PIEZOELECTRIC ELEMENT WITH EXTENDED LIFESPAN, ITS USE AND CORRESPONDING NEBULIZATION DEVICE

Abstract

This element (I) comprises a plate (1) made of a piezoelectric material which has, on the acoustic wave emission face, a first electrode (2) cooperating with a single connecting wire (4) and, on the opposite face (12), a second electrode (3) cooperating with two electrical connecting wires (5, 6) fixed on extensions (32, 34) of this second electrode. According to the invention, each wire (5, 6), cooperating with the second electrode (3) is such that the total geometric cross-section (π(D5)2 / 4) of the second wire is between 0.15 and 0.40 square millimeters (mm2), the diameter (d5) of each strand of this wire is between 0.035 and 0.060 millimeters (mm), and the total number of strands (n) is between 100 and 160. This combination of values ​​gives sufficient flexibility to the wire, thus reducing the mechanical stresses exerted at the junction between the strands and the brazing pad.This flexibility also allows the use of wires with small radial dimensions, ensuring use in an environment that promotes miniaturization. Figure for the abbreviation: [Fig. 5].

Description

Title of the invention: PIEZOELECTRIC ELEMENT WITH AN EXTENDED LIFESPAN, ITS USE AND CORRESPONDING NEBULIZATION DEVICE Technical field of the invention

[0001] The invention relates to the technical field of spraying devices capable of producing a mist of microdroplets from a liquid, and more particularly to devices in which microdroplets are generated by a piezoelectric element. More specifically, the invention relates to such a miniaturized device, which can be integrated into a small volume, and / or which allows for very precise control of the amount of mist generated. State of the art

[0002] Spraying devices capable of producing a microdroplet mist from a liquid by piezoelectric excitation are known as such. In these systems, the piezoelectric element can be combined with a micro-perforated membrane or an acoustic concentrator to promote mist production.

[0003] Nebulizing devices are particularly well known in which a piezoelectric element in contact with a volume of liquid generates ultrasonic waves that cause the formation of a mist of very small droplets. This size typically depends on the acoustic frequency of the excitation. It is typically between 2 pm and 10 pm for an acoustic frequency typically between 0.5 MHz and 5 MHz, and decreases as the acoustic frequency increases.

[0004] Such devices are described for example in WO 2017 / 093655 (ARECO). They typically take the form of a cylindrical plate with a circular diameter of about 5 mm to about 50 mm and a thickness of about 1 mm to 2 mm.

[0005] These piezoelectric wafers are commonly found in specialized stores, in various diameters and thicknesses. They are manufactured by sintering powders of a piezoelectric material. Two electrodes are then deposited on this wafer to allow their subsequent connection within an electrical circuit. Typically, the first face of the wafer receives a first electrode, which is generally a ground electrode, while the second opposite face receives a phase electrode.

[0006] Each electrode is made electrically contacted with a connecting element, for example an electrical wire, which allows the connection between the wafer and a remote electrical circuit. Electrical contact is generally achieved by a solder joint, but can also be achieved by other means, such as a layer of conductive adhesive.

[0007] By WO 2023 / 275843, the applicant sought to improve the service life of such piezoelectric wafers. To this end, this document provides for extension zones in the second electrode, and then assigns a connecting element to each of these extension zones. In other words, the current of the second electrode, generally the phase electrode, is distributed across two connections. The applicant has found that this reduces the connection failure rate as well as the number of failed connections.

[0008] The teaching of WO 2023 / 275843 makes it possible to significantly extend the service life of piezoelectric elements compared to the prior art, notably that of WO 2017 / 093655. Nevertheless, the applicant sought to further increase this service life. This aspect is particularly important from a financial point of view, since an extended service life reduces the frequency of maintenance technician interventions at the installation site of devices equipped with piezoelectric elements. Such a site is, for example, a supermarket, if the device is used for nebulizing fresh food products.

[0009] In view of the above, the invention aims to provide a piezoelectric element whose lifespan is further extended, compared to that conforming to the teaching of WO 2023 / 275843.

[0010] The invention also aims to provide such a piezoelectric element, the cost of which is not significantly higher than that which is the subject of WO 2023 / 275843.

[0011] The invention finally aims to provide such a piezoelectric element, which can be conveniently installed in an existing device, in particular an existing nebulizing device, previously equipped with a piezoelectric element of the prior art.

[0012] Objects of the invention

[0013] According to the invention, at least one of the above objectives is achieved by means of a piezoelectric element (I) for an acoustic wave emission device, said piezoelectric element comprising a plate (1) made of a piezoelectric material, of substantially cylindrical shape, in particular of circular cross-section with, in particular, a diameter between 5 mm and 100 mm, preferably between 10 mm and 50 mm, and with a thickness between 0.4 mm and 2.0 mm, preferably between 0.5 mm and 2.0 mm,

[0014] said plate comprising on a first face (10), called the "front face", which is the acoustic wave emission face, a first metallic conductivity layer capable of acting as a first electrode (2), forming in particular a disk and extending over at least 50%, and preferably at least 70% of the surface of said front face,

[0015] and said plate comprising on a second face (12), referred to as the "rear face", a second metallic conductivity layer capable of acting as a second electrode (3) and extending over at least 10%, preferably at least 20%, and even more preferably at least 50% of the surface of said rear face, said second electrode (3) comprising a body (30), in particular disc-shaped, as well as at least two extensions (32, 34) extending radially outwards from the body,

[0016] said piezoelectric element comprising a single electrical connecting wire (4) fixed to the first electrode (2) by means of a respective first fastening member (40) further ensuring an electrical connection, and at least two second electrical connecting wires (5, 6) fixed to the second electrode (3) at a respective extension (32, 34) by means of a respective second fastening member (7, 8) further ensuring an electrical connection

[0017] characterized in that at least the section of each second wire (5, 6), adjacent to the second electrode (3) and, in particular, the entirety of each second wire satisfies the following combination of values, denoted Kl:

[0018] - the total geometric cross-section (ir(D5)2 / 4) of the second wire is between 0.15 and 0.40 square millimeters (mm2),

[0019] - the diameter (d5) of each strand, forming said second wire, is between 0.035 and 0.060 millimeter (mm); and

[0020] - the total number of strands (n) is between 100 and 160.

[0021] According to other features, which can be implemented, individually or in any technically compatible combinations, with the piezoelectric element above:

[0022] - at least the section of each second wire, adjacent to the second electrode, verifies the the following combination of values, denoted K2

[0023] - the total geometric cross-section of the second wire is between 0.20 and 0.35 square millimeters (mm2),

[0024] - the diameter (d5) of each strand is between 0.040 and 0.055 millimeters (mm); and

[0025] - the total number of strands (n) is between 110 and 150.

[0026] - at least the section of each second wire, adjacent to the second electrode is, in In particular, the entirety of each second wire satisfies the following combination of values, denoted K3

[0027] - the total geometric cross-section of the second wire is between 0.25 and 0.30 square millimeters (mm2),

[0028] - the diameter (d5) of each strand is between 0.045 and 0.050 millimeters (mm); and

[0029] - the total number of strands (n) is between 120 and 140.

[0030] - each second fastening member (7,8) has a so-called contact face (71) ensuring both mechanical and electrical contact with a respective connecting wire (3,4), said contact face being located at a distance (D71) from the periphery (14) of the plate, such that the ratio (D71 / D1) between this distance and the diameter (Dl) of the plate (1) is less than 1 / 10, preferably 1 / 20.

[0031] - each second fastening member (7,8) has a so-called contact face (71) ensuring both mechanical and electrical contact with a respective connecting wire (3,4), said contact face being located at a distance (D71) from the periphery (14) of the plate having a value of less than 3 mm, preferably 2 mm.

[0032] - at least the section of each first wire (4), adjacent to the first electrode (2) and, in particular, the entirety of each first wire satisfies the combination of values ​​K1, preferably the combination of values ​​K2, even more preferably the combination of values ​​K3.

[0033] The invention also relates to the use of the above piezoelectric element in a nebulizing device.

[0034] The invention finally relates to a nebulization device comprising at least one piezoelectric element such as above. Description of the figures

[0035] The invention will be described below, with reference to the accompanying drawings, given solely by way of non-limiting examples, in which:

[0036] [Fig.1] is a perspective view, illustrating a piezoelectric element according to the invention.

[0037] [Fig.2] is a front view, showing in particular the rear face of the element piezoelectric according to the invention.

[0038] [Fig.3] is a large-scale end view illustrating the structure of a wire of connection used in the piezoelectric element according to the invention.

[0039] [Fig.4] is a much larger scale view, illustrating the electrical connection between an electrode belonging to the piezoelectric element as well as the connecting wire of the [Fig.3].

[0040] [Fig.5] is another view on a much larger scale, according to arrow V on [Fig.4], illustrating this electrical connection from another angle. Detailed description

[0041] Figures 1 and 2 illustrate a piezoelectric element according to the invention, which is designated as a whole by reference numeral I. This element comprises, firstly, a cylindrical plate 1 with a circular cross-section, which is produced by sintering a powder of a piezoelectric material. Its principal axis, forming the generator, is denoted XI, its opposite faces 10 and 12, and its lateral wall 14. In what follows, the first face 10 will be referred to as the "front face," while the second face 12 will be referred to as the "back face." The diameter DI of the plate is typically between 5 and 100 millimeters (mm), preferably between 10 and 50 millimeters. Furthermore, the thickness El of this same plate is typically between 0.4 mm and 2.0 mm, preferably between 0.5 mm and 2.0 mm.

[0042] The front face 10 is equipped with a first electrode 2, forming a ground electrode, which extends over at least 50% and, preferably, at least 70% of the front face. In a manner known per se, this electrode is extended by a band 20 covering a portion of the side wall 14, and then by a termination 22 extending to the outer periphery of the rear face 12. This geometry, commonly called a "wrap-up electrode," advantageously allows the first electrode 2 to make contact with the second face 12 of the wafer 1, thanks to the termination 22.

[0043] The rear face 12 is equipped with a second electrode 3, forming a phase electrode, which extends over at least 10%, preferably at least 20%, and even more preferably at least 50% of the rear face. According to the teaching of WO 2023 / 275843, this electrode 3 comprises a disc-shaped main body 30, extended radially outwards by extensions 32 and 34. With particular reference to [Fig. 2], it is noted:

[0044] - C3 the center of electrode 3,

[0045] - C22, C32 and C34 are the respective centers of termination 22 as well as extensions 32.34

[0046] - D22, D32 and D34 are the diameters connecting the center C3 of the electrode and the centers C22, C32 and C34 respectively.

[0047] In the illustrated embodiment, the angle a22 between the first adjacent diameters D22 and D32 is, for example, between 5 and 90 degrees, in particular between 10 and 45 degrees. Furthermore, the angle a32 between the other adjacent diameters D32 and D34 is, for example, between 5 and 270 degrees, in particular between 5 and 180 degrees, more particularly between 10 and 90 degrees.

[0048] This piezoelectric element I is suitable for use in electrotechnical devices, performing an ultrasonic emission function. Conventionally, the ultrasonic emission occurs through the front face 10, with the rear face 12 providing the electrical connection. For this purpose, electrical connection elements are provided, linking electrodes 2 and 3 with an electrical circuit (not shown), of any suitable type.

[0049] A first electrical connecting wire 4 cooperates with the first electrode 2 via a solder pad 40, shown schematically. Furthermore, in accordance with the teaching of WO 2023 / 275843, a pair of second electrical connecting wires 5 and 6 cooperate with the second electrode 3 at the extensions 32 and 34. For this purpose, two respective solder pads 7 and 8, each made of any suitable material, are provided on each of these extensions. Each pad 40, 7, and 8 forms a fixing element for each wire, also ensuring electrical contact between the aforementioned wire and a respective electrode.

[0050] We will now describe in more detail both the structure of the wire 5 and the solder pad 7, it being understood that the structure of the other wire 6 and its solder pad 8 are identical. As shown in [Fig. 3], the connecting wire 5 is formed by a multiplicity of strands labeled 5a to 5n, with n representing the total number of strands. Advantageously, each conductive strand is solid while having a circular cross-section. The material constituting the various arms is typically copper, generally in the so-called annealed metallurgical state.

[0051] Figures 4 and 5 schematically illustrate the solder pad 7. In these figures, this pad is represented in a generally parallelepiped shape.

[0052] - 70 denotes its so-called lower face for connection with the termination 32 belonging electrode 2,

[0053] - 71 its so-called inner lateral face for connection with wire 5,

[0054] - 72 its so-called upper face opposite face 70,

[0055] - 73 its so-called outer lateral face opposite face 71, as well as

[0056] - 74 and 75 its two other so-called transverse faces.

[0057] As can be seen more particularly in [Fig. 5], each of the strands 5a to 5n is in both mechanical and electrical contact with the solder pad. In [Fig. 5], the contact areas Za and Zi, between the pad 7 and two of the conductive strands 5a and 5i, are shown more specifically.

[0058] The very nature of the connecting wire, which impacts its interaction with the soldering pad, constitutes an essential feature of the present invention, distinguishing it from WO 2023 / 275843. It should be noted that, in the latter document, the applicant had sought to add at least one electrical connection element compared to what was previously known, in order to increase the lifespan of the piezoelectric element. However, in WO 2023 / 275843, the applicant considered that protecting the soldering pad from mechanical stresses did not extend this lifespan.

[0059] On the contrary, in the present invention, the applicant has focused on the specific structure of the connecting wire 5. In particular, it has identified that increasing the flexibility of the connecting wire reduces the stresses exerted on the solder pad. This reduction in stress ensures a more durable electrical contact between the constituent strands of the wire and the solder pad, which allows for a significant extension of the overall lifespan of the piezoelectric element.

[0060] The flexibility of the connecting wire 5 can be characterized by the combination of the following parameters, namely

[0061] - the total geometric cross-section of this wire 5, which corresponds to ir(D5)2 / 4, the diameter D5 of the wire being referenced on [Fig.3];

[0062] - the diameter of each strand, denoted d5 in [Fig.3], it being understood that it is assumed that the different arms have the same diameter; and

[0063] - the total number of strands, which we have seen is equal to m

[0064] As can be seen in [Fig. 3], the strands do not occupy the entire geometric cross-section of the wire. In other words, adjacent strands are separated by empty areas 52. The total geometric cross-section, as defined above, is therefore greater than the total conductive cross-section, which can be defined as the number of strands multiplied by the cross-section of each of these strands.

[0065] According to the invention, the following combination, denoted Kl, of wire parameters makes it possible to significantly increase the lifespan of the piezoelectric element I. In this regard, this combination is as follows:

[0066] - total geometric cross-section ir(D5)2 / 4 of wire 5, between 0.15 and 0.40 square millimeters (mm2),

[0067] - diameter d5 of each strand, between 0.035 and 0.060 millimeters (mm); and

[0068] - total number n of strands, between 100 and 160.

[0069] It should be noted that the overall cross-section above can also be expressed according to the AWG (American Wire Gauge) standard. In essence, this cross-section corresponds to an AWG between approximately 21 and approximately 25. It should be recalled that the overall geometric cross-section above is greater than the product of the diameter of each strand and the total number of these strands, given the presence of empty areas between adjacent strands.

[0070] According to an advantageous feature of the invention, the following combination, denoted K2, of wire parameters makes it possible to increase in a particularly significant way the lifetime of the piezoelectric element I. With this in mind, the combination is as follows:

[0071] - total geometric cross-section of wire 5 between 0.20 and 0.35 square millimeters (mm2), i.e. an AWG between approximately 22 and approximately 24;

[0072] - diameter of each strand between 0.040 and 0.055 millimeters (mm); and

[0073] - total number of strands between 110 and 150.

[0074] According to a particularly advantageous feature of the invention, the following combination, denoted K3, of wire parameters makes it possible to significantly increase the lifespan of the piezoelectric element I. In this regard, this combination is as follows:

[0075] - total geometric cross-section of the wire between 0.25 and 0.30 square millimeters (mm2), i.e. a AWG close to 23;

[0076] - diameter of each strand between 0.045 and 0.050 millimeters (mm); and

[0077] - total number of strands between 120 and 140.

[0078] The applicant has observed that the combinations K1 to K3, presented above, induce the following technical effects. Firstly, they provide sufficient flexibility to the wire to significantly reduce the mechanical stresses exerted at the junction between the wire strands and the solder pad. This flexibility also allows the use of wires with small radial dimensions, thus enabling their use in an environment conducive to miniaturization.

[0079] On the other hand, the applicant has found that it is not advantageous to produce wires with a flexibility exceeding that conferred by the aforementioned ranges of values. Indeed, if the flexibility is further increased, no additional reduction in mechanical stress between the strand junction and the solder pad will be achieved. On the contrary, a wire with excessively high flexibility has a structure that is susceptible to weakening, which is contrary to the desired technical effect.

[0080] Furthermore, increasing the number of strands 5a to 5n constituting wire 5, compared to the prior art materialized by WO 2023 / 275843, makes it possible to maintain a sufficient number of functional contact areas, such as those Za and Zi in [Fig. 5]. This ensures electrical continuity between the connecting wire and the solder pad and, consequently, the correct operation of the piezoelectric element.

[0081] According to a particularly advantageous feature of the invention, the face 71 of the solder pad 7 is located in the immediate vicinity of the periphery of the wafer, namely its lateral wall 14. Let D71 denote the distance separating this face 71 from this lateral wall 14. Advantageously, the ratio D71 / D1 between this distance D71 and the diameter DI of plate 1 is less than 1 / 10, preferably 1 / 20. Furthermore, the value of this distance D71 is advantageously less than 3 mm, preferably 2 mm.

[0082] Positioning the connection face 71 of the solder pad in the immediate vicinity of the periphery of the wafer further reduces the risk of the connecting strands 5a to 5n detaching from this solder pad. Without being bound by theory, this phenomenon can be explained by the fact that the further this connection face is from the center of the wafer, the less it is subjected to vibrations that could cause the aforementioned strands to detach from the solder pad.

[0083] With further reference to Figures 1 and 2, a tube 9 extends around the periphery of a portion of the wires 4, 5, and 6. This prevents uncontrolled movement between these wires, which could increase the risk of them being pulled away from the solder pad. Advantageously, the material of this tube is chosen so as not to significantly reduce the flexibility of the wires at their junction with the solder pad. For example, this material could be chosen from the silicone family.

[0084] The fabrication of the piezoelectric element I, as described above, is carried out according to steps known per se. This fabrication includes, in particular, the deposition of electrodes 2 and 3 onto wafer 1, the deposition of protective coatings not shown on these electrodes, the polarization of the wafer, and the deposition of additional protective coatings. These different phases conform to those described, for example, with reference to [Fig. 1] of document WO 2023 / 275843, previously discussed.

[0085] It can be seen that for a piezoelectric element according to the invention, the average lifespan is significantly extended thanks to the overall increase in the flexibility of each second wire. This lifespan was measured, firstly, for a significant number of plates satisfying the Kl combination above. Secondly, this same lifespan was measured for a significant number of plates according to the prior art.

[0086] Each of these prior art plates is equipped with three wires, namely one connecting wire to the first electrode and two connecting wires to the second electrode. The latter have a cross-section close to that of the wires according to the invention. However, the number of strands constituting each of these prior art wires is significantly lower than in the invention, since this number is close to 10. Consequently, the cross-section of each of the prior art strands is considerably larger than according to the invention. It has been noted an extension of the lifespan of approximately 30%, for the group of pads according to the invention, compared to the pads according to the prior art.

[0087] The applicant observed that the increase in the lifespan of the piezoelectric element, achieved through a more flexible connecting wire, is particularly significant for the phase electrode 3. In contrast, this effect is considerably less noticeable for the ground electrode 2. Consequently, the connecting wire 4 can be of any suitable type, particularly one conforming to the prior art. It is nevertheless advantageous, at least in some cases, for it to have a flexibility close to that of wires 5 and 6, namely, to satisfy one of the combinations K1, K2, or K3 above.

[0088] The invention is applicable to other geometric arrangements between the solder pads, allowing the connection of the three wires 4, 5 and 6. By way of examples not shown, the solder pads 7 and 8 can be located on the same side of the solder pad 40, but at angles different from those a22 and a32. Alternatively, these solder pads 7 and 8 can be provided on either side of the pad 40.

[0089] In the example described and illustrated, the fastening element is formed by a solder pad. As an alternative, equivalent solutions can be provided, ensuring both mechanical fastening and electrical continuity. These include, among others, a layer of conductive adhesive.

[0090] The invention also finds application in a piezoelectric element comprising more than two connecting wires on the phase electrode. In this case, each of these wires has a flexibility as defined above with reference to wire 5, namely that it conforms to one of the combinations K1, K2, or K3. However, since this embodiment does not allow for a significant reduction in the failure rate compared to the main embodiment shown in the preceding figures, the additional cost of this solution is justified only in specific cases.

[0091] In the example described and illustrated, the entire length of each connecting wire 5 and 6, and possibly also 4, possesses the flexibility defined above. However, in some cases, it is possible that only the section of these wires located near the solder pads exhibits such flexibility. The other sections of these wires may then exhibit less flexibility.

[0092] The invention applies particularly to nebulization systems designed to generate a so-called dry fog with a droplet size typically between approximately 1 µm and approximately 10 µm. It is advantageously implemented with piezoelectric elements in the form of a cylindrical plate, the circular diameter of which is between approximately 10 mm and approximately 30 mm, preferably between approximately 12 mm and approximately 25 mm, and even more preferably between 12 mm and 25 mm. Their thickness determines their resonant frequency; it is advantageously between approximately 0.5 mm and approximately 2 mm, preferably between approximately 0.8 mm and approximately 1.3 mm. In an advantageous embodiment, the plate has a circular diameter between 15 mm and 25 mm and a thickness between 0.5 mm and 2.0 mm, and preferably between 0.6 mm and 1.7 mm.

[0093] By way of example, for a thickness of approximately 1 mm, the resonant frequency is on the order of 1.7 MHz. For a greater thickness, the resonant frequency decreases, while for a smaller thickness, it increases. Such a piezoelectric element with a diameter of 20 mm can absorb a current typically between approximately 2 A and approximately 2.5 A, with the power absorbed being on the order of 40 W to 50 W. Generally speaking, for use in a nebulizing device, a piezoelectric element with an acoustic emission frequency between 0.5 MHz and 10 MHz is advantageously chosen.

Claims

1. Demands Piezoelectric element (I) for an acoustic wave emission device, said piezoelectric element comprising a plate (1) made of a piezoelectric material, of substantially cylindrical shape, in particular of circular cross-section, with a diameter of between 5 mm and 100 mm, preferably between 10 mm and 50 mm, and with a thickness of between 0.4 mm and 2.0 mm, preferably between 0.5 mm and 2.0 mm, said plate comprising on a first face (10), referred to as the "front face", which is the acoustic wave emission face, a first metallic conductivity layer capable of acting as a first electrode (2), forming in particular a disk and extending over at least 50%, and preferably at least 70%, of the surface area of ​​said front face, and said plate comprising on a second face (12), referred to as the "rear face", a second metallic conductivity layer capable of acting as a second electrode (3) and extending over at least 10%preferably at least 20%, and even more preferably at least 50% of the surface area of ​​said rear face, said second electrode (3) comprising a body (30), in particular disc-shaped, and at least two extensions (32, 34) extending radially outwards from the body, said piezoelectric element comprising a single electrical connecting wire (4) fixed to the first electrode (2) by means of a respective first fastening member (40) further ensuring an electrical connection, and at least two second electrical connecting wires (5, 6) fixed to the second electrode (3) at the level of a respective extension (32, 34) by means of a respective second fastening member (7, 8) further ensuring an electrical connection characterized in that at least the section of each second wire (5, 6) adjacent to the second electrode (3) and, in particular, the entire length of each second wire satisfies the following combination of values,noted Kl:, - the total geometric cross-section (ir(D5)2 / 4) of the second wire is between 0.15 and 0.40 square millimeters (mm2), - the diameter (d5) of each strand, forming said second wire, is between 0.035 and 0.060 millimeter (mm); and - the total number of strands (n) is between 100 and 160.

2. Piezoelectric element according to claim 1, characterized in that at least the section of each second wire, adjacent to the second electrode, satisfies the following combination of values, denoted K2 - the total geometric cross-section of the second wire is between 0.20 and 0.35 square millimeters (mm2), - the diameter (d5) of each strand is between 0.040 and 0.055 millimeters (mm); and - the total number of strands (n) is between 110 and 150.

3. Piezoelectric element according to claim 2, characterized in that at least the section of each second wire, adjacent to the second electrode, is, in particular, the entirety of each second wire satisfies the following combination of values, denoted K3 - the total geometric cross-section of the second wire is between 0.25 and 0.30 square millimeters (mm2), - the diameter (d5) of each strand is between 0.045 and 0.050 millimeters (mm); and - the total number of strands (n) is between 120 and 140.

4. Piezoelectric element according to any one of the preceding claims, characterized in that each second fixing member (7,8) has a so-called contact face (71) ensuring both mechanical and electrical contact with a respective connecting wire (3,4), said contact face being located at a distance (D71) from the periphery (14) of the plate, such that the ratio (D71 / D1) between this distance and the diameter (Dl) of the plate (1) is less than 1 / 10, preferably 1 / 20.

5. Piezoelectric element according to any one of the preceding claims, characterized in that each second fixing member (7,8) has a so-called contact face (71) ensuring both mechanical and electrical contact with a respective connecting wire (3,4), said contact face being located at a distance (D71) from the periphery (14) of the plate having a value of less than 3 mm, preferably 2 mm.

6. Piezoelectric element according to any one of the preceding claims, characterized in that at least the section of each first

7.

8. wire (4), adjacent to the first electrode (2) and, in particular, the entirety of each first wire satisfies the combination of K1 values, preferably the combination of K2 values, even more preferably the combination of K3 values. Use of a piezoelectric element according to any one of the preceding claims, in a nebulizing device. Nebulizing device comprising at least one piezoelectric element according to any one of claims 1 to 6.

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