A flexible force and magnetic dual-mode sensor array

Abstract

The application discloses a flexible force and magnetic dual-mode sensor array. The sensor array comprises a matrix of rectangular conductive copper skins distributed on the upper surface of a conversion layer, each of the rectangular conductive copper skins has a strip-shaped conductive copper skin with the same width on one side, a magnetostrictive film is attached to the rectangular conductive copper skin, and a piezoelectric film force sensitive layer covers the conversion layer of the flexible circuit board. The number of the rectangular conductive copper skins and the conductive thin layer units is 9, and a 3*3 array is formed. The application has the excellent characteristics of easy miniaturization and simple circuit, and has the excellent performances of high sensitivity, short response time and recovery time and good compatibility, so that the design and manufacturing of the force and magnetic dual-mode sensor are greatly simplified.

Description

Technical fields:

[0001] This invention relates to the field of force and magnetic sensor technology, and more specifically, to a dual-mode sensor array capable of detecting force and magnetism and its fabrication method. Background technology:

[0002] As large-scale models like chatGPT are increasingly deployed on various smart terminals, mobile intelligent robots will be continuously integrated into various application scenarios. Currently, when mobile grasping robots grasp an object in a certain space, they need to pre-set a fixed movement trajectory or establish a location coordinate map for that space. If the object is placed in a new space, its original location coordinate information will become invalid. This pre-set positioning method makes it difficult to flexibly apply mobile grasping robots to various scenarios. Therefore, real-time detection of object position information and real-time perception of the position of the mobile robot's manipulator become crucial for mobile robots to flexibly adapt to various application scenarios. Real-time detection of object position information can be achieved using a pressure sensor array to locate the object's position on the sensor array. A permanent magnet is installed at the tip of the robotic finger; the relative spatial position between the manipulator and the sensor array can be perceived in real time through the response of the magnetic sensor array. Therefore, a dual-modal sensor capable of simultaneously sensing force and magnetism can be used.

[0003] In current force-magnetic dual-mode sensors, a specific sensing layer (made of materials such as magnetostrictive thin films) serves as the sensing element, and circuits and other devices act as signal conversion devices. These methods utilize the properties of materials and electrical mechanisms to convert force-magnetic physical quantities into electrical signals. For example, patent CN 115435818A, a contact / non-contact force-magnetic dual-mode sensing sensor based on a magnetostrictive thin film (publication date: December 6, 2022), provides a force-magnetic dual-mode detection sensor that uses a magnetostrictive thin film as the sensing element and a coil as the signal conversion device. The use of coil elements necessitates a relatively complex driving circuit for this sensor and prevents the miniaturization of the sensing unit, making it difficult to construct a dense sensing array. Summary of the Invention:

[0004] The purpose of this invention is to address the shortcomings of current technologies by proposing a flexible force-magnetic dual-modal sensor array. Each unit of this array sensor consists of a force-sensitive layer, a magnetic-sensitive layer, and a conversion layer. A planar flexible sensing structure is formed by vertically arranging the P(VDF-TrFE) piezoelectric film force-sensitive layer, the magnetostrictive film magnetic-sensitive layer, and the flexible circuit board conversion layer. This structure can sense changes in the magnetization state of the magnetostrictive film and the stress changes experienced by the P(VDF-TrFE) piezoelectric film under force-magnetic conditions. Through the tight coupling between the magnetostrictive film and the P(VDF-TrFE) piezoelectric film, the magnetostrictive film converts the magnetic signal into a force signal and transmits it to the P(VDF-TrFE) piezoelectric film. The P(VDF-TrFE) piezoelectric film then converts the force signal from the magnetostrictive film and the external contact force signal into an electrical signal. The sensing of force-magnetic dual-modal information is achieved by measuring the output electrical signal. Furthermore, this invention employs an electrodeposition process under an induced magnetic field to fabricate the magnetostrictive film array, ensuring the consistency of each sensing unit while reducing fabrication difficulty and cost, and improving the surface normal force-magnetic sensitivity. This invention uses a P(VDF-TrFE) piezoelectric thin film to sense changes in the magnetization state of a magnetostrictive thin film. It eliminates the need for coil structures and drive circuits, offering advantages such as easy miniaturization and simple circuitry. It exhibits high sensitivity, short response and recovery times, and good compatibility. By using a single structure and wires to simultaneously sense force and magnetic signals, it greatly simplifies the design and manufacture of force-magnetic dual-mode sensors.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A flexible force-magnetic dual-mode sensor array includes: a matrix of rectangular conductive copper sheets distributed on the upper surface of a conversion layer, each rectangular conductive copper sheet having a strip of conductive copper sheet of the same width on one side; a magnetostrictive film attached to the rectangular conductive copper sheets; a piezoelectric thin film force-sensitive layer covering the flexible circuit board conversion layer, wherein the portion of the piezoelectric thin film force-sensitive layer directly above the strip of conductive copper sheet is a cut-out blank area; matrix-distributed conductive thin-layer units are distributed on the piezoelectric thin-film force-sensitive layer and the cut-out area, and the projection position of each conductive thin-layer unit overlaps with the positions of a set of rectangular conductive copper sheets, the blank area, and the strip of conductive copper sheet;

[0007] The rectangular conductive copper foil and the conductive thin layer unit are each in a quantity of 9, forming a 3*3 array;

[0008] The rectangle is preferably a square with a side length of 5-10 mm; the distance between adjacent square conductive copper sheets is 4-5 mm, and the distance between each square conductive copper sheet and the corresponding strip conductive copper sheet is 1-2 mm.

[0009] The conductive thin layer is made of conductive silver paste, silver or copper conductive tape; the thickness ranges from 1 to 1000 micrometers.

[0010] The piezoelectric thin film sensitive layer is made of P(VDF-TrFE) material; its thickness ranges from 1 to 100 micrometers.

[0011] The magnetostrictive thin film material is Fe-Co, Fe-Ni, Fe-Ga, or Terfenol; the thickness ranges from 1 to 100 micrometers.

[0012] The conversion layer is a flexible circuit board.

[0013] The square conductive copper foil has a thickness of 50–200 micrometers and a side length of 5–10 mm.

[0014] The strip-shaped conductive copper foil has a thickness of 50–200 micrometers and a width of 1–3 mm.

[0015] The fabrication method of the flexible force-magnetic dual-mode sensor array includes the following steps:

[0016] (1) Co-Fe magnetostrictive thin films were prepared by electrodeposition under an induced magnetic field:

[0017] The strip of conductive copper on the flexible circuit board was sealed with electroplating tape. The flexible circuit board and the square conductive copper on it were acid-washed and used as the cathode. The platinum plate was used as the anode. Co-Fe alloy electrodeposition solution was used as the electrolyte. The two plates were placed vertically and parallel to each other in the electrolyte. Under DC magnetic field environment and DC power supply, the pH of the electrolyte was controlled at 2.5-3.5 by adding dilute sulfuric acid solution. After deposition, the flexible circuit board was removed, cleaned with alcohol, and then air-dried to obtain 9 magnetostrictive films deposited on the flexible circuit board.

[0018] The electrodeposition solution comprises ferric sulfate, cobalt sulfate, complexing agent, buffer, antioxidant, and surface brightener, using electrolyzed water as the solvent. The concentrations of the components are: FeSO4·7H2O 0.01–0.1 mol / L, CoSO4·7H2O 0.1–0.5 mol / L, sodium citrate 0.2–0.5 mol / L, boric acid 0.2–0.3 mol / L, ascorbic acid 0.5–2 g / L, saccharin 1–3 g / L, and sodium dodecyl sulfate 0.01–0.05 g / L.

[0019] The magnetic field strength is set at 50–500 kA / m; the current is controlled at 0.30–0.40 A / cm. 2 The pH of the electrolyte was controlled at 2.5–3.5 by adding 10% dilute sulfuric acid solution dropwise, and the electrodeposition time was 20–100 min.

[0020] (2) P(VDF-TrFE) piezoelectric thin films were prepared by spin coating:

[0021] A flexible circuit board with a deposited Co-Fe thin film is placed on a spin coater and a P(VDF-TrFE) solution is spin-coated. The solution is then annealed at 120–140°C for 3.5–4.5 hours. Finally, the circuit board is polarized in an electric field of 125–130 MV / m for 25–35 minutes to obtain a piezoelectric thin film.

[0022] The solvent for the P(VDF-TrFE) solution is DMF, with a concentration of 5–20 g / 100 ml; the spin coater speed is 1000–2000 r / min, and the spin coat is repeated 3–10 times, with each spin coat lasting 60–120 seconds.

[0023] (3) Prepare conductive thin layers using chemical plating:

[0024] Cut the P(VDF-TrFE) piezoelectric film above the strip conductive copper skin on the flexible circuit board to expose the strip conductive copper skin. Place the silicone mold on the flexible circuit board, aligning the nine cutouts of the silicone mold with the nine rectangular sections formed by the square conductive copper skin 5 and the strip conductive copper skin. Then, clamp the silicone mold and the flexible circuit board with two rigid clamps, ensuring that the rectangular cutouts of the rigid clamps correspond to the cutouts of the silicone mold 9. Tighten the screws to form nine groove-shaped containers. Add the sensitizer stannous sulfate to the nine groove-shaped containers, and then drip silver plating solution into the nine groove-shaped containers at room temperature. Grow for 10-15 minutes, and then wash off the silver plating solution. Repeat the "drip silver plating solution-growth-washing" process 1-3 times to obtain nine conductive films of silver material with a thickness of 30-60 micrometers.

[0025] The essential features of this invention are:

[0026] Current magnetic sensors employ a three-layer structure of magnetostrictive film / piezoelectric film / magnetostrictive film, used for magnetic detection. However, the magnetostrictive film in these sensors is typically produced as a thin sheet using a rolling process or magnetron sputtering. These processes are difficult to implement on flexible circuit boards or are prohibitively expensive.

[0027] This invention employs electrodeposition to fabricate a magnetostrictive film onto a flexible circuit board; a magnetoelectric composite material composed of a piezoelectric thin film is used as the sensing material; and an electrodeposition method under an induced magnetic field is used to control the material structure, induce vertical anisotropy, and obtain a surface normal force-magnetic sensing material.

[0028] The beneficial effects of this invention are as follows:

[0029] 1. Compared with other existing flexible force-magnetic dual-mode sensors, which employ complex circuit components such as drive coils and pickup coils and require a drive circuit for operation, this force-magnetic dual-mode sensor does not require a drive circuit; it only needs to acquire the voltage signal output by the sensor.

[0030] 2. In the fabrication of the magnetostrictive film of this invention, an FPC is used as the substrate, and an electrodeposition method is employed to simultaneously fabricate all units on the sensing array, ensuring a consistent thickness of the magnetostrictive film fabricated on the FPC. This eliminates the problem of inconsistent response effects among various sensing units on the array fabricated using traditional adhesive methods. Compared with the magnetron sputtering method, the fabrication method of this invention has a lower cost.

[0031] 3. The sensor of this invention has natural coupling between its various layers, without any intermediate adhesive medium, resulting in a large magneto-electric coupling coefficient and high efficiency.

[0032] 4. This invention employs an electrodeposition method under an induced magnetic field to control the material's structure, resulting in a surface-normal mechanosensitive material. This leads to a higher saturation magnetic induction intensity in the surface normal direction, significantly improving the magnetostriction and piezomagnetic coefficient. With an applied magnetic field of 500 kA / m, the saturation magnetic induction intensity of the magnetostrictive film obtained without an induced magnetic field is 4.09 kA / m, while the saturation magnetic induction intensity of the magnetostrictive film prepared using the electrodeposition method under a 50 kA / m induced magnetic field reaches 8.9 kA / m. With an applied magnetic field of 15 kA / m, the magnetostriction rate of the magnetostrictive film obtained without an induced magnetic field is 65.4 ppm, while the magnetostriction rate of the magnetostrictive film prepared using the electrodeposition method under a 50 kA / m induced magnetic field reaches 80.2 ppm. When the applied magnetic field is 50 kA / m, the piezomagnetic coefficient of the magnetostrictive film obtained by electrodeposition without the induced magnetic field is 6.1 nm / A, while the piezomagnetic coefficient of the magnetostrictive film prepared by electrodeposition with the induced magnetic field of 50 kA / m is 7.8 nm / A. Attached image description:

[0033] Figure 1 This is a schematic diagram of a flexible force-magnetic dual-mode sensor array structure.

[0034] Figure 2 Circuit diagram of flexible circuit board

[0035] Figure 3 Silicone mold used for fabricating conductive thin layer 1 using chemical silver plating

[0036] Figure 4 Hard fixture used for fabricating conductive thin layer 1 using chemical silver plating

[0037] Figure 5 This diagram shows the positional correspondence between the flexible circuit board, silicone mold, and rigid fixture when fabricating a conductive thin layer using the chemical silver plating method.

[0038] Figure 6 A schematic diagram of an electrodeposition apparatus using an induced magnetic field.

[0039] Figure 7 : This is a comparison of the performance of magnetostrictive films prepared under an induced magnetic field of 50 kA / m and without an induced magnetic field; among them, Figure 7 (a) Comparison of magnetization curves of magnetostrictive films prepared under induced magnetic field and without induced magnetic field; Figure 7 (b) Comparison of magnetostriction rate curves of magnetostrictive films prepared under induced magnetic field and without induced magnetic field; Figure 7 (c) Comparison of piezomagnetic coefficient curves of magnetostrictive films prepared under induced magnetic field and without induced magnetic field;

[0040] In the diagram: 1-Conductive thin-film unit; 2-Piezoelectric thin film (force-sensitive layer); 3-Magnetostrictive thin film (magnetically-sensitive layer); 4-Flexible circuit board (conversion layer); 5-Square conductive copper foil on the flexible circuit board; 6-Strip conductive copper foil on the flexible circuit board; 7-FPC interface; 8-Rigid clamp; 9-Silicone mold; 10-Through hole; 11-Platinum electrode; 12-Magnetic pole of DC magnetic field regulated power supply; Detailed implementation method:

[0041] Example 1: This array-type force-magnetic dual-mode sensor utilizes the magnetostrictive and piezoelectric effects to detect mechanical and magnetic properties. The Fe-Co magnetostrictive thin film layer 3 detects the magnetic field through magnetostriction, while the P(VDF-TrFE) piezoelectric film layer 2 detects externally applied forces using the piezoelectric effect. This ME composite material structure converts changes in force and magnetic field into electrical signals, enabling simultaneous monitoring of changes in both forces and magnetic fields. By integrating the magnetostrictive and piezoelectric effects, the sensor can sensitively detect and convert these changes into readable signals, providing relevant information about force and magnetic fields.

[0042] The invention will be further described in detail below with reference to the figures. This embodiment is only for specific illustration of the invention and should not be regarded as a limitation on the scope of protection.

[0043] The flexible force-magnetic dual-mode sensor array structure described in this invention is as follows: Figure 1As shown, the sensor includes: rectangular conductive copper sheets 5 are matrix-distributed on the upper surface of the flexible circuit board conversion layer 4, and each rectangular conductive copper sheet 5 has a strip conductive copper sheet 6 of the same width on one side; a magnetostrictive film 3 is attached to the rectangular conductive copper sheets 5; a piezoelectric film force-sensitive layer 2 covers the magnetostrictive film 3, the rectangular conductive copper sheets 5, the strip conductive copper sheets 6 and the flexible circuit board conversion layer 4, and the portion of the piezoelectric film force-sensitive layer 2 directly above the strip conductive copper sheets 6 is a blank area that has been cut out; matrix-distributed conductive thin-layer units 1 are distributed on the piezoelectric film force-sensitive layer 2 and the blank area, and the projection position of each conductive thin-layer unit 1 overlaps with the positions of a set of rectangular conductive copper sheets 5, the blank area and the strip conductive copper sheets 6;

[0044] The rectangular conductive copper foil 5 and the conductive thin layer unit 1 are both 9 in number, forming a 3*3 array;

[0045] The rectangle is preferably a square with a side length of 10mm; the distance between adjacent square conductive copper sheets 5 is 4-5mm, and the distance between each square conductive copper sheet 5 and the corresponding strip conductive copper sheet 6 is 1-2mm.

[0046] The conductive thin layer 1 is a conductive material attached to the upper side of the piezoelectric film force-sensitive layer, and naturally adheres to the strip of conductive copper foil 6 on the flexible circuit board. Its material is conductive silver paste, silver or copper conductive tape; the thickness ranges from 1 to 1000 micrometers (the thickness used in this embodiment is 20 micrometers).

[0047] The force-sensitive layer 2 is a piezoelectric thin film made of P(VDF-TrFE); its thickness ranges from 1 to 100 micrometers (the thickness used in this embodiment is 20 micrometers);

[0048] The magnetically sensitive layer 3 is a magnetostrictive thin film, and the material is Fe-Co, Fe-Ni, Fe-Ga, or Terfenol, etc. (Fe is used in this embodiment). 30 Co 70 The thickness ranges from 1 to 100 micrometers (the thickness used in this embodiment is 20 micrometers);

[0049] The conversion layer 4 is a flexible circuit board, with its three base layers made of polyimide (PI) and a conductive layer made of copper sandwiched between them. The thickness of the flexible circuit board is 100–200 micrometers (110 micrometers is used in this embodiment). Its specific circuit structure diagram is shown below. Figure 2 As shown, the main components of this flexible circuit board include a square conductive copper foil 5, a strip conductive copper foil 6, and an FPC interface 7.

[0050] The square conductive copper foil 5 has a thickness of 50-200 micrometers (50 micrometers is used in this embodiment) and a width of 5-10 mm (10 mm is used in this embodiment).

[0051] The strip-shaped conductive copper sheet 6 has a thickness of 50-200 micrometers (50 micrometers is used in this embodiment), a length equal to the width of the square conductive copper sheet 5, and a width of 1-3 mm (1 mm is used in this embodiment). It is 1-2 mm away from the square conductive copper sheet 5 (2 mm is used in this embodiment).

[0052] The FPC interface 7 is reinforced with PI.

[0053] In preparing the conductive thin layer 1 using chemical plating, this invention designs a silicone mold 9 and a rigid fixture 8, as shown below. Figure 3 , Figure 4 As shown. According to Figure 5 The positional correspondence is used as follows: During use, the silicone mold 9 and the flexible circuit board 4 are tightly bonded together. Then, two rigid clamps 8 are used to hold the silicone mold 9 and the flexible circuit board 4 in place. M3 screws are installed and tightened in the M3 through holes of the rigid clamps 8 to ensure a tighter fit between the silicone mold 9 and the flexible circuit board 4. This ensures that the silver plating solution remains within the hollowed-out grooves of the silicone mold 9 for a long time during the chemical plating process, preventing it from spreading.

[0054] The silicone mold 9 is 2mm thick, has a certain degree of elasticity, and is waterproof; the nine hollow rectangular sections in the middle are 10mm*13mm in size.

[0055] The rigid clamp 8 is 1.6mm thick and made of FR-4 material, which has high hardness. The through hole 10 on it is an M3 type hole, and the nine hollow rectangular parts in the middle are 10mm*13mm in size.

[0056] A method for fabricating a flexible force-magnetic dual-mode sensor array includes the following steps:

[0057] (1) Co-Fe magnetostrictive thin films were prepared by electrodeposition under an induced magnetic field, including the following steps:

[0058] The strip of conductive copper foil 6 on the flexible circuit board 4 is sealed with electroplating tape. The flexible circuit board 4 and the square conductive copper foil 5 on it are acid-washed and used as the cathode. The platinum plate 11 is used as the anode. Co-Fe alloy electrodeposition solution is used as the electrolyte. The two plates are placed vertically and parallel to each other in the electrolyte. A DC magnetic field environment is provided by a DC magnetic field constant current power supply. The electrodeposition device is placed in the DC magnetic field environment, with the magnetic field perpendicular to the two plates. The magnetic field strength is 50 kA / m. Under the condition of 50℃, a DC power supply is used with constant current output, and the current is controlled at 0.35 A / cm. 2 The pH of the electrolyte was controlled at 3 by adding 10% dilute sulfuric acid solution. The electrodeposition time was 40 minutes and the deposition thickness was 20 micrometers (the size is consistent with the "square conductive copper foil"). After the deposition was completed, the flexible circuit board was removed, cleaned with alcohol, and then air-dried to obtain 9 magnetostrictive films 3 deposited on the flexible circuit board 4.

[0059] The electrodeposition solution is composed of ferric sulfate, cobalt sulfate, complexing agent, buffer, antioxidant, and surface brightener, and uses electrolyzed water as a solvent. Specifically, it contains 0.05 mol / L FeSO4·7H2O, 0.3 mol / L CoSO4·7H2O, 0.3 mol / L sodium citrate, 0.2 mol / L boric acid, 1.0 g / L ascorbic acid, 2 g / L saccharin, and 0.03 g / L sodium dodecyl sulfate.

[0060] (2) The P(VDF-TrFE) piezoelectric thin film was prepared by spin coating, including the following steps:

[0061] A certain mass of P(VDF-TrFE) powder was placed in a DMF solution at a concentration ratio of 12g / 100ml, and heated and stirred until the P(VDF-TrFE) was completely dissolved in the DMF solution. A flexible circuit board with a deposited Co-Fe thin film was placed on a spin coater, and the spin coater speed was adjusted to 2000 r / min. The spin coat was repeated 5 times, with 1ml of solution added each time, and the coating time was 120 seconds. After drying, a film thickness of approximately 20 micrometers was obtained. The obtained film was placed in an oven and annealed at 120℃ for 4 hours. Finally, the annealed P(VDF-TrFE) piezoelectric film was polarized in an electric field of 125 MV / m for 30 minutes to obtain a P(VDF-TrFE) piezoelectric film 2 with good piezoelectric properties.

[0062] (3) The conductive thin layer 1 is prepared by chemical plating, which includes the following steps:

[0063] Cut off the P(VDF-TrFE) piezoelectric film above the strip of conductive copper 6 on the flexible circuit board to expose the strip of conductive copper 6. Figure 3The silicone mold 9 is placed on the flexible circuit board 4, with its nine cutouts aligned with the nine rectangular sections formed by the square conductive copper foil 5 and the strip conductive copper foil 6. Air bubbles between the silicone mold 9 and the flexible circuit board 4 are pressed out to ensure a tight fit. Two rigid clamps 8 then hold the silicone mold 9 and the flexible circuit board 4 together, with the rectangular cutouts of the rigid clamps 8 corresponding to the cutouts of the silicone mold 9. M3 screws are installed in the M3 through-holes to keep the rigid clamps firmly in place, completing the installation of the silver plating mold and forming nine trough-shaped containers. Stannous sulfate, a sensitizer, is added to the nine trough-shaped containers and left to stand for 30-60 seconds to allow a layer of stannous ions to be adsorbed onto the surface. Afterward, the containers are rinsed naturally with a slow stream of water. During the rinsing process, the stannous ions hydrolyze into a gel-like substance that adheres to the surface, serving as seeds for silver growth during the silver plating process. Then, at room temperature (ideally 10-15℃), 2-4 ml of silver plating solution (a mixture of glucose and silver ammonia solution, using a chemical silver plating solution from Zirconium Vanadium Technology) is added to each tank container. The solution is left for 10 minutes, then rinsed off. New silver plating solution is added again, and this process is repeated three times to obtain nine conductive films 1 made of silver with a thickness of 30-60 micrometers. The conductive films 1 are electrically connected to the strip-shaped conductive copper foil 6.

[0064] Example 2: Other steps are the same as in Example 1, except that in the preparation method of the flexible force-magnetic dual-mode sensor array, no magnetic field is applied in step (1), that is, the magnetic field magnitude is 0kA / m.

[0065] The method of using the flexible force-magnetic dual-mode sensor array includes the following steps:

[0066] This sensor can measure both force and magnetism, and can be used in contact / non-contact object positioning systems. The sensor's FPC interface leads to the positive and negative terminals of nine sensing units. Each terminal of the FPC interface is connected to an amplifier circuit to amplify the voltage signal output by the sensor. The output of the amplifier circuit is then connected to the AD acquisition port of a microcontroller, which acquires the amplified voltage signal. The microcontroller's serial port is connected to a computer via a TTL-to-USB connector. The data acquired by the microcontroller is sent to the MATLAB serial port on the computer via serial communication. A time-division modal isolation measurement algorithm is used to process the data received from the MATLAB serial port to obtain the force and magnetism modes of physical quantity information.

[0067] When measuring magnetism, the contact force on the sensor array is kept constant. Changing the distribution of the surrounding magnetic field will change the output voltage signal of the sensor. The output voltage signal is amplified by an amplifier circuit, the amplified signal is collected by a microcontroller and transmitted to the MATLAB serial port of the computer, and the data is processed by a time-division modal isolation measurement algorithm to obtain the magnetic field distribution information at this time.

[0068] When measuring contact force, the magnetic field distribution around the sensor array is kept constant. Changing the magnitude and distribution of the contact force on the sensor array will change the output voltage signal of the sensor. Similarly, the output voltage signal is amplified by an amplification circuit, the amplified signal is acquired by a microcontroller and transmitted to the MATLAB serial port of the computer, and the data is processed by a time-division modal isolation measurement algorithm to obtain the magnitude and distribution information of the contact force at this time.

[0069] The protocols or software involved in this invention are all known technologies.

[0070] Magnetization curves of magnetostrictive films electrodeposited under an induced magnetic field of 50 kA / m and those electrodeposited without an induced magnetic field were measured using a vibrating sample magnetometer (VSM). The test data were then processed to obtain... Figure 7 (a) Comparison of magnetization curves of magnetostrictive films electrodeposited under an induced magnetic field of 50 kA / m and without an induced magnetic field. When the applied magnetic field is 500 kA / m, the saturation magnetic flux density of the magnetostrictive film electrodeposited without an induced magnetic field is 4.09 kA / m, while the saturation magnetic flux density of the magnetostrictive film electrodeposited under an induced magnetic field of 50 kA / m reaches 8.9 kA / m. It can be concluded that the magnetostrictive film electrodeposited under an induced magnetic field of 50 kA / m exhibits a higher degree of magnetization when affected by a magnetic field compared to the magnetostrictive film prepared without an induced magnetic field, and is more sensitive to changes in the external magnetic field, thus producing a larger dimensional change response.

[0071] The WK-22 multi-parameter magnetic measurement system was used. The sample was fixed on the strain gauge of the testing system and placed within the magnetic field space generated by the DC magnetic field power supply. The strain signal was recorded by changing the magnitude of the DC magnetic field. The obtained data was then processed to obtain... Figure 7 (b) and Figure 7 (c) Figure 7(b) The curves show a comparison of the magnetostriction rates of magnetostrictive films prepared under an induced magnetic field of 50 kA / m and without an induced magnetic field. When the applied magnetic field is 15 kA / m, the magnetostriction rate of the magnetostrictive film obtained by electrodeposition without an induced magnetic field is 65.4 ppm, while the magnetostriction rate of the magnetostrictive film prepared by electrodeposition under an induced magnetic field of 50 kA / m reaches 80.2 ppm. This indicates that the magnetostrictive film prepared under an induced magnetic field has a greater magnetostriction rate than the magnetostrictive film prepared without an induced magnetic field under different magnetic field environments, and its sensitivity to magnetic fields is also higher. Figure 7 (c) Curve (c) compares the piezomagnetic coefficients of magnetostrictive films prepared under induced magnetic fields and without induced magnetic fields. With an applied magnetic field of 50 kA / m, the piezomagnetic coefficient of the magnetostrictive film prepared by electrodeposition without an induced magnetic field is 6.1 nm / A, while the piezomagnetic coefficient of the magnetostrictive film prepared by electrodeposition under a 50 kA / m induced magnetic field is 7.8 nm / A. This shows that the magnetostrictive film prepared under an induced magnetic field has a larger piezomagnetic coefficient than the magnetostrictive film prepared without an induced magnetic field under different magnetic field environments. Magnetostrictive materials with larger piezomagnetic coefficients have advantages such as high-precision measurement, high-sensitivity control, and fast response.

[0072] Depend on Figure 7 The curves show that the magnetostrictive film prepared by electrodeposition under an induced magnetic field has a higher sensitivity to magnetic fields, which helps to improve the performance of the force-magnetic dual-mode sensor array.

[0073] Matters not covered in this invention are common knowledge.

Claims

1. A flexible force-magnetic dual-mode sensor array, characterized in that... The sensor array includes: rectangular conductive copper sheets distributed in a matrix on the upper surface of the conversion layer, with a strip conductive copper sheet of the same width on one side of each rectangular conductive copper sheet; a magnetostrictive film attached to the rectangular conductive copper sheets; a piezoelectric thin film force-sensitive layer covering the conversion layer, with the portion of the piezoelectric thin film force-sensitive layer directly above the strip conductive copper sheet being a cut-out blank area; and matrix-distributed conductive thin-layer units distributed on the piezoelectric thin-film force-sensitive layer and the cut-out area, wherein the projected position of each conductive thin-layer unit overlaps with the positions of a set of rectangular conductive copper sheets, blank areas, and strip conductive copper sheets. The rectangular conductive copper foil and the conductive thin layer unit are each in a quantity of 9, forming a 3*3 array.

2. The flexible force-magnetic dual-mode sensor array as described in claim 1, characterized in that: The rectangle is a square with a side length of 5-10mm; the distance between adjacent square conductive copper sheets is 4-5mm, and the distance between each square conductive copper sheet and the corresponding strip conductive copper sheet is 1-2mm.

3. The flexible force-magnetic dual-mode sensor array as described in claim 1, characterized in that the conductive thin layer is made of conductive silver paste, silver or copper conductive tape; and the thickness ranges from 1 to 1000 micrometers; The piezoelectric thin film force-sensitive layer is made of P(VDF-TrFE) material; its thickness ranges from 1 to 100 micrometers. The magnetostrictive thin film material is Fe-Co, Fe-Ni, Fe-Ga, or Terfenol; the thickness ranges from 1 to 100 micrometers. The conversion layer is a flexible circuit board; The rectangular conductive copper foil is a square conductive copper foil with a thickness of 50~200 micrometers and a side length of 5~10mm; The strip-shaped conductive copper foil has a thickness of 50~200 micrometers and a width of 1~3mm.

4. The method for fabricating the flexible force-magnetic dual-mode sensor array as described in claim 1, characterized in that: Includes the following steps: (1) Co-Fe magnetostrictive thin films were prepared by electrodeposition under an induced magnetic field: The strip of conductive copper on the flexible circuit board was sealed with electroplating tape. The flexible circuit board and the square conductive copper on it were acid-washed and used as the cathode. The platinum plate was used as the anode. Co-Fe alloy electrodeposition solution was used as the electrolyte. The two plates were placed vertically and parallel to each other in the electrolyte. Under DC magnetic field environment and DC power supply, the pH of the electrolyte was controlled at 2.5~3.5 by adding dilute sulfuric acid solution. After deposition, the flexible circuit board was removed, cleaned with alcohol, and then air-dried to obtain 9 magnetostrictive films deposited on the flexible circuit board. The electrodeposition solution comprises ferric sulfate, cobalt sulfate, complexing agent, buffer, antioxidant, and surface brightener, with electrolyzed water as the solvent. The concentrations of the components are: 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, and sodium dodecyl sulfate 0.01~0.05g / L. The magnetic field strength is set at 50~500 kA / m; the current is controlled at 0.30~0.40 A / cm. 2 The pH of the electrolyte is controlled at 2.5-3.5 by adding dilute sulfuric acid solution dropwise, and the electrodeposition time is 20-100 min. (2) P(VDF-TrFE) piezoelectric thin films were prepared by spin coating: A flexible circuit board with a deposited Co-Fe thin film is placed on a spin coater and a P(VDF-TrFE) solution is spin-coated. The solution is then annealed at 120-140°C for 3.5-4.5 hours. Finally, the circuit board is polarized in an electric field of 125-130 MV / m for 25-35 minutes to obtain a piezoelectric thin film. The solvent for the P(VDF-TrFE) solution is DMF, with a concentration of 5~20g / 100ml; (3) Prepare conductive thin layers using chemical plating: Cut the P(VDF-TrFE) piezoelectric film above the strip conductive copper skin on the flexible circuit board to expose the strip conductive copper skin. Place a silicone mold on the flexible circuit board, aligning the nine cutouts of the silicone mold with the nine rectangular sections formed by the square and strip conductive copper skins. Then, clamp the silicone mold and the flexible circuit board with two rigid clamps, ensuring the rectangular cutouts of the rigid clamps correspond to the cutouts of the silicone mold. Tighten the screws to form nine groove-shaped containers. Add the sensitizer stannous sulfate to the nine groove-shaped containers, and then drip a silver plating solution into the nine groove-shaped containers at room temperature. Grow for 10-15 minutes, then wash off the silver plating solution. Repeat the "drip silver plating solution-growth-washing" process 1-3 times to obtain nine conductive films of silver material with a thickness of 30-60 micrometers.

5. The method for fabricating the flexible force-magnetic dual-mode sensor array as described in claim 4, characterized in that: In step (2), the spin coater speed is 1000~2000 r / min, and the spin coat is repeated 3~10 times, with each spin coat lasting 60~120 seconds.

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