Magnetoelectric sensor and preparation method thereof

Abstract

The invention relates to the technical field of magnetic detection, in particular to a magnetoelectric sensor and a preparation method thereof. A magnetoelectric sensor comprises a permanent magnet; the magnetoelectric composite part is provided with a magnetoelectric unit comprising a magnetostrictive material layer and piezoelectric material layers electrically and fixedly arranged on the two sides of the magnetostrictive material layer; the circuit module is electrically connected with the magnetoelectric composite part and is provided with a circuit board used for processing an input electric signal generated by the magnetoelectric composite part; and the shell is made of a material capable of shielding set frequency interference and is provided with a first cavity for accommodating the permanent magnet, the magnetoelectric composite part and the circuit module. The invention aims to provide the magnetoelectric composite part with higher precision and higher magnetoelectric coefficient.

Description

Technical Field

[0001] The present invention relates to the field of magnetic detection technology, and in particular to a magnetoelectric sensor and a preparation method thereof. Background Art

[0002] Magnetic sensors are devices that convert changes in the magnetic properties of sensitive components caused by external factors such as magnetic fields, currents, stress and strain, temperature, and light into electrical signals, thereby detecting the corresponding physical quantity. Currently, magnetic sensors are widely used in various fields of national economy, national defense construction, and daily life. With the advent of the information society, the status and role of magnetic sensors will become even more prominent. To date, more than 20 types of magnetic sensors have been launched on the market.

[0003] The operating principles of magnetic sensors primarily include electromagnetic induction, the Hall effect, and the magnetoresistance effect. Magnetoelectric sensors, among others, convert measured quantities (such as vibration, displacement, and rotational speed) into electrical signals through magnetoelectric effects. Using the principle of electromagnetic induction, magnetoelectric sensors convert input motion velocity into an induced potential output. Without the need for an auxiliary power supply, they can convert the mechanical energy of the measured object into an easily measurable electrical signal.

[0004] However, in existing magnetoelectric sensors, a research focus is on how to improve the magnetoelectric coefficient and thus improve the magnetoelectric performance of the magnetoelectric sensor. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the object of the present invention is to provide a magnetoelectric sensor and a preparation method to provide a magnetoelectric composite with higher precision and higher magnetoelectric coefficient.

[0006] To achieve the above objectives, the first aspect of the present invention provides the following technical solution: a magnetoelectric sensor, characterized in that it includes a permanent magnet; a magnetoelectric composite component having a magnetoelectric unit including a magnetostrictive material layer and a piezoelectric material layer electrically fixedly arranged on both sides of the magnetostrictive material layer; a circuit module electrically connected to the magnetoelectric composite component and having a circuit board for processing the input electrical signal generated by the magnetoelectric composite component; and a housing made of a material that can shield interference of a set frequency and having a first cavity for accommodating the permanent magnet, the magnetoelectric composite component, and the circuit module.

[0007] As an embodiment of the present invention, the circuit module also includes a guide frame and a battery, the magneto-electric composite and the battery are respectively arranged on both sides of the circuit board and electrically connected to the circuit board; the guide frame is used to guide the installation of the circuit board and the battery; the battery is used to power the circuit board; wherein the guide frame includes a first section and a second section that are fixedly arranged, the second section is arranged between the battery and the circuit board, and the first section extends from the first section to the magneto-electric composite and is partially fitted with the first cavity.

[0008] As an embodiment of the present invention, the guide frame also includes a third section, which is arranged at an end of the first section away from the second section, and the first section, the second section and the third section are enclosed to accommodate the circuit board; and / or, the circuit module also includes an elastic gasket, which is arranged at least between the first section and the circuit board.

[0009] As an embodiment of the present invention, the signal input end of the circuit board is electrically connected to the magneto-electric composite component, and the negative pole of the input end, the negative pole of the output end and the negative pole of the battery are electrically connected to the shell respectively to achieve electrical shielding; wherein the circuit board is used to achieve impedance matching, signal amplification and filtering functions for the input electrical signal.

[0010] As an embodiment of the present invention, the shell includes a first shell, and a second shell and a third shell that are detachably fixed to the first shell respectively, the third shell can at least accommodate the permanent magnet and the magneto-electric composite component, and the first shell can at least accommodate the circuit module; wherein the first shell is made of a transparent conductive film of indium tin oxide covered with polymethyl methacrylate as a base, so that the second shell is at least partially transparent and shields interference of specific frequencies; and / or, the second shell and the third shell are made of any one of aluminum alloy and steel.

[0011] As an embodiment of the present invention, a stop ring is provided on the outer wall of the first shell on the side close to the second shell; the shell further includes a bushing, which is detachably mounted on the first shell and the third shell and is detachably connected to the outer wall of the first shell on the side close to the third shell of the stop ring; the second shell is detachably connected to the outer wall of the first shell on the side close to the second shell of the stop ring; and / or, the shell further includes a connector and a stress spring provided in the first cavity; one side of the stress spring is electrically contacted with the circuit module, and the other side is electrically contacted with the second shell, and the stress spring is used to make the circuit module and the second shell abut when the second shell is fixed to the first shell; the connector is detachably arranged on the second shell and is electrically connected to the circuit module to transmit the output electrical signal after the circuit board processes the electrical signal generated by the magnetoelectric composite material.

[0012] As an embodiment of the present invention, the magnetostrictive material layer of the magnetoelectric unit is made of Terfenol-D magnetized along the length direction, and the piezoelectric material layer is made of PMN-PT polarized along the thickness direction, wherein the crystallographic orientation of the single crystal of PMN-PT is The surface of the piezoelectric material layer close to the magnetostrictive material layer is covered with a thin film electrode, and the thin film electrode is electrically connected to the circuit board to provide an input electrical signal to the circuit board.

[0013] As an embodiment of the present invention, the magnetoelectric composite is coaxially provided with a plurality of magnetoelectric units; wherein two adjacent magnetoelectric units share the piezoelectric material layer; and / or the magnetostrictive material layer of the magnetoelectric unit and the piezoelectric material layer are fixed by epoxy resin.

[0014] The second aspect of the present invention provides a preparation method for a magnetoelectric composite element in the magnetoelectric sensor according to the first aspect of the present invention, wherein the magnetostrictive material layer of the magnetoelectric unit is made of Terfenol-D and the piezoelectric material layer is made of PMN-PT, and the preparation method comprises: controlling the polarization of the piezoelectric material layer along the thickness direction; taking the crystallographic orientation as the The PMN-PT is cut to prepare a piezoelectric material layer; and magnetostrictive material layers made of Terfenol-D are fixed on both sides of the piezoelectric material layer.

[0015] Compared with the prior art, the present invention has the following advantages: the magnetoelectric sensor prepared by using a composite magnetoelectric material comprising a magnetostrictive material layer and piezoelectric material layers electrically fixedly arranged on both sides of the magnetostrictive material layer has a higher magnetoelectric coefficient and is simple to prepare. The magnetoelectric coefficient it produces is more than two orders of magnitude higher than that of a single-phase material. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 is a perspective view of a magnetoelectric sensor provided by one embodiment of the present invention; Figure 2 is another perspective view of a magnetoelectric sensor provided by one embodiment of the present invention; Figure 3 is a structural diagram of a magnetoelectric composite member provided by one embodiment of the present invention; Figure 4is a structural diagram of a guide frame provided by another embodiment of the present invention; Figure 5 This is a verification table of the humidity stability characteristics of the magnetoelectric composite material provided by the embodiment of the present invention.

[0018] Figure 6 (a) shows the background signal of the magnetoelectric sensor. Figure 6 (b) shows the detection results of ferromagnetic materials by magnetoelectric sensors Description of reference numerals: 100. Permanent magnet; 200, magnetoelectric composite; 210, magnetoelectric unit; 211, magnetostrictive material layer; 212, piezoelectric material layer; 300, circuit module; 310, guide frame; 311, first section; 312, second section; 313, third section; 314, second cavity; 320, gasket; 330, circuit board; 340, battery; 400 , housing; 410 , first shell; 411 , stop ring; 420 , second shell; 430 , third shell; 440 , connector; 450 , stress spring; 460 , bushing; 470 , first cavity. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention. In the present invention, unless otherwise specified, the directional words used, such as "up", "down", "left", "right", "front", and "back", generally refer to the up, down, left, and right of the device in actual use or working state, specifically the drawing direction in the accompanying drawings.

[0020] It should be noted that the order of description of the following embodiments does not limit the preferred order of the embodiments of the present invention. In addition, in the following embodiments, the description of each embodiment has its own focus. For parts not described in detail in one embodiment, please refer to the relevant description of other embodiments.

[0021] See also Figure 1-4The present invention first provides a magnetoelectric sensor. The magnetoelectric sensor includes a permanent magnet 100, a magnetoelectric composite 200, a circuit module 300 and a shell 400. The shell 400 can be made of a material that can shield frequency interference, and has a first cavity 470 for accommodating the permanent magnet 100, the magnetoelectric composite 200 and the circuit module 300. It can be understood that the material of the shell that can shield frequency interference only needs to be able to shield the set frequency, and does not need to shield all frequencies. For example, the shell 400 is made of a high conductivity material such as aluminum alloy or steel, and can thus shield interference of the set frequency. Preferably, it can shield 50HZ. The purpose of shielding 50HZ is that 50Hz is industrial frequency interference, which is highly common and has a greater impact on the measurement accuracy of the sensor.

[0022] The permanent magnet 100 is used to provide a stable bias magnetic field. As a magnetic material that can generate a persistent magnetic field and does not require external energy input to maintain its magnetism, the permanent magnet 100 has many embodiments in the prior art. For example, it can be neodymium iron boron (NdFeB), samarium cobalt (SmCo), aluminum nickel cobalt (AlNiCo), ferrite, and rare earth-iron-boron (RE-Fe-B) alloy. Preferably, the permanent magnet 100 is neodymium iron boron (NdFeB). The advantages of this arrangement are that, on the one hand, it has a higher maximum magnetic energy product, which can provide stronger magnetic field strength and better magnetic field stability to enhance the magnetoelectric effect of the magnetoelectric composite 200; on the other hand, it has good corrosion resistance and durability, which can extend the service life of the sensor.

[0023] The magnetoelectric composite 200 includes at least one magnetoelectric unit 210. Figure 3 As shown, each magnetoelectric unit 210 includes a magnetostrictive material layer 211 and a piezoelectric material layer 212. The magnetostrictive material layer 211 can be made of the magnetostrictive alloy Terfenol-D, and the piezoelectric material layer 212 can be made of a piezoelectric single crystal PMN-PT single crystal. Magnetostrictive material layers 211 are electrically fixed on both sides of the piezoelectric material layer 212. The two magnetostrictive material layers 211 and the piezoelectric material layer 212 can be bonded together by conductive silver glue and epoxy resin to form a sandwich structure. In some embodiments, the magnetostrictive material layer 211 and the piezoelectric material layer 212 have the same size, for example, the length, width and thickness thereof are 12×6×1 mm. 3 .

[0024] Please continue reading Figure 1-4 The circuit module 300 is electrically connected to the magnetoelectric composite component 200 and is used to process the input electrical signal generated by the magnetoelectric composite component 200. Figure 1-Figure 2 As shown in this embodiment, the circuit module 300 includes a guide frame 310 , a spacer 320 , a circuit board 330 and a battery 340 .

[0025] Please refer to Figure 4 , the guide frame 310 may include a first section 311 fixedly arranged, and a second section 312 and a third section 313 respectively fixedly arranged at both ends of the first section 311. The first section 311, the second section 312 and the third section 313 are enclosed to form a second cavity 314, and the second cavity 314 can at least accommodate the circuit board 330. In Figure 4 this specific embodiment, the second cavity 314 has a structure after rotating 90° counterclockwise in a "U" shape. The circuit board 330 is arranged therein, the third section 313 is arranged above, the second section 312 is arranged below, and the upper and lower ends of the first section 311 are respectively fixedly connected to the second section 312 and the third section 313. One side of the second section 312 away from the first section 311 (i.e., the lower side of the second section 312) can be in electrical contact with the positive electrode of the battery 340, and one side of the third section 313 away from the first section 311 (i.e., the upper side of the third section 313) can be in electrical contact with the magnetoelectric composite 200. In some embodiments, the size of the second section 312 may not be less than the size of the third section 313 to facilitate the installation of the battery 340.

[0026] The gasket 320 can be made of an elastic insulating material and is arranged between the guide frame 310 and the circuit board 330 to protect the circuit board 330. That is, the gasket 320 is arranged in the second cavity of the guide frame 310. One side of the gasket 320 is in contact with the circuit board 330, and the other side is in contact with the second section 312 or the third section 313 of the guide frame 310. The gasket 320 is fixedly connected to the guide frame 310 or the gasket 320 is arranged between the circuit board 330 and the second section 312 (or the third section 313) and is slightly larger than the gap between the circuit board 330 and the second section 312 to achieve that the circuit board 330 is slightly abutted against the guide frame 310 to keep the relative position of the circuit board 330 fixed. The advantage of setting the gasket is that in the use of the magnetoelectric sensor, when it is applied to specific scenarios such as military or aerospace, it is necessary to ensure that it has good pressure-bearing capacity and can have better impact strength. By setting the gasket, it can well ensure that the circuit board in the gasket is not damaged, and thus well ensure the life of the entire magnetoelectric sensor.

[0027] Preferably, the gasket 320 is made of an insulating material, such as a rubber material. A through hole is provided on the gasket 320 to facilitate electrical connection of the circuit board 330 and the battery 340, the magnetoelectric composite 200, and the housing 400 via wires. The advantage of setting the gasket 320 to be made of an insulating material is that, since the circuit board 330 needs to process and analyze the input electrical signal generated by the magnetoelectric composite, it is necessary to ensure that the circuit board 330 itself is in an insulating environment, thereby avoiding being electrically conductive and causing a short circuit in the circuit board. By providing a gasket, on the one hand, the entire circuit board 330 can be placed in an insulating environment, and on the other hand, the entire circuit board 330 can have a higher impact resistance.

[0028] It is naturally understandable that the purpose of the guide frame 310 is to achieve a higher installation process for the permanent magnet 100, the magneto-electric composite 200 and the circuit module 300 by setting the guide frame 310 in the process of installing the circuit module 300 into the first cavity 470 of the housing 400. In particular, for the installation of the circuit module 300, since it is designed to install the circuit board and the electrical connection with other components, the installation steps are complicated. By setting the guide, the installation steps can be greatly simplified and the installation efficiency can be improved. In a specific installation scenario, the operator can pre-install the circuit board 330 in the circuit module into the guide frame 310 based on the guide frame 310, and then electrically connect the power line, signal input line, and signal output line of the circuit board 330 to other components through wires, and then install it into the first cavity 470 of the housing 400.

[0029] It is naturally understood that the third section 313 is not necessary. In another alternative embodiment, the guide frame 310 is an "L"-shaped structure, comprising only the first section 311 and the second section 312 positioned adjacent to the battery side 312. This can also effectively facilitate the guided installation process. In this case, the guide frame 310 includes a fixed first section 311 and a second section 312. The second section 312 is positioned between the battery 340 and the circuit board 330. The first section 311 extends from the second section 312 toward the magnetoelectric composite component 200 and partially engages with the first cavity 470.

[0030] In a specific installation scenario, the operator can pre-install the permanent magnet 100 and the magneto-electric composite 200 into the first cavity in sequence, and then install the gasket 320, the circuit board 330, the gasket 320, and the guide frame 310, and then install the battery 340. At this time, the installation sequence can also be optimized, and the circuit board 330 can be protected by arranging gaskets 320 on both sides of the circuit board 330.

[0031] Please continue reading Figure 1-Figure 2The battery 340 can be a button battery to provide working power for the circuit board 330, and the details will not be repeated.

[0032] The input terminal of circuit board 330 is connected to the output terminal of magnetoelectric composite 200, thereby processing the input electrical signal generated by the magnetoelectric composite, including impedance matching, signal amplification, and filtering. These processing functions can be implemented using integrated circuits or discrete components, and the details are not further described.

[0033] Preferably, the signal input end of the circuit board 330 is connected to the output end of the magnetoelectric composite 200 to obtain the input electrical signal generated by the magnetoelectric composite 200. The circuit board 330 is connected to the battery 340 so that the battery supplies power to the circuit board 330. The information processed from the input electrical signal is then output. The output method can be output via wires or wireless transmission, which is not specifically limited.

[0034] Preferably, the negative pole of the signal input terminal, the negative pole of the output terminal, and the negative pole of the power input terminal of the circuit board 330 are all connected to the shell and regarded as the ground, which plays an electrical shielding effect.

[0035] Therefore, through the magnetoelectric sensor provided by the present invention, by applying PMN-PT single crystal with ultra-high piezoelectric properties and giant magnetostrictive Terfenol-D alloy to prepare magnetoelectric composite materials, and processing the electrical signal input by the magnetoelectric composite through the circuit module, a magnetoelectric coefficient with a high magnetoelectric coefficient can be obtained. The preparation is simple, and the magnetoelectric coefficient it produces is more than two orders of magnitude of that of single-phase materials.

[0036] However, the inventors found in their research that if we want to further improve the accuracy of the magnetoelectric sensor, the key lies in optimizing the magnetoelectric composite, and more importantly, optimizing the cutting shape of the magnetoelectric composite. Different cutting shapes will directly lead to the piezoelectric coefficient d of the magnetoelectric sensor. 31 (That is, when a stress perpendicular to the polarization direction is applied, the ratio of the electric displacement generated along the polarization direction to the applied stress) is different. In addition, the difference in the combination of different magnetoelectric composite units will also lead to different piezoelectric coefficients d 31 The difference will affect the accuracy of the magnetoelectric sensor provided by the present invention.

[0037] Step 1: Place the PMN-PT single crystal in an X-ray crystal orientation instrument and determine its Orientation, cut along these three directions respectively, and the crystallographic orientation is The PMN-PT single crystal is then used to prepare the piezoelectric material layer 212.

[0038] Step 2: magnetizing the magnetostrictive material Terfenol-D in the composite magnetoelectric material along the length direction to obtain the magnetostrictive material layer 211 , and polarizing the piezoelectric material PMN-PT along the thickness direction.

[0039] Step 3: Place the piezoelectric material layer 212 on both sides of the magnetostrictive material layer 211 and bond them with epoxy resin to form a mechanical coupling, forming a spatial layered structure of magnetostrictive material layer 211-piezoelectric material layer 212-magnetostrictive material layer 211, that is, the magnetoelectric unit 210, so that the overall vibration mode of the magnetoelectric unit 210 is transverse length extension vibration.

[0040] During the preparation of the piezoelectric material layer 212, thin-film electrodes made of silver or gold can be applied to the upper and lower surfaces of the piezoelectric material layer 212 (i.e., the surfaces of the piezoelectric material layer 212 adjacent to the adjacent magnetostrictive material layer 211) using conductive silver paste or magnetron sputtering. The output electrical signal of the magnetoelectric unit is extracted from the thin-film electrodes on the upper and lower surfaces of the piezoelectric material layer and connected to the circuit board, thereby providing the circuit board with an input electrical signal.

[0041] Step 4: When multiple magnetoelectric units 210 for magnetoelectric sensors need to be prepared, repeat steps 1 to 3, but make the magnetoelectric units 210 coaxially arranged, and make two adjacent magnetoelectric units 210 share a magnetostrictive material layer, that is, a spatial layered structure of magnetostrictive material-piezoelectric material-magnetostrictive material-piezoelectric material.

[0042] According to the enterprise standards Q / SIC 2009-2022 and Q / SIC 2013-2022, the magnetoelectric composites prepared in this way and the magnetoelectric sensors prepared based on the magnetoelectric composites have a magnetoelectric coefficient change of about 0.06% and less than 0.1%, and the limit detection rate of the magnetoelectric sensor exceeds the nT level, which has very good magnetoelectric performance. <001> The composite magnetoelectric material of oriented PMN-PT has been improved by nearly 3 times.

[0043] Preferably, the magnetostrictive material layer 211 and the piezoelectric material layer 212 have the same size. More preferably, the length, width and thickness are 12×6×1 mm. 3 It is understood that in order to ensure that the overall vibration mode of the magnetoelectric unit 210 is a transverse length extension vibration, that is, to meet the dimensional requirements of the length extension vibration mode, it is sufficient to ensure that the dimension in the length direction is much larger than the dimension in the thickness direction, and there is no limitation on the specific size range. The reason for selecting this size is that it can provide the largest possible length dimension and the smallest possible thickness dimension while matching the existing magnetoelectric sensor design and process, thereby improving the accuracy of the entire magnetoelectric sensor.

[0044] In addition, the inventors also found in their research that when installing and manufacturing the magnetoelectric composite, since the permanent magnet 100, the magnetoelectric composite 200 and the circuit module 300 need to be installed, the entire installation process is relatively complicated and the installation process cannot be visualized, resulting in an increase in the product defect rate. Based on this, the inventors attempted to make further improvements.

[0045] Please continue reading Figure 1-4 The housing 400 is made of a material that can shield frequency interference and has a first cavity 470 that accommodates the permanent magnet 100, the magneto-electric composite 200, and the circuit module 300. Specifically, the housing 400 includes a first shell 410, a second shell 420, and a third shell 430. The second shell 420 and the third shell 430 are respectively detachably fixedly connected to the first shell 410. The first shell 410, the second shell 420, and the third shell 430 are all hollow and open cavities with the same inner diameter, thereby together forming the first cavity 470. The first shell 410 can accommodate at least the circuit module 300; the third shell 430 can accommodate at least the permanent magnet 100 and the magneto-electric composite 200.

[0046] First shell 410 is made of a polymethyl methacrylate (PMMA) substrate covered with an indium tin oxide (ITO) transparent conductive film, making it at least partially transparent and capable of shielding specific frequency interference. This design allows for easy observation of the internal structure while maintaining good electromagnetic shielding performance.

[0047] Therefore, when installing and manufacturing the electromagnetic sensor, by making the first shell 410 partially transparent, the installation process can be well visualized, thereby better implementing the installation process of the electromagnetic sensor and improving installation efficiency.

[0048] In other embodiments, the second shell 420 and the third shell 430 may be made of any one of aluminum alloy and steel. Preferably, the second shell 420 and the third shell 430 are made of the same material.

[0049] In some other embodiments, the housing 400 may further include a stop ring 411 , a connector 440 , a stress spring 450 , and a bushing 460 .

[0050] A stop ring 411 is fixed to the outer wall of the first shell 410 to prevent interference between the bushing 460 and the connector 440 and the first shell 410. The bushing 460 is removably mounted on the first shell 410 and the third shell 430 and is removably connected, preferably by threading, to the outer wall of the first shell 410 on the side of the stop ring 411 closest to the third shell 430. The purpose of providing a removable connection between the bushing 460 and the first shell 410 is to further enhance the impact resistance of the entire magnetoelectric composite 200 and extend its service life.

[0051] The stress spring 450 is disposed in the first cavity 470. One side of the stress spring 450 is in electrical contact with the negative electrode of the battery of the circuit module 300, and the other side is in electrical contact with the second shell 420. The stress spring 450 is used to abut against the circuit module and the second shell when the second shell is fixed to the first shell. Figure 1 In this embodiment, when the second shell 420 is fixed to the first shell 410 by threads, the stress spring 450 arranged in the first cavity is squeezed, so that the stress spring 450 abuts against the second shell 420 and the battery 340 of the circuit module 300, thereby completing the conduction between the second shell 420 and the battery 340 while fixing the battery 340.

[0052] Connector 440 is removably mounted on the second housing and electrically connected to the circuit module to transmit the output electrical signal generated by the magnetoelectric composite material after the circuit board processes the electrical signal. Preferably, connector 440 may be a BNC connector for connecting to the output signal terminal of circuit board 330 to transmit the output signal of circuit board 330 to an external device.

[0053] In summary, the magnetoelectric sensor of the present invention can be used to detect low-frequency magnetic fields, and has high sensitivity, low noise, and good environmental adaptability. Its compact structural design and modular assembly method are conducive to mass production and maintenance.

[0054] In order to verify the impact resistance of the magnetoelectric sensor provided by the present invention, an overload of 20,000 g was applied to five magnetoelectric sensors in an impact resistance experiment. The performance of the magnetoelectric sensors did not change before and after the experiment, proving that the impact resistance of the magnetoelectric sensors is intact and can withstand an overload of at least 20,000 g.

[0055] Figure 5 The humidity stability characteristics of the magnetoelectric composite material are given. It can be seen that the magnetoelectric composite material is almost completely unaffected by the environmental humidity. When the humidity changes from 15% to 95%, the magnetoelectric coefficient changes by about 0.06%, less than 0.1%.

[0056] Figure 6 (a) shows the background signal of the magnetoelectric sensor. It can be seen that the source of this noise is mainly 1 / f noise. Figure 6 (b) shows the detection results of the magnetoelectric sensor on ferromagnetic materials. Based on this result, that is, the size of the detected material, we can analyze that the limit detection rate of the magnetoelectric sensor exceeds the nT level, and it has preliminary practical application value.

[0057] The above is a detailed introduction to the scheme of the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

[0058] Reference throughout this specification to "one embodiment," "an embodiment," or "a specific embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention, and not necessarily in all embodiments. Thus, the various appearances of the phrases "in one embodiment," "in an embodiment," or "in a specific embodiment" in different places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics of any specific embodiment of the invention may be combined with one or more other embodiments in any suitable manner. It should be understood that other variations and modifications of the embodiments of the invention described and illustrated herein are possible in light of the teachings herein and are considered part of the spirit and scope of the invention.

[0059] It should also be understood that one or more of the elements shown in the figures may also be implemented in a more separate or more integrated manner, or even removed because they are inoperable in certain circumstances or provided because they may be useful depending on the application.

[0060] In addition, unless otherwise expressly indicated, any marking arrows in the drawings should be regarded as illustrative only and not limiting. Furthermore, unless otherwise indicated, the term "or" as used herein is generally intended to mean "and / or." Where a term is unclear in providing separation or combination capabilities, the combination of components or steps will also be considered as indicated.

Claims

1. A magnetoelectric sensor, characterized in that: include permanent magnet; A magnetoelectric composite part, comprising a magnetostrictive material layer and a magnetoelectric unit electrically fixedly disposed on both sides of the piezoelectric material layer; a circuit module, electrically connected to the magneto-electric composite, having a circuit board for processing an input electrical signal generated by the magneto-electric composite; The shell is made of a material capable of shielding frequency interference and has a first cavity for accommodating the permanent magnet, the magneto-electric composite component and the circuit module.

2. The magnetoelectric sensor according to claim 1, characterized in that: The circuit module also includes a guide frame and a battery. The magneto-electric composite and the battery are respectively arranged on both sides of the circuit board and are electrically connected to the circuit board. The guide frame is used to guide the installation of the circuit board and the battery. The battery is used to supply power to the circuit board. The guide frame includes a first section and a second section that are fixedly arranged, the second section is arranged between the battery and the circuit board, and the first section is extended from the first section toward the magneto-electric composite component and is partially fitted with the first cavity.

3. The magnetoelectric sensor according to claim 2, characterized in that: The guide frame further includes a third section, the third section is arranged at an end of the first section away from the second section, and the first section, the second section and the third section are arranged to enclose and accommodate the circuit board; And / or, the circuit module further includes an elastic gasket, and the elastic gasket is at least arranged between the first section and the circuit board.

4. The magnetoelectric sensor according to claim 2, characterized in that: The signal input end of the circuit board is electrically connected to the magnetoelectric composite component, and the negative pole of the input end, the negative pole of the output end and the negative pole of the battery are electrically connected to the shell respectively to achieve electrical shielding; wherein The circuit board is used to realize impedance matching, signal amplification and filtering functions for the input electrical signal.

5. The magnetoelectric sensor according to any one of claims 1 to 4, characterized in that: The housing comprises a first shell, and a second shell and a third shell respectively detachably fixed to the first shell, the third shell can at least accommodate the permanent magnet and the magneto-electric composite component, and the first shell can at least accommodate the circuit module; in The first shell is made of a transparent conductive film of indium tin oxide covered with polymethyl methacrylate as a substrate, so that the second shell is at least partially transparent and shields interference of a specific frequency; and / or the second shell and the third shell are made of any one of aluminum alloy and steel.

6. The magnetoelectric sensor according to claim 5, characterized in that: The outer wall of the first shell on the side close to the second shell is provided with a stop ring; the housing further comprises a bushing, which is detachably mounted on the first shell and the third shell and detachably connected to the outer wall of the first shell on the side close to the third shell of the stop ring; the second shell is detachably connected to the outer wall of the first shell on the side close to the second shell of the stop ring; And / or, the shell also includes a connector and a stress spring arranged in the first cavity; one side of the stress spring is electrically in contact with the circuit module, and the other side is electrically in contact with the second shell, and the stress spring is used to make the circuit module and the second shell abut when the second shell is fixed to the first shell; the connector is detachably arranged on the second shell and is electrically connected to the circuit module to transmit the output electrical signal after the circuit board processes the electrical signal generated by the magneto-electric composite material.

7. The magnetoelectric sensor according to any one of claims 1 to 4, characterized in that: The magnetostrictive material layer of the magnetoelectric unit is made of Terfenol-D magnetized along the length direction, and the piezoelectric material layer is made of PMN-PT polarized along the thickness direction. The crystallographic orientation of the single crystal of PMN-PT is ; The surface of the piezoelectric material layer close to the magnetostrictive material layer is covered with a thin film electrode, and the thin film electrode is electrically connected to the circuit board to provide an input electrical signal to the circuit board.

8. The magnetoelectric sensor according to any one of claims 1 to 4, characterized in that: The magnetoelectric composite is coaxially provided with a plurality of magnetoelectric units; wherein two adjacent magnetoelectric units share a magnetostrictive material layer; And / or, the magnetostrictive material layer of the magnetoelectric unit and the piezoelectric material layer are fixed by electrical bonding with epoxy resin.

9. A preparation method for preparing a magnetoelectric composite member in a magnetoelectric sensor according to any one of claims 1 to 8, characterized in that: The magnetostrictive material layer of the magnetoelectric unit is made of Terfenol-D, and the piezoelectric material layer is made of PMN-PT. The preparation method comprises: Controlling the polarization of Terfenol-D along the thickness direction to form a magnetostrictive material layer; The PMN-PT is controlled to be magnetized along the length direction to form a magnetostrictive material layer; the crystallographic orientation is cutting the PMN-PT to prepare a piezoelectric material layer; The magnetostrictive material layer made of Terfenol-D is fixed on both sides of the piezoelectric material layer for mechanical coupling to form the magnetoelectric unit.

10. The preparation method according to claim 9, characterized in that: The piezoelectric material layer and the magnetostrictive material layer have the same size, which is 12×6×1 mm 3 .

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