Flexible wide-frequency-domain magnetoelectric composite current sensor array

Abstract

The invention relates to a flexible wide-frequency-domain magnetoelectric composite current sensor array. The sensor array is characterized in that conductive copper wires are distributed in a flexible circuit board conversion layer; the magnetoelectric composite units are attached to the flexible circuit board conversion layer and are arranged along the length direction; the magnetoelectric composite unit is divided into three layers, and a piezoelectric film force sensitive layer is clamped between two magnetostrictive films; the conversion layer is in a right-angle U shape, two cross beams parallel to the bottom edge are distributed on the side wall of the right-angle U shape at equal intervals, and the two cross beams and the middle of the bottom edge are each provided with a magnetoelectric composite unit. The current sensor has the advantages of being wide in frequency domain, short in response time and recovery time, high in sensitivity and small in size, and is extremely suitable for the field of current measurement of integrated electronic devices with limited space.

Description

Technical Field

[0001] The invention relates to the field of current measurement of integrated electronic devices with limited space, and in particular to a magneto-electric composite current sensor capable of realizing high-bandwidth frequency domain measurement. Background Art

[0002] With the development of electronic device integration, current sensors will develop in the direction of miniaturization, structural flexibility and self-power supply. Current current sensors mainly include contact and non-contact sensors. Among them, contact current sensors lack electrical isolation and pose safety risks. Non-contact current sensors have the advantages of high insulation, good safety and convenient measurement. Typical non-contact current sensors include current transformers, photocurrent sensors, Hall sensors and magnetoresistive sensors. However, the above sensors are not suitable for current measurement of integrated electronic devices due to their complex structure and large size. At present, current sensors based on magnetoelectric composite materials combine ferromagnetic and ferroelectric properties and have attracted much attention due to their low cost, light weight and flexibility. Magnetoelectric composite (ME) materials produce deformation in an alternating magnetic field, and the deformation is transmitted to the piezoelectric layer through mechanical coupling between layers, thereby inducing the electric polarization reaction of the piezoelectric layer and realizing the conversion of magnetic field to electric field.

[0003] In current magnetoelectric composite current sensors, current measurement is generally achieved at a single resonant frequency, and its structure cannot meet the requirements of integrated electronic devices for sensor structure miniaturization and bandwidth. For example, the document number is: 10.1088 / 1361-6463 / ad3f25 Magnetoelectric effect in Metglas-langatate ring heterostructure for current sensing. This paper proposes a ring-structured magnetoelectric composite current sensor, which improves the sensitivity of the current sensor and expands the current measurement range by utilizing the design of the ring structure. However, due to the space limitation of the ring structure itself, only a single magnetoelectric composite heterostructure can be set, so it only shows high measurement sensitivity at a single resonant frequency. Summary of the invention

[0004] The purpose of the present invention is to propose a flexible wide-band magnetoelectric composite current sensor array in view of the shortcomings in the current technology. Each unit of the array sensor is composed of a magnetostrictive layer, a piezoelectric layer and a magnetostrictive layer. The magnetostrictive film layer, the PVDF piezoelectric layer and the magnetostrictive film layer are arranged vertically to form a sandwich structure. Under different current corresponding magnetic field conditions, the magnetostrictive film and the PVDF piezoelectric film are tightly coupled. The magnetostrictive film can convert the magnetic signal into a force signal and transmit it to the PVDF piezoelectric film. The PVDF piezoelectric film converts the force signal from the magnetostrictive film into an electrical signal. The sense of the applied current is achieved by measuring the output electrical signal, and non-contact current measurement is completed. In view of the problems of narrow resonant frequency and low sensitivity of the existing magnetoelectric composite current sensor, the present invention adopts magnetoelectric composite units of different lengths and sizes in parallel at the center line position in the length direction, and is connected through a conversion layer to form an array structure. The structure has excellent performances of wide frequency domain, short response time and recovery time, high sensitivity and small size. It is extremely suitable for the field of current measurement of integrated electronic devices with limited space.

[0005] The technical solution of the present invention is: A flexible wide-band magnetoelectric composite current sensor array, the sensor comprising: a conductive copper wire is distributed inside a flexible circuit board conversion layer; a magnetoelectric composite unit is attached to the flexible circuit board conversion layer and arranged along the length direction; the magnetoelectric composite unit is divided into three layers, the bottom layer is a first magnetostrictive film, which is adhered to the conversion layer by epoxy resin glue; a piezoelectric film force sensitive layer covers the first magnetostrictive film; and finally a second magnetostrictive film is deposited; The number of the magnetostrictive units is 3, forming a 3*1 array; The sizes of the magnetoelectric composite units are 30mm×10mm, 27mm×10mm, and 24mm×10mm respectively; the distance between adjacent magnetoelectric composite units is 8mm; The force sensitive layer is a piezoelectric film made of PVDF with a thickness ranging from 1 to 100 microns; The first magnetic sensitive layer and the second magnetic sensitive layer are magnetostrictive films, and the material is Fe-Co, Fe-Ni, Fe-Ga or Terfenol; the thickness ranges from 1 to 100 microns; The conversion layer is in a right-angled U-shape, and two crossbeams parallel to the bottom edge are evenly spaced on the side wall of the right-angled U-shape, and a magnetoelectric composite unit is distributed in the middle of the two crossbeams and the bottom edge, wherein the long direction of the magnetoelectric composite unit is distributed along the U-shape direction, and the spacing between the crossbeams is 38mm; the width of the side wall and the bottom edge is 7mm; The conversion layer is a double-layer flexible circuit board made of polyimide (PI) with conductive copper wires distributed in it.

[0006] The size of the flexible circuit board is 110mm×45mm, the thickness of a single layer is 100 microns, and the size of the beam is 30×7mm.

[0007] The method for preparing the flexible wide-band magnetoelectric composite current sensor array comprises the following steps: (1) Preparation of Co-Fe magnetostrictive film by electrodeposition under induced magnetic field: The copper sheet was pickled and used as the cathode, the platinum plate was used as the anode, and the Co-Fe alloy electrodeposition solution was used as the electrolyte. The two plates were placed vertically and parallel to each other in the electrolyte. In a DC magnetic field environment and a DC power supply, the pH of the electrolyte was controlled at 2.5-3.5 by dropping a dilute sulfuric acid solution. After the deposition was completed, the copper sheet was taken out and cleaned with alcohol, and then air-dried to obtain a magnetostrictive film deposited on the copper sheet.

[0008] The electrodeposition solution comprises FeSO4·7H2O 0.01-0.1mol / L, CoSO4·7H2O 0.1-0.5mol / L, sodium citrate 0.2-0.5mol / L, boric acid 0.2-0.3mol / L, ascorbic acid 0.5-2g / L, saccharin 1-3g / L, sodium dodecyl sulfate 0.01-0.05g / L; The magnetic field value is: 50~500kA / m; the current is controlled at 0.30~0.40A / cm 2 , the pH of the electrolyte is controlled at 2.5-3.5 by adding 10% dilute sulfuric acid solution, and the electrodeposition time is 20-100 min; (2) Preparation of PVDF piezoelectric film by spin coating: The copper sheet on which the Co-Fe film obtained in step (1) is deposited is used as a substrate, placed on a spin coater, and PVDF is spin-coated, and then annealed at 120-140° C. for 3.5-4.5 hours; finally, it is placed in a field strength of 125-130 MV / m for polarization for 25-35 minutes to obtain a piezoelectric film; The solvent of the PVDF solution is DMF, and the concentration is 5-20 g / 100 ml. The speed of the spin coater is 1000-2000 r / min, and the spin coating is repeated 3-10 times, and each spin coating lasts 60-120 seconds. (3) Repeating the process (1) with the magnetostrictive-piezoelectric composite unit obtained in step (2) to obtain a magnetostrictive-piezoelectric-magnetostrictive sandwich structure of the magnetoelectric composite unit, peeling the prepared magnetoelectric composite unit from the copper sheet, and evenly gluing the magnetoelectric composite unit to a flexible circuit board embedded with copper wires using epoxy resin glue, and connecting them in parallel along the center line of the length direction to obtain an array structure.

[0009] The essential features of the present invention are: Current sensors in current technology are based on current measurement at a single resonant frequency. The devices are bulky and large in size. In addition, the magnetostrictive films of such current sensors are thin sheets made by a rolling process or by magnetron sputtering. These processes are often costly and are not suitable for current measurement in integrated electronic devices with limited space.

[0010] The present invention adopts the method of electrodeposition to prepare a Co-Fe film with excellent performance; and adopts the electrodeposition method under an induced magnetic field to regulate the material structure and induce perpendicular anisotropy, and finally designs an array structure to realize current measurement in a wide frequency domain.

[0011] The beneficial effects of the present invention are: 1. Other flexible magnetoelectric composite current sensors use complex circuit elements, such as drive coils and pickup coils, which require drive circuits to drive. Compared with other existing flexible magnetoelectric composite current sensors, the present invention does not require a drive circuit to drive, but only needs to collect the voltage signal output by the sensor.

[0012] 2. The magnetoelectric composite unit in the sensor of the present invention is naturally coupled between the layers, without any intermediate viscous medium, and has a large magnetoelectric coupling coefficient and high efficiency.

[0013] 3. The present invention adopts the method of electrodeposition under an induced magnetic field to regulate the structure of the material, and obtains a magnetostrictive film with excellent performance, so that the saturation magnetic induction intensity and piezomagnetic coefficient of the material are improved. When the external magnetic field is 50kA / m, the saturation magnetic induction intensity of the magnetostrictive film obtained by electrodeposition without an induced magnetic field is 4.09kA / m, and the saturation magnetic induction intensity of the magnetostrictive film prepared by the electrodeposition method under an induced magnetic field of 50kA / m can reach 8.9kA / m. When the external magnetic field is 50kA / m, the piezomagnetic coefficient of the magnetostrictive film obtained by electrodeposition without an induced magnetic field is 6.1nm / A, and the piezomagnetic coefficient of the magnetostrictive film prepared by the electrodeposition method under an induced magnetic field of 50kA / m is 7.8nm / A.

[0014] 4. The present invention adopts an array structure design to achieve wide-band current detection. The improved magnetoelectric composite current sensor exhibits a higher magnetoelectric coefficient in the range of 39-52kHZ, which broadens the resonant frequency band of a single current sensor. At the same time, three peaks appear in the optimized sensor resonant frequency band, and the three peaks correspond to the resonant frequencies of a single sensor, which means that the combination of multiple magnetoelectric composite units can achieve the broadening of the resonant frequency band. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the structure of a flexible magnetoelectric composite current sensor array. Figure 2 Circuit diagram for flexible printed circuit board Figure 3 Schematic diagram of the structure of the magnetoelectric composite unit Figure 4 Schematic diagram of the electrodeposition process device using an induced magnetic field Figure 5 : is a performance comparison diagram of magnetostrictive films prepared in an induced magnetic field of 50kA / m and in an environment without an induced magnetic field; wherein, Figure 5 (a) Comparison of magnetization curves of magnetostrictive films prepared under induced magnetic field and without induced magnetic field; Figure 5 (b) Comparison of the piezomagnetic coefficient curves of magnetostrictive films prepared under induced magnetic field and without induced magnetic field; Figure 6 The magnetoelectric coupling coefficient diagram of the flexible magnetoelectric composite current sensor array at different resonant frequencies In the figure: 1-conductive copper wire; 2-flexible circuit board (conversion layer); 3-magnetoelectric composite unit; 4-FPC interface; 5-first magnetostrictive film (magnetic sensitive layer); 6-piezoelectric film (force sensitive layer); 7-second magnetostrictive film (magnetic sensitive layer); 8-magnetic pole of DC magnetic field stabilizing power supply; 9-copper skin; 10-platinum electrode; DETAILED DESCRIPTION

[0016] The flexible magnetoelectric composite current sensor array uses magnetostrictive effect and piezoelectric effect to detect current. The Fe-Co magnetostrictive film layer senses the change of magnetic field under different currents and deforms through magnetostrictive effect, while the PVDF piezoelectric film layer uses piezoelectric effect to detect external force. Through the structure of this ME composite material, the change of magnetic field under different currents is converted into electrical signals to realize current monitoring. By integrating magnetostrictive effect and piezoelectric effect, the sensor can sensitively detect and convert it into a readable signal to provide relevant information about the current.

[0017] The invention is further described in detail below in conjunction with the figures. This embodiment is only a specific description of the invention and is not to be regarded as limiting the scope of protection.

[0018] The flexible magnetoelectric composite current sensor array structure of the present invention is as follows Figure 1 As shown, the sensor comprises: a conductive copper wire 1 is distributed inside a flexible circuit board conversion layer 2; a magnetoelectric composite unit is attached to the flexible circuit board conversion layer 2 and arranged along the length direction; the magnetoelectric composite unit is divided into three layers, the bottom layer is a first magnetostrictive film 5, which is adhered to the conversion layer by epoxy resin glue; a piezoelectric film force sensitive layer 6 covers the first magnetostrictive film 5; and finally a second magnetostrictive film 7 is deposited; The number of the magnetostrictive units is 3, forming a 3*1 array; The sizes of the magnetoelectric composite units are 30mm×10mm, 27mm×10mm, and 24mm×10mm in order, based on the beam closest to the U-shaped opening and approaching the bottom edge of the U-shape (different lengths represent different resonant frequencies of each unit, and wide frequency domain measurement can be achieved after parallel connection); the distance between adjacent magnetoelectric composite units is 8mm; The force sensitive layer 6 is a piezoelectric film made of PVDF; the thickness ranges from 1 to 100 microns (the thickness used in this embodiment is 20 microns); The first magnetic sensitive layer 5 and the second magnetic sensitive layer 7 are magnetostrictive films, and the material is Fe-Co, Fe-Ni, Fe-Ga or Terfenol (Fe is used in this embodiment). 30 Co 70 ); the thickness range is 1 to 100 microns (the thickness used in this embodiment is 20 microns); The conversion layer 2 is in a right-angled U-shape, and two cross beams parallel to the bottom edge are evenly spaced on the side wall of the right-angled U-shape, and a magnetoelectric composite unit is distributed in the middle of the two cross beams and the bottom edge, wherein the long direction of the magnetoelectric composite unit is distributed along the U-shape direction, and the spacing between the cross beams is 38 mm; the width of the side wall and the bottom edge is 7 mm; The conversion layer 2 is a double-layer flexible circuit board made of polyimide (PI), in which the conductive copper wire 1 is distributed, and the material is copper. The size of the flexible circuit board is 110mm×45mm, the thickness of a single layer is 100 microns, and the size of the crossbeam is 30×7mm.

[0019] The specific circuit structure diagram is as follows Figure 2 As shown (due to layout reasons, Figure 1-2 The sensor arrays are all placed horizontally, that is, the bottom edge and the crossbeam are both vertical). The main components of the flexible circuit board include conductive copper wires 1 and FPC interfaces 4.

[0020] The FPC interface 4 is reinforced with PI.

[0021] The preparation method for a flexible mechano-magnetic dual-mode sensor array comprises the following steps: (1) A Co-Fe magnetostrictive film is prepared by an electrodeposition method under an induced magnetic field, comprising the following steps: The copper sheet 5 is pickled and used as the cathode, the platinum plate 11 is used as the anode, and the Co-Fe alloy electrodeposition solution is used as the electrolyte. The two plates are placed vertically and parallel to each other in the electrolyte, and a DC magnetic field constant current power supply is used to provide a DC magnetic field environment. The electrodeposition device is placed in the DC magnetic field environment, and the magnetic field is perpendicular to the two plates. The magnetic field size is 50kA / m at a temperature of 50°C. A DC power supply is used, and a constant current output mode is adopted. The current is controlled at 0.35A / cm 2, the pH of the electrolyte was controlled at 3 by dropping 10% dilute sulfuric acid solution, the electrodeposition time was 40 minutes, the deposition thickness was 20 microns, after the deposition was completed, the copper skin was taken out and cleaned with alcohol, and then quickly air-dried, to obtain three kinds of magnetostrictive films 5 deposited on the copper skin 8; The electrodeposition solution is composed of iron sulfate, cobalt sulfate, complexing agent, buffer, antioxidant and surface brightener, and uses electrolyzed water as solvent, specifically containing FeSO4·7H2O 0.05mol / L, CoSO4·7H2O0.3mol / L, sodium citrate 0.3mol / L, boric acid 0.2mol / L, ascorbic acid 1.0g / L, saccharin 2g / L, sodium dodecyl sulfate 0.3g / L; (2) The PVDF piezoelectric film is prepared by spin coating, comprising the following steps: According to the concentration ratio of 12g / 100ml, PVDF powder is placed in DMF, heated and stirred to completely dissolve PVDF in the DMF solution. The copper sheet with the deposited Co-Fe film is placed on the spin coater as the substrate, and the spin coater speed is adjusted to 80r / min. Repeat the spin coating 8 times, drip 1ml of solution each time, spin coat for 60 seconds, and dry to obtain a film thickness of about 25 microns. The obtained film is placed in an oven and annealed at 120°C for 4 hours. Finally, the annealed PVDF piezoelectric film is placed in a field strength of 125MV / m for polarization for 30 minutes (normal polarization) to obtain a PVDF piezoelectric film 6 with good piezoelectric properties.

[0022] (3) Repeat the process of (1) to obtain a magnetoelectric composite unit with a magnetostrictive-piezoelectric-magnetostrictive sandwich structure, peel off the prepared magnetoelectric composite unit from the copper sheet, use epoxy resin glue to evenly adhere the magnetoelectric composite unit to the flexible circuit board, and connect them in parallel along the center line of the length direction to obtain an array structure.

[0023] Example 2 The other steps are the same as those in Example 1, except that in the method for preparing the flexible magnetomechanical dual-modal sensor array, no magnetic field is applied in step (1), that is, the magnetic field magnitude is 0 kA / m.

[0024] The method for using the flexible force-magnetic dual-mode sensor array comprises the following steps: This sensor can measure the physical quantity of current and can be used in the field of current measurement of integrated electronic devices with limited space. The FPC interface of the sensor leads to the positive and negative poles of the three unit sensing units. Each positive and negative pole of the FPC interface is connected to the amplifier circuit respectively to amplify the voltage signal output by the sensor, and the output end of the amplifier circuit is connected to the AD acquisition port of the single-chip microcomputer, and the amplified voltage signal is collected by the single-chip microcomputer. The serial port interface of the single-chip microcomputer is connected to the computer through the TTL to USB connector, and the data collected by the single-chip microcomputer is sent to the matlab serial port of the computer through serial communication. The data received by the matlab serial port is processed by the time-sharing modal isolation measurement algorithm to obtain the physical quantity information of the current.

[0025] When measuring the current, the sensor array remains unchanged, and different currents are passed through the solenoid. At this time, the surrounding magnetic field changes, and the magnetostrictive films 5 and 7 of the magnetoelectric composite unit will sense the change in the surrounding magnetic field and deform. The deformation is transmitted to the piezoelectric film 6, and the deformation is converted into a voltage signal. The voltage signal is transmitted to the FPC interface through the conductive copper wire 1. The output voltage signal is amplified by the amplifier circuit, the amplified signal is collected by the single-chip microcomputer and transmitted to the matlab serial port of the computer, and the data is processed by the time-sharing modal isolation measurement algorithm, so that the current information at this time can be obtained.

[0026] The protocols and software involved in the present invention are all well-known technologies.

[0027] The magnetization curves of the magnetostrictive film electrodeposited under an induced magnetic field of 50 kA / m and the magnetostrictive film electrodeposited without an induced magnetic field were tested by vibrating sample magnetometer VSM. Figure 5 (a), that is, the magnetization curve comparison diagram of the magnetostrictive film prepared by electrodeposition under an induced magnetic field of 50kA / m and without an induced magnetic field. When the external magnetic field is 500kA / m, the saturation magnetic induction intensity of the magnetostrictive film obtained by electrodeposition without an induced magnetic field is 4.09kA / m, and the saturation magnetic induction intensity of the magnetostrictive film prepared by electrodeposition under an induced magnetic field of 50kA / m can reach 8.9kA / m. It can be concluded that the magnetostrictive film obtained by electrodeposition under an induced magnetic field of 50kA / m has a higher degree of magnetization when affected by a magnetic field, is more sensitive to changes in the external magnetic field, and can produce a larger dimensional change response than the magnetostrictive film prepared without an induced magnetic field.

[0028] The multi-parameter magnetic measurement system WK-22 is used to fix the sample on the strain gauge of the test system and place it in the magnetic field space generated by the DC magnetic field stabilized current power supply. The strain signal is recorded by changing the size of the DC magnetic field. The obtained data is processed to obtain Figure 5 (b). Figure 5 (b) Curve is a comparison of the piezomagnetic coefficient curves of magnetostrictive films prepared under induced magnetic field and without induced magnetic field. When the external magnetic field is 50kA / m, the piezomagnetic coefficient of the magnetostrictive film obtained by electrodeposition without induced magnetic field is 6.1nm / A, and the piezomagnetic coefficient of the magnetostrictive film prepared by electrodeposition under 50kA / m induced magnetic field is 7.8nm / A. It can be seen that the magnetostrictive film prepared under induced magnetic field has a larger piezomagnetic coefficient under different magnetic field environments than the magnetostrictive film prepared without induced magnetic field. The magnetostrictive material with a larger piezomagnetic coefficient has the advantages of high-precision measurement, high-sensitivity control, and rapid response.

[0029] Depend on Figure 6 From the curve, we can see that the improved magnetoelectric composite current sensor shows a higher magnetoelectric coefficient in the range of 39-52kHZ, which broadens the resonance frequency band of a single current sensor. At the same time, three peaks appear in the resonance frequency band of the optimized sensor, and the three peaks correspond to the resonance frequencies of a single sensor, which means that the combination of multiple sensors can achieve the broadening of the resonance frequency band.

[0030] Matters not covered by the present invention are known technologies.

Claims

1. A flexible broadband magnetoelectric composite current sensor array, characterized by The sensor comprises: conductive copper wires are distributed inside the conversion layer of the flexible circuit board; magnetoelectric composite units are attached to the conversion layer of the flexible circuit board and arranged along the length direction; the magnetoelectric composite units are divided into a three-layer structure, and a force sensitive layer is sandwiched between two magnetostrictive films; The number of the magnetostrictive units is 3, forming a 3*1 array; The force sensitive layer is a piezoelectric film made of PVDF with a thickness ranging from 1 to 100 microns; The magnetostrictive film material is Fe-Co, Fe-Ni, Fe-Ga or Terfenol; the thickness ranges from 1 to 100 microns; The conversion layer is in a right-angled U-shape, and two cross beams parallel to the bottom edge are evenly spaced on the side wall of the right-angled U-shape, and a magnetoelectric composite unit is distributed in the middle of the two cross beams and the bottom edge, wherein the long direction of the magnetoelectric composite unit is distributed along the U-shape direction; The conversion layer is a double-layer flexible circuit board made of polyimide (PI) with conductive copper wires distributed in it.

2. The flexible wide-band magnetoelectric composite current sensor array according to claim 1, characterized in that The spacing between the beams is 38mm; the width of the side walls and bottom edges is 7mm; The sizes of the magnetoelectric composite units are 30mm×10mm, 27mm×10mm, and 24mm×10mm respectively; the distance between adjacent magnetoelectric composite units is 8mm; The size of the flexible circuit board is 110mm×45mm, the thickness of a single layer is 100 microns, and the size of the beam is 30×7mm.

3. The method for preparing the flexible wide-band magnetoelectric composite current sensor array according to claim 1, characterized in that The following steps are involved: (1) Preparation of Co-Fe magnetostrictive film by electrodeposition under induced magnetic field: A copper sheet is pickled and used as a cathode, a platinum plate is used as an anode, a Co-Fe alloy electrodeposition solution is used as an electrolyte, the two plates are placed vertically and parallel to each other in the electrolyte, a dilute sulfuric acid solution is added dropwise in a DC magnetic field environment and a DC power supply to control the pH of the electrolyte to 2.5-3.5, after the deposition is completed, the copper sheet is taken out and cleaned with alcohol, and then air-dried to obtain a magnetostrictive film deposited on the copper sheet; The electrodeposition solution comprises FeSO4·7H2O 0.01-0.1mol / L, CoSO4·7H2O 0.1-0.5mol / L, sodium citrate 0.2-0.5mol / L, boric acid 0.2-0.3mol / L, ascorbic acid 0.5-2g / L, saccharin 1-3g / L, sodium dodecyl sulfate 0.01-0.05g / L; The magnetic field value is: 50~500kA / m; the current is controlled at 0.30~0.40A / cm 2 , the pH of the electrolyte is controlled at 2.5-3.5 by adding 10% dilute sulfuric acid solution, and the electrodeposition time is 20-100 min; (2) Preparation of PVDF piezoelectric film by spin coating: The copper sheet on which the Co-Fe film obtained in step (1) is deposited is used as a substrate, placed on a spin coater, and PVDF is spin-coated, and then annealed at 120-140° C. for 3.5-4.5 hours; finally, it is placed in a field strength of 125-130 MV / m for polarization for 25-35 minutes to obtain a piezoelectric film; The solvent of the PVDF solution is DMF, and the concentration is 5-20 g / 100 ml. The speed of the spin coater is 1000-2000 r / min, and the spin coating is repeated 3-10 times, and each spin coating lasts 60-120 seconds. (3) Repeating the process (1) with the magnetostrictive-piezoelectric composite unit obtained in step (2) to obtain a magnetostrictive-piezoelectric-magnetostrictive sandwich structure of the magnetoelectric composite unit, peeling the prepared magnetoelectric composite unit from the copper sheet, and evenly gluing the magnetoelectric composite unit to a flexible circuit board embedded with copper wires using epoxy resin glue, and connecting them in parallel along the center line of the length direction to obtain an array structure.

Images