A vector magnetic sensor based on acoustic wave driven ferromagnetic resonance effect

Abstract

The application discloses a kind of vector magnetic sensor based on acoustic wave driven ferromagnetic resonance, including processing component and two groups of interdigital transducing components, each group of interdigital transducing components includes input interdigital transducer and output interdigital transducer, and a certain space distance is arranged between input and output interdigital transducer in each group of interdigital transducing components to form delay line structure, two delay line structures are crossed same and are set at 45 ° angle, and magnetic film made of ferromagnetic material is grown in the space distance of two delay line structures, and the direction of the magnetic field sensed by two delay line structures is-45 ° with the direction of acoustic wave propagation in the delay line structure.The processing component is analyzed by collecting the electrical signal of input and output interdigital transducer in two groups of interdigital transducing components, and the size of the magnetic field measured by each delay line structure is obtained, and then the size and direction of external magnetic field are obtained by vector synthesis.The application can simultaneously detect the direction and size of external magnetic field.

Description

Technical Field

[0001] This invention belongs to the field of magnetic sensor technology, and more specifically, relates to a vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance. Background Technology

[0002] A magnetic sensor is a device that converts an external magnetic field signal into an electrical signal. Magnetic sensing technology has wide applications in industrial equipment and electronic instruments, such as magnetic resonance imaging, automatic control of production, process industries, coal mine exploration, current measurement, vehicle inspection, defect location, military, and medical fields.

[0003] Currently, acoustic magnetic sensors based on the magnetostrictive effect of materials have a relatively mature theoretical and experimental foundation, and can detect the magnitude of the magnetic field in a single direction. However, due to the anisotropy of the magnetic thin film, they cannot detect the direction of the external magnetic field. As a result, in practical applications, such as vehicle detection, when the direction of the magnetic field cannot be detected, the location information of the detected emission source will be missing, leading to errors or inability to determine the location information of the detected target. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance, which can simultaneously detect the direction and magnitude of an external magnetic field.

[0005] To achieve the above objectives, the present invention provides a vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance, comprising a processing component and two sets of interdigital transducers disposed on the surface of a piezoelectric substrate. Each set of interdigital transducers includes an input interdigital transducer and an output interdigital transducer. A spatial distance of not less than 100 μm is provided between the input and output interdigital transducers in each set of interdigital transducers to form a delay line structure. The two delay line structures are identical and intersect at a 45° angle. A magnetic thin film made of ferromagnetic material is grown within the spatial distance between the two delay line structures, and the direction of the external magnetic field sensed by the two delay line structures is -45° to the direction of acoustic wave propagation in the delay line structure.

[0006] The processing unit is used to perform the following process: (1) Acquire and process the electrical signal V output by the interdigital transducer in each group of interdigital transducers. out and the radio frequency electrical signal V input to the interdigital transducer in The acoustic wave propagation parameters S, which vary with acoustic wave frequency, in each delay line structure were calculated. 21 S 21 =20lg(V out / V in (2) Analyze and determine the acoustic wave propagation parameters S in each delay line structure. 21The maximum value of the sound wave frequency is obtained by substituting the sound wave frequency into the curve of the external magnetic field changing with the sound wave frequency, and the magnetic field magnitude measured by each delay line structure is obtained; (3) The magnetic field magnitudes measured by the two delay line structures are vector synthesized to obtain the direction and magnitude of the external magnetic field.

[0007] The vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance provided by this invention uses two pairs of input and output interdigital transducers to form two delay line structures. The two delay line structures are set at a 45° angle, so that each delay line structure and the sensing module composed of the magnetic thin film have independent magnetic sensing directions, which can effectively realize the measurement of the direction and magnitude of the external magnetic field.

[0008] In one embodiment, the method for establishing the curve of the calibrated magnetic field changing with the sound wave frequency in the above-mentioned processing unit is as follows:

[0009] Before operation, external magnetic fields of different magnitudes are applied to the magnetic thin film region of the vector sensor, and the electrical signals V output by the interdigital transducers in each group are collected under different external magnetic field magnitudes. out and the radio frequency electrical signal V input to the interdigital transducer in And correspondingly calculate the sound wave propagation parameters S in the two delay line structures as a function of sound wave frequency under different external magnetic field magnitudes. 21 ;

[0010] The sound wave propagation parameter S in the two delay line structures was determined and analyzed based on different external magnetic field magnitudes. 21 The maximum value of the sound wave frequency is used to construct calibration curves of the magnetic field in each delay line structure as a function of the sound wave frequency.

[0011] In one embodiment, the input terminals of the input interdigital transducers in the two sets of interdigital transducers receive the same radio frequency electrical signal.

[0012] In one embodiment, the magnetic thin film is made of metallic nickel or metallic iron.

[0013] In one embodiment, the thickness of the magnetic thin film is less than 200 nm.

[0014] In one embodiment, the magnetic thin film adopts a polygonal or circular structure.

[0015] In one embodiment, the piezoelectric substrate is a piezoelectric plate, a piezoelectric thin film, or a heterogeneous integrated structure.

[0016] In one embodiment, the piezoelectric substrate is made of a piezoelectric single crystal material.

[0017] In one embodiment, the piezoelectric single crystal material is quartz, lithium niobate, lithium tantalate, or aluminum nitride.

[0018] In one embodiment, both the input interdigital transducer and the output interdigital transducer in the two sets of interdigital transducers are made of a metal material, including aluminum, copper, silver, or gold. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance according to an embodiment of the present invention;

[0020] Figure 2 This is a test curve of the sound wave frequency response to the magnetic field when the angle between the magnetic field and the direction of sound wave propagation is 0° and -45°, respectively, according to an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] To address the problem that traditional acoustic magnetic sensors based on the magnetostrictive effect of materials cannot detect the direction of external magnetic fields, this invention provides a vector magnetic sensor based on acoustically driven ferromagnetic resonance, such as... Figure 1 As shown, the vector magnetic sensor includes a processing component and two sets of interdigital transducers disposed on the surface of the piezoelectric substrate 50. Each set of interdigital transducers includes an input interdigital transducer 10 and an output interdigital transducer 20 made of metal. The input and output interdigital transducers in the two sets of interdigital transducers can be fabricated on the surface of the piezoelectric substrate 50 by microelectromechanical processes.

[0023] Each interdigital transducer unit has an input interdigital transducer 10 and an output interdigital transducer 20 with a spatial distance of not less than 100 μm forming a delay line structure. Within the spatial distance between the two delay line structures, a magnetic thin film 30 made of a ferromagnetic material is grown. Specifically, the ferromagnetic material can be metallic nickel or iron. Because the magnetic thin film provided in this embodiment uses a ferromagnetic material, its anisotropy is negligible compared to the magnetic thin films made of conventional FeCoSiB material, so its selectivity for the direction of the magnetic field is determined by the angle between the magnetic field and the direction of sound wave propagation.

[0024] The intensity of the interaction between the external magnetic field and the sound wave can be expressed as εb1sin2φ0, where ε is the strain caused by the sound wave, b1 is the magnetoelastic coupling coefficient, and φ0 is the angle between the magnetic field and the direction of sound wave propagation. When φ0 is 0°, the intensity of the interaction between the external magnetic field and the sound wave is zero; when φ0 is -45°, the intensity of the interaction between the external magnetic field and the sound wave reaches its maximum. Figure 2 This is a test curve of the sound wave frequency response to the magnetic field when the angle between the magnetic field and the direction of sound wave propagation is 0° and -45°, respectively, according to an embodiment of the present invention. Figure 2 It is known that when the angle between the magnetic field and the direction of sound wave propagation is 0°, the sound wave frequency has almost no response to the magnetic field, while when the angle between the magnetic field and the direction of sound wave propagation is -45°, the sound wave frequency has the maximum response to the magnetic field. Therefore, this embodiment provides a magnetic sensor composed of two delay line structures. For each delay line structure, the angle between the direction of the sensed magnetic field and the direction of sound wave propagation is -45° to obtain the maximum response. Furthermore, the two delay line structures are arranged at a 45° angle. Under this design, when one delay line structure is performing magnetic sensing, the other delay line structure has almost no response, thereby realizing independent sensing by the two delay line structures.

[0025] The working principle of the vector magnetic sensor provided in this embodiment is as follows: an radio frequency electrical signal is input to the input interdigital transducer, and a sound wave of the target frequency is generated through the inverse piezoelectric effect. The sound wave propagates to the magnetic thin film region. When an external magnetic field acts on the magnetic thin film region, the magnetization vector of the magnetic thin film region is uniformly magnetized. The sound wave introduces an equivalent alternating magnetic field that acts on the magnetization vector. The frequency of the alternating magnetic field is consistent with the frequency of the sound wave. When the frequency is close to the ferromagnetic resonance frequency of the magnetic thin film, the alternating magnetic field will excite ferromagnetic resonance. The ferromagnetic resonance will cause the sound wave frequency to shift. The sound wave reaches the output interdigital transducer and outputs an electrical signal through the piezoelectric effect.

[0026] The processing unit provided in this embodiment acquires and analyzes the electrical signals of the input and output interdigital transducers in the two sets of interdigital transducers to obtain the magnitude of the magnetic field measured by each delay line structure, and then uses vector synthesis to obtain the magnitude and direction of the external magnetic field. The specific execution steps are as follows:

[0027] S10, collect and analyze the electrical signal V output by the interdigital transducer in each group of interdigital transducers. out and the radio frequency electrical signal V input to the interdigital transducer in The acoustic wave propagation parameters S, which vary with acoustic wave frequency, in each delay line structure were calculated. 21 S 21 =20lg(V out / V in ).

[0028] In this embodiment, when the sound wave frequency f = v / 2p is S 21It has a maximum value, where v represents the sound wave velocity, which can be determined based on the material of the piezoelectric substrate, and p represents the center-to-center distance between adjacent metal strips of the interdigital transducer. This maximum value S varies with the magnitude of the external magnetic field. 21 The corresponding sound wave frequency will shift.

[0029] S20, Analyze and determine the acoustic wave propagation parameters S in each delay line structure. 21 The maximum value of the sound wave frequency is obtained by substituting this sound wave frequency into a pre-calibrated curve of the magnetic field changing with the sound wave frequency, thus obtaining the magnitude of the magnetic field measured by each delay line structure.

[0030] In this embodiment, the method for establishing the curve of the calibrated magnetic field changing with the frequency of the sound wave is as follows: (1) Before operation, apply external magnetic fields of different magnitudes to the magnetic thin film area of ​​the vector sensor, and simultaneously collect the electrical signal V output by the interdigital transducer in each group of interdigital transducers under different external magnetic field magnitudes. out and the radio frequency electrical signal V input to the interdigital transducer in And correspondingly calculate the sound wave propagation parameters S in the two delay line structures as a function of frequency under different external magnetic field magnitudes. 21 (2) Analyze and determine the acoustic wave propagation parameters S in the two delay line structures under different external magnetic field magnitudes. 21 The maximum value of the sound wave frequency is used to construct calibration curves of the magnetic field in each delay line structure as a function of the sound wave frequency.

[0031] S30, based on the principle of vector synthesis, performs vector synthesis on the magnetic field magnitudes measured by the two delay line structures to obtain the direction and magnitude of the external magnetic field.

[0032] In this embodiment, since the magnetic field directions sensed by the two delay lines are at a -45° angle to the direction of sound wave propagation in the delay line structure, and the magnitudes of the magnetic fields measured by the two delay line structures are obtained through step S20, the direction and magnitude of the external magnetic field can be obtained according to the principle of vector synthesis.

[0033] Specifically, the piezoelectric substrate structure provided in this embodiment can be a piezoelectric bulk material, a piezoelectric thin film, or a heterogeneous integrated structure. The piezoelectric substrate 50 can be made of a piezoelectric single crystal material, such as quartz, lithium niobate, lithium tantalate, and aluminum nitride. The magnetic thin film 30 can be circular or polygonal in shape, and its thickness can be set below 200 nm. The input interdigital transducer 10 and the output interdigital transducer 20 in the two sets of interdigital transducer components can be made of metals such as aluminum, copper, silver, or gold.

[0034] The vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance provided in this embodiment uses two pairs of input and output interdigital transducers to form two delay line structures. The two delay line structures are set at a 45° angle, so that each delay line structure and the sensing module composed of the magnetic thin film have independent magnetic sensing directions, which can effectively realize the measurement of the direction and magnitude of the external magnetic field.

[0035] The structure of the vector magnetic sensor provided by the present invention will be described in detail below with reference to specific embodiments.

[0036] Example 1 provides a vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance, including a piezoelectric substrate, a magnetic thin film, a first input interdigital transducer, a first output interdigital transducer, a second input interdigital transducer, and a second output interdigital transducer.

[0037] The piezoelectric substrate uses a 128° Y-cut X-propagation lithium niobate bulk material. The input and output interdigital transducers are made of aluminum with a thickness of 100 nm, and the center-to-center distance p between adjacent metal strips is 2.5 μm. The magnetic thin film is made of nickel with a thickness of 50 nm. The first input and first output interdigital transducers are components of the first delay line structure, and the first-dimensional external magnetic field is at a -45° angle to the direction of sound wave propagation in the first delay line structure. The second input and second output interdigital transducers are components of the second delay line structure, and the second-dimensional external magnetic field is at a -45° angle to the direction of sound wave propagation in the second delay line structure.

[0038] Example 2 provides a vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance, including a piezoelectric substrate, a magnetic thin film, a first input interdigital transducer, a first output interdigital transducer, a second input interdigital transducer, and a second output interdigital transducer.

[0039] The piezoelectric substrate employs a heterogeneous integrated structure. The top layer is a 600 nm thick, 42° Y-cut, X-propagation lithium tantalate single crystal; the middle layer is a 500 nm thick silicon dioxide layer; and the bottom layer is a single-crystal silicon substrate. The input and output interdigital transducers are made of copper, with a thickness of 80 nm, and the center-to-center distance p between adjacent metal strips is 1 μm. The magnetic thin film is made of nickel, with a thickness of 50 nm. The first input and first output interdigital transducers are components of the first delay line structure, with the first-dimensional external magnetic field forming a -45° angle with the direction of sound wave propagation in the first delay line structure. The second input and second output interdigital transducers are components of the second delay line structure, with the second-dimensional external magnetic field forming a -45° angle with the direction of sound wave propagation in the second delay line structure.

[0040] Example 3 provides a vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance, including a piezoelectric substrate, a magnetic thin film, a first input interdigital transducer, a first output interdigital transducer, a second input interdigital transducer, and a second output interdigital transducer.

[0041] The piezoelectric substrate uses a 600 nm thick, 42° Y-cut X-propagation lithium tantalate single-crystal thin film. The input and output interdigital transducers are made of metallic silver, with a thickness of 80 nm, and the center-to-center distance p between adjacent metal strips is 1.25 μm. The magnetic thin film is metallic nickel, with a thickness of 100 nm. The first input and first output interdigital transducers are components of the first delay line structure, with the first-dimensional external magnetic field forming a -45° angle with the direction of sound wave propagation in the first delay line structure. The second input and second output interdigital transducers are components of the second delay line structure, with the second-dimensional external magnetic field forming a -45° angle with the direction of sound wave propagation in the second delay line structure.

[0042] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance, characterized in that, The device includes a processing component and two sets of interdigital transducers disposed on the surface of a piezoelectric substrate. Each set of interdigital transducers includes an input interdigital transducer and an output interdigital transducer. A delay line structure is formed between the input and output interdigital transducers in each set of interdigital transducers with a spatial distance of not less than 100 μm. The two delay line structures are identical and intersect at a 45° angle. A magnetic thin film made of ferromagnetic material is grown within the spatial distance between the two delay line structures, and the direction of the external magnetic field sensed by the two delay line structures is at -45° to the direction of sound wave propagation in the delay line structure. The anisotropy of the magnetic thin film is negligible, so its selectivity to the direction of the magnetic field is determined by the angle between the magnetic field and the direction of sound wave propagation. The processing unit is used to perform the following process: (1) Acquire and process the electrical signals output by the interdigital transducers in each group of interdigital transducers. V out and the radio frequency electrical signal input to the interdigital transducer V in The acoustic propagation parameters of each delay line structure as a function of acoustic frequency were calculated. S 21 , S 21 =20 lg ( V out / V in (2) Analyze and determine the acoustic wave propagation parameters in each delay line structure. S 21 The maximum value of the sound wave frequency is obtained by substituting the sound wave frequency into the curve of the external magnetic field changing with the sound wave frequency, and the magnetic field magnitude measured by each delay line structure is obtained; (3) The magnetic field magnitudes measured by the two delay line structures are vector synthesized to obtain the direction and magnitude of the external magnetic field.

2. The vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance according to claim 1, characterized in that, In the aforementioned processing components, the method for establishing the curve of the calibrated magnetic field changing with the frequency of the sound wave is as follows: Before operation, external magnetic fields of different magnitudes are applied to the magnetic thin film region of the vector magnetic sensor, and the electrical signals output by the interdigital transducers in each group are collected under different external magnetic field magnitudes. V out and the radio frequency electrical signal input to the interdigital transducer V in And correspondingly, the sound wave propagation parameters in the two delay line structures, varying with the sound wave frequency, are calculated under different external magnetic field magnitudes. S 21 ; The sound wave propagation parameters in the two delay line structures were analyzed and determined based on different external magnetic field magnitudes. S 21 The maximum value of the sound wave frequency is used to construct calibration curves of the magnetic field in each delay line structure as a function of the sound wave frequency.

3. The vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance according to claim 1, characterized in that, The input terminals of the input interdigital transducers in both sets of interdigital transducers receive the same radio frequency electrical signal.

4. The vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance according to claim 1, characterized in that, The magnetic thin film is made of metallic nickel or metallic iron.

5. The vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance according to claim 1, characterized in that, The thickness of the magnetic thin film is less than 200 nm.

6. The vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance according to claim 1, characterized in that, The magnetic thin film adopts a polygonal or circular structure.

7. The vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance according to claim 1, characterized in that, The piezoelectric substrate is a piezoelectric plate, a piezoelectric thin film, or a heterogeneous integrated structure.

8. The vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance according to claim 1, characterized in that, The piezoelectric substrate is made of piezoelectric single crystal material.

9. The vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance according to claim 8, characterized in that, The piezoelectric single crystal material is quartz, lithium niobate, lithium tantalate, or aluminum nitride.

10. The vector magnetic sensor based on acoustic wave-driven ferromagnetic resonance according to claim 1, characterized in that, Both the input interdigital transducer and the output interdigital transducer in the two sets of interdigital transducer components are made of metal materials, including aluminum, copper, silver or gold.

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