Device for detecting BTEX by using polymer with fluorobenzyl

Abstract

A device (1A) for detecting a BTEX component (3A) in a phase (5A), said device (1A) comprising a sensor (7A) for generating a signal (S) representative of the result of the detection, said sensor comprising a layer (9A) of a material (11A) intended to be in physical contact with said phase, the material comprising a polymer comprising the following sequence: (I) in which R-Bz is a unit repeating n times, n is an integer greater than 10, R is an organic group, and Bz is a substituted benzyl group of formula: (Bz) in which at least three of Z1, Z2, Z3, Z4, and Z5 are independently selected from fluorine atoms, and at most the other two are selected from hydrogen, halogen atoms, and C1-C2 alkyl groups.

Description

TECHNICAL FIELD

[0001] The present invention relates to a device for detecting BTEX components in a liquid phase or in a gaseous phase, comprising a sensor adapted to generate a signal representative of the detection result.

[0002] The present invention also relates to a method for detecting BTEX components using such a device. BACKGROUND

[0003] In the oil and petrochemical industry, BTEX refers to benzene, toluene, ethylbenzene and xylene isomers, these aromatic hydrocarbons being considered either alone or in mixture. BTEX is generally in an aqueous phase. Detecting these chemical components is essential for managing potentially contaminated soils and groundwaters within and from industrial sites. BTEX can also be present in a gaseous phase, for example in a contaminated atmosphere.

[0004] Today, existing solutions are directly deployed in monitoring wells that must be drilled. Sometimes, BTEX is optically measured (for example using ultraviolet light, around 260 nm). However, these direct solutions are expensive and can have calibration problems and generate drifts due to exposure to the contaminant. Moreover, they can expose the operator to the contaminant.

[0005] More traditional indirect solutions require sampling by pumping the groundwater to the surface. The BTEX concentration is then determined in situ using portable analyzers, or subsequently in laboratories remote from the industrial site. However, these solutions introduce a significant delay between sampling and measurement, and losses of contaminant can occur during the transport of the sample.

[0006] To our knowledge, there is no permanent solution of this type of detection. Of course, various techniques are known for detecting all kinds of components, but none is able to solve the problem of detecting chemical components such as BTEX in a liquid phase (for example water-saturated soil) or in a gaseous phase (for example atmosphere). SUMMARY

[0007] The aim of the present invention is to solve or improve the problems mentioned above, in particular in order to allow the detection of BTEX components with good sensitivity and selectivity, in particular in a difficult-to-access underground liquid phase or in an atmosphere.

[0008] To this end, the present invention proposes a device for detecting BTEX components in a liquid phase or in a gaseous phase, said device comprising a sensor adapted to generate a signal representative of the detection result, said sensor comprising at least one layer of material sensitive to BTEX components and intended to be in physical contact with the phase, said material comprising a polymer comprising a sequence of the following formula:

[0009]

[0010] wherein:

[0011] R-Bz is a unit which is repeated n times,

[0012] n is an integer greater than 10,

[0013] R is an organic group, and

[0014] Bz is an at least partially substituted benzyl group of formula:

[0015]

[0016] wherein at least three of Z1, Z2, Z3, Z4and Z5are independently selected to be a fluorine atom, and at most two other of Z1, Z2, Z3, Z4and Z5are selected from the group consisting of hydrogen, a halogen atom and a C1-C2alkyl group.

[0017] In other embodiments, the device comprises one or more of the following features, taken alone or in any technically possible combination:

[0018] - Z1, Z2, Z3, Z4and Z5are fluorine atoms;

[0019] - the R-Bz unit has the formula:

[0020]

[0021] wherein R1is selected from the group consisting of -CH2-, -C2H4- and -C(O)O-, and R2, R3, R4are each independently selected from the group consisting of hydrogen and a C1-C6alkyl group;

[0022] - R1is -C(O)O-;

[0023] - R2is -CH3, and R3and R4are hydrogen;

[0024] - R2, R3and R4are hydrogen;

[0025] - the layer extends on a surface of the sensor and has a thickness perpendicular to the surface, the thickness being comprised between 600 nm and 1000 nm;

[0026] - the sensor is a bulk acoustic wave sensor or a surface plasmon resonance sensor;

[0027] - the sensor is a surface acoustic wave sensor;

[0028] - the sensor comprises:

[0029] - a piezoelectric substrate comprising lithium tantalate, the substrate having a surface extending in a longitudinal direction,

[0030] - an interdigital transducer on said surface for receiving an electrical signal and transmitting an electrical response signal, said interdigital transducer being adapted to convert the signal into surface acoustic waves in a longitudinal direction,

[0031] - at least a first mirror on said surface adapted to receive a first portion of said surface acoustic waves and to generate a first echo towards said interdigital transducer by mechanical reflection and / or re-emission of the first portion of said surface acoustic waves, and

[0032] - at least a first layer comprising said polymer, said first layer being on the surface between said transducer and said first mirror and being adapted to interact with said BTEX components, thereby changing the propagation speed of said first echo along said first layer,

[0033] said transducer being adapted to convert said first echo into at least a portion of said response signal;

[0034] - said sensor further comprises:

[0035] - a second mirror on said surface adapted to receive a second portion of said surface acoustic waves and to generate a second echo towards said transducer by mechanical reflection or re-emission of the second portion of said surface acoustic waves,

[0036] - a second layer of metal and / or polymer on the surface between said transducer and said second mirror,

[0037] - a third mirror on said surface adapted to receive a third portion of said surface acoustic waves and to generate a third echo towards said transducer by mechanical reflection and / or re-emission of said third portion of said surface acoustic waves, and

[0038] - a third layer of metal and / or polymer on the surface between said second mirror and said third mirror,

[0039] said transducer being adapted to receive said second echo and said third echo and to convert said second echo and said third echo into at least a portion of said response signal;

[0040] - said transducer and said first mirror comprise aluminum;

[0041] - said transducer and / or said first mirror is an interdigital transducer having split-fingers extending in a transverse direction perpendicular to said longitudinal direction; and

[0042] - said transducer and / or said first mirror is an interdigital transducer having a sinusoidal apodization.

[0043] The present application also proposes a method for detecting BTEX components in a liquid or gaseous phase, comprising the following steps:

[0044] - obtaining a device as described above,

[0045] - bringing into physical contact the layer and the phase,

[0046] - generating a signal representative of the detection result, and

[0047] - receiving and interpreting the signal. BRIEF DESCRIPTION OF DRAWINGS

[0048] The application and its advantages will be better understood by reading the following description, given solely by way of example and with reference to the appended drawings, in which:

[0049] Figure 1 is a schematic view of a device according to the application,

[0050] Figure 2 is a schematic view of the interaction of the polymers present in the device shown Figure 1 with the BTEX components,

[0051] Figure 3 is a schematic view of the sensor of the device shown Figure 1 in the device shown

[0052] Figure 4 is a schematic view of the sensor of the device shown Figure 3 in the device shown

[0053] Figure 5 is a schematic view of the pattern of interdigital transducers or mirrors of the sensor shown Figure 3 in the device shown Figure 4 in the device shown

[0054] Figure 6 and Figure 7 are schematic views of two patterns forming the pattern shown Figure 5 in the device shown

[0055] Figure 8 is a graph showing the measured delay between the second echo and the first echo (used as a reference) and between the third echo and the first echo, expressed as a phase difference, obtained with the sensor shown Figure 3 in the device shown Figure 4 in the device shown DETAILED DESCRIPTION

[0056] Device and polymer

[0057] A device 1A according to the application will now be described with reference to Figure 1 the drawings.

[0058] The device 1A is suitable for detecting, in a liquid phase or in a gaseous phase 5A, a BTEX component 3A as defined above.

[0059] The device 1A comprises a sensor 7A suitable for generating a signal S representative of the detection result, the sensor 7A comprising at least one layer 9A of material 11A sensitive to the BTEX component 3A and intended to be in physical contact with the phase 5A.

[0060] The sensor 7A is advantageously connected, by wire or wirelessly, to a remote system 13A suitable for receiving the signal S. The sensor 7A can be of different types.

[0061] For example, the sensor 7A is a surface acoustic wave (SAW) sensor.

[0062] In another embodiment, the sensor 7A is a bulk acoustic wave (BAW) sensor.

[0063] As a variant, the sensor 7A is a surface plasmon resonance (SPR) sensor.

[0064] For example, the phase 5A is a liquid (for example groundwater) or a gas (for example the atmosphere).

[0065] The material 11A comprises a polymer comprising a sequence of the following formula (I):

[0066]

[0067] wherein:

[0068] R-Bz is a unit repeated n times,

[0069] n is an integer greater than 10,

[0070] R is an organic radical, and

[0071] Bz is an at least partially substituted benzyl radical.

[0072] Each radical Bz has the following formula (Bz):

[0073]

[0074] wherein at least three of Z1, Z2, Z3, Z4and Z5are independently selected to be fluorine atoms, and at most two others of Z1, Z2, Z3, Z4and Z5are independently selected from hydrogen, a halogen atom and a C1-C2alkyl radical.

[0075] For example, the polymer is formed by said sequence, with a hydrogen or an organic radical, for example an alkyl radical, at both ends of the sequence.

[0076] For example, material 11A comprises at least 90 wt%, preferably at least 99 wt% of polymer, based on the total weight of material 11A.

[0077] The polymer is adapted to selectively interact with BTEX component 3A and to change the propagation velocity of SAW and BAW in the respective sensor, or the optical index in a SPR sensor.

[0078] Without being bound by a technical or scientific explanation, the inventors believe that, as Figure 2 illustrated in Figure 1, wherein the two Bz groups are close enough to each other to be able to interact with the aromatic groups of BTEX component 3A through π-π stacking to retain the BTEX component. This provides selectivity to sensor 7A.

[0079] For example, the two Bz groups involved in the π-π stacking extend in planes PI, P2, preferably parallel to each other, and are spaced apart by a distance Dl comprised between 0.30 and 0.80 nm, preferably between 0.50 and 0.60 nm.

[0080] In case phase 5A is aqueous, the inventors also believe that the at least three fluorine atoms present in each Bz group provide hydrophobicity to the polymer, which helps to attract (arrow Fl) BTEX component 3A by pushing (arrow F2) water molecules 15A away. This provides sensitivity to sensor 7A.

[0081] For example, sensitive layer 9A has a contact angle (characterizing its hydrophobicity) of at least 110°.

[0082] Moreover, it is believed that each Bz group is linked to the R group in the polymer through a -CH2- group, which advantageously provides solubility to the polymer, so that a thin layer of the polymer can be deposited, for example, by spin-coating.

[0083] For example, layer 9A extends on surface 17A of sensor 7A and has a thickness E perpendicular to surface 17A, which is advantageously comprised between 600 nm and 1000 nm.

[0084] For example, n is comprised between 10 and 132.

[0085] In a particular embodiment, all Bz groups in the n units have the same Zl, Z2, Z3, Z4 and Z5. As a variant, some Bz groups can be different from each other.

[0086] “Halogen” means a fluorine, chlorine, bromine or iodine atom.

[0087] Preferably, at least four of Zl, Z2, Z3, Z4 and Z5 are fluorine atoms.

[0088] More preferably, Z1, Z2, Z3, Z4and Z5are fluorine atoms. In other words, the Bz group is a 2,3,4,5,6-pentafluorobenzyl group.

[0089] For example, independently of formula (Bz), the unit R-Bz has the following formula (II):

[0090]

[0091] wherein R1is selected from the group consisting of -CH2-, -C2H4- and -C(O)O-, preferably -C(O)O-, and R2, R3, R4are each independently selected from hydrogen and C1-C6alkyl, preferably C1-C2alkyl.

[0092] Preferably, R1is -C(O)O-.

[0093] In a particular embodiment, R2is -CH3and R3and R4are hydrogen. The polymer is preferably poly(2,3,4,5,6-pentafluorobenzyl methyl methacrylate) or pPFBMA of the following formula (III):

[0094]

[0095] In another particular embodiment, R2, R3and R4are hydrogen. Preferably, the polymer is poly(2,3,4,5,6-pentafluorobenzyl acrylate) or pPFBA of the following formula (IV):

[0096]

[0097] Example of a device with SAW sensor

[0098] Reference will now be made to Figure 3 The device 10 is described.

[0099] The device 10 comprises a device 12 according to the application (equivalent to the device 1A in Figure 1 exposed to the monitored environment, for example buried in the soil 14.

[0100] The device 10 advantageously comprises a system 18 (equivalent to the system 13A in Figure 1 for example located above the soil 14 and adapted to emit an electrical signal 20 to the device 12 and to receive an electrical response signal 22 from the device via a line 24.

[0101] As a variant (not shown), the device 10 can comprise a plurality of devices similar to the one shown and / or a plurality of systems similar to the system 18 shown.

[0102] The soil 14 is for example water-saturated and contains a BTEX component, for example toluene, which is to be detected by the device 10. For example, the BTEX component is carried or pushed by the water present in the soil 14. It is assumed here that the BTEX component and the water constitute a miscible or immiscible water-liquid phase 23. The word "phase" does not imply here that the BTEX component is miscible with water.

[0103] In the illustrated embodiment, the device 10 is advantageously able to detect another chemical component, for example a BTEX different from toluene, or another analyte, for example H2S.

[0104] According to other variants, the device 10 is able to detect more than two different chemical components.

[0105] By "detecting a chemical component", it is meant that the device 10 is adapted to provide information showing the presence of said chemical component in the vicinity of the apparatus 12, preferably in a quantitative or semi-quantitative manner.

[0106] For example, the apparatus 12 is intended to be placed in the soil 14 and is adapted to send information via the response signal 22 when interrogated by the system 18.

[0107] For example, the apparatus 12 comprises a casing 26 permeable to the liquid phase 23 and a sensor 28 located inside the casing.

[0108] As a variant (not shown), the sensor 28 is wireless, for example configured as a co-target of a geological radar, known as GPR. The sensor then comprises an antenna (not shown).

[0109] For example, the casing 26 comprises a grid 34 adapted to let the liquid phase 23 containing the BTEX component flow into the casing.

[0110] The grid 34 is advantageously located in the upper part of the casing 26.

[0111] For example, the sensor 28 Figure 3 and Figure 4 is a SAW sensor.

[0112] As a variant (not shown), the sensor 28 is a BAW or SPR sensor.

[0113] In this embodiment, the sensor 28 comprises a piezoelectric substrate 36 having a surface 38 extending in a longitudinal direction L, and an interdigital transducer IDT located on the surface 38, adapted to convert the signal 20 into a surface acoustic wave 40 in the longitudinal direction L by the piezoelectric effect.

[0114] The sensor 28 advantageously comprises a second mirror M2 and a third mirror M3 located on the surface 38, adapted to receive a second portion and a third portion of the surface acoustic wave 40 and to generate a second echo E2 and a third echo E3 towards the transducer IDT by mechanical reflection or re-emission of said second and third portions of the surface acoustic wave.

[0115] The sensor 28 advantageously comprises a second mirror M2 and a third mirror M3 located on the surface 38, adapted to receive a second portion and a third portion of the surface acoustic wave 40 and to generate a second echo E2 and a third echo E3 towards the transducer IDT by mechanical reflection or re-emission of said second and third portions of the surface acoustic wave.

[0116] The sensor 28 advantageously comprises a second layer 42 of said polymer located on the surface 38 between the transducer IDT and the second mirror M2, and a third layer 43 of the polymer located on the surface 38 between the second mirror M2 and the third mirror M3.

[0117] In a particular embodiment, the sensor 28 further comprises a fourth mirror M4 (only shown in Figure 4 Fig. 2) located on the surface 38, adapted to receive a fourth portion of the surface acoustic wave and to generate a fourth echo E4 towards the transducer IDT by mechanical reflection and / or re-emission of said fourth portion of the surface acoustic wave. The sensor 28 advantageously comprises a fourth layer 45 containing a metal and / or a second polymer, said fourth layer being located on the surface 38 between the first mirror M1 and the fourth mirror M4.

[0118] The sensor 28 is advantageously configured to form a reflection delay line, generating in this embodiment four echoes E1 to E4.

[0119] In this embodiment, the first layer 41, the second layer 42 and the third layer 43 have the same properties, thus providing redundant information.

[0120] The second polymer can be polyisobutylene (PIB).

[0121] In a particular embodiment (not shown), the first echo E1 can be used as a reference for the other echoes.

[0122] In other embodiments (not shown), depending on the properties of the layers 41, 42, 43, 45 and on their number, the echoes can provide information on the shift due to the temperature, and / or the detection of another chemical component (in the case where the second polymer is different from said polymer), and / or redundant information on the detection of the BTEX components or of other elements.

[0123] Depending on the number of mirrors and on the nature of the layer on the surface 38 between the mirror and the transducer IDT, these elements can be located in other relative positions.

[0124] The sensor 28 is advantageously configured so that the surface acoustic waves 40 along the first layer 41 and advantageously along the layers 42, 43 and 45 comprise Love waves. This allows to maximize the energy confinement within the sensor 28 in order to maximize its gravimetric sensitivity.

[0125] The substrate 36 is advantageously made of stoichiometric lithium tantalate (LiTa03), for example YXl / 36°, although any crystalline orientation yielding pseudo-shear waves (for example YXl / 42°) would satisfy the requirements of a sensor operating in liquid.

[0126] The substrate 36 is adapted to propagate pseudo-shear waves, which can be confined on the surface 38 by: metallizing the free surface to slow down the waves and thus confine the energy to the surface by a conductive boundary condition; and / or coating the surface with a polymer whose acoustic speed is slower than the shear waves in the piezoelectric substrate bulk.

[0127] The substrate 36 is for example a rectangular plate having a length in the longitudinal direction L of for example 10 mm and a width in a transverse direction T perpendicular to the longitudinal direction L of for example 3 mm. The substrate 36 has for example a thickness of 300 pm to 500 pm, which is sufficient to avoid interaction of the surface acoustic waves with the opposite side of the wafer.

[0128] In a particular embodiment, the transducer IDT, the first mirror M1, the second mirror M2, the third mirror M3 and the fourth mirror M4 are structurally similar to each other.

[0129] For example, the second mirror M2 and the third mirror M3, if present, are located on one side of the transducer IDT in the longitudinal direction L, while the first mirror M1 and the fourth mirror M4, if present, are located on the other side. For example, the third mirror M3 is farther from the transducer IDT than the second mirror M2, and the fourth mirror M4 is farther from the transducer than the first mirror M1.

[0130] Advantageously, the mirrors are placed along the longitudinal direction L so that the echoes they generate are successively received by the transducer IDT and are easily isolated from each other, for example spaced apart from each other by at least 0.5 ps.

[0131] The transducer IDT is adapted to convert the first echo E1 and, in this embodiment, the second echo E2, the third echo E3 and the fourth echo E4 into a response signal 22 by the piezoelectric effect.

[0132] In this embodiment, the transducer IDT, the first mirror M1, the second mirror M2, the third mirror M3 and the fourth mirror M4 are structurally similar to each other (although not represented in the same way in Figure 3 as in the prior art), since here it is considered at low (sub-500 MHz) frequencies, the electrical re-emission is used as a reflection method, instead of the mechanical reflection of the prior art. Therefore, hereinafter only the transducer IDT will be described.

[0133] As a variant (not shown), the mirrors M1 to M4 can be different from the transducer IDT, and / or can be different from each other, for example by adjusting the number of electrodes in each mirror, so that the return power is the same for all echoes.

[0134] The transducer IDT is advantageously formed of a single patterned metal layer, for example aluminum or gold if corrosion resistance is required.

[0135] The transducer IDT comprises two electrodes 44, 46 Figure 4 and Figure 5 ), respectively comprising two bases 48, 50 extending longitudinally and transversely spaced from each other. The electrodes 44, 46 respectively comprise two sets of finger structures 52, 54 extending transversely from one of the bases 48, 50 towards the other base, and vice versa.

[0136] The transducer IDT is interdigital, the finger structures 52 from one set being alternately arranged with the finger structures 54 from the other set along a midline D parallel to the longitudinal direction L.

[0137] In the embodiment, each finger structure 52 of one set is transversely opposite a corresponding finger structure 54 of the other set.

[0138] The finger structures 52, 54 are transversely spaced by a distance D2 Figure 4 for example 10 pm. The shortest finger structures have a length D3 in the transverse direction T of for example 10 pm.

[0139] In the embodiment shown in Figure 4 and Figure 5 , each of the finger structures 52, 54 is interdigital. Each finger structure is divided into two half-finger structures 52A, 52B. For example, the width of a half-finger structure in the longitudinal direction L is equal to the distance between the half-finger structures.

[0140] In an embodiment, the transducer IDT has a sinusoidal apodization, since in each of the two sets of fingers 52, 54, one of the two finger structures defines a first portion SI of a sinusoidal curve and the other of the two finger structures defines a second portion S2 of the sinusoidal curve in the longitudinal direction L. For example, each of the first portion SI of the sinusoidal curve and the second portion S2 of the sinusoidal curve corresponds to a half-period. The finger structure forming the first portion SI or the second portion S2 of the sinusoidal curve defines a longitudinal period D4, for example 41 pm.

[0141] The finger structures 52, 54 and the bases 48, 50 have a thickness perpendicular to the substrate 36 of, for example, 0.5 pm.

[0142] As a variant, as illustrated in Figure 6 The finger structures 52, 54 are not bifurcated. For example, the width of the finger structures 52, 54 in the longitudinal direction L is equal to the distance between two consecutive finger structures.

[0143] According to another variant, as illustrated in Figure 7 The transducer IDT has a simple apodization structure, since each set of finger structures 52, 54 comprises long finger structures and short finger structures alternating in the longitudinal direction.

[0144] Having bifurcated finger structures and a sinusoidal apodization structure makes the echo advantageously stronger.

[0145] The main mechanism for the transmission of the wave back from the mirror to the IDT is mechanical reflection and re-emission. The former effect is caused by the variation in the speed of sound, which is caused on the one hand by the mechanical mass loading reflection and on the other hand by the change in the electrical boundary conditions as the wave propagates from free space to the electrode-patterned metallized area. It has been noted that these two effects exhibit opposite signals in the case of lithium niobate substrates, while they are superimposed in the case of lithium tantalate. In re-emission, an electric current is induced in the mirror electrodes by the incoming acoustic wave, thus creating a stress in the lattice of the substrate 36 and consequently a new acoustic wave, which propagates in both directions away from the mirror structure patterned as the IDT itself. It is observed that this produces the strongest echo and therefore the lowest insertion loss in the reflection coefficient.

[0146] The polymer layer thickness allows the optimization of the weight sensitivity by the confinement of the acoustic wave in the polymer in Love mode guided waves.

[0147] The layers 41, 42, 43, 45 are advantageously adapted to guide and confine the acoustic wave and its echo within the substrate 36.

[0148] The system 18 is advantageously adapted to use the response signal 22 in order to detect the BTEX components.

[0149] As a variant, the system 18 is adapted to send the response signal 22 to a remote computer (not shown) adapted to use the response signal.

[0150] The central frequency of the signal 20 is for example comprised between 100 and 500 MHz.

[0151] The operation of the device 10 results from its structure and will now be described in order to illustrate the method for detecting BTEX components according to the application.

[0152] In this embodiment, the aim is to detect BTEX components in a water-soluble or immiscible liquid phase in a water-saturated soil 14.

[0153] The signal 20 is for example emitted by the system 18, then received by the transducer IDT and converted into a surface acoustic wave 40 in the longitudinal direction L.

[0154] A first part of the surface acoustic wave 40 is received by the first mirror M1. The first mirror M1 generates a first echo E1 towards the interdigital transducer IDT by mechanical reflection and / or re-emission of said first part of the surface acoustic wave. The first layer 41 ensures that the first part of the surface acoustic wave and the first echo E1 can propagate along the substrate 36.

[0155] A second part and a third part of the surface acoustic wave 40 are received by the second mirror M2 and the third mirror M3, a second echo E2 and a third echo E3 towards the transducer IDT being generated by mechanical reflection or re-emission of said second part and third part of the surface acoustic wave 40.

[0156] In this embodiment, the enclosure 26 allows the liquid phase 23 surrounding the device 12 to be in contact with the first polymer layer 41. In the presence of a BTEX component in the liquid phase 23, the BTEX component interacts with the polymer and modifies the propagation speed of the acoustic wave along the first layer 41 and the third layer 43, thereby affecting the first echo E1 and the third echo E3, as Figure 8 illustrated.

[0157] The first echo E1, the second echo E2 and the third echo E3 are converted by the interdigital transducer IDT into at least one part of the response signal 22. The response signal 22 is representative of the first echo E1, the second echo E2 and the third echo E3.

[0158] The response signal 22 is then used in order to detect the BTEX components and advantageously other chemical components.

[0159] Thanks to the above-described features, the device 12 allows detecting BTEX components with good sensitivity and selectivity.

[0160] Examples of synthesis and deposition of polymers

[0161]

[0162] Ten grams of 2,3,4,5,6-pentafluorobenzyl alcohol (50.5 mmol) were reacted with 7 mL (47 mmol) of methacrylic anhydride at 110 °C for 4 hours.

[0163] The obtained crude was washed thoroughly with a 10% w / v aqueous solution of potassium carbonate. The pure compound was obtained by distillation of the mixture (Bp: 118 °C at 40 mbar).

[0164]

[0165] Three mL of (2,3,4,5,6-pentafluorobenzyl)methyl acrylate were heated with 40 mg of benzoyl peroxide as catalyst at 70 °C for 2 hours to obtain the corresponding polymer. The transparent block was dissolved in 20 mL of dichloromethane and the solution was added dropwise in 200 mL of ethanol. Poly(2,3,4,5,6-pentafluorobenzyl methyl acrylate) (pPFBMA) was filtered as a white powder.

[0166] The pPFBMA was characterized by FTIR spectroscopy and by XPS analysis. 1 The number of repeating units was determined to be 50 by deep analysis of the H NMR spectrum.

[0167] A lithium tantalate piezoelectric substrate 36 of a reflective delay line acoustic sensor made by patterning Al interdigital electrodes and a mirror was thoroughly washed with dichloromethane, acetone, ethanol and isopropanol. The surface was activated by anisotropic oxygen plasma for 5 minutes. A monolayer of TiPrime (adhesion promoter) was deposited by spin coater (speed 3000 rpm, acceleration 900 rpm 2 for 30 s). Then, a solution of 15% w / v pPFBMA in 1,2-dichloroethane was deposited under the same spin coating conditions to obtain a polymer layer with a thickness of 600-1000 nm.

[0168] Then, the functionalized acoustic sensor was baked at 110 °C for 2 hours.

[0169] Experimental detection of BTEX

[0170] A SAW sensor 28 as described above (layers 41, 42 and 43 of functionalized pPFBMA with a thickness of 850 nm) was exposed to aqueous solutions with different concentrations of toluene, rinsing with water after each exposure to toluene. The phase change was monitored using the sensor at a working frequency of 100 MHz as a function of the duration of the exposure.

[0171] The results are shown in Figure 8 where the first echo E1 Figure 8Figure 6: Phase shift (in degrees) of the first echo El (top) and the third echo E3 (bottom) as a function of time (in hours).

[0172] where f is the sensor center frequency and τ is the time delay of the echoes, 800 ns for the first echo El and 2400 ns for the third echo E3, resulting in a differential measurement where dτ is the difference in time delay between the echoes.

[0173] The phase shift is proportional to the toluene concentration and the acoustic delay, the echo E3 is returned by a mirror located three times the delay away from the echo El.

[0174] This experiment demonstrates that the sensor can effectively detect toluene in aqueous solution. The measurements were made using a Rohde & Schwarz ZVC8 vector network analyzer in a wired configuration. The time domain response of the sensor was derived from the frequency domain measurements of the network analyzer by calculating the inverse Fourier transform and selecting the phase at the maximum return power.

[0175] The sequence of toluene concentration exposures in water was as follows:

[0176] 1) 0.19 g.L -1

[0177] 2) 0.05 g.L -1

[0178] 3) 0.12 g.L -1

[0179] 4) 0.14 g.L -1

[0180] 5) 0.19 g.L -1

[0181] The concentration was derived from the UV absorption of the solution near 260 nm.

[0182] When the SAW sensor 28 was exposed to toluene-water solutions, a strong decrease in phase was observed. The phase shift was proportional to the toluene concentration. The solution was then flushed with water, bringing it back to the initial baseline (i.e. no phase shift).

[0183] In this experiment, toluene was injected at a concentration of 0.19 g / 1 between 0.5 and 1 hour after the baseline in water, followed by water injection to return to the baseline level, indicating the reversibility of the sensing layer to toluene absorption. At 2.5 hours, toluene was injected at a concentration of 0.05 g / 1, followed by toluene at 0.12 g / 1, then flushed in pure water at 5 hours to return to baseline. Between 5.5 and 12 hours, another series of three concentrations was injected, with increasing concentrations in the order of 0.14 g / 1, 0.15 g / 1 and 0.19 g / 1, with water flushing between each exposure step to return to baseline, until the entire setup was washed with water from 12 to 25 hours, indicating the stability of the polymer layer 41 to long-term exposure to water.

[0184] This experiment was performed in a laboratory setup with minimal temperature variation (less than 1 K during the experiment), allowing for reproducible analysis of the measurements with two sensing layers 41 and 42 made from the same polymer layer.

[0185] All toluene concentrations in water were measured at the beginning and end of the exposure sequence using UV-Vis absorbance at 261 and 268 nm.

[0186] In another practical embodiment, the layers 41, 42 and 43 can be different as described above.

[0187] The layers 41 and 42 were also checked for insensitivity to the presence of non-BTEX components, such as ethanol. The sensor was exposed to an ethanol-water solution with 10 wt% ethanol, and no phase shift was measured.

Claims

1. A device (1A; 12) for detecting a BTEX component (3A) in a liquid or gaseous phase (5A), said device comprising a sensor (7A; 28) adapted to generate a signal (S) indicative of the result of the detection, said sensor (7A; 28) comprising at least one layer (9A; 41) of a material (11A) sensitive to said BTEX component (3A) and intended to be in physical contact with the phase (5A), said material (11A) comprising a polymer comprising a sequence of the following formula (I): wherein: R-Bz is a unit repeated n times, n is an integer greater than 10, R is an organic group, and Bz is a benzyl group at least partially substituted of the following formula (Bz): wherein: at least three of Z1, Z2, Z3, Z4 and Z5 are independently selected to be fluorine atoms, and at most two other of Z1, Z2, Z3, Z4 and Z5 are selected from hydrogen, a halogen atom and a C1-C2 alkyl group. Z1, Z2, Z3, Z4 and Z5 are fluorine atoms. said unit R-Bz has the following formula (II): wherein: R1 is selected from the group consisting of -CH2-, -C2H4- and -C(O)O-, and R2, R3, R4 are each independently selected from hydrogen and a C1-C6 alkyl group. R1 is -C(O)O-. R2 is -CH3 and R3 and R4 are hydrogen. R2, R3 and R4 are hydrogen. said layer (11A; 41) extends on a surface (17A; 38) of said sensor (7A; 28) and has a thickness (E) perpendicular to said surface (17A; 38), said thickness (E) being comprised between 600 nm and 1000 nm. said sensor (7A) is a bulk acoustic wave sensor or a surface plasmon resonance sensor.

2. The device (1A; 12) according to claim 1, wherein said sensor (28) is a surface acoustic wave sensor.

3. The device (1A; 12) according to claim 1 or 2, wherein said sensor (28) comprises: - a piezoelectric substrate (36) comprising lithium tantalate, said substrate (36) having a surface (38) extending in a longitudinal direction (L), - an interdigital transducer (IDT) located on said surface (38) for receiving an electrical signal (20) and transmitting an electrical response signal (22), said interdigital transducer (IDT) being adapted to convert the signal (20) into surface acoustic waves (40) in the longitudinal direction (L), - at least a first mirror (M1) located on said surface (38) adapted to receive a first portion of said received surface acoustic waves (40) and to generate a first echo (E1) towards said interdigital transducer (IDT) by mechanical reflection and / or re-emission of said first portion of said surface acoustic waves (40), and 4. The device (1A; 12) according to claim 3, wherein - at least a first layer (41) comprising said polymer, said first layer (41) being located on the surface (38) between said transducer (IDT) and said first mirror (M1) and being adapted to interact with said BTEX component so as to change the propagation speed of said first echo (E1) along said first layer (41), 5. The device (1A; 12) according to claim 4, wherein said transducer (IDT) being adapted to convert said first echo (E1) into at least a portion of said response signal (22).

6. The device (1A; 12) according to claim 4, wherein said sensor (28) further comprises:

7. The device (1A; 12) according to any one of claims 1 to 6, wherein ​ 8. The device (1A) according to any one of claims 1 to 7, wherein, ​ 9. The apparatus (12) according to any one of claims 1 to 7, wherein, ​ 10. The apparatus (12) of claim 9, wherein, ​ ​ ​ ​ ​ ​ 11. The apparatus (12) of claim 10, wherein, ​ - a second mirror (M2) located on the surface (38) and adapted to receive a second portion of the surface acoustic wave (40) and to generate a second echo (E2) towards the transducer (IDT) by mechanical reflection or re-emission of the second portion of the surface acoustic wave (40), - a second layer (42) of metal and / or polymer located on the surface (38) between the transducer (IDT) and the second mirror (M2), - a third mirror (M3) located on the surface (38) and adapted to receive a third portion of the surface acoustic wave (40) and to generate a third echo (E3) towards the transducer (IDT) by mechanical reflection and / or re-emission of the third portion of the surface acoustic wave (40), and - a third layer (43) of metal and / or polymer located on the surface (38) between the second mirror (M2) and the third mirror (M3), the transducer (IDT) being adapted to receive the second echo (E2) and the third echo (E3) and to convert the second echo (E2) and the third echo (E3) into at least a portion of the response signal (22).

12. The apparatus (12) of claim 10 or 11, wherein The transducer (IDT) and the first mirror (M1) comprise aluminum.

13. The apparatus (12) according to any one of claims 10 to 12, wherein, The transducer (IDT) and / or the first mirror (M1) is an interdigital transducer having interdigital fingers (52, 54) extending in a transverse direction (T) perpendicular to the longitudinal direction (L).

14. The apparatus (12) according to any one of claims 10 to 13, wherein, The transducer (IDT) and / or the first mirror (M1) is an interdigital transducer having sinusoidal-shaped tapers (S1, S2).

15. A method of detecting a BTEX component (3A) in a liquid or gaseous phase (5A), comprising the steps of: - obtaining a device (1A; 12) according to any one of claims 1 to 14, - bringing the layer (11A; 41) into physical contact with the phase (5A), - generating a signal (S; 22) representative of the detection result, and - receiving and interpreting the signal (S; 22).

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