Thermal excitation piezoresistive detection self-oscillation resonant inertial sensor

Abstract

The invention discloses a thermal excitation piezoresistive detection self-oscillation resonant inertial sensor, and belongs to the field of micro electro mechanical systems. Comprising an inertia force sensitive module, a frequency modulation module and a self-excited oscillation module which are integrally connected, and the inertia force sensitive module senses acceleration and converts the acceleration into axial force applied to the frequency modulation module; the frequency modulation module changes the effective rigidity by receiving the axial force to complete frequency modulation; the self-excited oscillation module forms alternating thermal expansion force through a closed loop of the self-excited oscillation module, and self-excited oscillation of the frequency modulation module is completed under the action of the alternating thermal expansion force. By coupling the resonator and the DETF beam, the problem that no transverse vibration mode accelerometer exists at home and abroad at present is solved, and meanwhile, the problems that the transverse vibration mode of the resonator is consistent with the mass motion direction of the accelerometer, so that the overall mode of the acceleration is influenced, the sensitivity is reduced and the like are solved.

Description

Technical Field

[0001] The invention belongs to the field of micro-electromechanical systems, and in particular relates to a thermally excited piezoresistive detection self-oscillation resonant inertial sensor. Background Art

[0002] MEMS accelerometer is a miniaturized acceleration sensor that combines microelectronics and micromechanics to convert acceleration signals into electrical signals. This sensor has been widely used in many fields, such as automotive safety systems, consumer electronics, medical devices, aerospace and military, due to its small size, light weight, low power consumption, low cost and high reliability.

[0003] Ultra-low power micro-nano sensors are typical representatives of intelligent sensor technology in the post-Moore era. They are the core sensing components of long-term wireless sensor networks and new-generation micro-intelligent equipment. Ultra-low power MEMS accelerometers are widely used in many fields due to their low power consumption and high performance. For example, in medical health monitoring, they can be used for vital sign monitoring, hearing aids, pacemakers, automatic external defibrillators and other medical equipment to provide accurate motion signal capture and health monitoring; in industrial monitoring, they can be used to monitor the vibration, tilt and motion state of the machine to predict equipment failure or perform process control. At the same time, they can be used for automobile tire pressure monitoring, electric vehicle battery monitoring, etc. to ensure vehicle safety and improve energy efficiency. However, high-performance micro-nano sensors usually come with complex detection and control electronic circuit systems; taking high-precision resonant accelerometers as an example, more than 99% of their power consumption is used for heating of electronic components in the frequency tracking system. Therefore, the main problem limiting the power consumption of accelerometers is that their control circuit power consumption is too high. Summary of the invention

[0004] Technical issues to be solved:

[0005] In order to avoid the shortcomings of the prior art, the present invention provides a thermally excited piezoresistive detection self-excited oscillation resonant inertial sensor, which couples the nanobeam to the DETF beam, drives it to the bending vibration mode through thermal drive, and then conducts the acceleration transmitted by the mass block to the axial stress applied to the DETF beam (the length direction of the DETF beam is defined as the axial direction), thereby changing the effective stiffness of the structure, and converting the lateral vibration mode of the nanobeam into the bending vibration mode of the DETF slender beam, thereby realizing acceleration detection. The present invention solves the problem that there is no lateral vibration mode accelerometer at home and abroad at present by coupling the resonator with the DETF beam, and at the same time avoids the lateral vibration mode of the resonator being consistent with the mass movement direction of the accelerometer, thereby affecting the overall acceleration mode and reducing the sensitivity.

[0006] The technical solution of the present invention is: a thermally excited piezoresistive detection self-excited oscillation resonant inertial sensor, comprising an inertial force sensitive module, a frequency modulation module, and a self-excited oscillation module which are integrally connected, wherein the inertial force sensitive module senses acceleration and converts the acceleration into an axial force applied to the frequency modulation module; the frequency modulation module changes the effective stiffness by receiving the axial force to complete the 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 sensitive module includes a mass block and levers connected to both sides thereof, the mass block is connected to a corresponding number of anchor points through multiple elastic beams for sensing acceleration, and the levers on both sides are respectively used to convert acceleration into axial forces 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 groups of notched grooves are symmetrically arranged on the opposite sides where the levers are not installed. Anchor points are arranged at the outer ends of the notched grooves, and each anchor point is connected to the inner end of each notched groove 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 comprises a DETF slender beam, and the axial direction of the DETF slender beam 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 a parallel double beam.

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

[0012] A further technical solution of the present invention is that: the thermal piezoresistive mechanical resonator can be in any of the three forms of a DETF double-ended driving beam, a DETF intermediate driving beam or a single driving beam;

[0013] The DETF double-end driving beam comprises two DETF slender beams arranged in parallel, and the two ends of the two DETF slender beams are respectively connected to DETF short and thick beams, the outer end of the DETF short and thick beam at one end is fixed to the anchor point, and the outer end of the DETF short and thick beam at the other end is connected to the lever, and the outer sides of the connection between the two DETF short and thick beams on the anchor point side and the two DETF slender beams are vertically connected to nano beams;

[0014] The DETF intermediate driving beam comprises two DETF slender beams arranged in parallel, and the two ends of the two DETF slender beams are respectively connected to DETF short and thick beams, the outer end of the DETF short and thick beam at one end is fixed to the anchor point, and the outer end of the DETF short and thick beam at the other end is connected to the lever, and the two DETF short and thick beams on the anchor point side are connected to the inner side of the connection between the two DETF slender beams through a vertically arranged nano beam;

[0015] The single driving beam comprises a single DETF slender beam, one end of which is connected to a lever and the other end is connected to a DETF short and thick beam. The outer end of the DETF short and thick beam is connected to an anchor point, and a nanobeam is vertically arranged at the connection between the DETF short and 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 thermal piezoresistive mechanical resonator is:

[0018] A direct current is injected into the nanobeam, causing its temperature to rise, and thermal expansion causes the nanobeam strain to increase;

[0019] Based on the silicon material property that the nanobeam has a negative piezoresistance coefficient, thermal expansion causes the piezoresistance coefficient to decrease, resulting in a decrease in the resistance of the nanobeam, which in turn causes its temperature to drop, and the nanobeam begins to thermally contract, resulting in a decrease in strain.

[0020] This cycle repeats itself, forming an alternating thermal expansion force;

[0021] Under the action of the alternating thermal expansion force, the thermo-piezoresistive mechanical resonator vibrates with a constant amplitude after being started.

[0022] A method for detecting acceleration of a thermally excited piezoresistive self-oscillation resonant inertial sensor, the specific steps are as follows:

[0023] An electrode is connected to the nanobeam of the self-excited oscillation module, and the nanobeam vibrates under the action of a DC bias signal of the driving electrode;

[0024] The mass block of the inertial force sensitive module receives the acceleration change and generates inertial force;

[0025] The generated inertial force is converted into an axial force applied to the frequency modulation module through the lever of the inertial force sensitive module, that is, acting on the DETF slender beam, causing its stiffness to change;

[0026] The detection electrode outputs an alternating current signal containing the amplitude information of the 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 is obtained by detecting the change in the ratio of the above two voltage signals.

[0028] Beneficial Effects

[0029] The beneficial effects of the present invention are as follows: the overall structural design of the thermally driven piezoresistive detection accelerometer of the present invention consists of two parts with symmetrical characteristic structures, which can realize the structural differential function; its working principle adopts the traveling wave mode, and utilizes its required structure and simple geometric relationship and other characteristics to avoid signal sensitivity attenuation caused by structural or process errors; the design converts the lateral 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 lateral vibration mode of the resonator for acceleration detection, avoiding the interference of the lateral vibration of the resonator on the overall mode of the accelerometer, and filling the vacancy of this modal accelerometer.

[0030] Based on the actual verification, the theoretical magnification of the lever is 10 times and the cross sensitivity of the spring beam is 0.15%. The simulation shows that the sensitivity of the structure is 303Hz / g. Since the lateral expansion mode of the nanobeam is converted into the bending vibration mode of the slender beam, the stiffness is greatly reduced, which is 3 orders of magnitude higher than other accelerometers with this lateral vibration mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the structure in the embodiment of the present invention; (a) is a top view of the structure; (b) is a partial enlarged view of the DETF double-end driving beam; (c) is a partial enlarged view of the single driving beam; (d) is a partial enlarged view of the DETF middle driving beam; (e) is a three-dimensional schematic diagram of the structure;

[0032] Figure 2 Schematic diagram of the self-oscillation principle in an embodiment of the present invention;

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

[0034] Explanation of the accompanying drawings: 1-1 is the first spring beam, 1-2 is the second spring beam, 1-3 is the third spring beam, 1-4 is the fourth spring beam; 2 is the mass block; 3-1 is the first lever, 3-2 is the second lever; 4-1 is the first DETF slender beam, 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, 5-4 is the fourth nanobeam; 6-1 is the first DETF short and thick beam, 6-2 is the second DETF short and thick beam; 7 is the anchor point. DETAILED DESCRIPTION

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

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0037] The present invention aims to get rid of the limitation of sensor power consumption by electronic circuit system, and intends to study the sensitive element of nanomechanical acceleration sensor based on the principle of thermal excitation piezoresistive detection (thermal piezoresistive): using the heat generated by bias current to compensate the vibration loss of resonator, combining with negative piezoresistive effect to form a self-feedback loop, thereby eliminating complex control circuits and converting electrical energy into kinetic energy of sensor sensitive element more efficiently; adjusting the stiffness of nanomechanical thermal piezoresistive resonator by inertial force, realizing inertial force perception based on frequency modulation output. The vibration of thermal piezoresistive resonator is different from the bending vibration of traditional resonator, and belongs to the axial expansion vibration of nanobeam.

[0038] The above technical solution is further described below with reference to the accompanying drawings and examples:

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

[0040] In one embodiment, the inertial force sensitive module includes a mass block and levers connected to both sides thereof. 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 acceleration into axial forces applied to the frequency modulation modules on both sides.

[0041] Preferably, the mass block is a rectangular flat plate structure, and two groups of notched grooves are symmetrically arranged on the two opposite sides where the lever is not installed. Anchor points are arranged at the outer ends of the notched grooves, and each anchor point is connected to the inner end of each notched groove by an elastic beam to form a working plane for acceleration detection.

[0042] In one embodiment, the frequency modulation module comprises a DETF elongated beam, wherein the axial direction of the DETF elongated beam is perpendicular to the length direction of the lever.

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

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

[0045] Preferably, the thermal piezoresistive mechanical resonator can be in any of the three forms of a DETF double-ended driving beam, a DETF intermediate driving beam or a single driving beam;

[0046] Reference Figure 1 As shown in Figure (b), the DETF double-end driving beam includes two DETF slender beams arranged in parallel, and the two ends of the two DETF slender beams are respectively connected to DETF short and thick beams, the outer end of the DETF short and thick beam at one end is fixed to the anchor point, and the outer end of the DETF short and thick beam at the other end is connected to the lever, and the outer sides of the connection between the two DETF short and thick beams on the anchor point side and the two DETF slender beams are vertically connected with nano beams;

[0047] Reference Figure 1 As shown in Figure (d), the DETF intermediate driving beam includes two DETF slender beams arranged in parallel, and the two ends of the two DETF slender beams are respectively connected to DETF short and thick beams, the outer end of the DETF short and thick beam at one end is fixed to the anchor point, and the outer end of the DETF short and thick beam at the other end is connected to the lever, and the two DETF short and thick beams on the anchor point side are connected to the inner side of the connection between the two DETF slender beams through a vertically arranged nanobeam;

[0048] Reference Figure 1 As shown in Figure (c), the single driving beam includes a single DETF slender beam, one end of which is connected to the lever and the other end is connected to the DETF short and thick beam. The outer end of the DETF short and thick beam is connected to the anchor point, and a nanobeam is vertically arranged at the connection between the DETF short and 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, referring to Figure 1As shown in Figure (a), a thermally excited piezoresistive detection self-excited oscillation resonant inertial sensor includes: a mass block 2, spring beams 1-1, 1-2, 1-3, 1-4, a number of anchor points 7, levers 3-1, 3-2 and thermal piezoresistance mechanical resonators located on both sides of the mass block. The thermal piezoresistance mechanical resonator consists of three parts: a DETF slender beam, a DETF short and thick beam (length ratio of 5:1, thickness ratio of 2:1) and a nanobeam. The movement of the mass block 2 is amplified by the lever amplification mechanism and converted into an axial force applied to the DETF beam of the thermal piezoresistance mechanical resonator, thereby frequency modulating the resonator. The spring beam is used to suppress the influence of unnecessary interference on the nanometer 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 the working mechanism.

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

[0053] Since the overall structure involved in the above embodiment is composed of two parts with symmetrical characteristics, half of the part is taken as an example when explaining its basic working principle. The specific working process is as follows:

[0054] Thermally excited piezoresistive detection 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 thermal piezoresistive nanomechanical resonator is firstly achieved by injecting a direct current. The current flowing through the nanobeam will increase its temperature, and the nanobeam will produce thermal expansion, which will increase the strain of the nanobeam. Since the material used for the nanobeam is silicon material with a negative piezoresistance coefficient, thermal expansion will cause the piezoresistance coefficient to decrease, resulting in a decrease in the resistance of the nanobeam, which in turn causes its temperature to decrease, and the nanobeam will begin to thermally contract, and the strain will decrease. This cycle will repeat, forming an alternating thermal expansion force. Under the action of the alternating thermal expansion force, the thermal piezoresistive nanomechanical resonator vibrates with a constant amplitude after starting.

[0055] In one embodiment, the resonant detection method of inertial force is as follows: the two nano-beams of the thermal piezoresistive resonant accelerometer vibrate under the action of the DC bias signal of the driving electrode. When the input acceleration changes, the inertial force generated by the mass block acts on the DETF slender beam, causing its stiffness to change, and the detection electrode outputs an AC current signal containing the amplitude information of the two resonators. After the current signal is processed by the circuit, two voltage signals proportional to the resonator amplitude are output. Therefore, the change of the acceleration signal of the mass block can be obtained by detecting the change in the ratio of the above two voltage signals.

[0056] In order to improve the sensitivity of the accelerometer, a specific expression of the accelerometer sensitivity is derived theoretically. Taking the lower half as an example, the sensitivity of the accelerometer is given by the following formula:

[0057]

[0058] Among them, ρt m S m are respectively the density, thickness and area of ​​the mass block; S r is the cross-sectional area of ​​the resonator; k ff is the bending stiffness of the equivalent flexible spring beam; k rc is the resonator compression stiffness, ω 0r is the resonant frequency of the resonator; σ buck is the resonator yield limit.

[0059] From the above formula, we can know that the accelerometer sensitivity S aω It has a certain relationship with many parameters, and the changes in these parameters will have an impact on the sensitivity. Therefore, analyzing the impact trend of these parameters on the sensitivity of the accelerometer is of great value for subsequently breaking through the accuracy limit of existing MEMS accelerometers.

[0060] In one embodiment, the substrate material used for the chip-level thermally driven piezoresistive detection resonant accelerometer is single crystal silicon, that is, from top to bottom it is single crystal silicon layer-silicon dioxide crystal layer-single crystal silicon layer, and the acceleration structure placed on the upper surface of the substrate includes three parts: an inertial force sensitive 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 top single crystal silicon layer, and the inertial force sensitive module and the frequency modulation module are realized by etching on the surface of the top single crystal silicon layer.

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

[0062] Preferably, refer to Figure 3 As shown, the resonant frequencies and sensitivities of the three structures of DETF double-ended driving beam, DETF intermediate driving beam or single driving beam are:

[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 to reduce power consumption

[0064] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A thermally excited piezoresistive detection self-oscillation resonant inertial sensor, characterized in that: It includes an inertial force sensitive module, a frequency modulation module, and a self-excited oscillation module which are integrally connected. The inertial force sensitive module senses acceleration and converts the acceleration into an axial force applied to the frequency modulation module. The frequency modulation module changes the effective stiffness by receiving the axial force to complete the 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.

2. According to claim 1, a thermally excited piezoresistive detection self-oscillation resonant inertial sensor is characterized by: The inertial force sensitive module includes a mass block and levers connected to both sides thereof. 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 acceleration into axial forces applied to the frequency modulation modules on both sides.

3. According to claim 2, a thermally excited piezoresistive detection self-oscillation resonant inertial sensor is characterized by: The mass block is a rectangular flat plate structure, and two groups of notched grooves are symmetrically arranged on the opposite sides where the lever is not installed. Anchor points are arranged at the outer ends of the notched grooves, and each anchor point is connected to the inner end of each notched groove by an elastic beam to form a working plane for acceleration detection.

4. According to claim 2, a thermally excited piezoresistive detection self-oscillation resonant inertial sensor is characterized by: The frequency modulation module comprises a DETF slender beam, wherein the axial direction of the DETF slender beam is perpendicular to the length direction of the lever.

5. The thermally excited piezoresistive detection self-oscillation resonant inertial sensor according to claim 4, characterized in that: The DETF slender beam has a structural form of a single beam or a parallel double beam.

6. The thermally excited piezoresistive detection self-oscillation resonant inertial sensor according to claim 5, characterized in that: The self-excited oscillation module includes a DETF short and thick beam and a nano beam, one end of the DETF short and 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 and thick beam and the DETF slender beam, and the whole constitutes a thermal-piezoresistive mechanical resonator.

7. The thermally excited piezoresistive detection self-oscillation resonant inertial sensor according to claim 6, characterized in that: The thermal-piezoresistive mechanical resonator can be in any of the three forms of a DETF double-ended driving beam, a DETF intermediate driving beam or a single driving beam; The DETF double-end driving beam comprises two DETF slender beams arranged in parallel, and the two ends of the two DETF slender beams are respectively connected to DETF short and thick beams, the outer end of the DETF short and thick beam at one end is fixed to the anchor point, and the outer end of the DETF short and thick beam at the other end is connected to the lever, and the outer sides of the connection between the two DETF short and thick beams on the anchor point side and the two DETF slender beams are vertically connected to nano beams; The DETF intermediate driving beam comprises two DETF slender beams arranged in parallel, and the two ends of the two DETF slender beams are respectively connected to DETF short and thick beams, the outer end of the DETF short and thick beam at one end is fixed to the anchor point, and the outer end of the DETF short and thick beam at the other end is connected to the lever, and the two DETF short and thick beams on the anchor point side are connected to the inner side of the connection between the two DETF slender beams through a vertically arranged nano beam; The single driving beam comprises a single DETF slender beam, one end of which is connected to a lever and the other end is connected to a DETF short and thick beam. The outer end of the DETF short and thick beam is connected to an anchor point, and a nanobeam is vertically arranged at the connection between the DETF short and thick beam and the DETF slender beam.

8. The thermally excited piezoresistive detection self-oscillation resonant inertial sensor according to claim 7, characterized in 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.

9. The thermally excited piezoresistive detection self-oscillation resonant inertial sensor according to claim 8, characterized in that: The self-excited oscillation method of the thermal piezoresistive mechanical resonator is: A direct current is injected into the nanobeam, causing its temperature to rise, and thermal expansion causes the nanobeam strain to increase; Based on the silicon material property that the nanobeam has a negative piezoresistance coefficient, thermal expansion causes the piezoresistance coefficient to decrease, resulting in a decrease in the resistance of the nanobeam, which in turn causes its temperature to drop, and the nanobeam begins to thermally contract, resulting in a decrease in strain. This cycle repeats itself, forming an alternating thermal expansion force; Under the action of the alternating thermal expansion force, the thermo-piezoresistive mechanical resonator vibrates with a constant amplitude after being started.

10. An acceleration detection method for a thermally excited piezoresistive self-oscillation resonant inertial sensor as claimed in any one of claims 1 to 9, characterized in that The specific steps are as follows: An electrode is connected to the nanobeam of the self-excited oscillation module, and the nanobeam vibrates under the action of a DC bias signal of the driving electrode; The mass block of the inertial force sensitive module receives the acceleration change and generates inertial force; The generated inertial force is converted into an axial force applied to the frequency modulation module through the lever of the inertial force sensitive module, that is, acting on the DETF slender beam, causing its stiffness to change; The detection electrode outputs an alternating current signal containing the amplitude information of the 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 is obtained by detecting the change in the ratio of the above two voltage signals.

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