several technical functions:
  • the lateral holes 606 can accommodate means for holding the sensor, for example to fix the plates 201, 301 to the other elements of the sensor.
  • An advantage of this embodiment is to allow the installation of the SAW transducers inside the sensor 100 while ensuring the connection using printed circuits on the plates themselves.
  • said support plates comprise openings arranged to allow the circulation of air and the separation of particles according to their size.
  • An advantage of this embodiment is to allow the circulation of airflow at the level of the transducers, while allowing the selective measurement in size and in real time of the concentration of particles.
  • the support plates 201, 301 comprise connectors 60 intended to supply the SAW 600 transducer and to recover the signals corresponding to the measurement of the concentration of the particles.
  • An advantage of this embodiment is that it can at the same time feed the SAW 600 transducers and recover the electrical signals containing the information relating to the concentration of particles.
  • Each SAW 600 transducer has two vibrating surfaces: a "measurement” part and a “reference” part.
  • the airflow to be analyzed deposits the particles on the "measurement” part.
  • the particles deposited on this surface modify the vibration frequency of the surface itself, while the vibration frequency of the "reference” part remains unchanged.
  • the SAW 600 transducers are placed slightly offset by a few mm with respect to the airflow passage holes of the elements 203 and 303.
  • the SAW 600 transducer offset relative to the airflow passage holes of the elements 202 and 203 is for example between 1 and 5 mm. This arrangement makes it possible to direct the flow of air directly on the "measurement” part of the SAW transducer, leaving the frequency of vibration of the "reference" part unchanged.
  • the interdigitated SAW 600 combs can be connected to PCBs with gold microfilts.
  • the device comprises means for controlling the flow of air through the stages connected in cascade.
  • An advantage of this embodiment is the ability to adjust the airflow through the device.
  • the SAW 600 transducers have a mechanical and chemical functionalization of their surface.
  • An advantage of this embodiment is to facilitate adhesion of the particles to the surface of the transducer.
  • the SAW 600 transducers have a mechanical and chemical functionalization of their surface with a Teflon TM layer.
  • An advantage of this embodiment is to facilitate adhesion of the particles to the surface of the transducer without permanently bonding them, which is important to clean / regenerate the transducer surface after use.
  • the vibration frequency of the SAW transducers is between 100 and 270 MHz.
  • An advantage of this embodiment is to use a higher vibration frequency than that used in other microbalance systems, which increases the sensitivity of the mass measurement.
  • the vibration frequency of the SAW transducers is preferably between 1 10 and 130 MHz.

Abstract

A sensor for real-time measurement of the concentration of particles in the atmosphere comprises: • an air inlet for receiving an air stream (40) in which the concentration of particles is to be measured; • at least two stages (20, 30) arranged in cascade and designed to separate the particles according to size, the air inlet being connected to at least one of the two stages; • at least one of the stages (20, 30) comprising means for measuring in real time the concentration of particles; the sensor being characterised in that the means for measuring in real time the concentration of particles comprise at least one surface acoustic wave (SAW) transducer.

Description

Capteur pour la mesure de la concentration atmosphérique de particules  Sensor for the measurement of the atmospheric concentration of particles
DOMAINE DE L'INVENTION L'invention concerne le domaine des capteurs de pollution atmosphérique et plus précisément le domaine des instruments pour la mesure en temps réel de la concentration de particules polluantes présentes dans l'atmosphère. FIELD OF THE INVENTION The invention relates to the field of air pollution sensors and more specifically to the field of instruments for the real-time measurement of the concentration of polluting particles present in the atmosphere.
ETAT DE L'ART STATE OF THE ART
La qualité de l'air est un paramètre essentiel pour assurer une bonne qualité de vie, notamment dans les villes et dans les agglomérations urbaines. Parmi les causes de pollution atmosphérique, les particules de quelques μηι de diamètre sont particulièrement dangereuses pour la santé humaine. Ces particules sont produites en grande partie par des activités humaines liées à l'industrie et aux transports. Elles sont responsables de risques sanitaires tels que l'altération des fonctions pulmonaires et peuvent entraîner une diminution de l'espérance de vie. Air quality is an essential parameter for ensuring a good quality of life, especially in cities and urban areas. Among the causes of air pollution, particles of a few μηι in diameter are particularly dangerous for human health. These particles are produced largely by human activities related to industry and transportation. They are responsible for health risks such as impaired lung function and can lead to decreased life expectancy.
Les particules fines (PM ou « Particulate Matter » en anglais) sont souvent classées suivant leur taille. On utilise l'appellation PM10 pour les particules ayant un diamètre aérodynamique inférieur à 10 μηι et PM2.5 pour les particules de diamètre inférieur à 2.5 μηι. Le diamètre aérodynamique d'une particule est défini comme étant le diamètre d'une sphère, de densité unitaire (1 g/cm3), ayant la même vitesse limite de chute qu'une particule dans un fluide. Il décrit le comportement aéraulique des particules dans le flux d'air. Fine particles (PM or "Particulate Matter" in English) are often classified according to their size. The PM10 name is used for particles having an aerodynamic diameter of less than 10 μηι and PM2.5 for particles with a diameter of less than 2.5 μηι. The aerodynamic diameter of a particle is defined as the diameter of a sphere, of unit density (1 g / cm 3 ), having the same limit speed of fall as a particle in a fluid. It describes the aeraulic behavior of the particles in the airflow.
Les épisodes de pollution atmosphérique intense deviennent aujourd'hui de plus en plus fréquents et les institutions doivent mettre en place des solutions - souvent dans l'urgence - pour contrer ces phénomènes. Ces solutions requièrent un suivi en temps réel de la concentration atmosphérique de particules fines. La nécessité de déployer un réseau dense de capteurs est de plus en plus ressentie. Episodes of intense atmospheric pollution are becoming more and more frequent today and institutions need to put in place solutions - often urgently - to counter these phenomena. These solutions require real-time monitoring of the atmospheric concentration of fine particles. The need to deploy a dense network of sensors is increasingly felt.
Aujourd'hui deux méthodes de mesure des particules sont principalement utilisées : Today two methods of measuring particles are mainly used:
• Les techniques optiques : ces techniques reposent sur la perturbation d'un faisceau lumineux par le passage des particules à travers le faisceau même ; • Les techniques gravi métriques : ces techniques consistent à accumuler les particules sur un filtre puis à le quantifier par pesée directe ou indirecte. • Optical techniques: these techniques are based on the disturbance of a light beam by the passage of particles through the beam itself; • Gravimetric techniques: these techniques consist in accumulating the particles on a filter and then quantifying it by direct or indirect weighing.
Les dispositifs exploitant des techniques optiques comportent des coûts de réalisation élevés et, même s'ils sont assez compacts et portables, ils ont généralement une faible sélectivité en taille des particules. Devices employing optical techniques have high realization costs and, even if they are quite compact and portable, they generally have a low particle size selectivity.
Les dispositifs gravi métriques les plus simples fonctionnent par impaction des particules sur un filtre qui est ensuite pesé. Même si ces dispositifs ont une bonne sélectivité en taille et des coûts relativement peu élevés, ils ne permettent pas un suivi en temps réel de la concentration de particules. Les systèmes à jauge beta reposent sur une technique d'absorption d'électrons. Ces systèmes ont l'avantage d'être très fiables mais, en plus de leur coût élevé, ils demandent la présence d'une source radioactive, ce qui peut en diminuer la portabilité. The simplest gravimetric devices operate by impaction of the particles on a filter which is then weighed. Although these devices have good size selectivity and relatively low costs, they do not allow real-time monitoring of the particle concentration. The beta gauge systems rely on an electron absorption technique. These systems have the advantage of being very reliable but, in addition to their high cost, they require the presence of a radioactive source, which can reduce the portability.
Les systèmes gravimétriques TEOM® (Tapered Elément Oscillating Microbalance) reposent sur l'utilisation d'une microbalance et sont utilisés pour le suivi réglementaire dans certains pays. Ces systèmes permettent le suivi en temps réel de la concentration de particules mais ils ne permettent pas une bonne sélectivité tout en gardant des coûts relativement élevés. TEOM ® gravimetric systems (Tapered Element Oscillating Microbalance) are based on the use of a microbalance and are used for regulatory monitoring in some countries. These systems allow real-time monitoring of the particle concentration but they do not allow good selectivity while keeping costs relatively high.
RESUME DE L'INVENTION Pour remédier aux inconvénients des systèmes actuellement disponibles, la présente invention porte sur un dispositif capable notamment du suivi en temps réel de la concentration de particules dans l'atmosphère tout en assurant une bonne portabilité du système, des coûts limités et la possibilité de réaliser des réseaux de capteurs. SUMMARY OF THE INVENTION To overcome the drawbacks of the systems currently available, the present invention relates to a device capable in particular of real-time monitoring of the concentration of particles in the atmosphere while ensuring good portability of the system, limited costs and the possibility of creating sensor networks.
L'invention porte sur un capteur pour la mesure en temps réel de la concentration atmosphérique de particules comportant : The invention relates to a sensor for real-time measurement of the atmospheric concentration of particles comprising:
• une entrée d'air adaptée pour recevoir un flux d'air dont la concentration atmosphérique de particules est à mesurer ;An air inlet adapted to receive a flow of air whose atmospheric concentration of particles is to be measured;
• au moins deux étages montés en cascade et configurés pour séparer les particules selon leur taille, ladite entrée d'air étant connectée à au moins un des deux étages ; • au moins un desdits étages comprenant des moyens de mesure en temps réel de la concentration des particules; At least two stages cascaded and configured to separate the particles according to their size, said air inlet being connected to at least one of the two stages; At least one of said stages comprising means for real-time measurement of the concentration of the particles;
lesdits moyens de mesure en temps réel de la concentration des particules comportant au moins un transducteur à Ondes Acoustiques de Surface ou Surface Acoustic Wave (SAW) en anglais. said real-time particle concentration measurement means comprising at least one Surface Acoustic Wave (SAW) transducer.
On entend par entrée d'air une entrée connue de l'homme du métier telle qu'une canule adaptée à l'aspiration de l'air dont l'on veut mesurer la concentration de particules. On entend par étage un empilement de pièces adaptées pour que l'air puisse s'écouler à travers l'étage et adaptées à filtrer les particules suivant leur taille. Par exemple, une ou plusieurs pièces composant l'étage peuvent posséder un ou plusieurs trous de diamètre adapté à la taille des particules à retenir et au débit d'air employé. On entend par moyens de mesure en temps réel une ou plusieurs composantes adaptées, par exemple, pour fournir un signal proportionnel à la masse de particules présentes dans le flux d'air traversant le dispositif. By air inlet is meant an inlet known to those skilled in the art such as a cannula adapted to the suction of air for which it is desired to measure the concentration of particles. The term "floor" means a stack of parts adapted so that the air can flow through the stage and adapted to filter the particles according to their size. For example, one or more parts of the floor may have one or more holes of diameter adapted to the size of the particles to be retained and the air flow used. Real-time measurement means means one or more components adapted, for example, to provide a signal proportional to the mass of particles present in the air flow passing through the device.
Plus spécifiquement, le capteur selon l'invention utilise comme moyens de mesure des transducteurs à Onde Acoustique de Surface (ou transducteur SAW en anglais). Ces transducteurs sont utilisés en guise de microbalance pouvant mesurer la masse de particules se déposant sur leur surface. More specifically, the sensor according to the invention uses as measuring means surface acoustic wave transducers (or SAW transducer in English). These transducers are used as a microbalance that can measure the mass of particles deposited on their surface.
Le capteur selon l'invention permet donc une mesure sélective des particules en différentiant PM10 et PM2.5. The sensor according to the invention therefore allows a selective measurement of the particles by differentiating PM10 and PM2.5.
Un avantage de l'invention est de proposer un capteur pour le suivi en temps réel de la concentration de particules atmosphériques, ledit capteur étant de taille réduite et donc ayant une grande portabilité. Le volume utile est par exemple de l'ordre de 750 cm3. An advantage of the invention is to provide a sensor for real-time monitoring of the concentration of atmospheric particles, said sensor being of reduced size and therefore having a high portability. The useful volume is for example of the order of 750 cm 3 .
Un autre avantage de l'invention est l'utilisation de transducteurs de type SAW. Ces transducteurs ont une sensibilité plus grande par rapport à d'autres types de microbalances comme les microbalances à quartz classiques. En utilisant les transducteurs SAW, on peut estimer un gain d'un facteur 5 à 10 en sensibilité par rapport à une microbalance à quartz. De plus, le dispositif selon l'invention permet d'atteindre une résolution très élevée de l'ordre de quelques ng/cm2 . Another advantage of the invention is the use of SAW type transducers. These transducers have a greater sensitivity compared to other types of microbalances such as conventional quartz microbalances. Using the SAW transducers, we can estimate a gain of a factor of 5 to 10 in sensitivity by compared to a quartz microbalance. In addition, the device according to the invention makes it possible to achieve a very high resolution of the order of a few ng / cm 2 .
Avantageusement, le temps de réponse de ce système est très rapide et inférieur à 10 minutes. Advantageously, the response time of this system is very fast and less than 10 minutes.
De plus, le capteur nécessite une faible maintenance et il peut fonctionner jusqu'à six mois sans intervention. In addition, the sensor requires low maintenance and can operate up to six months without intervention.
Au-delà des caractéristiques évoquées précédemment, le capteur selon l'invention peut présenter une ou plusieurs des caractéristiques suivantes considérées individuellement ou selon toutes les combinaisons techniquement possibles : Beyond the characteristics mentioned above, the sensor according to the invention may have one or more of the following characteristics considered individually or in any technically possible combination:
• l'entrée d'air comprend un élément de protection, ledit élément de protection étant destiné à empêcher la pénétration de gouttelettes d'eau ou de particules macroscopiques à l'intérieur de la structure en cascade tout en permettant la circulation de l'air ; The air intake comprises a protection element, said protection element being intended to prevent the penetration of water droplets or macroscopic particles inside the cascade structure while allowing the circulation of air ;
• l'élément de protection est un tronc de cône creux ayant une face ouverte ;  The protection element is a hollow cone frustum having an open face;
• le capteur comprend des moyens de contrôle du flux d'air à travers les étages connectés en cascade ;  The sensor comprises means for controlling the flow of air through the stages connected in cascade;
• le flux d'air à l'intérieur des étages en cascade est réglé pour avoir un débit compris entre 0.45 et 5.5 l/min ;  • the air flow inside the cascade stages is set to have a flow rate between 0.45 and 5.5 l / min;
• le capteur comporte trois étages montés en cascade et configurés pour retenir respectivement les particules de diamètre supérieur à 10 μηπ, celles de diamètre compris entre 10 μηι et 2,5 μηι et celles de diamètre inférieur à 2,5 μηι ;  • the sensor has three stages cascaded and configured to retain particles of diameter greater than 10 μηπ respectively, those with a diameter between 10 μηι and 2.5 μηι and those with a diameter less than 2.5 μηι;
• la première plaque de filtrage comporte au moins un trou de diamètre compris entre 3 mm et 8 mm, la deuxième plaque de filtrage au moins un trou de diamètre compris entre 1 mm et 3 mm et la troisième plaque de filtrage au moins un trou de diamètre compris entre 0,7 et 0,9 mm ; The first filtering plate comprises at least one hole having a diameter of between 3 mm and 8 mm, the second filtering plate at least one hole having a diameter of between 1 mm and 3 mm and the third filtering plate at least one hole of diameter between 0.7 and 0.9 mm;
• le capteur comprend des plaques de support pour lesdits moyens de mesure de la concentration des particules ; The sensor comprises support plates for said means for measuring the concentration of the particles;
• lesdites plaques de support comportent des ouvertures agencées de façon à permettre la circulation de l'air et la séparation des particules suivant leur taille ; lesdites plaques de support comportent des connecteurs et des circuits imprimés destinés à l'alimentation du transducteur SAW et à la récupération des signaux correspondant à la mesure de la concentration des particules ; Said support plates comprise openings arranged so as to allow the circulation of air and the separation of the particles according to their size; said support plates comprise connectors and printed circuits for supplying the SAW transducer and recovering the signals corresponding to the measurement of the concentration of the particles;
les transducteurs SAW présentent une fonctionnalisation mécanique et chimique de leur surface pour faciliter l'adhésion des particules à la surface du transducteur ;  the SAW transducers have a mechanical and chemical functionalization of their surface to facilitate the adhesion of the particles to the surface of the transducer;
les transducteurs SAW présentent une fonctionnalisation mécanique et chimique de la surface avec une couche en Teflon™ pour faciliter l'adhésion des particules à la surface du transducteur ;  SAW transducers exhibit mechanical and chemical surface functionalization with a Teflon ™ layer to facilitate adhesion of particles to the surface of the transducer;
la fréquence de vibration des transducteurs SAW est comprise entre 100 et 270 MHz ;  the vibration frequency of the SAW transducers is between 100 and 270 MHz;
la fréquence de vibration des transducteurs SAW est comprise de préférence entre 1 10 et 130 MHz ;  the vibration frequency of the SAW transducers is preferably between 1 and 130 MHz;
le capteur comporte une pluralité de transducteurs SAW. lesdites plaques de support et lesdits transducteurs SAW sont placés au niveau du deuxième et du troisième étage montés en cascade.  the sensor comprises a plurality of SAW transducers. said support plates and said SAW transducers are located at the second and third stages cascaded.
LISTE DES FIGURES D'autres caractéristiques et avantages de l'invention ressortiront clairement de la description qui en est donnée ci-dessous, à titre indicatif et nullement limitatif, en référence aux figures annexées, parmi lesquelles : LIST OF FIGURES Other features and advantages of the invention will emerge clearly from the description which is given below, by way of indication and in no way limiting, with reference to the appended figures, among which:
• La figure 1 montre une vue en coupe du capteur selon l'invention ; • Figure 1 shows a sectional view of the sensor according to the invention;
• La figure 2 montre une vue en coupe du capteur selon l'invention, le plan de coupe étant normal au plan de coupe de la figure 1 ;  • Figure 2 shows a sectional view of the sensor according to the invention, the section plane being normal to the sectional plane of Figure 1;
• La figure 3a montre l'arrivée d'air du capteur selon l'invention ;  • Figure 3a shows the air intake of the sensor according to the invention;
• La figure 3b montre un élément de protection de l'entrée d'air dans un capteur selon l'invention ;  • Figure 3b shows a protection element of the air inlet in a sensor according to the invention;
• La figure 4a montre une plaque d'accélération du flux d'air utilisée pour trier les particules suivant leur taille dans un capteur selon l'invention ;  FIG. 4a shows an airflow acceleration plate used to sort the particles according to their size in a sensor according to the invention;
• La figure 4b montre une plaque d'impaction pour la récolte des particules de taille supérieure à 10 μηι dans un capteur selon l'invention ; • La figure 4c montre une plaque d'accélération du flux d'air utilisée pour trier les particules suivant leur taille dans un capteur selon l'invention ; FIG. 4b shows an impaction plate for the collection of particles larger than 10 μm in a sensor according to the invention; FIG. 4c shows an airflow acceleration plate used for sorting the particles according to their size in a sensor according to the invention;
• La figure 4d montre une plaque d'accélération du flux d'air utilisée pour trier les particules suivant leur taille dans un capteur selon l'invention ;  FIG. 4d shows an airflow acceleration plate used for sorting the particles according to their size in a sensor according to the invention;
« La figure 5 montre une plaque de support d'un transducteur SAW dans un capteur selon l'invention.  FIG. 5 shows a support plate of a SAW transducer in a sensor according to the invention.
DESCRIPTION DETAILLEE DETAILED DESCRIPTION
La figure 1 montre une vue en coupe du capteur 100. Le capteur 100 selon l'invention comporte : FIG. 1 shows a sectional view of the sensor 100. The sensor 100 according to the invention comprises:
- Une entrée d'air 40 pour permettre l'entrée de l'air dont l'on veut mesurer la concentration de particules à l'intérieur du capteur ; - An air inlet 40 to allow the entry of air which is to measure the concentration of particles inside the sensor;
- Un élément de protection 50 de l'entrée d'air 40, ledit élément de protection 50 ayant une surface ouverte 501 ;  A protection element 50 of the air inlet 40, said protection element 50 having an open surface 501;
- Un étage 10 comprenant une plaque 102 dite plaque d'accélération du flux d'air ou plaque de filtrage et une plaque d'impaction 101 , ladite plaque d'impaction destinée à retenir les particules de diamètre supérieur à 10 μηι ; A stage 10 comprising a plate 102 called an airflow acceleration plate or filtering plate and an impaction plate 101, said impaction plate intended to retain particles with a diameter greater than 10 μm;
- Un étage 20 comprenant une plaque 203 dite plaque d'accélération du flux d'air ou plaque de filtrage, un élément 202 destiné à lier la plaque 203 à une plaque 201 , ladite plaque 201 étant une plaque de support d'un élément pour la mesure en temps réel de la concentration de particules, notamment un transducteur SAW ; A stage 20 comprising a plate 203 called an airflow acceleration plate or filtering plate, an element 202 intended to bind the plate 203 to a plate 201, said plate 201 being a support plate of an element for real-time measurement of particle concentration, including a SAW transducer;
- Un étage 30 comprenant une plaque 303 dite plaque d'accélération du flux d'air ou plaque de filtrage, un élément 302 destiné à lier la plaque 303 à une plaque 301 , ladite plaque 301 étant une plaque de support d'un élément pour la mesure en temps réel de la concentration de particules, notamment un transducteur SAW ;  A stage 30 comprising a plate 303 called an airflow acceleration plate or filtering plate, an element 302 intended to bind the plate 303 to a plate 301, said plate 301 being a support plate of an element for real-time measurement of particle concentration, including a SAW transducer;
- Des connecteurs 60 pour relier les transducteurs SAW pour la mesure en temps réel de la concentration de particules à l'extérieur du capteur ;  Connectors 60 for connecting the SAW transducers for real-time measurement of the concentration of particles outside the sensor;
- Un élément 70 pour la sortie de l'air dont la concentration de particules a été mesuré. L'entrée d'air 40 ramène l'air dont l'on veut mesurer la concentration de particules à l'intérieur du capteur. Elle est protégée par l'élément de protection 50 comportant la face ouverte 501 , le rôle de l'ouverture 501 étant de laisser passer l'air à analyser. An element 70 for the exit of air whose particle concentration has been measured. The air inlet 40 brings air to measure the concentration of particles inside the sensor. It is protected by the protection element 50 having the open face 501, the role of the opening 501 being to let the air to be analyzed.
Un avantage de la présence de l'élément 50 est d'empêcher l'arrivée de particules macroscopiques ou de gouttelettes d'eau à l'intérieur du capteur, éléments qui pourraient perturber l'opération de mesure. An advantage of the presence of the element 50 is to prevent the arrival of macroscopic particles or water droplets inside the sensor, elements that could disturb the measurement operation.
Selon un mode de réalisation de l'invention, l'élément 50 a la forme d'un tronc de cône creux. According to one embodiment of the invention, the element 50 has the shape of a hollow truncated cone.
Un avantage de ce mode de réalisation est de faciliter l'écoulement de la pluie autour de la canule 40 d'entrée de l'air, tout en empêchant l'eau de pénétrer à l'intérieur du dispositif. An advantage of this embodiment is to facilitate the flow of rain around the air inlet cannula 40 while preventing water from entering the interior of the device.
Selon un mode de réalisation de l'invention, le dispositif comporte une pluralité d'étages 10, 20, 30 montés en cascade et configurés pour retenir des particules de diamètres différents. Un avantage de ce mode de réalisation est de pouvoir mesurer séparément les concentrations de particules de taille différente. According to one embodiment of the invention, the device comprises a plurality of stages 10, 20, 30 cascaded and configured to retain particles of different diameters. An advantage of this embodiment is that it is possible to separately measure the particle concentrations of different size.
Selon un mode de réalisation de l'invention, le dispositif comporte trois étages (10, 20, 30) montés en cascade et configurés pour retenir respectivement les particules de diamètre supérieur à 10 μηπ, celles de diamètre compris entre 10 μηι et 2,5 μηι et celles de diamètre inférieur à 2,5 μηι. According to one embodiment of the invention, the device comprises three stages (10, 20, 30) cascaded and configured to retain particles of diameter greater than 10 μηπ respectively, those with a diameter of between 10 μηι and 2.5 μηι and those with a diameter of less than 2.5 μηι.
Un avantage de ce mode de réalisation est de mesurer sélectivement les concentrations des particules PM10 et PM 2.5, particulièrement importantes pour le contrôle de la qualité de l'air. An advantage of this embodiment is to selectively measure the concentrations of PM10 and PM 2.5 particles, which are particularly important for the control of air quality.
Le dispositif 100 de figure 1 est équipé de trois étages 10, 20, 30. Chacun de ces étages a le double rôle de sélectionner les particules suivant leur taille et de mesurer la quantité de particules ayant une taille donnée. The device 100 of FIG. 1 is equipped with three stages 10, 20, 30. Each of these stages has the double role of selecting the particles according to their size and of measuring the quantity of particles having a given size.
L'étage 10, connecté à l'arrivée d'air, comporte la plaque 102 d'accélération du flux d'air. Cette plaque permet d'arrêter les particules de diamètre supérieur à 10 μηι. L'étage 10 comporte également la plaque d'impaction 101 destinée à accueillir les particules de diamètre supérieur à 10 μηι. The stage 10, connected to the air inlet, comprises the plate 102 for acceleration of the air flow. This plate makes it possible to stop the particles of diameter greater than 10 μηι. The stage 10 also comprises the impaction plate 101 intended to accommodate particles with a diameter greater than 10 μm.
Les étages 20 et 30 permettent le suivi en temps réel de la concentration de particules en accueillant les transducteurs SAW. L'étage 20 comporte la plaque 203 d'accélération du flux d'air et d'arrêt des particules de diamètre compris entre 10 μηι et 2,5 μηι. Ces particules sont mesurées à niveau de l'étage 20. L'étage 20 comporte également l'élément 202 liant l'élément 203 et la plaque 201 de support du transducteur SAW. Stages 20 and 30 allow real-time tracking of particle concentration by accommodating SAW transducers. The stage 20 includes the plate 203 for acceleration of the air flow and for stopping particles of diameter between 10 μηι and 2,5 μηι. These particles are measured at the stage 20. The stage 20 also comprises the element 202 linking the element 203 and the support plate 201 of the SAW transducer.
Un avantage de ce mode de réalisation est de permettre la mesure en temps réel de la concentration de particules ayant diamètre compris entre 10 μηι et 2,5 μηι. Ces particules PM10 sont particulièrement importantes pour la vérification de la qualité de l'air. An advantage of this embodiment is that it allows the measurement in real time of the concentration of particles having a diameter of between 10 μηι and 2,5 μηι. These PM10 particles are particularly important for the verification of air quality.
L'étage 30 comporte une plaque d'accélération 303 du flux d'air et d'arrêt des particules de diamètre inférieur à 2,5 μηι. L'étage 30 comporte également un élément 302 de liaison entre l'élément 303 et la plaque 301 de support du transducteur SAW. The stage 30 comprises an acceleration plate 303 of the air flow and stopping particles with a diameter of less than 2.5 μm. The stage 30 also comprises a connecting element 302 between the element 303 and the support plate 301 of the SAW transducer.
Un avantage de ce mode de réalisation est de permettre la mesure en temps réel de la concentration de particules ayant diamètre inférieur à 2,5 μηπ, dites aussi PM2.5. Les particules PM2.5 sont particulièrement importantes pour la vérification de la qualité de l'air. Donc en combinant les mesures effectuées à niveau des étages 20 et 30 on parvient à la mesure de la concentration des particules PM10. An advantage of this embodiment is that it allows the measurement in real time of the concentration of particles having a diameter of less than 2.5 μηπ, also called PM2.5. PM2.5 particles are particularly important for the verification of air quality. Thus, by combining the measurements made at stages 20 and 30, it is possible to measure the concentration of PM10 particles.
Les câbles sont connectés grâce aux connecteurs 60. Selon un mode de réalisation les câbles et les connecteurs 60 sont de type SMA. Les câbles de connexion permettent d'alimenter les transducteurs SAW et de récupérer les signaux relatifs à la concentration mesurée de particules. The cables are connected through the connectors 60. According to one embodiment, the cables and the connectors 60 are of the SMA type. The connection cables are used to feed the SAW transducers and to recover the signals relating to the measured concentration of particles.
L'élément 70 est la sortie de l'air dont la concentration de particules a été mesurée. Cet élément permet de raccorder le capteur 100 à la pompe qui assure la circulation du flux d'air à l'intérieur du dispositif. Element 70 is the air outlet whose particle concentration has been measured. This element makes it possible to connect the sensor 100 to the pump which circulates the flow of air inside the device.
Selon un mode de réalisation de l'invention le flux d'air à l'intérieur des étages en cascade est réglé pour avoir un débit compris entre 0,45 et 5.5 l/min. Selon un mode préféré de réalisation de l'invention le flux d'air est réglé pour avoir un débit de 3 l/min. According to one embodiment of the invention, the flow of air inside the cascade stages is set to have a flow rate of between 0.45 and 5.5 l / min. According to a preferred embodiment of the invention the air flow is set to have a flow rate of 3 l / min.
Un avantage de ce mode de réalisation est de comporter une faible consommation énergétique, le débit étant relativement faible. Pour que la sélection en taille des particules soit vraiment efficace, les trous dans les plaques d'accélération 102, 203 et 303 doivent être dimensionnés correctement par rapport au débit d'air choisi. An advantage of this embodiment is to have a low energy consumption, the flow rate being relatively low. For the particle size selection to be truly effective, the holes in the acceleration plates 102, 203 and 303 must be sized correctly with respect to the selected airflow.
Selon un mode de réalisation de l'invention la première plaque d'accélération 102 comporte au moins un trou de diamètre compris entre 3 mm et 8 mm, la deuxième plaque d'accélération 203 au moins un trou de diamètre compris entre 1 mm et 3 mm et la troisième plaque d'accélération 303 au moins un trou de diamètre compris entre 0,7 et 0,9 mm. According to one embodiment of the invention, the first acceleration plate 102 comprises at least one hole of diameter comprised between 3 mm and 8 mm, the second accelerating plate 203 at least one hole of diameter between 1 mm and 3 mm. mm and the third acceleration plate 303 at least one hole of diameter between 0.7 and 0.9 mm.
Un avantage de ce mode de réalisation est de dimensionner le nombre et la taille des trous à chaque étage pour que la filtration et la sélection en taille des particules soit efficace pour un débit d'air donné. An advantage of this embodiment is to size the number and size of the holes at each stage so that the filtration and size selection of the particles is effective for a given airflow.
La figure 2 montre une vue en coupe du capteur 100, le plan de coupe étant normal au plan de coupe de la figure 1 . FIG. 2 shows a sectional view of the sensor 100, the section plane being normal to the sectional plane of FIG. 1.
La figure 3a montre l'entrée d'air 40 du capteur 100. Les trous 401 d'entrée de l'air permettent à l'air de rentrer à l'intérieur du dispositif. La figure 3b montre l'élément de protection 50 comportant une face ouverte 501 , ledit élément de protection adapté pour empêcher l'entrée de gouttelettes ou de particules macroscopiques à l'intérieur du dispositif. Figure 3a shows the air inlet 40 of the sensor 100. The air inlet holes 401 allow air to enter the interior of the device. Figure 3b shows the protective element 50 having an open face 501, said protective element adapted to prevent the entry of droplets or macroscopic particles within the device.
Un avantage de ce mode de réalisation est d'empêcher l'entrée de gouttelettes d'eau ou de particules macroscopiques à l'intérieur du dispositif. La figure 4a montre la plaque d'accélération 102 du flux d'air positionnée à niveau de l'étage 10 ou première plaque d'accélération. An advantage of this embodiment is to prevent the entry of water droplets or macroscopic particles into the device. Figure 4a shows the acceleration plate 102 of the air flow positioned at the stage 10 or first acceleration plate.
La plaque 102 comporte un trou central 105 et des trous latéraux 106. The plate 102 has a central hole 105 and lateral holes 106.
Avantageusement, le trou central 105 permet d'accélérer le flux d'air quand il passe à travers cet élément. Les particules de plus grande inertie sont déviées de la trajectoire du flux d'air. Plus particulièrement, les particules de diamètre supérieur à 10 μηι sont arrêtées à niveau de la plaque d'impaction 101 . Advantageously, the central hole 105 accelerates the flow of air when it passes through this element. The particles of greater inertia are deviated from the path of the airflow. More particularly, the particles of diameter greater than 10 μηι are stopped at the level of the impaction plate 101.
Les trous latéraux 106 peuvent accueillir des moyens de maintien du capteur, par exemple pour fixer les différentes plaques qui forment le capteur. Pour que le filtrage des particules suivant leur taille soit efficace, la taille des trous présents à chaque étage doit être dimensionnée en fonction du débit d'air utilisé. Selon un mode de réalisation préféré, pour un flux d'air de (3 ± 0,3) l/min, le trou sur la plaque 102 possède un diamètre de (7 ± 1 ) mm. Par exemple, pour des flux de (0,50 ± 0,05) et (5,0 ± 0,5) l/min le trou possède un diamètre respectivement de (3,0 ± 0,3) et (8 ± 1 ) mm. The lateral holes 106 can accommodate means for holding the sensor, for example to fix the different plates that form the sensor. For filtering particles to their size is effective, the size of holes in each floor must be sized according to the air flow used. According to a preferred embodiment, for an air flow of (3 ± 0.3) 1 / min, the hole on the plate 102 has a diameter of (7 ± 1) mm. For example, for flows of (0.50 ± 0.05) and (5.0 ± 0.5) 1 / min the hole has a diameter of respectively (3.0 ± 0.3) and (8 ± 1) ) mm.
La figure 4b montre la deuxième partie de l'étage 10 composée par une plaque d'impaction 101 . La plaque 101 comprend des ouvertures 108 et des trous 107. FIG. 4b shows the second part of the stage 10 composed by an impaction plate 101. The plate 101 comprises openings 108 and holes 107.
Les particules de diamètre supérieur à 10 μηι se déposent sur cette plaque. Les ouvertures 108 permettent au flux d'air contenant les particules de diamètre inférieur à 10 μηι de s'écouler vers l'étage 20. Particles with a diameter greater than 10 μηι are deposited on this plate. The openings 108 allow the flow of air containing the particles of diameter less than 10 μηι to flow to the stage 20.
Les trous latéraux 107 peuvent accueillir des moyens de maintien du capteur, par exemple pour fixer les différentes plaques qui forment le capteur. The lateral holes 107 can accommodate means for holding the sensor, for example to fix the different plates that form the sensor.
Selon un mode de réalisation particulièrement avantageux la plaque d'impaction 101 peut être recouverte d'une couche en Teflon® pour faciliter l'adhésion des particules à la surface de la plaque 101 même. According to a particularly advantageous embodiment of the impaction plate 101 can be covered with a Teflon ® layer to facilitate the adhesion of the particles on the surface of the plate 101 even.
La figure 4c représente la plaque d'accélération 203 du flux d'air à niveau de l'étage 20 du capteur 100. La plaque 203 comporte un trou central 205 et des trous latéraux 206. FIG. 4c shows the acceleration plate 203 of the air flow at the level of the stage 20 of the sensor 100. The plate 203 comprises a central hole 205 and lateral holes 206.
Le trou central 205 permet d'accélérer le flux d'air quand il passe à travers cet élément. Les particules de plus grande inertie sont déviées de la trajectoire du flux d'air. Plus particulièrement, les particules de diamètre supérieur à 2,5 μηι sont arrêtées à niveau de la plaque 201 de support du transducteur SAW. The central hole 205 accelerates the flow of air as it passes through this element. The particles of greater inertia are deviated from the path of the air flow. More particularly, particles with a diameter greater than 2.5 μηι are stopped at the level of the support plate 201 of the SAW transducer.
Cet élément permet d'arrêter les particules de diamètre compris entre 10 μηι et 2.5 μηι à niveau de l'étage 20. Les trous latéraux 206 peuvent accueillir des moyens de maintien du capteur, par exemple pour fixer les différentes plaques qui forment le capteur. This element makes it possible to stop the particles of diameter between 10 μηι and 2.5 μηι at the stage 20. The lateral holes 206 can accommodate means for holding the sensor, for example to fix the different plates that form the sensor.
Comme pour l'élément 102, dans ce cas aussi la taille des trous doit être choisie en fonction du débit d'air pour que le filtrage des particules suivant leur taille soit efficace. Selon un mode de réalisation préféré, pour un débit d'air égal à (3 ± 0,3) l/min le trou sur la plaque 203 possède un diamètre de (3,0 ± 0,5) mm. Si un débit de l'ordre de (0,50 ± 0,05) l/min est choisi le trou doit posséder un diamètre de (1 ,0 ± 0,3) mm. En revanche pour un débit plus élevé de l'ordre de (5,0 ± 0,5) l/min la plaque 203 doit posséder deux trous chacun de diamètre égal à (2,0 ± 0,3) mm. La figure 4d montre la plaque 303 d'accélération du flux d'air. La plaque 303 comporte deux trous centraux 305 et des trous latéraux 306. As for the element 102, in this case also the size of the holes must be chosen as a function of the air flow so that the particle filtering according to their size is effective. According to a preferred embodiment, for an air flow rate equal to (3 ± 0.3) 1 / min, the hole on the plate 203 has a diameter of (3.0 ± 0.5) mm. If a flow rate of (0.50 ± 0.05) l / min is chosen, the hole must have a diameter of (1.0 ± 0.3) mm. On the other hand, for a higher flow rate of the order of (5.0 ± 0.5) l / min, the plate 203 must have two holes each of diameter equal to (2.0 ± 0.3) mm. Figure 4d shows the plate 303 of acceleration of the air flow. The plate 303 has two central holes 305 and side holes 306.
Les deux trous centraux 305 permettent d'accélérer le flux d'air quand il passe à travers cet élément. Les particules de plus grande inertie sont déviées de la trajectoire du flux d'air. Plus particulièrement, les particules de diamètre compris entre 2,5 et 0^3 μηι sont arrêtées à niveau de la plaque 301 de support du transducteur SAW. The two central holes 305 make it possible to accelerate the flow of air as it passes through this element. The particles of greater inertia are deviated from the path of the air flow. More particularly, the particles with a diameter of between 2.5 and 0 ^ 3 μηι are stopped at the level of the support plate 301 of the SAW transducer.
Les trous latéraux 306 peuvent accueillir des moyens de maintien du capteur, par exemple pour fixer les différentes plaques qui forment le capteur. The lateral holes 306 can accommodate means for holding the sensor, for example to fix the different plates that form the sensor.
Si un débit d'air de (3,0 ± 0,3) l/min est choisi, selon un mode de réalisation préféré, la plaque 303 possède deux trous, chacun de diamètre égal à (0,8 ± 0,1 ) mm. Pour un débit d'air de (0,50 ± 0,05) l/min la plaque 303 comporte un seul trou de diamètre égal à (0,7 ± 0,1 ) mm. Pour un débit d'air égal à (5,0 ± 0,5) l/min la plaque 303 comprend 2 trous chacun de diamètre égal à (0,9 ± 0,1 ) mm. If an air flow rate of (3.0 ± 0.3) l / min is chosen, according to a preferred embodiment, the plate 303 has two holes, each of diameter equal to (0.8 ± 0.1) mm. For an air flow of (0.50 ± 0.05) l / min the plate 303 has a single hole of diameter equal to (0.7 ± 0.1) mm. For an air flow rate equal to (5.0 ± 0.5) l / min the plate 303 comprises 2 holes each of diameter equal to (0.9 ± 0.1) mm.
Un exemple de dimensionnement des trous des plaques 102, 203 et 303 en fonction du débit d'air à analyser est présenté par le tableau suivant : An example of sizing the holes of the plates 102, 203 and 303 as a function of the air flow to be analyzed is presented by the following table:
Débit (litre par Diamètre des trous Flow rate (liter per hole diameter
N Plaque (figure 4) Nombre de trous  N Plate (Figure 4) Number of holes
minute) (mm)  minute) (mm)
102 1 3,0 ± 0,3  102 1 3.0 ± 0.3
0,50 ± 0,05  0.50 ± 0.05
203 1 1,0 ± 0,3 303 1 0,7 ± 0,1 203 1 1.0 ± 0.3 303 1 0.7 ± 0.1
102 1 7 ± 1  102 1 7 ± 1
3,0 ± 0,3 203 1 3,0 ± 0,5  3.0 ± 0.3 203 1 3.0 ± 0.5
303 2 0,8 ± 0,1  303 2 0.8 ± 0.1
102 1 8 ± 1  102 1 8 ± 1
5,0 ± 0,5 203 2 2 ,0 ± 0,3  5.0 ± 0.5 203 2 2, 0 ± 0.3
303 2 0,9 ± 0,1  303 2 0.9 ± 0.1
Avantageusement, en choisissant un débit compris entre 0,5 et 3 l/min le dispositif a une consommation énergétique réduite, ce qui permet d'avoir une autonomie prolongée. En revanche un débit élevé, même si plus coûteux en terme d'énergie de fonctionnement, permet des acquisitions plus rapides et précises. Advantageously, by choosing a flow rate between 0.5 and 3 l / min the device has a reduced energy consumption, which allows to have an extended autonomy. On the other hand, a high throughput, even if more expensive in terms of operating energy, allows faster and more precise acquisitions.
Selon un mode de réalisation de l'invention le capteur comprend au moins une plaque de support (201 ,301 ) pour les moyens de mesure de la concentration des particules. According to one embodiment of the invention, the sensor comprises at least one support plate (201, 301) for the means for measuring the concentration of the particles.
La figure 5 montre une des plaques de support 201 , 301 des transducteurs SAW 600. Ces plaques ont plusieurs fonctions techniques : FIG. 5 shows one of the support plates 201, 301 of the SAW 600 transducers. These plates have several technical functions:
• Accueillir le transducteur SAW 600 ; • Welcome the SAW 600 transducer;
• Accueillir les circuits imprimés 604 et les connecteurs 60 adaptés pour relier les SAW 600 à l'extérieur ;  • Accommodate 604 PCBs and 60 connectors suitable for connecting SAW 600s to the outside;
• Accueillir les trous 603 nécessaires à l'écoulement de l'air à analyser.  • Accommodate the 603 holes required for the flow of the air to be analyzed.
Les trous latéraux 606 peuvent accueillir des moyens de maintien du capteur, par exemple pour fixer les plaques 201 , 301 aux autres éléments du capteur. The lateral holes 606 can accommodate means for holding the sensor, for example to fix the plates 201, 301 to the other elements of the sensor.
Un avantage de ce mode de réalisation est de permettre l'installation des transducteurs SAW à l'intérieur du capteur 100 tout en assurant la connexion à l'aide de circuits imprimés sur les plaques mêmes. Selon un mode de réalisation de l'invention lesdites plaques de support comportent des ouvertures agencées de façon à permettre la circulation de l'air et la séparation des particules suivant leur taille. An advantage of this embodiment is to allow the installation of the SAW transducers inside the sensor 100 while ensuring the connection using printed circuits on the plates themselves. According to one embodiment of the invention said support plates comprise openings arranged to allow the circulation of air and the separation of particles according to their size.
Un avantage de ce mode de réalisation est de permettre la circulation du flux d'air à niveau des transducteurs, tout en permettant la mesure sélective en taille et en temps réel de la concentration de particules. An advantage of this embodiment is to allow the circulation of airflow at the level of the transducers, while allowing the selective measurement in size and in real time of the concentration of particles.
Selon un mode de réalisation de l'invention, les plaques de support 201 ,301 comportent des connecteurs 60 destinés à l'alimentation du transducteur SAW 600 et à la récupération des signaux correspondant à la mesure de la concentration des particules. According to one embodiment of the invention, the support plates 201, 301 comprise connectors 60 intended to supply the SAW 600 transducer and to recover the signals corresponding to the measurement of the concentration of the particles.
Un avantage de ce mode de réalisation est de pouvoir en même temps alimenter les transducteurs SAW 600 et récupérer les signaux électriques contenant les informations relatives à la concentration de particules. An advantage of this embodiment is that it can at the same time feed the SAW 600 transducers and recover the electrical signals containing the information relating to the concentration of particles.
Chaque transducteur SAW 600 comporte deux surfaces vibrantes : une partie « mesure » et une partie « référence ». Le flux d'air à analyser dépose les particules sur la partie « mesure ». De façon connue, les particules déposées sur cette surface modifient la fréquence de vibration de la surface même, pendant que la fréquence de vibration de la partie « référence » reste inaltérée. En mesurant la différence entre la fréquence originelle et celle altérée par la présence des particules déposées on peut remonter à la masse des particules déposées sur la partie « mesure ». Each SAW 600 transducer has two vibrating surfaces: a "measurement" part and a "reference" part. The airflow to be analyzed deposits the particles on the "measurement" part. In a known manner, the particles deposited on this surface modify the vibration frequency of the surface itself, while the vibration frequency of the "reference" part remains unchanged. By measuring the difference between the original frequency and that altered by the presence of the deposited particles we can go back to the mass of the particles deposited on the "measurement" part.
Les transducteurs SAW 600 sont placés légèrement en décalé de quelques mm par rapport aux trous de passage du flux d'air des éléments 203 et 303. Le décalage des transducteurs SAW 600 par rapport aux trous de passage du flux d'air des éléments 202 et 203 est par exemple compris entre 1 et 5 mm. Cette disposition permet de diriger le flux d'air directement sur la partie « mesure » du transducteur SAW, en laissant inaltérée la fréquence de vibration de la partie « référence ». The SAW 600 transducers are placed slightly offset by a few mm with respect to the airflow passage holes of the elements 203 and 303. The SAW 600 transducer offset relative to the airflow passage holes of the elements 202 and 203 is for example between 1 and 5 mm. This arrangement makes it possible to direct the flow of air directly on the "measurement" part of the SAW transducer, leaving the frequency of vibration of the "reference" part unchanged.
Les peignes interdigités des SAW 600 peuvent être reliés aux circuits imprimés par des microfils en or. The interdigitated SAW 600 combs can be connected to PCBs with gold microfilts.
Selon un mode de réalisation de l'invention, le dispositif comprend des moyens de contrôle du flux d'air à travers les étages connectés en cascade. Un avantage de ce mode de réalisation est la possibilité de régler le débit d'air à travers le dispositif. According to one embodiment of the invention, the device comprises means for controlling the flow of air through the stages connected in cascade. An advantage of this embodiment is the ability to adjust the airflow through the device.
Selon un mode de réalisation de l'invention, les transducteurs SAW 600 présentent une fonctionnalisation mécanique et chimique de leur surface. Un avantage de ce mode de réalisation est de faciliter l'adhésion des particules à la surface du transducteur. According to one embodiment of the invention, the SAW 600 transducers have a mechanical and chemical functionalization of their surface. An advantage of this embodiment is to facilitate adhesion of the particles to the surface of the transducer.
Selon un mode de réalisation de l'invention, les transducteurs SAW 600 présentent une fonctionnalisation mécanique et chimique de leur surface avec une couche en Teflon™. Un avantage de ce mode de réalisation est de faciliter l'adhésion des particules à la surface du transducteur sans les coller définitivement, ce qui est important pour pouvoir nettoyer/régénérer le surface des transducteurs après utilisation. According to one embodiment of the invention, the SAW 600 transducers have a mechanical and chemical functionalization of their surface with a Teflon ™ layer. An advantage of this embodiment is to facilitate adhesion of the particles to the surface of the transducer without permanently bonding them, which is important to clean / regenerate the transducer surface after use.
Selon un mode de réalisation de l'invention la fréquence de vibration des transducteurs SAW est comprise entre 100 et 270 MHz. Un avantage de ce mode de réalisation est d'utiliser une fréquence de vibration plus élevée que celle utilisée dans d'autres systèmes à microbalance, ce qui permet d'augmenter la sensibilité de la mesure de masse. According to one embodiment of the invention, the vibration frequency of the SAW transducers is between 100 and 270 MHz. An advantage of this embodiment is to use a higher vibration frequency than that used in other microbalance systems, which increases the sensitivity of the mass measurement.
Selon un mode de réalisation de l'invention la fréquence de vibration des transducteurs SAW est comprise préférentiellement entre 1 10 et 130 MHz. According to one embodiment of the invention, the vibration frequency of the SAW transducers is preferably between 1 10 and 130 MHz.

Claims

Revendications claims
1 . Capteur pour la mesure en temps réel de la concentration atmosphérique de particules comportant : 1. Sensor for real-time measurement of the atmospheric concentration of particles comprising:
• une entrée d'air adaptée pour recevoir un flux d'air (40) dont la concentration atmosphérique de particules est à mesurer ;  An air inlet adapted to receive an air flow (40) whose atmospheric concentration of particles is to be measured;
• au moins deux étages (20, 30) montés en cascade et configurés pour séparer les particules selon leur taille, ladite entrée d'air étant connectée à au moins un des deux étages ;  At least two stages (20, 30) cascaded and configured to separate the particles according to their size, said air inlet being connected to at least one of the two stages;
• au moins un desdits étages (20, 30) comprenant des moyens de mesure en temps réel de la concentration des particules;  At least one of said stages (20, 30) comprising means for real-time measurement of the concentration of the particles;
le capteur étant caractérisé en ce que :  the sensor being characterized in that:
- lesdits moyens de mesure en temps réel de la concentration des particules comportent au moins un transducteur à Ondes Acoustiques de Surface ou Surface Acoustic Wave (SAW) en anglais ;  said means for measuring in real time the concentration of the particles comprise at least one Surface Acoustic Wave or Surface Acoustic Wave (SAW) transducer in English;
- il comprend au moins une plaque de support (201 ,301 ) pour lesdits moyens de mesure de la concentration des particules ;  it comprises at least one support plate (201, 301) for said means for measuring the concentration of the particles;
- ladite au moins une plaque de support (201 ,301 ) comporte des ouvertures (603) agencées de façon à permettre la circulation de l'air et la séparation des particules suivant leur taille ;  - said at least one support plate (201, 301) has openings (603) arranged to allow the circulation of air and separation of particles according to their size;
- ladite au moins une plaque de support (201 , 301 ) comporte des connecteurs (60) et des circuits imprimés (604) destinés à l'alimentation du transducteur SAW (600) et à la récupération des signaux correspondant à la mesure de la concentration des particules.  said at least one support plate (201, 301) comprises connectors (60) and printed circuit boards (604) for supplying the SAW transducer (600) and for recovering the signals corresponding to the measurement of the concentration. particles.
2. Capteur selon la revendication précédente caractérisé en ce qu'il comprend des moyens de contrôle du flux d'air à travers les étages connectés en cascade. 2. Sensor according to the preceding claim characterized in that it comprises means for controlling the flow of air through the stages connected in cascade.
3. Capteur selon la revendication précédente précédentes caractérisé en ce que le flux d'air à l'intérieur des étages en cascade est réglé pour avoir un débit compris entre 0.45 et 5.5 l/min. 3. Sensor according to the previous preceding claim characterized in that the air flow inside the cascade stages is set to have a flow rate between 0.45 and 5.5 l / min.
4. Capteur selon l'une des revendications précédentes caractérisé en ce qu'il comporte trois étages (10, 20, 30) montés en cascade et configurés pour retenir respectivement les particules de diamètre supérieur à 10 μηι (10), celles de diamètre compris entre 10 μηι et 2,5 μηι (20) et celles de diamètre inférieur à 2,5 μηι (30). 4. Sensor according to one of the preceding claims characterized in that it comprises three stages (10, 20, 30) cascaded and configured to respectively retain the particles of diameter greater than 10 μηι (10), those of diameter included between 10 μηι and 2,5 μηι (20) and those with a diameter less than 2,5 μηι (30).
5. Capteur selon la revendication précédente caractérisé en ce que chacun des trois étages (10, 20, 30) comprend une plaque de filtrage (102, 203, 303), la plaque de filtrage (102) du premier étage (10) comportant au moins un trou de diamètre compris entre 3 mm et 8 mm, la plaque de filtrage (203) du deuxième étage au moins un trou de diamètre compris entre 1 mm et 3 mm et la plaque de filtrage (303) du troisième étage (30) au moins un trou de diamètre compris entre 0,7 et 0,9 mm ; 5. Sensor according to the preceding claim characterized in that each of the three stages (10, 20, 30) comprises a filter plate (102, 203, 303), the filter plate (102) of the first stage (10) having at minus one diameter hole of between 3 mm and 8 mm, the filter plate (203) of the second stage at least one hole of diameter between 1 mm and 3 mm and the filter plate (303) of the third stage (30) at least one hole having a diameter of between 0.7 and 0.9 mm;
6. Capteur selon les revendications 3, 4 et 5, caractérisé en ce que le flux d'air à l'intérieur des étages en cascade est égal à 3 litres par minute, la plaque de filtrage (102) du premier étage (10) comprend un seul trou de diamètre égal à 7 mm, la plaque de filtrage (203) du deuxième étage (20) comprend un seul trou de diamètre égal à 3 mm et la plaque de filtrage (303) du troisième étage (30) comprend deux trous ayant chacun un diamètre de 0,8 mm. 6. Sensor according to claims 3, 4 and 5, characterized in that the air flow inside the cascade stages is equal to 3 liters per minute, the filter plate (102) of the first stage (10) comprises a single hole of diameter equal to 7 mm, the filter plate (203) of the second stage (20) comprises a single hole of diameter equal to 3 mm and the filtering plate (303) of the third stage (30) comprises two holes each having a diameter of 0.8 mm.
7. Capteur selon les revendications 3, 4 et 5 caractérisé en ce que le flux d'air à l'intérieur des étages en cascade est réglé pour avoir un débit de 5 litres par minute, la plaque de filtrage (102) du premier étage (10) comprend un seul trou de diamètre égal à 7 mm, la plaque de filtrage (203) du deuxième étage (20) comprend deux trous de diamètre égal à 2 mm et la plaque de filtrage (303) du troisième étage (30) comprend deux trous ayant chacun un diamètre de 0,9 mm. 7. Sensor according to claims 3, 4 and 5 characterized in that the air flow inside the cascade stages is set to have a flow rate of 5 liters per minute, the filter plate (102) of the first stage (10) comprises a single hole of diameter equal to 7 mm, the filter plate (203) of the second stage (20) comprises two holes of diameter equal to 2 mm and the filtering plate (303) of the third stage (30) includes two holes each having a diameter of 0.9 mm.
8. Capteur selon la revendication 1 et l'une des revendications 5 à 7 caractérisé en ce que Les transducteurs SAW (600) sont placés en décalé par rapport aux trous de passage du flux d'air des plaques de filtrages de sorte à diriger le flux d'air directement sur la partie « mesure » du transducteur SAW, en laissant inaltérée la fréquence de vibration de la partie « référence ». 8. Sensor according to claim 1 and one of claims 5 to 7 characterized in that the SAW transducers (600) are offset from the air flow passage holes of the filter plates so as to direct the airflow directly on the "measurement" part of the SAW transducer, leaving the frequency of vibration of the "reference" part unchanged.
9. Capteur selon l'une des revendications précédentes caractérisé en ce que les transducteurs SAW (600) présentent une fonctionnalisation mécanique et chimique de la surface avec une couche en Teflon™ pour faciliter l'adhésion des particules à la surface du transducteur. 9. Sensor according to one of the preceding claims characterized in that SAW transducers (600) have a functional mechanical and chemical surface with a Teflon ™ layer to facilitate adhesion of particles to the surface of the transducer.
10. Capteur selon l'une des revendications précédentes caractérisé en ce que les transducteurs SAW (600) vibrent à une fréquence comprise entre 100 MHz et 270 MHz. 10. Sensor according to one of the preceding claims characterized in that the SAW transducers (600) vibrate at a frequency between 100 MHz and 270 MHz.
PCT/EP2017/058261 2016-04-06 2017-04-06 Sensor for measuring the concentration of particles in the atmosphere WO2017174726A1 (en)

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