A flexible inductive magnetic pressure sensor and a flexible inductive magnetic pressure sensor array

Abstract

This invention provides a flexible inductive magnetic pressure sensor, comprising a magnetoelastic body unit, a magnetic sensing unit, and a magnetic rebound unit arranged sequentially from top to bottom, wherein the magnetization directions of the magnetoelastic body unit and the magnetic rebound unit are opposite. This invention also provides a flexible inductive magnetic pressure sensor array. Compared with the prior art, this invention utilizes the mutual repulsive force between the magnetoelastic body unit and the magnetic rebound unit with opposite magnetic poles to achieve rapid rebound of the magnetoelastic body, thereby reducing the hysteresis behavior of the inductive magnetic pressure sensor.

Description

Technical Field

[0001] This invention relates to the field of flexible electronics technology, and more specifically, to a flexible inductive magnetic pressure sensor and a flexible inductive magnetic pressure sensor array. Background Technology

[0002] Flexible sensors, due to their excellent tensile properties, conductivity, and conformability, are widely used in health diagnostics, motion monitoring, and human-computer interaction. However, due to the inherent viscoelasticity of soft materials, flexible sensors cannot quickly return to their initial shape during dynamic loading, resulting in significant signal hysteresis. This severely affects the accuracy of flexible sensor monitoring and hinders its practical application. Therefore, designing and fabricating a high-precision flexible sensor with low hysteresis remains a challenge. Inductive magnetic pressure sensors based on the giant magnetoresistance (GMI) effect of soft magnetic amorphous wires exhibit excellent sensitivity, and as described in patent CN104697678A, they can detect weak stress. However, the drum-shaped structure is not conducive to the thin-film fabrication of flexible sensors, and the rebound hysteresis problem of flexible magnetic films remains unresolved. Invention patent CN112857468A discloses a dual-mode sensor for detecting magnetic fields and strain. It detects magnetic field changes based on the GMI effect and strain based on the resistance change after the wire is stretched. The structure is simple; however, the rebound hysteresis problem of the stretched wire remains unsolved.

[0003] When using inductive flexible magnetic sensors to detect pressure, hard magnetic elastomers are the core component. These elastomers are composed of hard magnetic particles doped into an elastic substrate. Their force-to-magnetic conversion efficiency directly determines the sensing performance of the inductive magnetic pressure sensor, including sensitivity, accuracy, force self-decoupling, and detection range. Within a certain range, as the percentage of hard magnetic particles in the elastic substrate increases, the force-to-magnetic conversion efficiency of the hard magnetic elastomer increases. However, this leads to a slower rebound after being subjected to force, resulting in significant signal hysteresis. Summary of the Invention

[0004] The main technical problem solved by this invention is to provide a flexible inductive magnetic pressure sensor that utilizes the mutual repulsive force between the opposing magnetic poles of the magnetoelastic element and the magnetic rebound element to achieve rapid rebound of the magnetoelastic element, thereby reducing the hysteresis behavior of the inductive magnetic pressure sensor.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a flexible inductive magnetic pressure sensor, comprising a magnetoelastic body unit, a magnetic sensing unit, and a magnetic rebound unit arranged sequentially from top to bottom, wherein the magnetization directions of the magnetoelastic body unit and the magnetic rebound unit are opposite. The magnetoelastic body unit includes a first elastic matrix and a plurality of first permanent magnet particles, wherein the plurality of first permanent magnet particles are doped in the first elastic matrix. The magnetic sensing unit includes an inductor coil, a soft magnetic amorphous wire, a modulus reinforcing layer, a plurality of soft magnetic particles, and a second elastic matrix. The inductor coil and the soft magnetic amorphous wire are both disposed within the modulus reinforcing layer, and the inductor coil is wound on the soft magnetic amorphous wire. The plurality of soft magnetic particles are doped in the second elastic matrix. The modulus reinforcing layer is fixedly disposed on the second elastic matrix. The magnetic rebound unit includes a third elastic matrix and a plurality of second permanent magnet particles, wherein the plurality of second permanent magnet particles are doped in the third elastic matrix.

[0006] Preferably, the material of the first permanent magnet particle is selected from at least one of dFeB, SmCo, AlNiCo, and FeCrCo, and the material of the second permanent magnet particle is selected from at least one of NdFeB, SmCo, AlNiCo, and FeCrCo. After magnetization, both the magnetoelastic unit and the magnetic rebound unit are magnetic, and they are assembled on the flexible inductive magnetic pressure sensor that can magnetically rebound in a magnetically opposing manner. Therefore, there is a mutual repulsive force between the magnetoelastic unit and the magnetic rebound unit.

[0007] Preferably, the material of the first elastic matrix is ​​selected from one of photosensitive resin, polydimethylsiloxane PDMS, and aliphatic aromatic random copolyester, and the material of the third elastic matrix is ​​selected from one of photosensitive resin, polydimethylsiloxane PDMS, and aliphatic aromatic random copolyester.

[0008] Preferably, the material of the soft magnetic amorphous wire is selected from at least one of Co, Fe, and Ni.

[0009] Preferably, the material of the soft magnetic particles is selected from at least one of Fe3O4, Ni, Mn, and silver-plated nickel.

[0010] Preferably, the parameters of the soft magnetic amorphous wire are as follows: diameter 20-200μm, length 2-5mm.

[0011] Preferably, the parameters of the inductor coil are as follows: wire diameter of 0.01-0.05mm and number of turns of 50-410.

[0012] Preferably, the modulus reinforcement layer includes a housing with an opening at one end and a shielding post fixedly disposed within the housing. The shielding post is fixedly disposed at the bottom center of the housing, and a shielding cavity with an opening at one end is provided within the shielding post. The hollow inductor coil is disposed within the housing and wound around the shielding post. The soft magnetic amorphous wire is disposed within the shielding cavity. The function of the modulus reinforcement layer is to ensure that deformation of the sensor under pressure does not interfere with the coil, thus not interfering with the detection signal of the magnetic field.

[0013] Preferably, the macroscopic morphology of the magnetoelastic unit and the magnetic rebound unit are both flat films, and both have hollowed-out microscopic morphology.

[0014] Preferably, the soft magnetic particles are arranged in a gradient within the second elastic matrix.

[0015] The principle of this invention is as follows: Under external pressure, the upper magnetoelastic unit deforms, causing a change in the magnetic flux at the middle magnetic sensing unit. The change in the permeability of the amorphous filament generates a giant magnetoresistance effect. By monitoring the impedance change, the pressure can be sensed. After the pressure is released, the upper magnetoelastic unit can quickly rebound by relying on the magnetic repulsion formed by the opposite magnetization direction to the lower magnetic rebound unit.

[0016] Another object of the present invention is to provide a flexible inductive magnetic pressure sensor array, comprising at least two flexible inductive magnetic pressure sensors, wherein the at least two flexible inductive magnetic pressure sensors are arranged in series. The magnetically resilient flexible inductive magnetic pressure sensor array has the characteristics of being cut and spliced ​​for use.

[0017] Compared with the prior art, the present invention has the following advantages: First, the present invention utilizes the mutual repulsive force between the magnetoelastic unit with opposite magnetic poles and the magnetic rebound unit to achieve rapid rebound of the magnetoelastic body, thereby reducing the hysteresis behavior of the inductive magnetic pressure sensor.

[0018] Secondly, the flexible inductive magnetic pressure sensor array of the present invention, which is magnetically resilient, has the characteristics of being cut and spliced ​​for use. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the flexible inductive magnetic pressure sensor of the present invention;

[0020] Figure 2 This is a schematic diagram of the 2×2 magnetically resilient flexible inductive magnetic pressure sensor array structure of Embodiment 2 of the present invention.

[0021] Explanation of reference numerals in the attached figures:

[0022] 1-Magnetic elastomer unit; 2-Magnetic sensitive unit; 3-Magnetic rebound unit; 21-Modulus reinforcement layer; 22-Inductor coil; 23-Soft magnetic amorphous wire. Detailed Implementation

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0024] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0025] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This application specification and embodiments are merely exemplary.

[0026] An embodiment of the present invention provides a flexible inductive magnetic pressure sensor, comprising a magnetoelastic unit 1, a magnetic sensing unit 2, and a magnetic rebound unit 3 arranged sequentially from top to bottom, wherein the magnetization directions of the magnetoelastic unit 1 and the magnetic rebound unit 3 are opposite. The magnetoelastic unit 1 includes a first elastic matrix and a plurality of first permanent magnet particles, wherein the plurality of first permanent magnet particles are doped in the first elastic matrix. The magnetic sensing unit 2 includes an inductor coil 22, a soft magnetic amorphous wire 23, a modulus reinforcing layer 21, a plurality of soft magnetic particles, and a second elastic matrix. The inductor coil 22 and the soft magnetic amorphous wire 23 are both disposed within the modulus reinforcing layer 21, and the inductor coil 22 is wound on the soft magnetic amorphous wire 23. The plurality of soft magnetic particles are doped in the second elastic matrix, and the modulus reinforcing layer 21 is fixedly disposed on the second elastic matrix. The magnetic rebound unit 3 includes a third elastic matrix and a plurality of second permanent magnet particles, wherein the plurality of second permanent magnet particles are doped in the third elastic matrix.

[0027] Magnetoelastic unit 1 and magnetic spring unit 3 have the property of generating magnetic force (or magnetic field) on their own, which is equivalent to an elastic permanent magnet. They exhibit the phenomenon of opposite poles attracting each other and like poles repelling each other. At the same time, magnetoelastic unit 1 and magnetic spring unit 3 have magnetization directions with spatial magnetic poles facing each other, thus exhibiting the phenomenon of like poles repelling each other.

[0028] In a specific embodiment, the material of the first permanent magnet particle is selected from at least one of dFeB, SmCo, AlNiCo, and FeCrCo; the material of the second permanent magnet particle is selected from at least one of NdFeB, SmCo, AlNiCo, and FeCrCo; the material of the first elastic matrix is ​​selected from one of photosensitive resin, polydimethylsiloxane PDMS, and aliphatic aromatic random copolyester; the material of the third elastic matrix is ​​selected from one of photosensitive resin, polydimethylsiloxane PDMS, and aliphatic aromatic random copolyester; the material of the soft magnetic amorphous wire 23 is selected from at least one of Co, Fe, and Ni; and the material of the soft magnetic particle is selected from at least one of Fe3O4, Ni, Mn, and silver-coated nickel.

[0029] In a specific embodiment, the parameters of the soft magnetic amorphous wire 23 are as follows: diameter 20-200μm, length 2-5mm; the parameters of the inductor coil 22 are as follows: wire diameter 0.01-0.05mm, number of turns 50-410.

[0030] In a specific embodiment, the modulus reinforcing layer 21 includes a shell with an opening at one end and a shielding post fixedly disposed within the shell. The shielding post is fixedly disposed at the bottom center of the shell, and a shielding cavity with an opening at one end is disposed within the shielding post. A hollow inductor coil 22 is disposed within the shell and is wound around the shielding post. A soft magnetic amorphous wire 23 is disposed within the shielding cavity. Soft magnetic particles are arranged in a gradient in the second elastic matrix.

[0031] Both the macroscopic morphology of the magnetic elastomer unit 1 and the magnetic rebound unit 3 are flat films, and both have hollow microscopic morphology.

[0032] Embodiments of the present invention also provide a flexible inductive magnetic pressure sensor array, comprising at least two flexible inductive magnetic pressure sensors.

[0033] The technical effects of the present invention will be described below with reference to specific embodiments.

[0034] Example 1:

[0035] This embodiment provides a flexible inductive magnetic pressure sensor, including a magnetoelastic unit 1, a magnetic sensing unit 2, and a magnetic rebound unit 3 arranged sequentially from top to bottom. The magnetization directions of the magnetoelastic unit 1 and the magnetic rebound unit 3 are opposite. The magnetoelastic unit 1 includes a first elastic matrix and a plurality of first permanent magnet particles, which are doped in the first elastic matrix. The magnetic sensing unit 2 includes an inductor coil 22, a soft magnetic amorphous wire 23, a modulus reinforcing layer 21, a plurality of soft magnetic particles, and a second elastic matrix. The inductor coil 22 and the soft magnetic amorphous wire 23 are both disposed within the modulus reinforcing layer 21, and the inductor coil 22 is wound on the soft magnetic amorphous wire 23. The plurality of soft magnetic particles are doped in the second elastic matrix, and the modulus reinforcing layer 21 is fixedly disposed on the second elastic matrix. The magnetic rebound unit 3 includes a third elastic matrix and a plurality of second permanent magnet particles, which are doped in the third elastic matrix.

[0036] In this embodiment, the magnetic elastomer unit 1 is made by 3D printing, with 5 μm NdFeB particles doped in polyacrylate photosensitive resin at 25% wt. Its microstructure is a fabric structure with a fabric lattice size of 1 mm and the thickness of the magnetic elastomer unit 1 is 4 mm.

[0037] In this embodiment, the magnetic rebound unit 3 is made of NdFeB particles with a particle size of 5 μm doped in polyacrylate photosensitive resin at 25% wt, and is cast by mold, and its macroscopic morphology is a thin film with a thickness of 1 mm.

[0038] In this embodiment, both the magnetic elastomer unit 1 and the magnetic rebound unit 3 have a flat film macroscopic morphology and a hollow microscopic morphology, and the soft magnetic particles are arranged in a gradient in the second elastic matrix.

[0039] In this embodiment, the modulus reinforcing layer 21 includes a shell with an opening at one end and a shielding post fixedly disposed within the shell. The shielding post is fixedly disposed at the bottom center of the shell, and a shielding cavity with an opening at one end is disposed within the shielding post. A hollow inductor coil 22 is disposed within the shell and is wound around the shielding post. A soft magnetic amorphous wire 23 is disposed within the shielding cavity. The soft magnetic amorphous wire 23 in the magnetic sensitive unit 2 has a diameter of 60 μm and a length of 5 mm. The inductor coil 22 has a wire diameter of 0.01 mm and 166 turns.

[0040] When the inductor coil 22 of the flexible inductive magnetic pressure sensor in this embodiment is energized with an AC current of 200kHz and 1mA, a giant magnetoresistance (GMI) value of up to 408% can be obtained. The GMI effect is most obvious under a magnetic field of 0-40Oe.

[0041] Tests showed that the surface magnetic field of the magnetoelastic unit 1 was -60 Oe, and the recovery rate after 50% deformation was as high as 98%, with a rebound speed of -50 ms, which improved the hysteresis by 55% compared with the unmagnetized magnetoelastic.

[0042] Example 2

[0043] This embodiment provides a schematic diagram of a 2×2 magnetically resilient flexible inductive magnetic pressure sensor array structure.

[0044] This invention utilizes the mutual repulsive force between the opposing magnetic poles of the magnetoelastic unit 1 and the magnetic rebound unit 3 to achieve rapid rebound of the magnetoelastic, thereby reducing the hysteresis behavior of the inductive magnetic pressure sensor.

[0045] While the disclosure is as stated above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this invention.

Claims

1. A flexible inductive magnetic pressure sensor, characterized in that, The system includes a magnetoelastic unit (1), a magnetic sensitive unit (2), and a magnetic rebound unit (3) arranged sequentially from top to bottom. The magnetization directions of the magnetoelastic unit (1) and the magnetic rebound unit (3) are opposite. The magnetoelastic unit (1) includes a first elastic matrix and a plurality of first permanent magnet particles. The plurality of first permanent magnet particles are doped in the first elastic matrix. The magnetic sensitive unit (2) includes an inductor coil (22), a soft magnetic amorphous wire (23), a modulus reinforcing layer (21), a plurality of soft magnetic particles, and a second elastic matrix. The inductor coil (22) and the soft magnetic amorphous wire (23) are both disposed in the modulus reinforcing layer (21), and the inductor coil (22) is wound on the soft magnetic amorphous wire (23). The plurality of soft magnetic particles are doped in the second elastic matrix. The modulus reinforcing layer (21) is fixedly disposed on the second elastic matrix. The magnetic rebound unit (3) includes a third elastic matrix and a plurality of second permanent magnet particles. The plurality of second permanent magnet particles are doped in the third elastic matrix.

2. The flexible inductive magnetic pressure sensor as described in claim 1, characterized in that, The material of the first permanent magnet particle is selected from at least one of NdFeB, SmCo, AlNiCo, and FeCrCo, and the material of the second permanent magnet particle is selected from at least one of NdFeB, SmCo, AlNiCo, and FeCrCo.

3. The flexible inductive magnetic pressure sensor as described in claim 1, characterized in that, The material of the first elastic matrix is ​​selected from one of photosensitive resin, polydimethylsiloxane PDMS, and aliphatic aromatic random copolyester, and the material of the third elastic matrix is ​​selected from one of photosensitive resin, polydimethylsiloxane PDMS, and aliphatic aromatic random copolyester.

4. The flexible inductive magnetic pressure sensor as described in claim 1, characterized in that, The material of the soft magnetic amorphous wire (23) is selected from at least one of Co, Fe, and Ni.

5. The flexible inductive magnetic pressure sensor as described in claim 1, characterized in that, The soft magnetic particles are made of at least one of Fe3O4, Ni, Mn, and silver-plated nickel.

6. The flexible inductive magnetic pressure sensor as described in claim 1, characterized in that, The parameters of the soft magnetic amorphous wire (23) are as follows: diameter 20-200 μm, length 2-5 mm; and / or, The parameters of the inductor coil (22) are as follows: wire diameter is 0.01-0.05mm, and number of turns is 50-410.

7. The flexible inductive magnetic pressure sensor as described in claim 1, characterized in that, The modulus strengthening layer (21) includes a shell with an opening at one end and a shielding post fixedly disposed in the shell. The shielding post is fixedly disposed at the bottom center of the shell, and a shielding cavity with an opening at one end is disposed in the shielding post. The inductor coil (22) is disposed in the shell and is wound on the shielding post. The soft magnetic amorphous wire (23) is disposed in the shielding cavity.

8. The flexible inductive magnetic pressure sensor as described in claim 1, characterized in that, The macroscopic morphology of the magnetic elastomer unit (1) and the magnetic rebound unit (3) is a flat film, and the magnetic elastomer unit (1) and the magnetic rebound unit (3) both have a hollow microscopic morphology.

9. The flexible inductive magnetic pressure sensor as described in claim 1, characterized in that, The soft magnetic particles are arranged in a gradient within the second elastic matrix.

10. A flexible inductive magnetic pressure sensor array, characterized in that, It includes at least two flexible inductive magnetic pressure sensors as described in any one of claims 1-9, and the at least two flexible inductive magnetic pressure sensors are connected in series.

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