Pressure measurement device

Abstract

The present description relates to a pressure measurement device for a fluid circuit comprising a substrate (10) covered by N piezoelectric sensors (11) disposed in line on the same face of the substrate (10), N being an integer greater than or equal to 2, each piezoelectric sensor (11) comprising at least one organic piezoelectric layer (103) disposed between a first electrode (101) and a second electrode (102).

Description

DESCRIPTION TITLE: Pressure measuring device This application is based on, and claims priority from, French patent application number FR 23 / 12869 filed on November 22, 2023, entitled “Pressure measuring device”, which is considered to be an integral part of this description within the limits provided by law. Technical field

[0001] This description relates generally to devices for measuring pressure in a fluid, for example the devices can be used for measuring blood pressure, pressure in hydraulic systems or pressure in air circuits. Prior art

[0002] Pressure measuring devices for hydraulic systems can be used to detect leaks. These devices are stationary and allow pressure to be measured at fixed points. Each sensor gives a pressure at a given time. Leaks are detected when there is a pressure difference between the fixed points.

[0003] In the case of surgery, the devices used allow the measurement of coronary flow reserve (FFR for “Fractional Flow Reserve”). This measurement provides access to a value at a single point.

[0004] Thus, the different measuring devices give a value at a single point. They do not allow localized pressure gradients to be obtained in areas of interest. Summary of the invention

[0005] There is a need for a device to measure pressure and pressure gradients, in order to be able to identify possible overpressures or depressions due to pathologies or to detect possible leaks, in a precise manner.

[0006] This aim is achieved by a pressure measuring device for a fluid circuit comprising a substrate covered by N piezoelectric sensors arranged in line on the same face of the substrate with N an integer greater than or equal to 2, each piezoelectric sensor comprising at least one organic piezoelectric layer arranged between a first electrode and a second electrode.

[0007] Advantageously, N is between 2 and 10, preferably between 5 and 10.

[0008] Advantageously, the piezoelectric sensors comprise between 1 and 10 organic piezoelectric layers, preferably between 7 and 10 organic piezoelectric layers.

[0009] Advantageously, each piezoelectric sensor has a length of between 5 mm and 10 cm, preferably between 1 and 4 cm, and a width of between 1 mm and 2 cm, preferably between 1 mm and 1 cm.

[0010] Advantageously, each organic piezoelectric layer has a thickness of between 3 and 15 μm, preferably between 3 and 5 μm.

[0011] Advantageously, each organic piezoelectric layer is made of PVDF, or one of its copolymers, such as P(VDF-TrFE).

[0012] Advantageously, the first electrode and the second electrode are made of an electrically conductive polymer, preferably PEDOT-PSS.

[0013] Advantageously, the piezoelectric sensors are covered by an encapsulation layer of a polymer material, for example, PDMS, PMMA, PVDF or one of its derivatives.

[0014] This aim is also achieved by a method of manufacturing a pressure measuring device comprising a substrate covered by N piezoelectric sensors arranged in line on the same face of the substrate with N an integer greater than or equal to 2, each piezoelectric sensor comprising at least one organic piezoelectric layer arranged between a first electrode and a second electrode, a vacuum annealing step being carried out to crystallize the piezoelectric layer.

[0015] This aim is also achieved by a method for measuring the pressure in a fluid circuit, the method comprising a step during which a pressure measuring device is introduced into the fluid circuit, the measuring device comprising a substrate covered by N piezoelectric sensors arranged in line on the same face of the substrate with N an integer greater than or equal to 2, each piezoelectric sensor comprising at least one organic piezoelectric layer arranged between a first electrode and a second electrode, the pressure on the N piezoelectric sensors being measured independently, whereby it is determined whether the pressure is identical on the N piezoelectric sensors or whether the pressure is different between the N piezoelectric sensors. Brief description of the drawings

[0016] These and other features and advantages will be detailed in the following description of modes of particular realizations made without limitation in relation to the attached figures among which:

[0017] Figure 1 represents, schematically and in three dimensions, a device according to a particular embodiment of the invention;

[0018] Figure 2 shows, schematically and in section, a device according to another particular embodiment of the invention;

[0019] Figure 3 shows, schematically and in section, a device according to another particular embodiment of the invention;

[0020] Figure 4 represents, schematically and in top view, a device according to another particular embodiment of the invention;

[0021] Figure 5 is a graph representing the polarization as a function of the applied field for a device having a PEN substrate and for a device having a PI substrate, according to different particular embodiments of the invention;

[0022] Figure 6 is a graph representing the polarization as a function of the applied field for a device having been annealed at 150°C for 15 min and for a device having been subjected to vacuum annealing at 150°C for 15 min, according to different particular embodiments of the invention;

[0023] Figure 7 is a graph showing relative permittivity as a function of frequency for a device annealed at 150°C for 15 min and for a device annealed in vacuum at 150°C for 15 min, according to different particular embodiments of the invention;

[0024] Figure 8 is a graph showing current versus voltage for devices having PEN and PI substrates, the devices having been subjected to vacuum annealing at 150°C for 15 min, according to different particular embodiments of the invention;

[0025] Figure 9 is a graph showing relative permittivity versus frequency for devices having PEN and PI substrates, the devices having been subjected to vacuum annealing at 150°C for 15 min, according to various particular embodiments of the invention; and

[0026] Figure 10 is a graph showing resistance versus frequency for devices having PEN and PI substrates, the devices having been subjected to vacuum annealing at 150°C for 15 min, according to various particular embodiments of the invention. Description of the embodiments

[0027] The same elements have been designated by the same references in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same references and may have identical structural, dimensional and material properties.

[0028] For the sake of clarity, only the steps and elements useful for understanding the embodiments described have been represented and are detailed.

[0029] Unless otherwise specified, when referring to two elements connected together, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") together, this means that These two elements can be connected or linked through one or more other elements.

[0030] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "upper", "lower", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made unless otherwise specified to the orientation of the figures.

[0031] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "of the order of" mean to within 10%, preferably to within 5%.

[0032] Subsequently, we will more specifically describe devices for measuring blood pressure or the pressure in plumbing pipes or air conditioning circuits.

[0033] The device is interesting not only for measuring overpressure or depression in a fluid, but also for detecting the position of an anomaly.

[0034] The device is particularly interesting for vascular and cardiac surgery because the multiple sensors also allow blood pressure to be determined and any excess or depression pressures due to pathologies to be identified.

[0035] In surgery, measurement at several points simultaneously is particularly advantageous, unlike prior art devices which only allow measurement at a single point.

[0036] The device is also particularly interesting for leak detection in hydraulic systems. The device allows measurement in several points simultaneously, unlike prior art devices which are stationary and measure pressure between separate devices. With prior art devices, leaks are detected between two fixed points, which does not allow the exact origin of a leak to be determined.

[0037] In the case of plumbing maintenance (for example for hydraulic circuits or air circuits), the device can detect possible leaks even if invisible or inaccessible from the outside.

[0038] However, the device can also be used to measure pressure in any type of fluid.

[0039] We will now describe the device in more detail with reference to the attached figures.

[0040] As shown in Figures 1, 2 and 3, the pressure measuring device for a fluid circuit comprises a substrate 10 covered by N piezoelectric sensors 11 arranged in line on the same face of the substrate 10.

[0041] N is an integer greater than or equal to 2.

[0042] The device may comprise between 2 and 10 sensors 11 arranged in line on the same face of the substrate 10, preferably between 5 and 10 sensors 11 arranged in line on the same face of the substrate 10. By between X and Y, it is meant here and hereinafter that the terminals are included.

[0043] Each sensor 11 comprises at least one organic piezoelectric layer 103 arranged between a first electrode 101 (also called lower electrode) and a second electrode 102 (also called upper electrode).

[0044] The device is fundamentally distinguished from the prior art by the presence of several sensors organic piezoelectrics 11 arranged in line on the same face of the substrate 10.

[0045] When pressure is applied to a sensor 11, it is mechanically deformed, which generates an electrical signal. The sensors 11 can be deformed independently of each other, which allows for a detailed analysis of the pressure at several points in the fluid circuit.

[0046] Thus, each of the sensors 11 provides information on the pressure. By processing the information from the different sensors 11, it is possible to determine whether there is overpressure or underpressure. It is also possible to determine the position of the anomaly precisely.

[0047] The device comprising the sensors is elongated, preferably portable, capable of measuring pressures and pressure gradients. This device allows any area of ​​the duct to be reached.

[0048] The substrate 10 comprises a first main face 10a and a second main face 10b.

[0049] According to an advantageous embodiment, the sensors 11 are arranged only on one of the faces of the substrate, for example on the first face 10a (figure 3).

[0050] According to another advantageous embodiment, the device comprises a first line of N sensors 11 arranged on the first face of the substrate 10a and a second line of N' sensors arranged on the second main face 10b of the substrate 10. Preferably, N is identical to N'.

[0051] Even more preferably, as shown in figures 1 and 2, the sensors 11 of the first line are arranged opposite the sensors 11 of the second line (i.e. N = N').

[0052] The arrangement of sensors 11 on either side of the substrate 10 makes it possible to have a flat, undeformed substrate 10. Preferably, the sensors 11, arranged opposite one another, are identical.

[0053] Thus, the device can comprise PN portions of sensors 11, with N greater than or equal to 2. Preferably, each PN portion of sensors comprises a sensor 11 arranged on the first face 10a of the substrate 10 or each PN portion of sensors comprises a first sensor 11 arranged on the first face 10a of the substrate 10 and a second sensor 11 arranged on the second face 10b of the substrate 10.

[0054] Preferably, the sensors 11 comprise between 1 and 10 piezoelectric layers 103. When the sensor 11 comprises several piezoelectric layers 103, the sensor 11 is formed from a stack comprising an alternation of piezoelectric layers 103 and electrodes 101, 102. In other words, the stack is formed from a pattern 100 comprising a piezoelectric layer 103 arranged between two electrodes 101, 102. The stack begins and ends with an electrode.

[0055] Each sensor 11 has a length L, for example, between 0.1 and 3 cm, preferably between 2 mm and 2 cm.

[0056] Each sensor 11 has, for example, a width 1 of between 0.1 cm and 2 cm, preferably between 0.1 cm and 1 cm.

[0057] Each piezoelectric layer 103 has a thickness, for example, between 3 and 15 μm, preferably between 3 and 5 μm. With such thicknesses, the detection of overpressures / depressions is facilitated.

[0058] The distance L' between two sensors 11 is, for example, between 0.1 and 1 cm, preferably between 0.1 and 0.5 cm.

[0059] The different sensors 11 may have the same or different dimensions. Preferably, the dimensions are identical.

[0060] For example, as shown in Figure 2, the device comprises three sensor portions P1, P2, P3. Each sensor portion comprises a sensor arranged on either side of the substrate 10. The first sensor portion P1 comprises sensors 11 having a single piezoelectric layer 103 (i.e. a single pattern 100). The second sensor portion P2 comprises sensors 11 having 4 piezoelectric layers (i.e. 4 patterns 100). The third sensor portion P3 comprises sensors 11 having two sensor layers (i.e. 2 patterns 100). The dimensions (length and thickness in particular) of the sensors 11 are different here.

[0061] The piezoelectric layers 103 are organic piezoelectric layers. Each piezoelectric layer 103 preferably comprises a polymer matrix made of PVDF or a PVDF copolymer. It may be a copolymer of vinylidene fluoride and at least one other monomer copolymerizable with VDF. Advantageously, the copolymer comprises at least 50 mol%, preferably at least 70 wt%, even more preferably at least 80 mol% of VDF, or even at least 90 mol% of VDF.

[0062] By way of illustration, the copolymerizable monomer(s) are, for example, chosen from chlorotrifluoroethylene (CTFE), chlorofluoroethylene (CFE), hexafluoropropylene (HEP), trifluoroethylene (VF 3 ), methyl methacrylate (MMA), tetrafluoroethylene (TFE), and perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl) ether (PMVE).

[0063] For example, the copolymer is a copolymer of poly(vinylidene fluoride-trifluoroethylene) PVDF / TrFe, also denoted P(VDF-TrFe) or PVDF-CTFE.

[0064] According to another embodiment, the polymer is not a ferroelectric polymer: it may be PVDF-HFP.

[0065] Each organic piezoelectric layer 103 may be a composite material. For example, the layer 103 may comprise, in addition to the polymer matrix, ferroelectric particles.

[0066] For example, ferroelectric particles are made of BaTiOs (BTO), PZT (lead zirconate titanoate), AIN, ZnO, or even SBN (Sr-Ba-Nb oxide) or SBT (Sr-Ba-Ti oxide).

[0067] Preferably, the electrodes 101, 102 are made of an electrically conductive polymer, preferably PEDOT-PSS (poly(3,4-ethylenedioxythiophene).

[0068] The electrodes 101, 102 have, for example, a thickness of between 0.1 and 3 μm, preferably between 1.5 and 2.5 μm.

[0069] The materials forming the different sensors 11 may be identical or different. Preferably, they are identical. Even more preferably, each sensor 11 comprises electrodes 101, 102 made of PEDOT-PSS and a piezoelectric layer 103 made of P(VDF-TrFe).

[0070] The substrate 10 may be a flexible substrate, that is to say it may deform reversibly.

[0071] The substrate 10 may be made of polyimide or PEN for example.

[0072] The thickness 10 of the substrate is, for example, between 25 pm and 125 pm.

[0073] The length of the substrate 10 will depend on the number of sensors. For example, it is between 0.5 and 20 cm, preferably between 0.5 cm and 10 cm.

[0074] The width l' of the substrate 10 may be between 1 mm and 2 cm, preferably between 2 mm and 2 cm.

[0075] Preferably, the length / width ratio of the substrate is between 1 and 100 and even more preferably between 3 and 20.

[0076] The substrate 10 has an elongated shape and can be used in narrow conduits.

[0077] Electrical connection means are arranged to carry the signal from the sensors to the receiver.

[0078] Several solutions can be considered to route the electrical signal from the sensors to the receiver.

[0079] According to a first embodiment, the connection is made by means of electrical wires (i.e. electrically conductive wires). The wires are, for example, in an electrically insulating sheath. The wires can be braided or positioned concentrically.

[0080] According to another embodiment, the connection is made by means of electrical tracks (i.e. electrically conductive tracks). The tracks can be printed on the substrate 10. The tracks can be arranged on a single face of the substrate 10 or on both faces of the substrate 10.

[0081] The tracks can be made of a metal (gold or silver for example) or an electrically conductive polymer material. For example, the electrically conductive polymer material is PEDOT:PSS. It can also be a polymer in which electrically conductive particles, for example carbon particles, are dispersed.

[0082] Several configurations are possible, in order to connect the electrical tracks and / or the electrical wires.

[0083] For example, it is possible to cover a portion of the lower electrode 101 with one of the electrical tracks.

[0084] The electrical tracks and / or electrical wires may be connected to the lower electrode 101 of a sensor by means of an electrically conductive glue (e.g., charged epoxy type) or by means of soldering.

[0085] Optionally, an electrically conductive plate (for example made of metal, in particular copper) can be positioned on the substrate 10, on the one hand, glued or welded to the lower electrode 101 and, on the other hand, glued or welded to the electric wire or to the electric track.

[0086] According to another embodiment, mechanical systems such as staples or rivets can be used to connect the sensor electrode to the wire or track.

[0087] The various connections can be covered with a cap. In particular, it is possible to use an electrically conductive cap. For example, the cap can include nanoparticles. The cap can be used to plug any holes and / or prevent breakdown phenomena.

[0088] It is also possible to increase the stiffness of the substrate 10 by locally adding an additional layer on the substrate. For example, this may be a polymer layer. The polymer may be the same or different from the polymer of the substrate. It may also be a metallized polymer layer. The polymer layers may be deposited by bonding. Alternatively, the additional layer is a dielectric layer, for example printed by screen printing. It may also be a metal foil. The foil may have a thickness between 10 and 1000 pm, preferably between 10 and 100 pm. The sheet can be made of zinc or aluminum.

[0089] The ground connection can be shared to divide the number of electrical tracks / wires. This reduces the footprint of the connections, and thus reduces the size of the substrate. This is particularly advantageous for small diameter fluid circuits, typically in the case of surgery.

[0090] The substrate 10 and the sensors 11 may be covered by an encapsulation layer. The encapsulation layer may be made of a polymer material, for example, polydimethylsiloxane (PDMS), poly(methyl methacrylate) (PMMA), polyvinylidene fluoride (PVDF) or a derivative thereof.

[0091] Encapsulation can be achieved by dipping, thermal evaporation or spraying a solution. The encapsulation step is advantageously carried out once the electrical connections have been made.

[0092] Radiopaque elements may be added to the device, for example, on the substrate 10 or on the encapsulation layer, between the sensor portions 11, in order to be able to ensure visual tracking of navigation in the target system. The elements are, for example, in the form of crosses, squares or dots.

[0093] The pressure measuring device can be made in the following steps:

[0094] a) depositing N electrically conductive zones on a substrate 10, the electrically conductive zones being arranged in line and being intended to form first electrodes 101,

[0095] b) forming piezoelectric layers 103 on the electrically conductive areas,

[0096] c) forming second electrodes 102 on the piezoelectric layers 103.

[0097] Thus, each piezoelectric sensor 11 comprises at least one organic piezoelectric layer 103 arranged between a first electrode 101 and a second electrode 102.

[0098] Steps a), b) and c) may be repeated to form a stack comprising several active layers. During the iteration, step a) is performed on the underlying piezoelectric layer 103.

[0099] The method further comprises a vacuum annealing step carried out to crystallize the piezoelectric layer.

[0100] In step b), the piezoelectric material layer can be deposited by spin coating. Other types of localized deposition can be used, such as screen printing or spraying, or even inkjet deposition. Preferably, the piezoelectric layer is deposited by screen printing. In one pass, the deposited thickness is between 1 and 20 μm. It is possible to superimpose several layers by screen printing until the desired final thickness is reached.

[0101] The method also includes a step of crystallizing the piezoelectric material layer. This irradiation is for example carried out with UV flash light, with a flash or pulse duration of between approximately 500 ps and 2 ms, a fluence (energy delivered per unit area) of between approximately 15 J / cm 2 and 25 J / cm 2, and with light of wavelength between approximately 200 nm and 380 nm. The number of flashes, or pulses, of UV light produced during this irradiation varies depending on the thickness over which the piezoelectric material is to be crystallized. For example, for a thickness of P(VDF-TrFe) equal to about 2 pm, the irradiation can be implemented with a fluence equal to about 17 J / cm 2 , a pulse duration equal to approximately 2 ms and a number of pulses equal to 5.

[0102] The piezoelectric material, possibly having undergone previous crystallization, is then subjected to annealing, for example, carried out at approximately 130°C for approximately 60 min, to finalize the total crystallization of the material.

[0103] The crystallization of the material can therefore be carried out in two stages: firstly, irradiation by UV light pulse to properly crystallize the second face of the material layer in order to increase its thermal conductivity, then thermal annealing completing the crystallization for the rest of the material not crystallized by the previous irradiation.

[0104] Alternatively, annealing can be carried out under vacuum. For example, this can be annealing at a temperature between 100 and 150°C. The pressure is, for example, 1 mbar. Vacuum annealing is, for example, carried out for a duration between 1 and 3 min.

[0105] When the piezoelectric material is a P(VDF-TrFe) based copolymer, a polarization step of the material is carried out before its use. This step can be carried out, for example, by applying a direct current voltage to its terminals, via the electrodes. This polarization is carried out only once for the entire lifetime of the material. This polarization by direct current can be done at room temperature or hot (up to about 100°C). When the polarization is carried out at room temperature, it is possible to apply a direct voltage up to about 150V / pm of layer thickness for a duration for example between a few seconds and a few minutes. For example, a voltage of 120V / pm will be applied for 20s. When the polarization is carried out hot, for example at a temperature of around 90°C, a direct voltage for example between approximately 50 V and 80 V per micron of layer thickness can be applied for a duration for example between approximately 1 min and 5 min. The temperature is then lowered until it reaches room temperature, then the electric field applied to the material, via the applied direct voltage, is stopped. Such polarizations allow PVDF to achieve a remanent polarization between 6 pC / cm 2 and 9 pC / cm 2 , for example about 8 pC / cm 2 .

[0106] The dipoles inside the layer remain oriented in this way, even when the material is no longer subjected to this electric field. The material can be polarized in this way by applying an initial polarization voltage across the electrodes. A material thickness of less than or equal to about 2 μm will preferably be chosen to promote the polarization of the material of this capacity, and the level of the electric voltage applied between the electrodes to achieve the initial polarization of the material (when the material must be initially polarized).

[0107] Annealing is advantageously carried out at the end of the process or between the different stages. Annealing is, for example, at a temperature between 100°C and 150°C, preferably around 100°C to remove residual traces of solvent and / or finalize the crystallization of the material.

[0108] At the end of the process, contact is advantageously made.

[0109] The device is simple to use. It allows you to measure the pressure in a fluid circuit (gas or liquid). The measurement process includes the following steps: - Introduce the pressure measuring device as described previously into the fluid circuit, - Measure the pressure on the N piezoelectric sensors 11, the pressure of each sensor 11 being measured independently, whereby it is determined whether the pressure is identical on the N piezoelectric sensors 11 or whether the pressure is different between the N piezoelectric sensors 11.

[0110] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will occur to those skilled in the art.

[0111] Finally, the practical implementation of the embodiments and variants described is within the reach of the person skilled in the art from the functional indications given above.

[0112] Illustrative and non-limiting examples of different embodiments

[0113] In these examples, the substrate with an area of ​​1 mm x 1 cm is locally covered by sensor portions. The sensors comprise PVDF-TrFE piezoelectric layers. The electrodes are made of PEDOT:PSS.

[0114] The substrate is either poly(ethylene naphthalate) (PEN) or polyimide (PI). First, the piezoelectric layers are polarized (Figure 5).

[0115] The influence of annealing on polarization and permittivity was also studied: one of the devices was subjected to a simple anneal at 150°C for 15 minutes and the other of the devices was subjected to a vacuum anneal (1 mbar) at 150°C for 15 minutes. The substrates are made of PI for these measurements (Figures 6 and 7). The vacuum annealing is preferred to simple annealing because it allows to obtain active layers with fewer grain boundaries and therefore less electrical leakage. The performance of the sensor is improved

[0116] Figures 8, 9 and 10 show different properties (intensity as a function of applied voltage, permittivity as a function of frequency, resistance as a function of frequency) of the devices depending on the nature of the substrate (PEN or PI). These devices were subjected to vacuum annealing at 150°C for 15 min.

Claims

CLAIMS 1. Pressure measuring device for a fluid circuit comprising a substrate (10) covered by N piezoelectric sensors (11) arranged in line on the same face of the substrate (10) with N an integer greater than or equal to 2, each piezoelectric sensor (11) comprising several organic piezoelectric layers (103), each organic piezoelectric layer (103) being arranged between a first electrode (101) and a second electrode (102).

2. Pressure measuring device according to claim 1, characterized in that N is between 2 and 10, preferably between 5 and 10.

3. Pressure measuring device according to one of the preceding claims, characterized in that the piezoelectric sensors (11) comprise between 7 and 10 organic piezoelectric layers (103).

4. Pressure measuring device according to any one of the preceding claims, characterized in that each piezoelectric sensor (11) has a length of between 5 mm and 10 cm, preferably between 1 and 4 cm, and a width of between 1 mm and 2 cm, preferably between 1 mm and 1 cm.

5. Pressure measuring device according to any one of the preceding claims, characterized in that each organic piezoelectric layer (103) has a thickness of between 3 and 15 μm, preferably between 3 and 5 μm.

6. Pressure measuring device according to any one of the preceding claims, characterized in that each organic piezoelectric layer (103) is made of PVDF, or one of its copolymers, such as P(VDF-TrFE).

7. Pressure measuring device according to any one of the preceding claims, characterized in that the first electrode (101) and the second electrode (102) are made of an electrically conductive polymer, preferably PEDOT-PSS.

8. Pressure measuring device according to any one of the preceding claims, characterized in that the piezoelectric sensors (11) are covered by an encapsulation layer made of a polymer material, for example, PDMS, PMMA, PVDF or one of its derivatives.

9. Method for manufacturing a pressure measuring device comprising a substrate (10) covered by N piezoelectric sensors (11) arranged in line on the same face of the substrate (10) with N an integer greater than or equal to 2, each piezoelectric sensor (11) comprising several organic piezoelectric layers (103), each organic piezoelectric layer being arranged between a first electrode (101) and a second electrode (102), The method being characterized in that a vacuum annealing step is carried out to crystallize the organic piezoelectric layers (103).

10. Method for measuring the pressure in a fluid circuit, the method comprising a step during which a pressure measuring device is introduced into the fluid circuit, the measuring device comprising a substrate (10) covered by N piezoelectric sensors (11) arranged in line on the same face of the substrate (10) with N an integer greater than or equal to 2, each piezoelectric sensor (11) comprising several organic piezoelectric layers (103), each organic piezoelectric layer (103) being arranged between a first electrode (101) and a second electrode (102), the pressure on the N piezoelectric sensors (11) being measured independently, whereby it is determined whether the pressure is identical on the N piezoelectric sensors (11) or whether the pressure is different between the N piezoelectric sensors (11).

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