Piezoresistive micro-electromechanical current sensor integrated with magnetic sensitive unit and multi-mode detection method

Abstract

The invention provides a piezoresistive micro electro mechanical system (MEMS) current sensor integrated with a magnetic sensitive unit and a multi-mode detection method, which can be applied to the technical field of MEMS sensing. The deformable elastic structure comprises a supporting end and a free end, and the supporting end is connected with the base plate; the magnetic sensing unit is integrated on the surface of the free end of the deformable elastic structure and is used for changing the deformable elastic structure; and the piezoresistive detection units are distributed at the substrate and the supporting end of the deformable elastic structure, form a Wheatstone bridge through a distributed pressure-sensitive element network to capture the variable quantity, and realize dual-mode current analysis of static deformation detection and dynamic resonance modulation based on differential signal processing. According to the current sensor, the limitation of a traditional single structure is broken through, high-precision and wide-range current detection is realized through the topological reconfigurability of the elastic structure, the multi-structure and material compatibility of the magnetic sensing unit and a piezoresistive network self-compensation mechanism, and different requirements in various scenes are met.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-electro-mechanical systems (MEMS) sensing technology, and more specifically, to a piezoresistive micro-electro-mechanical current sensor integrated with a magnetic sensitive unit and a multi-mode detection method. Background Art

[0002] Currently, the mainstream current sensors that have been widely equipped in the power system mainly include fluxgate, Rogowski coil, current transformer, Hall device, and magnetoresistive device, etc. However, fluxgate, Rogowski coil, current transformer, etc. all have problems such as large volume, high cost, and difficulty in system integration. Hall devices have large temperature drift and are difficult to achieve high precision. Magnetoresistive devices have problems such as poor linearity and high processing difficulty. With the development of the power grid system, especially for the requirements of high-precision, high-frequency current acquisition, embedded monitoring, multi-functional system integration, and multi-node deployment in application scenarios such as smart grid, industrial Internet of Things, and charging piles, the existing current sensors cannot meet the requirements of high precision, miniaturization, and low cost.

[0003] MEMS (Micro-Electro-Mechanical Systems) current sensors can achieve miniaturization and low-cost batch manufacturing based on micro-nano processing technology. In recent years, the high-sensitivity current detection technology integrating magnetic materials into cantilever beams has become a research hotspot at home and abroad. However, the sensing methods of MEMS current sensors mostly focus on piezoelectric, capacitive, optical, etc. The device process is complex and the consistency is poor. At present, it is difficult to achieve low-cost batch manufacturing and application. At the same time, the detection mode is single and the application range is narrow. There is a large gap between the sensitivity and precision and the current mainstream current sensors. Therefore, there is an urgent need to develop MEMS current sensors with high precision, easy integration, and batch manufacturing. Summary of the Invention

[0004] (I) Technical Problems to be Solved

[0005] The present invention provides a piezoresistive micro-electro-mechanical current sensor integrated with a magnetic sensitive unit and a multi-mode detection method, which is used to at least partially solve one of the above technical problems.

[0006] (II) Technical Solutions

[0007] According to a first aspect of the present invention, there is provided a piezoresistive micro-electro-mechanical current sensor integrated with a magnetic sensitive unit, including: a substrate; a deformable elastic structure including a support end and a free end, the support end being connected to the substrate; a magnetic sensitive unit integrated on the surface of the free end of the deformable elastic structure for causing the deformable elastic structure to change; and a piezoresistive detection unit distributed on the substrate and the support end of the deformable elastic structure for converting the change amount into a differential voltage signal and leading it out.

[0008] According to an embodiment of the present invention, the piezoresistive detection unit includes a piezoresistive element and an ohmic contact, which together form a Wheatstone bridge structure.

[0009] According to an embodiment of the present invention, the sensor further includes electrodes distributed on the surface of the substrate.

[0010] According to an embodiment of the present invention, the topological configuration of the deformable elastic structure includes at least one of a cantilever beam, a doubly clamped beam, a thin plate, a shell, or a three-dimensional folded beam.

[0011] According to an embodiment of the present invention, the magnetic sensitive unit is at least one of a magnet, a magnetic thin film, or a conductive coil integrated into the deformable elastic structure.

[0012] According to an embodiment of the present invention, the geometric topology of the piezoresistive element includes at least one of a U-shaped, a spiral-shaped, or a branched structure; the doping type of the piezoresistive element is p-type or n-type.

[0013] According to an embodiment of the present invention, it further includes: a reference elastic structure symmetrically arranged with the deformable elastic structure; a piezoresistive detection unit is disposed on the surface of one end of the reference elastic structure connected to the substrate, and a multi-level network including a main detection bridge circuit and an auxiliary compensation bridge circuit is formed between the piezoresistive detection unit on the surface of the reference elastic structure and the piezoresistive detection unit on the surface of the deformable elastic structure.

[0014] According to a second aspect of the present invention, there is provided a multi-mode detection method for a piezoresistive microelectromechanical current sensor based on an integrated magnetic sensitive unit, including: deploying the current sensor on the surface of a current-carrying wire so that the magnetic sensitive unit is in a region of a gradient magnetic field; when the current-carrying wire is energized, the deformable elastic structure responds to the spatial magnetic field distribution of the current-carrying wire, generating deformation or stiffness change; converting the change amount of the deformable elastic structure into a differential voltage output through a Wheatstone bridge formed by the piezoresistive detection unit.

[0015] According to an embodiment of the present invention, the multi-mode detection method includes: when the deformable elastic structure generates deformation, analyzing an alternating current or a direct current through the linear mapping relationship between the voltage signal output by the piezoresistive detection unit and the current amplitude; when the deformable elastic structure generates a stiffness change, exciting the deformable elastic structure and obtaining the measured direct current through the resonant frequency offset.

[0016] According to an embodiment of the present invention, the multi-mode detection method further includes: when the deformable elastic structure generates deformation, adjusting the current detection sensitivity by optimizing the position distribution of the magnetic sensitive unit and the strain transfer efficiency of the piezoresistive element; when the deformable elastic structure generates a stiffness change, improving the resolution of the resonant frequency offset through a closed-loop feedback control circuit or a high-precision time-to-digital converter.

[0017] (III) Beneficial Effects

[0018] The piezoresistive microelectromechanical current sensor integrated with a magnetic sensitive unit and the multi-mode detection method provided by the present invention have at least the following beneficial effects:

[0019] The present invention breaks through the limitations of traditional single structures. Through the topological reconfigurability of elastic structures, multiple structures of magnetic sensitive units, material compatibility, and the self-compensation mechanism of the piezoresistive network, high-precision and wide-range current detection are achieved. Based on the magneto-force-electric coupling effect of elastic structures, the present invention innovatively proposes a cooperative working mode of static deformation detection and dynamic resonance modulation. Combined with the array arrangement strategy of magnetic sensitive units, full-range coverage detection of currents from milliamperes to kiloamperes is realized. This design breaks through the single-range limitation of traditional sensors, can meet the usage requirements of different scenarios, has high flexibility and universality, and effectively fills the technical gap in synchronous sensing of currents with a wide dynamic range under complex working conditions. By integrating the magnetic sensitive unit and the piezoresistive detection system into a silicon-based elastic structure through micro-nano processing technology, wafer-level batch manufacturing of miniaturized devices is achieved, which has the characteristics of high precision, small size, and low cost, and solves problems such as the difficulty of embedded monitoring, multi-system integration, and multi-node dense deployment of traditional power monitoring equipment BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Through the following description of the embodiments of the present invention with reference to the drawings, the above and other objects, features, and advantages of the present invention will become clearer. In the drawings:

[0021] Figure 1 Schematically shows a structural diagram of a piezoresistive microelectromechanical current sensor integrated with a magnetic sensitive unit according to an embodiment of the present invention;

[0022] Figure 2 Schematically shows a top view of a piezoresistive microelectromechanical current sensor integrated with a magnetic sensitive unit according to an embodiment of the present invention;

[0023] Figure 3 Schematically shows a schematic diagram of a multi-mode detection method based on a piezoresistive microelectromechanical current sensor integrated with a magnetic sensitive unit according to an embodiment of the present invention;

[0024] Figure 4 Schematically shows a schematic diagram of the principle of a multi-mode detection method based on a piezoresistive microelectromechanical current sensor integrated with a magnetic sensitive unit according to an embodiment of the present invention;

[0025] Figure 5 Schematically shows a measurement schematic diagram of a Wheatstone bridge detection circuit according to an embodiment of the present invention;

[0026] Figure 6 Schematically shows a schematic diagram of the force principle between a magnetic sensitive unit and a current-carrying wire in an embodiment of the present invention.

[0027]

Reference Signs

[0028] 1 - pressure - sensitive element; 2 - ohmic contact; 3 - electrode; 4 - deformable elastic structure; 5 - magnetic - sensitive unit; 6 - substrate; 7 - current - carrying wire; 8 - gradient magnetic field. Detailed Embodiments

[0029] To make the objectives, technical solutions and advantages of the present invention more clearly understood, the following further describes the present invention in detail with reference to specific embodiments and the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0030] The terms used herein are merely for describing specific embodiments and are not intended to limit the present invention. The terms "including", "comprising", etc. used herein indicate the presence of the feature, step, operation, and / or component, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0031] In the present invention, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be a direct connection, or indirectly connected through an intermediate medium, and can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "length", "circumferential", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the subsystem or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0033] Throughout the drawings, the same elements are denoted by the same or similar reference signs. When it may cause confusion in the understanding of the present invention, conventional structures or configurations will be omitted. And the shapes, sizes, and positional relationships of the components in the drawings do not reflect the true sizes, proportions, and actual positional relationships. In addition, any reference signs located between parentheses should not be construed as limiting.

[0034] Similarly, to streamline the present invention and assist in understanding one or more of the various disclosed aspects, in the above description of the exemplary embodiments of the present invention, the various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. Descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0035] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0036] An embodiment of the present invention provides a piezoresistive microelectromechanical current sensor integrated with a magnetic sensitive unit, comprising: a substrate; a deformable elastic structure including a support end and a free end, the support end being connected to the substrate; a magnetic sensitive unit integrated on the surface of the free end of the deformable elastic structure for causing a change in the deformable elastic structure; and a piezoresistive detection unit distributed on the substrate and the support end of the deformable elastic structure for converting the change amount into a differential voltage signal and leading it out. Among them, the piezoresistive detection unit forms a Wheatstone bridge through a distributed piezoresistive element network to capture the change amount, and realizes dual-mode current analysis of static deformation detection and dynamic resonance modulation based on differential signal processing.

[0037] Figure 1 The structural schematic diagram of a piezoresistive microelectromechanical current sensor integrated with a magnetic sensitive unit according to an embodiment of the present invention is schematically shown. Figure 2 The top view of a piezoresistive microelectromechanical current sensor integrated with a magnetic sensitive unit according to an embodiment of the present invention is schematically shown.

[0038] As Figure 1 , Figure 2 shown, the piezoresistive microelectromechanical current sensor integrated with a magnetic sensitive unit of this embodiment includes: a substrate 6, a deformable elastic structure 4, a magnetic sensitive unit 5, and a piezoresistive detection unit.

[0039] See Figure 1, one end (support end) of the deformable elastic structure 4 is connected to the substrate 6, and piezoresistive detection units are arranged on the surface of the substrate 6 and the support end of the deformable elastic structure 4. A magnetic sensitive unit 5 is arranged on the surface of the other end (free end) of the deformable elastic structure 4.

[0040] The magnetic sensitive unit 5 can respond to the gradient magnetic field 8 of the current-carrying wire 7 and drive the deformable elastic structure 4 to change. For example, the deformable elastic structure 4 will generate deformation or rigidity change under the drive of the magnetic sensitive unit 5. In response to the change of the deformable elastic structure 4, the change amount of the deformable elastic structure 4 is converted into a differential voltage signal and led out through the piezoresistive detection unit.

[0041] In some embodiments, the piezoresistive detection unit includes: a plurality of piezoresistive elements 1 and a plurality of ohmic contacts 2. Among them, the ohmic contacts 2 correspond to the piezoresistive elements 1, and each piezoresistive element 1 is correspondingly provided with a set of ohmic contacts 2. A Wheatstone bridge structure is formed by the distributed network of the plurality of piezoresistive elements 1 and the ohmic contacts 2 to capture the change amount.

[0042] In some embodiments, the piezoresistive detection unit forms a Wheatstone full bridge, half bridge or 1 / 4 bridge circuit composed of at least four piezoresistive elements 1, and at least one piezoresistive element 1 is arranged in the stress concentration area (support end) of the deformable elastic structure 4. The collective topology of the piezoresistive elements 1 may include at least one of a U-shaped, spiral-shaped or branched structure, and the doping type of the piezoresistive elements 1 may be p-type or n-type. For example, the piezoresistive elements 1 can be formed by synchronous ion implantation, epitaxy or thermal diffusion processes, so as to ensure the consistency of the initial resistance to the greatest extent and effectively improve the measurement accuracy of the microelectromechanical current sensor.

[0043] In some embodiments, a plurality of electrodes 3 are also distributed on the surface of the substrate 6 for leading out the converted differential voltage signal.

[0044] Exemplarily, the topological configuration of the deformable elastic structure 4 includes at least one of a cantilever beam, a doubly clamped beam, a thin plate, a shell or a three-dimensional folded beam. The magnetic sensitive unit 5 is at least one of a magnet, a magnetic thin film or a conductive coil integrated in the deformable elastic structure 4. The magnetization direction of the magnetic sensitive unit 5 is perpendicular to, parallel to or inclined to the main strain direction of the deformable elastic structure 4.

[0045] See Figure 2, in some embodiments, the piezoresistive MEMS current sensor may further include: a reference elastic structure, which is symmetrically arranged with the deformable elastic structure 4. A piezoresistive detection unit is disposed on the surface of one end (i.e., the support end) of the reference elastic structure connected to the substrate 6. A multi-level network including a main detection bridge circuit and an auxiliary compensation bridge circuit is formed between the piezoresistive detection unit on the surface of the reference elastic structure and the piezoresistive detection unit on the surface of the deformable elastic structure 4. Through differential voltage output, they jointly constitute a temperature-stress decoupling module to eliminate the common-mode error caused by ambient temperature and mechanical vibration. Among them, the topological configuration of the reference elastic structure is the same as that of the deformable elastic structure 4.

[0046] Exemplarily, both the reference elastic structure and the deformable elastic structure 4 are cantilever beams. Then, the deformable elastic structure 4 is the working cantilever beam, and the reference elastic structure is the reference cantilever beam. A magnetic sensitive unit 5 is disposed on the working cantilever beam so that the working cantilever beam deforms under the gradient magnetic field 8 of the current-carrying wire 7.

[0047] In some embodiments, the deformable elastic structure 4 and the magnetic sensitive unit 5 can be arranged in an array for high-order nonlinear correction or range extension.

[0048] Exemplarily, the material of the substrate 6 of the deformable elastic structure 4 can be any one or more of materials such as polysilicon, single-crystalline silicon, silicon carbide (SiC), diamond, or III-V group semiconductors. The material of the electrode can be any one or more of conductive metals such as gold, aluminum, or copper.

[0049] The piezoresistive MEMS current sensor integrated with a magnetic sensitive unit provided by the present invention integrates the magnetic sensitive unit and the piezoresistive detection system on a silicon-based elastic structure through micro-nano processing technology, realizing wafer-level batch manufacturing of miniaturized devices, with the characteristics of high precision, small size, and low cost, and solving the industry pain points that traditional power monitoring devices are difficult to embed for monitoring, multi-system integration, and multi-node dense deployment. This device can be directly applied to scenarios such as smart meters and charging piles, supporting the miniaturization upgrade of non-invasive current monitoring systems, and providing a high-cost-effective solution for the integration of industrial Internet of Things devices. Based on the magneto-force-electric coupling effect of the elastic structure, the present invention innovatively proposes a cooperative working mode of static deformation detection and dynamic resonance modulation, combined with the strategy of arrayed arrangement of magnetic sensitive units, to achieve full-range coverage detection of currents from milliamperes to kiloamperes. This design breaks through the single-range limitation of traditional sensors and can simultaneously meet the instantaneous kiloampere pulse monitoring of electric vehicle fast chargers and the milliampere-level leakage detection of microgrid devices, filling the technical gap of synchronous sensing of wide dynamic range currents under complex working conditions. The piezoresistive MEMS current sensor provided by the present invention, based on micro-nano processing technology, realizes miniaturization and batch manufacturing, and can be widely applied to scenarios such as smart grids, industrial Internet of Things, and charging piles, meeting the requirements of high-precision, high-frequency current acquisition, embedded monitoring, multi-functional system integration, and multi-node deployment.

[0050] Figure 3 Schematically shows a schematic diagram of a multi - mode detection method of a piezoresistive micro - electromechanical current sensor based on an integrated magnetic - sensitive unit according to an embodiment of the present invention. Figure 4 Schematically shows a schematic diagram of the principle of a multi - mode detection method of a piezoresistive micro - electromechanical current sensor based on an integrated magnetic - sensitive unit according to an embodiment of the present invention.

[0051] As Figure 3 、 Figure 4 shown, for example, this detection method may include operation S110 to operation S130.

[0052] In operation S110, the current sensor is deployed on the surface of the current - carrying wire 7, so that the magnetic - sensitive unit 5 is in the region of the gradient magnetic field 8.

[0053] In operation S120, when the current - carrying wire 7 is energized, the deformable elastic structure 4 responds to the spatial magnetic - field distribution of the current - carrying wire 7 and generates deformation or stiffness change.

[0054] In operation S130, the change amount of the deformable elastic structure 4 is converted into a differential voltage output through a Wheatstone bridge formed by a piezoresistive detection unit.

[0055] In some embodiments, when the magnetic - sensitive unit 5 is in the region of the gradient magnetic field 8, the deformable elastic structure 4 interacts with the gradient magnetic field 8. Through the multi - physical - field coupling of magneto - force - electricity, the deformable elastic structure 4 responds to the spatial magnetic - field distribution of the current - carrying wire 7 and generates deformation or stiffness change.

[0056] The deformation or stiffness change of the deformable elastic structure 4 respectively corresponds to detection methods in different modes. Refer to Figure 4 , in some embodiments, the piezoresistive MEMS current sensor can achieve non - invasive detection of current in a static mode and a dynamic mode.

[0057] When the deformable elastic structure 4 generates deformation under the action of electromagnetic force, the static detection mode is triggered: the deformation amount generated by the deformable elastic structure 4 is converted into a differential voltage output through a Wheatstone bridge, and the static mode can be used to detect direct - current and alternating - current.

[0058] When the deformable elastic structure 4 generates stiffness change under the action of electromagnetic force, the dynamic detection mode is triggered: the deformable elastic structure 4 generates additional stiffness. After exciting the deformable elastic structure 4 to resonate, the resonance frequency change is detected through a Wheatstone bridge converted into a differential voltage to achieve the detection of direct - current. Optionally, in the dynamic detection mode, the excitation method of the deformable elastic structure 4 is any one or more of piezoelectric, electrostatic, electromagnetic, thermoelectric, optical drive, etc.

[0059] In some embodiments, in the static detection mode, the current detection sensitivity can be adjusted by optimizing the position distribution of the magnetic susceptibility unit 5 and the strain transfer efficiency of the piezoresistive element 1. In the dynamic mode, by improving the resolution of the resonant frequency offset through a closed-loop feedback control circuit or a high-precision time-to-digital converter, the resolution of the resonant frequency offset can be improved to less than 0.01 Hz.

[0060] Figure 5 Schematically shows the measurement principle diagram of the Wheatstone bridge detection circuit according to an embodiment of the present invention.

[0061] Taking the topological configuration of the deformable elastic structure 4 as a cantilever beam as an example, the detection method of the embodiment of the present invention is further described. Combining Figure 2 , two piezoresistive units located on the surface of the cantilever beam (i.e., the deformable elastic structure 4) constitute the main detection bridge circuit, and two piezoresistive units located on the substrate 6 constitute the auxiliary compensation bridge circuit.

[0062] Continue to refer to Figure 5 , Figure 5 The R in pizeo corresponds to the piezoresistive unit at the support end of the working cantilever beam in the main detection bridge circuit, and R pizeo will change with the change of the vibration amplitude of the cantilever beam. R temp corresponds to the piezoresistive unit at the support end of the reference cantilever beam in the auxiliary compensation bridge circuit and serves as the temperature compensation resistor for R pizeo . R pizeo and R temp together with the other two resistors constitute a Wheatstone bridge, and their initial resistances are all R. After R pizeo is stressed, its resistance changes to ΔR. Usually, ΔR << R, then the output signal V out is:

[0063]

[0064] Among them, V bridge is the bias voltage of the Wheatstone bridge.

[0065] Since the piezoresistive strip at the support end of the working cantilever beam is simultaneously affected by mechanical stress and temperature strain, while the reference cantilever beam is only affected by temperature strain, the temperature term can be eliminated through the differential output of the Wheatstone bridge, and the resistance change can be converted into a differential voltage signal of the same frequency. Moreover, since R temp is close enough to R pizeo , that is, they have a common heat dissipation environment, so first-order temperature compensation can be better realized.

[0066] Figure 6 Schematically shows the force principle diagram between the magnetic susceptibility unit and the current-carrying wire in the embodiment of the present invention.

[0067] Figure 6 The magnetic sensitive unit 5 therein is a permanent magnet, and the current-carrying wire 7 is a two-core wire. Under the Figure 5 structural parameters shown, for a two-wire current i with a center distance of 2d in the current-carrying wire 7, at a position with a distance of z on its perpendicular bisector, for a magnet with a magnetization intensity of Br, a volume of V, and a magnetization direction of z, the electromagnetic force F current is:

[0068]

[0069] Exemplarily, when detecting current in the static detection mode, since the free end of the cantilever beam (i.e., the deformable elastic structure 4) integrates the magnetic sensitive unit 5 magnetized perpendicular to the cantilever plane, when approaching the wire carrying current, the cantilever beam will have a displacement change. Then, the resistance of the U-shaped piezoresistive strip (i.e., the piezoresistive element 1) arranged at the support end will change. Therefore, for an alternating current, the cantilever beam will be subjected to an alternating driving force, and the Wheatstone bridge will output a voltage signal with the same frequency as the alternating current to the subsequent amplification circuit. The larger the current, the larger the amplitude of the voltage output signal. For a direct current, the cantilever beam will be subjected to a constant deflection force, and the piezoresistive unit at the support end of the cantilever beam will generate a constant change ΔR. At this time, connect the input electrode 3 to an AC voltage source, and the Wheatstone bridge will output a voltage signal with the same frequency as the AC voltage source to the subsequent amplification circuit. The larger the current, the larger the amplitude of the voltage output signal.

[0070] Exemplarily, when detecting a direct current in the dynamic detection mode, after the cantilever beam is subjected to the electromagnetic force, its resonance frequency will change. Based on the Wheatstone bridge, the current detection is realized by detecting the change in the resonance frequency. The resonance frequency f of the cantilever beam in the dynamic detection mode is:

[0071]

[0072] where m* is the effective mass of the cantilever beam, M is the effective mass of the magnetic material, and k beam is the equivalent stiffness of the cantilever beam, and k current is the additional stiffness generated by the current, and its magnitude is:

[0073]

[0074] According to this principle, the magnitude of the direct current to be measured can be obtained.

[0075] The embodiments of the present invention have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Although the embodiments have been described separately above, this does not mean that the measures in each embodiment cannot be used advantageously in combination. Without departing from the scope of the present invention, those skilled in the art can make various substitutions and modifications, and these substitutions and modifications should all be included within the protection scope of the present invention.

Claims

1. A piezoresistive microelectromechanical current sensor integrated with a magnetic susceptibility unit, characterized in that, Comprising: A substrate (6); A deformable elastic structure (4), including a support end and a free end, the support end being connected to the substrate (6); A magnetic sensitive unit (5), integrated on the surface of the free end of the deformable elastic structure (4), for causing a change in the deformable elastic structure (4); A piezoresistive detection unit, distributed on the substrate (6) and the support end of the deformable elastic structure (4), for converting the change amount into a differential voltage signal and leading it out.

2. The piezoresistive microelectromechanical current sensor according to claim 1, characterized in that, The piezoresistive detection unit includes: Piezo - sensitive elements (1) and ohmic contacts (2), jointly forming a Wheatstone bridge structure.

3. The piezoresistive microelectromechanical current sensor according to claim 1, characterized in that, The sensor further includes: Electrodes (3), distributed on the surface of the substrate (6).

4. The piezoresistive microelectromechanical current sensor according to claim 1, wherein The topological configuration of the deformable elastic structure (4) includes at least one of a cantilever beam, a doubly - clamped beam, a thin plate, a shell, or a three - dimensional folded beam.

5. The piezoresistive microelectromechanical current sensor according to claim 1, wherein The magnetic sensitive unit (5) is at least one of a magnet, a magnetic thin film, or a conductive coil integrated in the deformable elastic structure (4).

6. The piezoresistive microelectromechanical current sensor according to claim 2, wherein The geometric topology of the piezo - sensitive element (1) includes at least one of a U - shape, a spiral shape, or a branched structure; The doping type of the piezo - sensitive element (1) is p - type or n - type.

7. The piezoresistive microelectromechanical current sensor according to claim 1, wherein It further includes: A reference elastic structure, symmetrically arranged with the deformable elastic structure (4); A piezoresistive detection unit is arranged on the surface of the end of the reference elastic structure connected to the substrate (6), and a multi - level network including a main detection bridge circuit and an auxiliary compensation bridge circuit is formed between the piezoresistive detection unit on the surface of the reference elastic structure and the piezoresistive detection unit on the surface of the deformable elastic structure.

8. A multimode detection method for a piezoresistive microelectromechanical current sensor integrated with a magnetic sensitive unit according to any one of claims 1-7, characterized in that, The method includes: Deploying the current sensor on the surface of a current - carrying wire (7), such that the magnetic sensitive unit (5) is in the region of a gradient magnetic field (8); When the current - carrying wire (7) is energized, the deformable elastic structure responds to the spatial magnetic field distribution of the current - carrying wire, generating a deformation or a change in stiffness; Converting the change amount of the deformable elastic structure into a differential voltage output through the Wheatstone bridge formed by the piezoresistive detection unit.

9. The multimode detection method according to claim 8, wherein The detection method further includes: When the deformable elastic structure generates a deformation, analyzing an alternating or direct current through the linear mapping relationship between the voltage signal output by the piezoresistive detection unit and the current amplitude; When the deformable elastic structure generates a change in stiffness, exciting the deformable elastic structure and obtaining the measured direct current through the resonance frequency offset.

10. The multimode detection method according to claim 8, characterized in that, The detection method further includes: When the deformable elastic structure generates a deformation, adjusting the current detection sensitivity by optimizing the position distribution of the magnetic sensitive unit and the strain transfer efficiency of the piezo - sensitive element; When the deformable elastic structure generates a change in stiffness, improving the resolution of the resonance frequency offset through a closed - loop feedback control circuit or a high - precision time - to - digital converter.

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