Ultrahigh-sensitivity two-dimensional nano-electromechanical resonant accelerometer based on sliding coupling and method

Abstract

The invention belongs to the technical field of inertial sensing, and particularly relates to an ultrahigh-sensitivity two-dimensional nano-electromechanical resonant accelerometer based on sliding coupling and a method. Wherein a left side groove, a central support and a right side through groove are arranged on the double-groove substrate, the graphene strip is fixed on the double-groove substrate, the mass block is arranged in the right side through groove and is positioned below the right suspended graphene strip, the source electrode is fixed at the left side end part of the graphene strip, and the drain electrode is fixed at the right side end part of the graphene strip. The grid electrode is fixed on the double-groove substrate in the left groove; according to the invention, the reduction effect of the suspended mass block on the resonant frequency is overcome, and the resonant frequency and the sensitivity are improved in order of magnitude; on one hand, large inertia force can be partially released through sliding boundary conditions, the detection range is widened, and the bottleneck problem that high sensitivity and wide range are difficult to consider at the same time is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of inertial sensing, and in particular relates to an ultra-high sensitivity two-dimensional nanoelectromechanical resonant accelerometer based on sliding coupling and a method thereof. Background Art

[0002] Microelectromechanical (MEMS) accelerometers are one of the earliest sensors studied in the MEMS field. Based on their sensing mechanism, they can be categorized as resonant, capacitive, piezoelectric, optical, and piezoresistive. Resonant MEMS accelerometers, which use silicon micromechanical resonators as sensing elements, have become a key development direction for the next generation of high-performance MEMS accelerometers due to their high detection accuracy, excellent linearity, large measurement range, and strong resistance to environmental noise. They are widely used in applications requiring high precision and high stability, such as inertial navigation, gravity detection, and smart wearable devices. Therefore, this study proposes to employ the resonant principle for acceleration sensing.

[0003] However, due to limitations in processing technology and the temperature sensitivity of materials, key performance indicators such as sensitivity and range of silicon micro-accelerometers have reached bottlenecks, and they cannot yet meet the performance requirements of high-precision navigation and guidance in large shock environments. Therefore, domestic and foreign scholars have conducted extensive research on silicon micro-resonant accelerometers. However, since most studies have always used the mass-lever-resonator sensing architecture, the means of improving sensitivity are mostly limited to optimizing the micro-lever mechanism and increasing the mass size, and the performance improvement effect has reached its limit. Therefore, conducting accelerometer research has significant scientific research value and engineering application potential, but related research is currently mainly focused on the micron scale and has reached a performance bottleneck. How to use smaller, more sensitive, and lower-power nanoelectromechanical resonators for acceleration measurement to break through the performance limits of existing accelerometers urgently requires in-depth research and exploration. Therefore, developing a new acceleration sensing architecture suitable for nanoelectromechanical resonators is of great significance.

[0004] In 2015, Adam M. Hurst and others at Columbia University first unveiled a nanoelectromechanical accelerometer based on a two-dimensional graphene suspended mass transconductor structure, achieving a breakthrough in both accelerometer size and performance across multiple scales, sparking a wave of research into third-generation nanoaccelerometers. Due to limitations in material properties and processing techniques, research on nanoelectromechanical accelerometers is still in its early stages. While the existing "single-groove suspended graphene mass" sensing architecture can significantly reduce sensor size and exhibit excellent sensing performance, it struggles to overcome the significant negative impact of the large mass on resonant performance and range, making it difficult to achieve a balanced sensitivity and range. Two key challenges currently hinder the development of nanoaccelerometers:

[0005] (1) How to overcome the significant attenuation effect of large suspended masses on the resonant frequency of two-dimensional graphene strips and improve detection sensitivity by orders of magnitude;

[0006] (2) How to improve the inertial carrying capacity of atomically thin suspended graphene strips to achieve large-scale acceleration detection. Summary of the Invention

[0007] To address the above-mentioned problems, the present invention proposes an ultra-high-sensitivity two-dimensional nanoelectromechanical resonant accelerometer and method based on sliding coupling. This is a nanoelectromechanical (NEMS) accelerometer with a large-range, ultra-high-sensitivity sensing architecture based on sliding coupling. It uses a two-dimensional graphene film with excellent electromechanical properties as the resonant main material of the accelerometer. The design can achieve inter-well sliding coupling with a double-groove suspended graphene mass block sensor structure. On the one hand, it can overcome the effect of the suspended mass block on the resonant frequency, achieving an order of magnitude increase in the resonant frequency and sensitivity; on the other hand, it can achieve partial release of the large inertial force through sliding boundary conditions, widen the detection range, and solve the bottleneck problem of balancing high sensitivity and large range. The present invention can significantly improve the sensitivity of the accelerometer, meeting the core requirements of weapon guidance, aerospace, attitude control, etc. in high-dynamic environments. It is also expected to be applied to high-precision sensing scenarios such as earthquake monitoring, precision industrial instruments, and autonomous driving, promoting technological upgrades in related industries.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] An ultra-high sensitivity two-dimensional nanoelectromechanical resonant accelerometer based on sliding coupling includes a double-groove substrate 1, a graphene strip 2, a mass block 3 and a metal electrode 4; wherein the double-groove substrate 1 is provided with a left groove 101 and a right through groove 103 on both sides of the rear end thereof, the portion of the double-groove substrate 1 between the left groove 101 and the right through groove 103 is a central support 102, one side of the graphene strip 2 is fixed to the upper surface of the double-groove substrate 1 on the left side of the left groove 101, and then is laid in sequence on top of the left groove 101, the central support 102 and the right through groove 103, so that the other side of the graphene strip 2 is fixed to the upper surface of the double-groove substrate 1 on the right side of the right through groove 103, wherein the portion of the graphene strip 2 located on the central support 102 is a sliding The graphene strip 203, the part of the graphene strip 2 located above the left groove 101 is the left suspended graphene strip 201, and the part of the graphene strip 2 located above the right through groove 103 is the right suspended graphene strip 202; a mass block 3 is provided in the right through groove 103, and the mass block 3 is located on the lower surface of the right suspended graphene strip 202 and contacts the right suspended graphene strip 202; the metal electrode 4 includes a source 401, a drain 402 and a gate 403, wherein the source 401 is fixed on the upper surface of the left end of the graphene strip 2 and the double-trench substrate 1, the drain 402 is fixed on the upper surface of the right end of the graphene strip 2 and the double-trench substrate 1, and the gate 403 is fixed on the double-trench substrate 1 in the left groove 101.

[0010] The double-trench substrate 1 is a SOI wafer with a top oxide layer, which is composed of four layers of materials connected together in sequence, namely, a silicon dioxide insulating layer 104, a single crystal silicon device layer 105, a buried oxide layer 106 and a substrate layer 107 from top to bottom.

[0011] The mass block 3 is a mass block made of a silicon dioxide insulating layer 104 and a single crystal silicon device layer 105, and is used to sense the inertial force generated by external acceleration. Together with the right suspended graphene strip 202, it constitutes an acceleration sensing unit. Specifically, the right through-groove 103 is a through-groove formed by hollowing out the silicon dioxide insulating layer 104, the single crystal silicon device layer 105, the buried oxide layer 106 and the substrate layer 107 at the rear end of the double-groove substrate 1, and the mass block 3 is formed by retaining part of the silicon dioxide insulating layer 104 and the single crystal silicon device layer 105 in the right through-groove 103.

[0012] The right through groove 103 on the double-groove substrate 1 is a through groove with a depth of micrometer level, so as to ensure that the mass block 3 has sufficient space for movement.

[0013] The left groove 101 on the double-grooved substrate 1 is a groove with a depth of hundreds of nanometers. The gate 403 on the bottom upper surface and the left suspended graphene strip 201 together form an electrostatic capacitor for driving the left suspended graphene strip 201 to vibrate.

[0014] The graphene strip 2 is a copper-based single-layer graphene grown by CVD, a single-layer or few-layer graphene prepared by mechanical exfoliation, or a single-layer or few-layer molybdenum disulfide.

[0015] The sliding graphene strip 203 is adhered to the upper surface of the central support 102 by van der Waals force, which restricts its vertical movement so that it can only slide in the horizontal direction.

[0016] A method for measuring environmental acceleration using an ultra-high-sensitivity two-dimensional nanoelectromechanical resonant accelerometer based on sliding coupling is disclosed. A suspended mass block 3 is provided on the lower surface of the center position along the length direction of a right suspended graphene strip 202 as an acceleration sensing unit, and a left suspended graphene strip 201 as a resonance detection unit. The two are connected by a sliding graphene strip 203, thereby achieving "acceleration sensing-resonance detection" separation. Specifically, external acceleration acts on the suspended mass block 3 to generate an inertial force, which is transmitted to the right suspended graphene strip 202, causing it to bend vertically and generate axial tension, which drives the sliding graphene strip 203 to move rightward, thereby causing the left suspended graphene strip 201 to undergo axial tensile deformation, further causing changes in the axial stress, linear spring stiffness, and resonant frequency of the left suspended graphene strip 201. Ultimately, the acceleration disturbance is converted into a resonant frequency offset of the left suspended graphene strip 201, achieving acceleration-tensile stress-spring stiffness-resonance frequency conversion, thereby achieving high-precision acceleration measurement.

[0017] A method for measuring environmental acceleration using an ultra-high-sensitivity two-dimensional nanoelectromechanical resonant accelerometer based on sliding coupling specifically includes the following:

[0018] Step 1: Apply a DC voltage Vs to the source 401 and a biased periodic alternating voltage V to the gate 403. DC +V AC cos(Ωt) generates electrostatic force; where V DC is a DC bias voltage, which is used to attract and tighten the left suspended graphene strip 201 downward and generate an initial axial tensile strain ε0, V AC cos(Ωt) is the voltage amplitude V AC , a periodic alternating driving voltage with an angular frequency of Ω, used to generate a periodic electrostatic force with a frequency of Ω near the natural frequency of the left suspended graphene strip 201, driving the left suspended graphene strip 201 into a resonant state, where t is time;

[0019] Step 2: Place the accelerometer in a standard environment to calibrate the linear sensing curve. When a vertical acceleration shock a1 is applied to the accelerometer, the mass block 3 with a mass of M converts the acceleration shock a1 into a vertical inertial force F=Ma1, which acts on the right suspended graphene strip 202, causing it to bend in the vertical direction and generate an axial tensile force T. At the same time, the mass block 3 generates a displacement x R ;

[0020] Step 3: The axial tensile force T of the right suspended graphene strip 202 will further pull the sliding graphene strip 203 to the right, generating a horizontal sliding displacement q, causing the actual length of the right suspended graphene strip 202 to increase, alleviating the bending deformation of the right suspended graphene strip 202 under the action of acceleration, and widening the acceleration detection range. At the same time, it also causes the actual length of the left suspended graphene strip 201 to shorten, generating an axial tensile strain change Δε, thereby further converting the axial tensile force T of the right suspended graphene strip 202 into an axial tensile strain ε0+Δε of the left suspended graphene strip 201 through sliding coupling;

[0021] Step 4: The axial tensile strain of the left suspended graphene strip 202 will change its own linear spring stiffness k(Δε), further causing the resonant frequency f of the left suspended graphene strip 201 to be (k(Δε) / m) 1 / 2 An offset occurs, the offset Δf(a) = [k(Δε) / m] 1 / 2 -[k(Δε=0) / m] 1 / 2 , where m is the effective mass of the left suspended graphene strip 201, and the acceleration impact a1 is finally converted into the resonant frequency offset Δf(a1) of the left suspended graphene strip 201, realizing the transformation of acceleration-tensile stress-spring stiffness-resonant frequency; k(Δε=0) is the linear spring stiffness of the left suspended graphene strip 201 under the initial axial tensile strain ε0;

[0022] Step 5: Measure the current signal output by the drain 402 in real time and obtain a spectrum image of the current signal through Fourier transform. This spectrum image contains a series of current spikes of different frequencies. The frequency value of the maximum current spike is read near the driving frequency Ω, which is the resonant frequency f1 of the left suspended graphene strip 201 under the acceleration impact a1. This completes the calibration of the resonant frequency f1 of the left suspended graphene strip 201 under the specific acceleration impact a1.

[0023] Step 6: Apply another different given acceleration shock a2 to the accelerometer again, repeat steps 2 to 5, and complete the calibration of the resonant frequency f2 of the left suspended graphene strip 201 under the given acceleration shock a2; through the two sets of data (a1, f1) and (a2, f2), the linear sensing curve expression of the accelerometer is fitted to obtain f = S·a+b, where a represents the acceleration shock, represents the intercept, represents acceleration sensitivity;

[0024] Step 7: Place the accelerometer in the test environment, measure the resonant frequency value f output by the accelerometer in real time by measuring the current signal output by the drain 402 in real time, and substitute it into the sensing curve f=S·a+b for calculation, so as to achieve real-time and accurate monitoring of the environmental acceleration changes and complete high-precision acceleration measurement.

[0025] The present invention has the following beneficial effects:

[0026] The present invention uses a "acceleration sensing-resonance detection" separation design to overcome the effect of the suspended mass on the resonant frequency, achieve an order of magnitude increase in resonant frequency and sensitivity, and break through the sensitivity limit of resonant accelerometers.

[0027] The present invention can release the stress of the right suspended graphene strip 202 caused by external acceleration to a certain extent through sliding coupling, broaden the acceleration detection range, and solve the bottleneck problem of achieving both high sensitivity and a large range.

[0028] The present invention benefits from the extremely low effective mass of two-dimensional graphene and the excellent inertial sensing ability of the suspended mass block, and a slight acceleration change will cause an obvious resonant frequency shift. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without paying any creative work.

[0030] Figure 1 is a schematic structural diagram of the accelerometer of the present invention;

[0031] Figure 2 A top view of the accelerometer of the present invention;

[0032] Figure 3 is a front view of the accelerometer of the present invention;

[0033] Figure 4 This is a working principle diagram of the accelerometer of the present invention;

[0034] Figure 5 This is a graph showing the relationship between acceleration and sensing based on theoretical simulation of the present invention;

[0035] Figure 6 is a graph showing the relationship between the vertical displacement and acceleration of the left and right suspended graphene strips;

[0036] Figure 7 is a graph showing the relationship between the lateral displacement and acceleration of the left and right suspended graphene strips;

[0037] Figure 8 is a graph showing the relationship between the axial tension and acceleration of a graphene strip;

[0038] Figure 9This is a schematic structural diagram of the accelerometer described in Example 3;

[0039] Figure 10 A top view of the accelerometer according to Example 3;

[0040] Figure 11 A front view of the accelerometer according to Example 3;

[0041] Figure 12 Schematic diagram of the structure of the accelerometer described in Example 4 (hiding the two-dimensional graphene film);

[0042] Figure 13 A top view of the accelerometer described in Example 4 (hiding the two-dimensional graphene film);

[0043] Figure 14 is an axial cross-sectional view of the accelerometer described in Example 4;

[0044] Figure 15 This is a front cross-sectional view of the accelerometer described in Example 4.

[0045] Wherein: 1- double trench substrate, 101- left trench, 102- center support, 103- right through-groove, 104- silicon dioxide insulation layer, 105- single crystal silicon device layer, 106- buried oxide layer, 107- substrate layer, 108- left through-groove, 109- center trench, 110- left support, 111- right support, 112- inner circular trench, 113- annular center support, 114- outer annular through-groove, 2- graphene Strips, 201-left suspended graphene strip, 202-right suspended graphene strip, 203-sliding graphene strip, 204-center sliding graphene film, 205-center suspended graphene strip, 206-right sliding graphene strip, 207-left sliding graphene strip, 208-suspended graphene drum, 209-suspended graphene ring, 3-mass block, 4-metal electrode, 401-source, 402-drain, 403-gate. DETAILED DESCRIPTION

[0046] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0047] Example 1

[0048] An ultra-high sensitivity two-dimensional nanoelectromechanical resonant accelerometer based on sliding coupling includes a double-groove substrate 1, a graphene strip 2, a mass block 3 and a metal electrode 4; wherein a left groove 101 and a right through-groove 103 are respectively provided on both sides of the rear end of the double-groove substrate 1, the left groove 101 is arranged above one side of the rear end of the double-groove substrate 1, and the right through-groove 103 is arranged on the other side of the rear end of the double-groove substrate 1, and the part of the double-groove substrate 1 between the left groove 101 and the right through-groove 103 is a central support 102, one side of the graphene strip 2 is fixed to the upper surface of the double-groove substrate 1 on the left side of the left groove 101, and then is laid on the left groove 101, the central support 102 and the right through-groove 103 in sequence, so that the other side of the graphene strip 2 is fixed to the upper surface of the double-groove substrate 1 on the right side of the right through-groove 103, wherein the part of the graphene strip 2 located on the central support 102 In order to slide the graphene strip 203, the part of the graphene strip 2 located above the left groove 101 is the left suspended graphene strip 201, and the part of the graphene strip 2 located above the right through groove 103 is the right suspended graphene strip 202; a mass block 3 is provided in the right through groove 103, and the mass block 3 is formed by extending toward the rear end on the side wall of the double-groove substrate 1 of the right through groove 103, and the mass block 3 is located on the lower surface of the center position in the length direction of the right suspended graphene strip 202, and contacts the right suspended graphene strip 202; the metal electrode 4 includes a source 401, a drain 402 and a gate 403, wherein the source 401 is fixed on the upper surface of the left end of the graphene strip 2 and the double-groove substrate 1, the drain 402 is fixed on the upper surface of the right end of the graphene strip 2 and the double-groove substrate 1, and the gate 403 is fixed on the double-groove substrate 1 in the left groove 101.

[0049] The double-trench substrate 1 is a SOI wafer with a top oxide layer, which is composed of four layers of materials connected together in sequence, namely, a silicon dioxide insulating layer 104, a single crystal silicon device layer 105, a buried oxide layer 106 and a substrate layer 107 from top to bottom.

[0050] The mass block 3 is a mass block machined from a silicon dioxide insulating layer 104 and a single-crystal silicon device layer 105. It is used to sense the large inertial force generated by external acceleration and, together with the right suspended graphene strip 202, forms an acceleration sensing unit. Specifically, the right through-slot 103 is formed by hollowing out the silicon dioxide insulating layer 104, the single-crystal silicon device layer 105, the buried oxide layer 106, and the substrate layer 107 at the rear end of the double-trench substrate 1. The mass block 3 is formed by retaining a portion of the silicon dioxide insulating layer 104 and the single-crystal silicon device layer 105 within the right through-slot 103.

[0051] The right through groove 103 on the double-groove substrate 1 is a through-type micron-level deep through groove to ensure that the mass block 3 has sufficient movement space.

[0052] The left groove 101 on the double-grooved substrate 1 is a groove with a depth of hundreds of nanometers. The gate 403 on the bottom upper surface and the left suspended graphene strip 201 together form an electrostatic capacitor for driving the left suspended graphene strip 201 to vibrate.

[0053] The graphene strip 2 is a copper-based single-layer graphene grown by CVD, a single-layer or few-layer graphene prepared by mechanical exfoliation, or other two-dimensional materials such as a single-layer or few-layer molybdenum disulfide.

[0054] The sliding graphene strip 203 is adhered to the upper surface of the central support 102 by van der Waals force, which restricts its vertical movement so that it can only slide in the horizontal direction.

[0055] The source 401 and drain 402 respectively form a tight "sandwich" anchoring structure with the left suspended graphene strip 201, the right suspended graphene strip 202 and the double-groove substrate 1, which greatly reduces the support loss, contact resistance and contact thermal resistance of the anchoring structure, and improves the vibration quality factor and the current intensity between the source 401 and the drain 402.

[0056] The accelerometer described above works as follows:

[0057] A suspended mass block 3 is provided on the lower surface of the right suspended graphene strip 202 at the center of its length, serving as an acceleration sensing unit. The left suspended graphene strip 201 serves as a resonance detection unit. The two are connected by a sliding graphene strip 203, achieving the separation of "acceleration sensing and resonance detection." Specifically, external acceleration acts on the suspended mass block 3 to generate an inertial force, which is transmitted to the right suspended graphene strip 202, causing it to bend vertically and generate axial tension, which drives the sliding graphene strip 203 to move rightward. This in turn causes the left suspended graphene strip 201 to undergo axial tensile deformation, further causing changes in the axial stress, linear spring stiffness, and resonant frequency of the left suspended graphene strip 201. Ultimately, the acceleration disturbance is converted into a resonant frequency offset of the left suspended graphene strip 201, achieving the "acceleration-tensile stress-spring stiffness-resonance frequency" conversion, thereby achieving high-precision acceleration measurement.

[0058] Example 2

[0059] like Figure 1As shown, an ultra-high-sensitivity two-dimensional nanoelectromechanical resonant accelerometer based on sliding coupling includes a dual-groove substrate 1, a graphene strip 2, a mass block 3, and a metal electrode 4. A left groove 101 is provided above the rear end of one side of the dual-groove substrate 1, and a right through-groove 103 is provided at the rear end of the other side. The portion of the dual-groove substrate 1 between the left groove 101 and the right through-groove 103 serves as a central support 102. The two ends of the graphene strip 2 are fixed on the upper surface of the double-groove substrate 1, forming a left suspended graphene strip 201, a right suspended graphene strip 202 and a sliding graphene strip 203 located on the upper surface of the central support 102; the mass block 3 is fixed on the lower surface of the center position of the length direction of the right suspended graphene strip 202; the metal electrode 4 includes a source 401, a drain 402 and a gate 403, the source 401 is fixed on the upper surface of the left end of the left suspended graphene strip 201, the drain 402 is fixed on the upper surface of the right end of the right suspended graphene strip 202, and the gate 403 is fixed on the double-groove substrate 1 in the left groove 101.

[0060] The double-trench substrate 1 is an SOI wafer with a top oxide layer, which is composed of four layers of materials, namely, from top to bottom, a silicon dioxide insulating layer 104, a single crystal silicon device layer 105, a buried oxide layer 106, and a substrate layer 107; wherein, the silicon dioxide insulating layer 104 and the buried oxide layer 106 are used to achieve electrical isolation of the source 401, the drain 402 and the gate 403; the silicon dioxide insulating layer 104, the single crystal silicon device layer 105, the buried oxide layer 106, and the substrate layer 107 are used for patterning to form the double-trench substrate 1 and the mass block 3.

[0061] The mass block 3 is a mass block made of a silicon dioxide insulating layer 104 and a single crystal silicon device layer 105. It is used to sense the inertial force generated by external acceleration and together with the right suspended graphene strip 202 constitutes an acceleration sensing unit. In order to enhance the inertial force caused by acceleration, the mass block 3 needs to be designed to be large enough to obtain a large inertial mass. Its length size limit is the length of the right suspended graphene strip 201.

[0062] The right through groove 103 of the double-grooved substrate 1 is a through groove with a depth of micrometers, which ensures that the mass block 3 has sufficient movement space under the action of large acceleration, providing structural support for measuring acceleration within a wide range.

[0063] The left groove 101 of the double-grooved substrate 1 is a groove with a depth of hundreds of nanometers. The gate 403 on the bottom upper surface and the left suspended graphene strip 201 together form an electrostatic capacitor. When the sensor is working, a fixed DC voltage Vs is applied to the source 401, and a DC bias voltage V is applied to the gate 403. DCGenerate electrostatic attraction to attract and tighten the left suspended graphene strip 201 downward, improve the vibration quality factor of the left suspended graphene strip 201, and thus improve the acceleration detection accuracy. At the same time, apply an alternating voltage V AC cos(Ωt) generates a periodic electrostatic force with a frequency of Ω, driving the left suspended graphene strip 201 into a resonant state; the shallower the depth of the designed left groove 101, the stronger the electrostatic force felt by the left suspended graphene strip 201, but it is also more likely to cause electrostatic attraction, resulting in the rupture of the left suspended graphene strip 201.

[0064] The graphene strip 2 is a rectangular, high-aspect-ratio graphene strip made of copper-based single-layer graphene grown by CVD. Thanks to the extremely low effective mass and excellent mechanical properties of single-layer graphene, the right suspended graphene strip 202 can withstand acceleration shocks exceeding 10g, and the left suspended graphene strip 201 has an ultra-high resonant frequency in the megahertz range. The graphene strip 2 can also be made of single-layer or few-layer graphene prepared by mechanical exfoliation, or other two-dimensional materials such as single-layer or few-layer molybdenum disulfide and black phosphorus.

[0065] The sliding graphene strip 203 is adhered to the upper surface of the central support 102 by the van der Waals force, constraining its vertical movement so that it can only slide in the horizontal direction. By sliding the sliding graphene strip 203 left and right in the horizontal direction, on the one hand, the inertial force sensed by the right suspended graphene strip 202 can be transferred to the left suspended graphene strip 201, and ultra-high sensitive detection of acceleration can be achieved through the change of the resonant frequency of the left suspended graphene strip 201. On the other hand, the axial stress of the right suspended graphene strip 202 under the action of acceleration can be partially released, thereby improving the acceleration detection limit.

[0066] The source 401 and drain 402 respectively form a tight "sandwich" anchoring structure with the left suspended graphene strip 201, the right suspended graphene strip 202 and the double-groove substrate 1, which greatly reduces the support loss, contact resistance and contact thermal resistance of the anchoring structure, and improves the vibration quality factor and the current intensity between the source 401 and the drain 402.

[0067] The acceleration working principle of the embodiment of the present invention is as follows:

[0068] Step 1: Apply a fixed DC voltage Vs to the source 401 and apply a biased periodic alternating voltage signal V to the gate 403. DC +V AC cos(Ωt) generates electrostatic force; where V DC is a DC bias voltage, which is used to attract and tighten the left suspended graphene strip 201 downward and generate an axial tensile strain ε0, V AC cos(Ωt) is the voltage amplitude VAC , a periodic alternating driving voltage with an angular frequency of Ω, used to generate a periodic electrostatic force with a frequency of Ω near the natural frequency of the left suspended graphene strip 201, driving the left suspended graphene strip 201 into a resonant state, where t is time;

[0069] Step 2: Place the accelerometer in a standard environment to calibrate the linear sensing curve. When a vertical acceleration shock a1 is applied to the accelerometer, the mass block 3 with a mass of M converts the acceleration shock a1 into a vertical inertial force F=Ma1, which acts on the right suspended graphene strip 202, causing it to bend in the vertical direction and generate an axial tensile force T. At the same time, the mass block 3 generates a displacement x R , thereby converting the acceleration impact a1 into an axial tensile force T of the right suspended graphene strip 202;

[0070] Step 3: The axial tensile force T of the right suspended graphene strip 202 will further pull the sliding graphene strip 203 to the right, generating a horizontal sliding displacement q, causing the actual length of the right suspended graphene strip 202 to increase, alleviating the bending deformation of the right suspended graphene strip 202 under the action of acceleration, and widening the acceleration detection range. At the same time, it also causes the actual length of the left suspended graphene strip 201 to shorten, generating an axial tensile strain change Δε, thereby further converting the axial tensile force T of the right suspended graphene strip 202 into an axial tensile strain ε0+Δε of the left suspended graphene strip 201 through sliding coupling;

[0071] Step 4: The axial tensile strain of the left suspended graphene strip 202 will change its own linear spring stiffness k(Δε), further causing the resonant frequency f of the left suspended graphene strip 201 to be (k(Δε) / m) 1 / 2 An offset occurs, the offset Δf(a) = [k(Δε) / m] 1 / 2 -[k(Δε=0) / m] 1 / 2 , where m is the effective mass of the left suspended graphene strip 201, and the acceleration impact a1 is finally converted into the resonant frequency offset Δf(a1) of the left suspended graphene strip 201, realizing the transformation of acceleration-tensile stress-spring stiffness-resonant frequency; k(Δε=0) is the linear spring stiffness of the left suspended graphene strip 201 under the initial axial tensile strain ε0;

[0072] Step 5: Use a negative feedback closed-loop measurement circuit to measure the current signal output by the drain 402 in real time. Use Fourier transform to obtain a spectrum image of the current signal (the horizontal axis is the frequency of the left suspended graphene strip 201, and the vertical axis is the current value). The image contains a series of current spikes of different frequencies. The frequency value of the maximum current spike is read near the driving frequency Ω, which is the resonant frequency f1 of the left suspended graphene strip 201 under the acceleration impact a1. The resonant frequency f1 of the left suspended graphene strip 201 under the specific acceleration impact a1 is calibrated.

[0073] Step 6: Apply another different given acceleration shock a2 to the accelerometer again, repeat steps 2 to 5, and complete the calibration of the resonant frequency f2 of the left suspended graphene strip 201 under the given acceleration shock a2; through the two sets of data (a1, f1) and (a2, f2), the linear sensing curve expression of the accelerometer is fitted to obtain f = S·a+b, where a represents the acceleration shock, represents the intercept, represents acceleration sensitivity;

[0074] Step 7: Place the accelerometer in the test environment, measure the resonant frequency value f output by the accelerometer in real time by measuring the current signal output by the drain 402 in real time, and substitute it into the sensing curve f=S·a+b for calculation, so as to achieve real-time and accurate monitoring of the environmental acceleration changes and complete high-precision acceleration measurement.

[0075] Example 3

[0076] like Figure 9-11 As shown, the nanoelectromechanical resonant accelerometer structure can also be designed as an axisymmetric three-groove suspended graphene mass block structure; including a three-groove substrate, a graphene strip 2, a mass block 3 and a metal electrode 4, wherein the rear ends of both sides of the three-groove substrate are respectively provided with a left through groove 108 and a right through groove 103, and a central groove 109 is provided in the middle; one side of the graphene strip 2 is fixed to the upper surface of the three-groove substrate on the left side of the left through groove 108, and then laid on the left through groove 108, the left support 110, the central groove 109, the right support 111 and the right through groove 103 in sequence, so that the graphene strip 2 is fixed to the left side of ... The other side of the strip 2 is fixed to the upper surface of the three-groove substrate on the right side of the right through-groove 103, wherein the portion of the graphene strip 2 located on the left through-groove 108 is a left suspended graphene strip 201, the portion of the graphene strip 2 located on the left support 110 is a left sliding graphene strip 207, the portion of the graphene strip 2 located above the central groove 109 is a central suspended graphene strip 205, the portion of the graphene strip 2 located above the right support 111 is a right sliding graphene strip 206, and the portion of the graphene strip 2 located above the right through-groove 103 is a right suspended graphene strip 202;

[0077] A suspended mass block 3 is provided in each of the left through slot 108 and the right through slot 103. The mass block 3 in the left through slot 108 is located at the lower surface of the center position in the length direction of the left suspended graphene strip 201 and contacts the left suspended graphene strip 201. The suspended mass block 3 in the right through slot 103 is located at the lower surface of the right suspended graphene strip 202 and contacts the right suspended graphene strip 202.

[0078] The metal electrode 4 includes a source 401, a drain 402 and a gate 403, wherein the source 401 is fixed on the upper surface of the left end of the graphene strip 2 and the three-trench substrate, the drain 402 is fixed on the upper surface of the right end of the graphene strip 2 and the three-trench substrate, and the gate 403 is fixed on the three-trench substrate in the central trench 109.

[0079] A suspended mass block 3 is respectively provided in the left through slot 108 and the right through slot 103 as an acceleration sensing unit, and the central suspended graphene strip above the central groove 109 serves as a resonance unit. The three are connected by a sliding graphene strip above the supporting structure; under the action of external acceleration, the left and right graphene strips will synchronously and reversely stretch the central suspended graphene strip, converting the external acceleration into the resonant frequency offset of the central suspended graphene strip; through the symmetrical design, the stability of the sensor structure can be effectively improved and the stress concentration phenomenon can be reduced.

[0080] Example 4

[0081] The nanoelectromechanical resonant accelerometer structure can also be designed as a centrosymmetrical annular groove suspended graphene mass block structure; Figure 12-15 As shown, it includes an annular groove substrate, a graphene film, a mass block 3, and a metal electrode 4. The double-grooved substrate 1 is replaced with an annular groove substrate, which is provided with a concentric inner circular groove 112 and an outer annular through-groove 114, with a concentric annular center support 113 disposed therebetween. The graphene film is integrally fixed to the upper surface of the annular groove substrate, covering the inner circular groove 112, the outer annular through-groove 114, and the annular center support 113, forming a suspended graphene drum 208, a suspended graphene ring 209, and a central sliding graphene film 204. The portion of the graphene film located on the inner circular groove 112 is the suspended graphene drum 208, the portion of the graphene film located on the outer annular through-groove 114 is the suspended graphene ring 209, and the portion of the graphene film located above the annular center support 113 is the central sliding graphene film 204.

[0082] A suspended mass block 3 is provided in the outer annular groove 114. The mass block 3 is located on the outer ring of the annular central support 113 and on the lower surface of the center position of the radial width of the suspended graphene ring 209, contacting the suspended graphene ring 209.

[0083] A T-shaped groove is further provided on the annular groove base at the front end of the inner circular groove 112. The T-shaped groove passes through the mass block 3 and the annular center support 113 and is connected to both the inner circular groove 112 and the outer annular through groove 114.

[0084] The metal electrode 4 includes a source 401, a drain 402 and a gate 403, wherein the source 401 is fixed on the left upper surface of the graphene film, the drain 402 is fixed on the right upper surface of the graphene film, and the gate 403 is fixed on the inner circular groove 112 and the annular groove base 1 in the T-shaped groove.

[0085] A mass block 3 is provided in the outer annular groove 114 as an acceleration sensing unit, and a suspended graphene drum 208 above the inner circular groove 112 serves as a resonance unit. The two are connected by a central sliding graphene film 204 sliding above the annular central support 113; under the action of external acceleration, the suspended graphene ring 209 will radially stretch the suspended graphene drum 208, converting the external acceleration into a resonant frequency offset of the suspended graphene drum 208; through the central symmetric design, the stability of the sensor structure can be effectively improved and stress concentration can be reduced.

[0086] Example 5

[0087] Material replacement solution: Replace the material of graphene strip 2 with two-dimensional materials such as MoS2 and WS2, which are suitable for different frequency band requirements.

[0088] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the scope of protection of the present invention is not limited to the specific details of the above embodiments. Within the technical concept of the present invention, any technician familiar with the technical field can make equivalent replacements or changes based on the technical solution and inventive concept of the present invention within the technical scope disclosed by the present invention. These simple variations all fall within the scope of protection of the present invention.

Claims

1. An ultra-high sensitivity two-dimensional nanoelectromechanical resonant accelerometer based on sliding coupling, characterized in that: The invention comprises a double-groove substrate (1), a graphene strip (2), a mass block (3) and a metal electrode (4); wherein the double-groove substrate (1) is provided with a left groove (101) and a right through groove (103) on both sides of the rear end thereof, the double-groove substrate (1) portion between the left groove (101) and the right through groove (103) is a central support (102), one side of the graphene strip (2) is fixed on the upper surface of the double-groove substrate (1) on the left side of the left groove (101), and then is laid on the left groove (101), the central support (102) and the right through groove (103) in sequence, so that the other side of the graphene strip (2) is fixed on the upper surface of the double-groove substrate (1) on the right side of the right through groove (103), wherein the graphene strip (2) portion located on the central support (102) is a sliding graphene strip (203), and the portion located on the left groove (101) is a sliding graphene strip (203). The portion of the graphene strip (2) above the groove (101) is a left suspended graphene strip (201), and the portion of the graphene strip (2) above the right through groove (103) is a right suspended graphene strip (202); a mass block (3) is provided in the right through groove (103), and the mass block (3) is located on the lower surface of the right suspended graphene strip (202) and in contact with the right suspended graphene strip (202); the metal electrode (4) comprises a source electrode (401), a drain electrode (402), and a gate electrode (403), wherein the source electrode (401) is fixed on the upper surface of the left end portion of the graphene strip (2) and the double-groove substrate (1), the drain electrode (402) is fixed on the upper surface of the right end portion of the graphene strip (2) and the double-groove substrate (1), and the gate electrode (403) is fixed on the double-groove substrate (1) in the left groove (101).

2. The ultra-high sensitivity two-dimensional nanoelectromechanical resonant accelerometer based on sliding coupling according to claim 1, characterized in that: The double-groove substrate (1) is an SOI wafer with a top oxide layer, and is composed of four layers of materials connected in sequence, which are, from top to bottom, a silicon dioxide insulating layer (104), a single crystal silicon device layer (105), a buried oxide layer (106), and a substrate layer (107).

3. The ultra-high sensitivity two-dimensional nanoelectromechanical resonant accelerometer based on sliding coupling according to claim 2, characterized in that: The mass block (3) is a mass block made of a silicon dioxide insulating layer (104) and a single crystal silicon device layer (105), and is used to sense the inertial force generated by external acceleration, and together with the right suspended graphene strip (202) forms an acceleration sensing unit; specifically, the right through groove (103) is a through groove formed by hollowing out the silicon dioxide insulating layer (104), the single crystal silicon device layer (105), the buried oxide layer (106) and the substrate layer (107) at the rear end of the double groove substrate (1), and the mass block (3) is formed by retaining part of the silicon dioxide insulating layer (104) and the single crystal silicon device layer (105) in the right through groove (103).

4. The ultra-high sensitivity two-dimensional nanoelectromechanical resonant accelerometer based on sliding coupling according to claim 1, characterized in that: The right through groove (103) on the double-groove substrate (1) is a through-type through groove with a micron-level depth, so as to ensure that the mass block (3) has sufficient movement space.

5. The ultra-high sensitivity two-dimensional nanoelectromechanical resonant accelerometer based on sliding coupling according to claim 1, characterized in that: The left groove (101) on the double-groove substrate (1) is a groove with a depth of hundreds of nanometers, and the gate (403) on the upper surface of the bottom thereof and the left suspended graphene strip (201) together form an electrostatic capacitor for driving the left suspended graphene strip (201) to vibrate.

6. The ultra-high sensitivity two-dimensional nanoelectromechanical resonant accelerometer based on sliding coupling according to claim 1, characterized in that: The graphene strip (2) is a copper-based single-layer graphene grown by CVD, a single-layer or few-layer graphene prepared by a mechanical exfoliation method, or a single-layer or few-layer molybdenum disulfide.

7. The ultra-high sensitivity two-dimensional nanoelectromechanical resonant accelerometer based on sliding coupling according to claim 1, characterized in that: The sliding graphene strip (203) is adhered to the upper surface of the central support (102) by van der Waals force, which restricts its vertical movement so that it can only slide in the horizontal direction.

8. A method for measuring environmental acceleration using the ultra-high sensitivity two-dimensional nanoelectromechanical resonant accelerometer based on sliding coupling according to any one of claims 1 to 7, characterized in that: A suspended mass block (3) is provided on the lower surface of the center position in the length direction of the right suspended graphene strip (202) as an acceleration sensing unit, and a left suspended graphene strip (201) is provided as a resonance detection unit. The two are connected by a sliding graphene strip (203), thereby realizing the separation of "acceleration sensing-resonance detection". Specifically, external acceleration acts on the suspended mass block (3) to generate an inertial force, which is transmitted to the right suspended graphene strip (202), causing it to bend and deform in the vertical direction, generating an axial tension, driving the sliding graphene strip (203) to move rightward, thereby causing the left suspended graphene strip (201) to undergo axial tensile deformation, further causing the axial stress, linear spring stiffness and resonant frequency of the left suspended graphene strip (201) to change, and finally converting the acceleration disturbance into the resonant frequency offset of the left suspended graphene strip (201), realizing the conversion of acceleration-tensile stress-spring stiffness-resonance frequency, and thus realizing high-precision measurement of acceleration.

9. A method for measuring environmental acceleration using the ultra-high sensitivity two-dimensional nanoelectromechanical resonant accelerometer based on sliding coupling according to any one of claims 1 to 7, characterized in that: Specifically include the following: Step 1: Apply a DC voltage Vs to the source (401) and apply a biased periodic alternating voltage V to the gate (403). DC +V AC cos(Ωt) generates electrostatic force; Among them, V DC is a DC bias voltage, which is used to attract and tighten the left suspended graphene strip (201) downward and generate an initial axial tensile strain ε0, V AC cos(Ωt) is the voltage amplitude V AC , a periodic alternating driving voltage with an angular frequency of Ω, used to generate a periodic electrostatic force with a frequency of Ω near the natural frequency of the left suspended graphene strip (201), driving the left suspended graphene strip (201) into a resonant state, where t is time; Step 2: Place the accelerometer in a standard environment to calibrate the linear sensing curve. When the accelerometer is subjected to a vertical acceleration shock a (1) When the mass block (3) with a mass of M converts the acceleration impact a1 into a vertical inertial force F=Ma1, and acts on the right suspended graphene strip (202), causing it to bend in the vertical direction and generate an axial tensile force T. At the same time, the mass block (3) generates a displacement x R ; Step 3: The axial tensile force T of the right suspended graphene strip (202) will further pull the sliding graphene strip (203) to move rightward to generate a horizontal sliding displacement q, resulting in an increase in the actual length of the right suspended graphene strip (202), alleviating the bending deformation of the right suspended graphene strip (202) under the action of acceleration, widening the acceleration detection range, and also causing the actual length of the left suspended graphene strip (201) to shorten, generating an axial tensile strain variation Δε, thereby further converting the axial tensile force T of the right suspended graphene strip (202) into an axial tensile strain ε0+Δε of the left suspended graphene strip (201) through sliding coupling; Step 4: The axial tensile strain of the left suspended graphene strip (202) will change its own linear spring stiffness k(Δε), further causing the resonant frequency f of the left suspended graphene strip (201) to be (k(Δε) / m) 1 / 2 An offset occurs, the offset Δf(a) = [k(Δε) / m] 1 / 2 -[k(Δε=0) / m] 1 / 2 , where m is the effective mass of the left suspended graphene strip (201), and the acceleration impact a1 is finally converted into the resonant frequency offset Δf(a1) of the left suspended graphene strip (201), thereby realizing the conversion of acceleration-tensile stress-spring stiffness-resonant frequency; k (Δε=0) is the linear spring stiffness of the left suspended graphene strip (201) under the initial axial tensile strain ε0; Step 5: measuring the current signal output by the drain (402) in real time, obtaining a spectrum image of the current signal through Fourier transform, wherein the spectrum image includes a series of current peaks of different frequencies, and reading the frequency value of the maximum current peak near the driving frequency Ω, which is the resonant frequency f1 of the left suspended graphene strip (201) under the acceleration impact a1, thereby completing the calibration of the resonant frequency f1 of the left suspended graphene strip (201) under the specific acceleration impact a1; Step 6: Apply another different given acceleration shock a2 to the accelerometer again, repeat steps 2 to 5, and complete the calibration of the resonant frequency f2 of the left suspended graphene strip (201) under the given acceleration shock a2; through the two sets of data (a1, f1) and (a2, f2), the linear sensing curve expression f=S·a+b of the accelerometer is fitted, where a represents the acceleration shock, represents the intercept, represents acceleration sensitivity; Step seven, placing the accelerometer in the test environment, measuring the resonant frequency value f output by the accelerometer in real time by measuring the current signal output by the drain (402) in real time, and bringing it into the sensing curve f=S·a+b for calculation, thus achieving real-time and accurate monitoring of the environmental acceleration change and completing high-precision acceleration measurement.

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