A thermally excited piezoresistive detection self-excited oscillation resonant inertial sensor

Abstract

This invention discloses a thermally excited piezoresistive self-excited resonant inertial sensor, belonging to the field of microelectromechanical systems (MEMS). It comprises an integrated inertial force sensing module, a frequency modulation module, and a self-excited oscillation module. The inertial force sensing module senses acceleration and converts it into an axial force applied to the frequency modulation module. The frequency modulation module changes its effective stiffness by receiving the axial force, thus completing frequency modulation. The self-excited oscillation module generates alternating thermal expansion force through its own closed loop, achieving self-excited oscillation of the frequency modulation module under the action of this alternating thermal expansion force. This invention solves the problem of the lack of transverse vibration mode accelerometers both domestically and internationally by coupling the resonator with a DETF beam. It also avoids the problem of the resonator's transverse vibration mode aligning with the accelerometer's mass motion direction, which could affect the overall acceleration mode and reduce sensitivity.

Description

Technical Field

[0001] This invention belongs to the field of microelectromechanical systems (MEMS), specifically relating to a thermally excited piezoresistive detection self-excited oscillation resonant inertial sensor. Background Technology

[0002] MEMS accelerometers are miniaturized acceleration sensors that combine microelectronics and micromechanical technologies to convert acceleration signals into electrical signals. Due to their small size, light weight, low power consumption, low cost, and high reliability, these sensors are widely used in numerous fields, such as automotive safety systems, consumer electronics, medical devices, aerospace, and the military.

[0003] Ultra-low power micro / nano sensors are a typical representative of smart sensor technology in the post-Moore's Law era, serving as core sensing components for long-term wireless sensor networks and next-generation micro-intelligent equipment. Ultra-low power MEMS accelerometers, due to their low power consumption and high performance, are widely used in various fields. For example, in medical health monitoring, they can be used in vital sign monitoring, hearing aids, pacemakers, automated external defibrillators, and other medical devices, providing accurate motion signal capture and health monitoring. In industrial monitoring, they can be used to monitor machine vibration, tilt, and motion status, thereby predicting equipment failures or performing process control. They can also be used in automotive tire pressure monitoring and electric vehicle battery monitoring to ensure vehicle safety and improve energy efficiency. However, high-performance micro / nano sensors typically come with complex detection and control electronic circuit systems; for example, in a high-precision resonant accelerometer, over 99% of its power consumption is used for heating of electronic components in the frequency tracking system. Therefore, the main problem limiting the power consumption of accelerometers lies in the excessive power consumption of their control circuits. Summary of the Invention

[0004] The technical problem to be solved:

[0005] To overcome the shortcomings of existing technologies, this invention provides a thermally excited piezoresistive self-excited resonant inertial sensor. A nanobeam is coupled to a DETF beam, and thermally driven to a bending vibration mode. The acceleration transmitted by the mass is then converted into axial stress applied to the DETF beam (defined as the length direction of the DETF beam as the axial direction), thereby changing the effective stiffness of the structure and transforming the transverse vibration mode of the nanobeam into the bending vibration mode of the slender DETF beam, thus achieving acceleration detection. This invention solves the problem of the lack of transverse vibration mode accelerometers both domestically and internationally by coupling the resonator to the DETF beam. It also avoids the problem of the resonator's transverse vibration mode aligning with the accelerometer's mass motion direction, which could affect the overall acceleration mode and reduce sensitivity.

[0006] The technical solution of this invention is: a thermally excited piezoresistive detection self-excited oscillation resonant inertial sensor, comprising an integrally connected inertial force sensing module, a frequency modulation module, and a self-excited oscillation module. The inertial force sensing module senses acceleration and converts the acceleration into an axial force applied to the frequency modulation module; the frequency modulation module changes its effective stiffness by receiving the axial force to complete frequency modulation; the self-excited oscillation module forms an alternating thermal expansion force through its own closed loop, and completes the self-excited oscillation of the frequency modulation module under the action of the alternating thermal expansion force.

[0007] A further technical solution of the present invention is: the inertial force sensing module includes a mass block and levers respectively connected to its two sides. The mass block is connected to a corresponding number of anchor points through multiple elastic beams for sensing acceleration. The levers on both sides are used to convert the acceleration into axial force applied to the frequency modulation modules on both sides.

[0008] A further technical solution of the present invention is: the mass block is a rectangular flat plate structure, and two sets of notched channels are symmetrically arranged on opposite sides of the block without levers. Anchor points are provided at the outer ends of the notched channels, and each anchor point is connected to the inner end of each notched channel by an elastic beam to form a working plane for acceleration detection.

[0009] A further technical solution of the present invention is: the frequency modulation module includes a DETF slender beam, the axis of which is perpendicular to the length direction of the lever.

[0010] A further technical solution of the present invention is that the structure of the DETF slender beam is a single beam or parallel double beams.

[0011] A further technical solution of the present invention is: the self-excited oscillation module includes a DETF short thick beam and a nanobeam, one end of the DETF short thick beam is connected to the extension direction of the DETF slender beam, and the other end is connected to a lever; the nanobeam is vertically arranged at the connection between the DETF short thick beam and the DETF slender beam, and the whole constitutes a thermo-pressurized resonator.

[0012] A further technical solution of the present invention is that the thermo-pressurized resistor mechanical resonator can be any one of three forms: DETF double-ended drive beam, DETF intermediate drive beam, or single drive beam;

[0013] The DETF dual-end drive beam includes two parallel DETF slender beams, with DETF short thick beams connected to both ends of the two DETF slender beams respectively. The outer end of the DETF short thick beam at one end is fixed to the anchor point, and the outer end of the DETF short thick beam at the other end is connected to the lever. Nanobeams are vertically connected to the outer side of the connection between the two DETF short thick beams and the two DETF slender beams on the anchor point side.

[0014] The DETF intermediate drive beam includes two parallel DETF slender beams, with DETF short thick beams connected to both ends of the two DETF slender beams respectively. The outer end of one DETF short thick beam is fixed to the anchor point, and the outer end of the other DETF short thick beam is connected to the lever. The inner sides of the connection between the two DETF short thick beams and the two DETF slender beams on the anchor point side are connected by vertically arranged nanobeams.

[0015] The single drive beam includes a single DETF slender beam, one end of which is connected to a lever and the other end of which is connected to a DETF short thick beam. The outer end of the DETF short thick beam is connected to an anchor point. A nanobeam is vertically arranged at the connection between the DETF short thick beam and the DETF slender beam.

[0016] A further technical solution of the present invention is that the axial length ratio of the DETF slender beam and the DETF short and thick beam is 5:1, and the radial width ratio is 2:1.

[0017] A further technical solution of the present invention is: the self-excited oscillation method of the thermo-pressure resistor mechanical resonator is as follows:

[0018] Injecting direct current into the nanobeam raises its temperature, and thermal expansion leads to increased strain in the nanobeam.

[0019] Based on the silicon material property that nanobeams have a negative piezoresistive coefficient, thermal expansion leads to a decrease in the piezoresistive coefficient, which in turn reduces the resistance of the nanobeams, resulting in a decrease in their temperature. This causes the nanobeams to begin thermal contraction and a decrease in strain.

[0020] This cycle repeats continuously, creating alternating thermal expansion forces;

[0021] Under the action of alternating thermal expansion force, the thermo-pressurized resonator oscillates with a constant amplitude after it starts oscillating.

[0022] An acceleration detection method for a thermally excited piezoresistive self-excited resonant inertial sensor, comprising the following specific steps:

[0023] Electrodes are connected to the nanobeams of the self-excited oscillation module, and the nanobeams vibrate under the action of the DC bias signal of the driving electrode.

[0024] The mass block of the inertial force sensing module receives changes in acceleration and generates inertial force.

[0025] The inertial force generated is converted into an axial force applied to the frequency modulation module by levers of the inertial force sensing module, which acts on the DETF slender beam, causing its stiffness to change.

[0026] The detection electrode outputs an AC current signal containing the amplitude information of two nanobeams. After the current signal is processed by the circuit, two voltage signals proportional to the amplitude of the nanobeams are output.

[0027] The change in the acceleration signal of the mass block can be obtained by detecting the change in the ratio of the two voltage signals.

[0028] Beneficial effects

[0029] The beneficial effects of this invention are as follows: The thermally driven piezoresistive accelerometer structure of this invention is composed of two parts with symmetrical structural features, which can realize the structural differential function; its working principle adopts the traveling wave mode, and utilizes its required simple structure and geometric relationship to avoid signal sensitivity attenuation caused by structural or process errors; the design converts the transverse vibration of the resonator into the bending vibration of the DETF beam by coupling the nanomechanical resonator with the DETF slender beam, thereby obtaining an accelerometer that uses the transverse vibration mode of the resonator for acceleration detection, avoiding the interference of the transverse vibration of the resonator on the overall mode of the accelerometer, and filling the gap of this type of modal accelerometer.

[0030] Based on case studies, the theoretical amplification factor of the lever is 10x, and the cross sensitivity of the spring beam is 0.15%. Simulations show that the sensitivity of this structure is 303 Hz / g. By converting the lateral expansion mode of the nanobeam into the bending vibration mode of the slender beam, the stiffness is greatly reduced, resulting in a three-order-of-magnitude improvement in accelerometer performance compared to other accelerometers with this lateral vibration mode. Attached Figure Description

[0031] Figure 1 The following are schematic diagrams of the structure in the embodiments of the present invention: (a) is a top view of the structure; (b) is a partial enlarged view of the DETF double-end drive beam; (c) is a partial enlarged view of the single drive beam; (d) is a partial enlarged view of the DETF middle drive beam; (e) is a three-dimensional schematic diagram of the structure.

[0032] Figure 2 This is a schematic diagram of the self-excited oscillation principle in an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the working modes in an embodiment of the present invention;

[0034] Explanation of reference numerals in the attached diagram: 1-1 is the first spring beam, 1-2 is the second spring beam, 1-3 is the third spring beam, and 1-4 is the fourth spring beam; 2 is the mass block; 3-1 is the first lever, and 3-2 is the second lever; 4-1 is the first DETF slender beam, and 4-2 is the second DETF slender beam; 5-1 is the first nanobeam, 5-2 is the second nanobeam, 5-3 is the third nanobeam, and 5-4 is the fourth nanobeam; 6-1 is the first DETF short and thick beam, and 6-2 is the second DETF short and thick beam; 7 is the anchor point. Detailed Implementation

[0035] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0036] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0037] This invention aims to overcome the power consumption limitations of electronic circuit systems in sensors by researching a nanomechanical accelerometer sensing element based on the thermally excited piezoresistive (thermo-piezoresistive) principle. It utilizes the heat generated by the bias current to compensate for the vibration loss of the resonator, forming a self-feedback loop combined with the negative piezoresistive effect. This eliminates the need for complex control circuits, converting electrical energy more efficiently into the kinetic energy of the sensor sensing element. Furthermore, by adjusting the stiffness of the nanomechanical thermo-piezoresistive resonator through inertial force, inertial force sensing based on frequency modulation output is achieved. The vibration of the thermo-piezoresistive resonator differs from the bending vibration of traditional resonators; it belongs to the axial expansion vibration of a nanobeam.

[0038] The above technical solution will be further explained below with reference to the accompanying drawings and examples:

[0039] In one embodiment, a thermally excited piezoresistive detection self-excited oscillation resonant inertial sensor includes: an integrally connected inertial force sensing module, a frequency modulation module, and a self-excited oscillation module. The inertial force sensing module senses acceleration and converts the acceleration into an axial force applied to the frequency modulation module. The frequency modulation module changes its effective stiffness by receiving the axial force to complete frequency modulation. The self-excited oscillation module forms an alternating thermal expansion force through its own closed loop, and completes the self-excited oscillation of the frequency modulation module under the action of the alternating thermal expansion force.

[0040] In one embodiment, the inertial force sensing module includes a mass block and levers connected to its two sides. The mass block is connected to a corresponding number of anchor points through multiple elastic beams for sensing acceleration. The levers on both sides are used to convert the acceleration into axial forces applied to the frequency modulation modules on both sides.

[0041] Preferably, the mass block is a rectangular flat plate structure with two sets of notched channels symmetrically arranged on opposite sides without levers. Anchor points are provided at the outer ends of the notched channels, and each anchor point is connected to the inner end of each notched channel by an elastic beam to form a working plane for acceleration detection.

[0042] In one embodiment, the frequency modulation module includes a DETF slender beam, the axis of which is perpendicular to the length direction of the lever.

[0043] Preferably, the DETF slender beam has a single beam or parallel double beams.

[0044] In one embodiment, the self-excited oscillation module includes a DETF short thick beam and a nanobeam. One end of the DETF short thick beam is connected to the extension direction of the DETF slender beam, and the other end is connected to a lever. The nanobeam is vertically arranged at the connection between the DETF short thick beam and the DETF slender beam, and the whole constitutes a thermo-pressurized resonator.

[0045] Preferably, the thermo-pressurized resistor mechanical resonator can be any one of three types: DETF double-ended drive beam, DETF intermediate drive beam, or single drive beam.

[0046] Reference Figure 1 As shown in Figure (b), the DETF dual-end drive beam includes two parallel DETF slender beams. Both ends of the two DETF slender beams are connected to DETF short thick beams. The outer end of one DETF short thick beam is fixed to the anchor point, and the outer end of the other DETF short thick beam is connected to the lever. Nanobeams are vertically connected to the outer side of the connection between the two DETF short thick beams and the two DETF slender beams on the anchor point side.

[0047] Reference Figure 1 As shown in Figure (d), the DETF intermediate drive beam includes two parallel DETF slender beams. Both ends of the two DETF slender beams are connected to DETF short thick beams. The outer end of one DETF short thick beam is fixed to the anchor point, and the outer end of the other DETF short thick beam is connected to the lever. The inner side of the connection between the two DETF short thick beams and the two DETF slender beams on the anchor point side is connected by vertically arranged nanobeams.

[0048] Reference Figure 1 As shown in Figure (c), the single drive beam includes a single DETF slender beam, one end of which is connected to a lever and the other end of which is connected to a DETF short thick beam. The outer end of the DETF short thick beam is connected to an anchor point. A nanobeam is vertically arranged at the connection between the DETF short thick beam and the DETF slender beam.

[0049] Preferably, the axial length ratio of the DETF slender beam and the DETF short and thick beam is 5:1, and the radial width ratio is 2:1.

[0050] In one embodiment, refer to Figure 1As shown in Figure (a), a thermally excited piezoresistive self-excited resonant inertial sensor includes: a mass block 2, spring beams 1-1, 1-2, 1-3, and 1-4, several anchor points 7, levers 3-1 and 3-2, and thermally excited piezoresistive mechanical resonators located on both sides of the mass block. The thermally excited piezoresistive mechanical resonators consist of three parts: a slender DETF beam, a short, thick DETF beam (length-to-short ratio of 5:1, thickness-to-thin ratio of 2:1), and a nanobeam. The motion of the mass block 2 is amplified by the lever amplification mechanism and converted into an axial force applied to the DETF beams of the thermally excited piezoresistive mechanical resonator, thereby modulating the frequency of the resonator. The spring beams are used to suppress unnecessary interference to the nanobeams and reduce cross-sensitivity.

[0051] The above structure is divided into an inertial force sensing module, a frequency modulation module, and a self-excited oscillation module according to its working mechanism.

[0052] In one embodiment, the inertial force sensing module consists of spring beams 1-1, 1-2, 1-3, and 1-4; a mass block 2; and levers 3-1 and 3-2. Its main function is to sense acceleration and then convert the acceleration into an axial force applied to the DETF beams through a lever amplification structure. The frequency modulation module consists of slender DETF beams 4-1 and 4-2, which are mainly responsible for bearing the stress transmitted by the inertial force sensing module, thereby changing the effective stiffness and realizing frequency modulation. In this invention, it is designed as any one of three structures: a double-ended DETF driving beam, a middle DETF driving beam, or a single beam. The self-excited oscillation module consists of nanobeams 5-1, 5-2, 5-3, and 5-4, and a short, thick DETF beam. The nanobeams and the short, thick beam form a closed loop, achieving self-excited oscillation under the action of alternating thermal expansion force. The function of the short, thick beam structure is to reduce its resistance, so that the electrical energy in the loop can be converted into the kinetic energy of the slender beam more efficiently, further reducing the power consumption of the sensor.

[0053] Since the overall structure involved in the above embodiments consists of two parts with symmetrical features, the basic working principle is explained using one half as an example. The specific working process is as follows:

[0054] Thermally excited piezoresistive testing is a driving detection method that couples heat, electricity, and force. Its self-excited oscillation principle is as follows: Figure 2 As shown, the self-excited oscillation of the thermo-piezoresistive mechanical resonator begins with the injection of a direct current. The current flowing through the nanobeams causes their temperature to rise, leading to thermal expansion and increased strain. Since the nanobeams are made of silicon, a material with a negative piezoresistive coefficient, thermal expansion reduces this coefficient, resulting in decreased resistance and a drop in temperature. This causes thermal contraction and a decrease in strain. This cycle repeats, creating alternating thermal expansion forces. Under the influence of these alternating forces, the thermo-piezoresistive mechanical resonator oscillates with a constant amplitude after initiation.

[0055] In one embodiment, the resonant detection method for inertial force is as follows: Two nanobeams of a thermopiezoelectric resonant accelerometer vibrate under the action of a DC bias signal on the driving electrodes. When the input acceleration changes, the inertial force generated by the mass acts on the slender DETF beams, causing a change in their stiffness. An AC current signal containing the amplitude information of the two resonators is output through the detection electrodes. After the current signal is processed by the circuit, two voltage signals proportional to the resonator amplitudes are output. Therefore, the change in the mass acceleration signal can be obtained by detecting the change in the ratio of the two voltage signals.

[0056] To improve accelerometer sensitivity, a specific expression for accelerometer sensitivity was theoretically derived. Taking the lower half as an example, the accelerometer sensitivity is given by the following formula:

[0057]

[0058] Where, ρt m S m These represent the density, thickness, and area of ​​the mass block, respectively; S r k is the cross-sectional area of ​​the resonator; ff k represents the bending stiffness of an equivalent flexible spring beam. rc ω is the compressive stiffness of the resonator. 0r σ is the resonant frequency of the resonator; buck This represents the yield limit of the resonator.

[0059] From the above formula, it can be seen that the accelerometer sensitivity S aω The accelerometer is related to many parameters, and changes in these parameters will affect the sensitivity. Therefore, analyzing the influence trend of these parameters on the sensitivity of the accelerometer is of great value for breaking through the accuracy limit of existing MEMS accelerometers.

[0060] In one embodiment, the substrate material used in the chip-level thermally driven piezoresistive resonant accelerometer is single-crystal silicon, that is, from top to bottom, it consists of a single-crystal silicon layer, a silicon dioxide crystal layer, and a single-crystal silicon layer. The acceleration structure placed on the upper surface of the substrate includes three parts: an inertial force sensing module, a frequency modulation module, and a self-excited oscillation module. The self-excited oscillation module is formed by etching and sputtering metal on the surface of the uppermost single-crystal silicon layer, while the inertial force sensing module and the frequency modulation module are implemented by etching on the surface of the uppermost single-crystal silicon layer.

[0061] Preferably, the thickness of the topmost monocrystalline silicon layer is 10μm; in the inertial force sensitive module, the area of ​​the mass block is 2000μm×2000μm; spring beams 1-1, 1-2, 1-3, and 1-4 are each composed of a slender beam of 400μm×4μm and a 100μm square anchor point; the length and width of the input beams of levers 3-1 and 3-2 are 150μm and 3μm, respectively; the length and width of the lever arms are 870μm and 30μm, respectively; the length and width of the output beams are 40μm and 3μm, respectively; the length and width of the support beams are 15μm and 3μm, respectively; in the frequency modulation module, the length and width of the slender DETF beams 4-1 and 4-2 are 320μm and 3μm, respectively, with a spacing of 20μm; the length and width of the four short and thick beams are 20μm and 5μm, respectively; in the self-excited oscillation module, the length and width of the slender beams 5-1, 5-2, 5-3, and 5-4 are 20μm and 1μm, respectively.

[0062] Preferred, refer to Figure 3 As shown, the resonant frequencies and sensitivities of the three structures—DETF double-ended drive beam, DETF intermediate drive beam, and single drive beam—are as follows:

[0063] name resonant frequency Sensitivity Features Double-ended drive beam 491kHz 303Hz / g Strong anti-interference ability Single beam 497kHz 535Hz / g Simple structure, easy to process Intermediate drive beam 414KHz 405Hz / g The circuit is further simplified, reducing power consumption.

[0064] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A thermally excited piezoresistive detection self-excited oscillation resonant inertial sensor, characterized in that: It includes an integrated inertial force sensing module, a frequency modulation module, and a self-excited oscillation module. The inertial force sensing module senses acceleration and converts it into an axial force applied to the frequency modulation module. The frequency modulation module changes its effective stiffness by receiving the axial force to complete frequency modulation. The self-excited oscillation module generates alternating thermal expansion force through its own closed loop, and completes the self-excited oscillation of the frequency modulation module under the action of the alternating thermal expansion force. The inertial force sensing module includes a mass block and levers connected to its two sides. The mass block is connected to a number of anchor points through multiple elastic beams to sense acceleration. The levers on both sides are used to convert the acceleration into axial forces applied to the frequency modulation modules on both sides. The frequency modulation module includes a DETF slender beam, the axis of which is perpendicular to the length direction of the lever. The structural form of the DETF slender beam is a single beam or parallel double beams; The self-excited oscillation module includes a DETF short thick beam and a nano beam. One end of the DETF short thick beam is connected to the extension direction of the DETF slender beam, and the other end is connected to the lever. The nano beam is vertically arranged at the connection between the DETF short thick beam and the DETF slender beam, and the whole constitutes a thermo-pressurized resistor mechanical resonator. The thermo-pressurized resistor mechanical resonator is any one of three types: DETF double-ended drive beam, DETF intermediate drive beam, or single drive beam. The DETF dual-end drive beam includes two parallel DETF slender beams, with DETF short thick beams connected to both ends of the two DETF slender beams respectively. The outer end of the DETF short thick beam at one end is fixed to the anchor point, and the outer end of the DETF short thick beam at the other end is connected to the lever. Nanobeams are vertically connected to the outer side of the connection between the two DETF short thick beams and the two DETF slender beams on the anchor point side. The DETF intermediate drive beam includes two parallel DETF slender beams, with DETF short thick beams connected to both ends of the two DETF slender beams respectively. The outer end of one DETF short thick beam is fixed to the anchor point, and the outer end of the other DETF short thick beam is connected to the lever. The inner sides of the connection between the two DETF short thick beams and the two DETF slender beams on the anchor point side are connected by vertically arranged nanobeams. The single drive beam includes a single DETF slender beam, one end of which is connected to a lever and the other end of which is connected to a DETF short thick beam. The outer end of the DETF short thick beam is connected to an anchor point. A nanobeam is vertically arranged at the connection between the DETF short thick beam and the DETF slender beam.

2. The thermally excited piezoresistive detection self-excited oscillation resonant inertial sensor according to claim 1, characterized in that: The mass block is a rectangular flat plate structure with two sets of notched channels symmetrically arranged on opposite sides without levers. Anchor points are provided at the outer ends of the notched channels. An elastic beam connects each anchor point to the inner end of each notched channel to form a working plane for acceleration detection.

3. The thermally excited piezoresistive detection self-excited oscillation resonant inertial sensor according to claim 1, characterized in that: The axial length ratio of the DETF slender beams and the DETF short and thick beams is 5:1, and the radial width ratio is 2:

1.

4. The thermally excited piezoresistive detection self-excited oscillation resonant inertial sensor according to claim 3, characterized in that: The self-excited oscillation method of the thermo-pressurized resistor mechanical resonator is as follows: Injecting direct current into the nanobeam raises its temperature, and thermal expansion leads to increased strain in the nanobeam. Based on the silicon material property that nanobeams have a negative piezoresistive coefficient, thermal expansion leads to a decrease in the piezoresistive coefficient, which in turn reduces the resistance of the nanobeams, resulting in a decrease in their temperature. This causes the nanobeams to begin thermal contraction and a decrease in strain. This cycle repeats continuously, creating alternating thermal expansion forces; Under the action of alternating thermal expansion force, the thermo-pressurized resonator oscillates with a constant amplitude after it starts oscillating.

5. An acceleration detection method for a thermally excited piezoresistive self-excited resonant inertial sensor according to any one of claims 1-4, characterized in that... The specific steps are as follows: Electrodes are connected to the nanobeams of the self-excited oscillation module, and the nanobeams vibrate under the action of the DC bias signal of the driving electrode. The mass block of the inertial force sensing module receives changes in acceleration and generates inertial force. The inertial force generated is converted into an axial force applied to the frequency modulation module by levers of the inertial force sensing module, which acts on the DETF slender beam, causing its stiffness to change. The detection electrode outputs an AC current signal containing the amplitude information of two nanobeams. After the current signal is processed by the circuit, two voltage signals proportional to the amplitude of the nanobeams are output. The change in the acceleration signal of the mass block can be obtained by detecting the change in the ratio of the two voltage signals.

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