Method for measuring vibrations of micro / nano resonators based on optical and electrical signals

Abstract

The application discloses a kind of micro / nano resonator vibration measurement methods based on optical signal and electrical signal, as follows: design and preparation with excitation electrode and detection electrode micro / nano resonator;On excitation electrode, micro / nano resonator is excited by applying alternating voltage, and vibration information of micro / nano resonator is obtained by analysis;The frequency spectrum diagram obtained based on optical signal and electrical signal is compared, and the vibration natural frequency of micro / nano resonator is analyzed, and clear vibration mode chart is obtained after single-frequency excitation to vibration natural frequency.The application realizes the high-precision measurement of micro / nano resonator vibration frequency spectrum chart under the condition of small excitation, and observes vibration mode simultaneously.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-precision vibration measurement, and particularly relates to a micro / nano resonator vibration measurement method based on optical signals and electrical signals. BACKGROUND

[0002] With the continuous rapid development of material science, a large number of new materials with special properties are emerging. Two-dimensional micro / nano materials have become the main candidate materials for future micro / nano resonators because their mechanical properties have been highly enhanced at the atomic level. After graphene, various two-dimensional micro / nano materials have been studied as structural materials for micro / nano resonators, including superconducting NbSe2, semiconductor MoS2 and black phosphorus, which opens up a broad space for emerging applications.

[0003] Compared with device manufacturing and motion excitation, resonance detection is arguably the most technically challenging aspect of micro / nano resonator experimental research. Due to the small size of the device, the resonance signal amplitude is also small, and existing resonance detection techniques for macro resonators, such as capacitance readout, high-speed camera imaging, etc., may not be directly applicable or effective, and different techniques must be developed to better complete resonance detection. So far, most micro / nano resonators have been measured by optical or electrical methods. However, there are respective shortcomings in the measurement of optical or electrical methods alone. In optical method measurement, the measurement result is very sensitive to external environmental disturbance. When the external disturbance is large or the quality factor of the test piece is too low, noise will drown out the frequency signal of the resonator, or other peaks outside the frequency signal of the resonator will be generated, making it difficult to measure the frequency signal of the resonator. In electrical method measurement, due to the lack of direct observation of the vibration mode, it is difficult to conduct in-depth research on the dissipation mechanism, destructive interference effect, sound leakage path, effective modal mass and nonlinear modal coupling. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide a micro / nano resonator vibration measurement method based on optical signals and electrical signals to solve the problems of low measurement accuracy and inability to measure the vibration mode in the existing micro / nano resonator vibration measurement technology. The present application realizes high-precision measurement of the micro / nano resonator vibration frequency spectrum under the condition of small excitation, and observes the vibration mode at the same time.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0006] The micro / nano resonator vibration measurement method based on optical signals and electrical signals of the present application has the following steps:

[0007] 1) Design and prepare a micro / nano resonator with excitation electrodes and detection electrodes;

[0008] 2) applying AC voltage on the excitation electrode to excite the micro / nano resonator, using laser Doppler vibrometer to detect the vibration signal of the micro / nano resonator, at the same time, applying AC voltage with frequency difference on one end of the detection electrode, and measuring the current signal obtained after the voltage passes through the micro / nano resonator, and analyzing the vibration information of the micro / nano resonator;

[0009] 3) comparing the frequency spectrum diagrams based on the optical signal and the electrical signal, analyzing the vibration natural frequency of the micro / nano resonator, and obtaining clear vibration mode diagram after single-frequency excitation of the vibration natural frequency.

[0010] Further, the step 2) specifically comprises: applying AC voltage with frequency ω on the excitation electrode to excite the micro / nano resonator, and using laser Doppler vibrometer to detect the vibration through laser Doppler effect and optical heterodyne interference; when the micro / nano resonator vibrates at frequency ω under the excitation of the AC voltage, the capacitance between the micro / nano resonator and the excitation electrode changes periodically, and the charge on the micro / nano resonator changes periodically; so that the carrier concentration changes periodically (field effect), and the conductance also changes periodically; taking the micro / nano resonator as a frequency mixer, applying AC voltage with frequency ω+Δω on one end of the detection electrode, obtaining AC current with frequency Δω containing vibration information after frequency mixing, and inputting the voltage signal obtained after conversion by an impedance amplifier into a lock-in amplifier with reference signal Δω for detection, to obtain the vibration information of the micro / nano resonator.

[0011] Further, the step 3) specifically comprises: comparing the frequency spectrum diagrams based on the optical signal and the electrical signal, excluding the spurious peaks in the results based on the optical signal due to external interference, and analyzing the vibration natural frequency of the micro / nano resonator; applying AC voltage with frequency being the natural frequency of the micro / nano resonator on the excitation electrode, and obtaining clear vibration mode diagram based on the optical signal.

[0012] The present application has the following advantages:

[0013] The method of the present application can exclude the spurious peaks in the optical signal due to external interference through the electrical signal under small excitation force, find the frequency signal of the resonator submerged by external noise, obtain clear frequency spectrum diagram, and in-situ observe the corresponding vibration mode; the present application has the advantages of high precision and easy operation, and is suitable for popularization and use in micro-electromechanical system and nano-electromechanical system. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The present application has the following advantages: DETAILED DESCRIPTION

[0015] For the convenience of those skilled in the art to understand, the present application is further described below in conjunction with the embodiments and the accompanying drawings, and the content mentioned in the embodiments is not a limitation on the present application.

[0016] A micro / nano resonator vibration measurement method based on optical signals and electrical signals is provided, and the steps are as follows:

[0017] 1) Design and prepare a micro / nano resonator with an excitation electrode and a detection electrode;

[0018] 2) Apply an alternating voltage to the excitation electrode to excite the micro / nano resonator, use a laser Doppler vibration detector to detect the vibration signal of the micro / nano resonator, at the same time, apply an alternating voltage with a frequency difference to the excitation electrode to the detection electrode, and measure the current signal obtained after the voltage passes through the micro / nano resonator, and analyze the vibration information of the micro / nano resonator;

[0019] 3) Compare the frequency spectrum based on optical signals and electrical signals, analyze the vibration natural frequency of the micro / nano resonator, and obtain a clear vibration mode diagram after single-frequency excitation of the vibration natural frequency.

[0020] In the example, refer to Figure 1 as shown:

[0021] Step 1: Transfer the prepared multilayer two-dimensional micro / nano material film to a silicon substrate with an excitation electrode (Gate electrode in the figure) and a detection electrode (S electrode and D electrode in the figure), and require that the surface of the multilayer two-dimensional micro / nano material film is flat, without wrinkles or bubbles, etc.; The preparation and transfer of the multilayer two-dimensional micro / nano material film are as follows:

[0022] a) Use chemical vapor deposition or mechanical exfoliation method to prepare multilayer two-dimensional micro / nano material in the laboratory, and the multilayer two-dimensional micro / nano material that can exist stably at room temperature in the atmosphere can be used, such as multilayer graphene, multilayer molybdenum disulfide or multilayer hetero two-dimensional nanomaterials, etc.;

[0023] b) Take a pure silicon substrate, in order to ensure the cleanliness of the surface, first put the silicon substrate into acetone solution and ultrasonic clean for 5-8 minutes, then replace the acetone solution with isopropyl alcohol and ultrasonic clean for 5-8 minutes, after completion, again ultrasonic clean with ethanol solution for 5-8 minutes, and finally clean with ultrapure water for three to four times to clean the residual ethanol solution on the surface of the silicon substrate;

[0024] c) For the transfer of mechanically exfoliated multilayer two-dimensional micro / nano material film, it needs to be operated in a dust-free laboratory, spin the water-soluble layer on a clean silicon substrate, and transfer the spin-coated silicon wafer to a hot stage at 80°C for three minutes; spin the polymethyl methacrylate (PMMA) on the heated silicon substrate, and transfer the spin-coated silicon wafer to a hot stage at 100°C for five minutes; press the tape with the multilayer two-dimensional micro / nano material film to the silicon substrate, and after pressing for five minutes, tear the tape from the silicon substrate;

[0025] d) Determine the sample position under the microscope, dissolve the water-soluble layer below it, and transfer it to the test piece with an electrode. Anneal the test piece at 400°C for three hours to eliminate the polymethyl methacrylate layer.

[0026] Step two: Apply an alternating voltage with frequency ω to the Gate electrode to excite the multilayer two-dimensional micro / nano material film, and use laser to measure its vibration. When the laser irradiates the surface of the multilayer two-dimensional micro / nano material film, the frequency of the scattered light from its surface changes due to the vibration of the multilayer two-dimensional micro / nano material film. This frequency change is related to the speed, direction, wavelength of the moving object, and the direction of the incident light. When the speed, direction, wavelength, and direction of the incident light are known, the change in scattered light frequency is measured by the principle of optical heterodyne interference to obtain the speed of the moving object. At the same time, when the multilayer two-dimensional micro / nano material film vibrates at frequency ω under the excitation of alternating voltage, the capacitance between the multilayer two-dimensional micro / nano material film and the Gate electrode changes periodically, and a periodically changing charge is generated on the multilayer two-dimensional micro / nano material film. For a multilayer two-dimensional micro / nano material film with semiconductor properties, the periodically changing charge on it will cause the carrier concentration to change periodically (field effect), so the conductance will also change periodically.

[0027] Then apply an alternating voltage with frequency ω+Δω to the S electrode, use the multilayer two-dimensional micro / nano material film as a frequency mixer, and after mixing the conductance of the multilayer two-dimensional micro / nano material film with frequency component ω and the alternating voltage with frequency ω+Δω, the current output on the D electrode will contain several frequencies: Δω, 2ω+Δω. After converting the current signal to a voltage signal through an impedance amplifier and passing it through a lock-in amplifier with a reference signal frequency of Δω, only the amplitude of the Δω frequency component is tested, and other frequency components are ignored. By this method, the vibration signal of the multilayer two-dimensional micro / nano material film is converted to a low frequency signal area for detection, which can well exclude the interference of external factors and is more conducive to the detection of small signals.

[0028] The spectrum diagrams obtained based on the optical signal and the electrical signal are compared, the spurious peaks in the result obtained based on the optical signal due to external interference are excluded, and the natural frequency of vibration of the two-dimensional micro / nano material film is analyzed; an alternating voltage with a frequency being the natural frequency of vibration of the two-dimensional micro / nano material film is applied to the Gate electrode, and a clear vibration mode diagram is obtained based on the optical signal.

[0029] The method of the present application combines the advantages of optical measurement in visualizing the vibration mode and the advantages of electrical measurement in high precision, tunability, etc., reduces the influence of external disturbance, and obtains a clear spectrum diagram and the vibration mode of each peak.

[0030] The present application has many specific application approaches, and the above description is only the preferred embodiment of the present application. It should be pointed out that, for ordinary skilled persons in the technical field, some improvements can be made without departing from the principle of the present application, and these improvements should also be considered as the protection scope of the present application.

Claims

1. A method for measuring the vibration of a micro / nano-resonator based on an optical signal and an electrical signal, characterized in that, The steps are as follows: 1) design and prepare a micro / nano resonator with an excitation electrode and a detection electrode; 2) excite the micro / nano resonator by applying an alternating voltage on the excitation electrode, detect the vibration signal of the micro / nano resonator using a laser Doppler vibrometer, at the same time, apply an alternating voltage with a frequency difference from the alternating voltage applied on the excitation electrode on one end of the detection electrode, measure the current signal obtained after the voltage passes through the micro / nano resonator, and analyze the vibration information of the micro / nano resonator; 3) compare the frequency spectrum graphs obtained based on the optical signal and the electrical signal, analyze the vibration natural frequency of the micro / nano resonator, and obtain a clear vibration mode graph after single-frequency excitation of the vibration natural frequency; The step 2) specifically comprises: exciting the micro / nano resonator by applying an alternating voltage with a frequency of ω on the excitation electrode, and detecting the vibration of the micro / nano resonator by laser Doppler effect and optical heterodyne interference using a laser Doppler vibrometer; when the micro / nano resonator vibrates at a frequency of ω under the excitation of the alternating voltage, the capacitance between the micro / nano resonator and the excitation electrode changes periodically, generating a periodically changing electric charge on the micro / nano resonator; so that the carrier concentration changes periodically, and the conductance also changes periodically; the micro / nano resonator is used as a frequency mixer, an alternating voltage with a frequency of ω+Δω is applied on one end of the detection electrode, an alternating current with a frequency of Δω containing vibration information is obtained after mixing, and the voltage signal is converted into an alternating current by an impedance amplifier and input into a lock-in amplifier with a reference signal of Δω for detection, to obtain the vibration information of the micro / nano resonator. 2.The micro / nano-resonator vibration measurement method based on optical signal and electrical signal according to claim 1, wherein, The step 3) specifically comprises: comparing the frequency spectrum graphs obtained based on the optical signal and the electrical signal, excluding the spurious peaks in the results obtained based on the optical signal due to external interference, and analyzing the vibration natural frequency of the micro / nano resonator; applying an alternating voltage with a frequency of the natural frequency of the micro / nano resonator on the excitation electrode, and obtaining a clear vibration mode graph based on the optical signal.

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