Piezoelectric ceramic excitation device, atomic force microscope, surface force field detection device

Abstract

The present invention discloses a piezoelectric ceramic excitation device, comprising: a first piezoelectric ceramic, a first gasket and a second piezoelectric ceramic component stacked, wherein the first gasket is arranged between the first piezoelectric ceramic and the second piezoelectric ceramic components; the first piezoelectric ceramic is used to receive a first electrical signal and perform longitudinal flexural vibration under the excitation of the first electrical signal; the second piezoelectric ceramic component is used to receive a second electrical signal group and perform lateral torsional vibration under the excitation of the second electrical signal group. By adopting a piezoelectric ceramic stacking method, different piezoelectric ceramics in the piezoelectric ceramic excitation device are excited by different electrical signals, so that the piezoelectric ceramic excitation device can simultaneously perform lateral and longitudinal combined vibrations. The piezoelectric ceramic excitation device can be used for an atomic force microscope to measure non-contact interaction forces in the lateral and longitudinal directions, thereby increasing the spatial resolution of the atomic force microscope. The present invention also discloses an atomic force microscope, a surface force field detection device and a detection method.

Description

Technical Field

[0001] The present invention relates to the field of microscopes, and in particular to a piezoelectric ceramic excitation device, an atomic force microscope, a surface force field detection device and a detection method. Background Art

[0002] Since the invention of the atomic force microscope in 1986, it has become an important tool in many nanotechnology fields such as physics, materials, and biology. The atomic force microscope technology has been continuously updated and has attracted widespread interest at home and abroad in terms of improving spatial resolution, distinguishing material properties, and multi-environment measurement. The high-order harmonic technology and multi-frequency atomic force technology developed in recent years rely on analyzing the vibration response and vibration form of the probe to achieve fine characterization of the sample. These technologies not only focus on the signals of the basic eigenfrequency, but also focus on the signals of the higher-order eigenfrequency, reconstructing the interaction force information between the probe and the sample.

[0003] However, in traditional atomic force microscopy technology, the atomic force microscope uses the contact mode to measure the interaction force, and the lateral friction and longitudinal pressure of the probe and the sample under contact can be measured based on the four-quadrant signal. However, the above contact measurement method results in low spatial resolution of the atomic force microscope and is unable to measure the spatial force field in the non-contact state. Summary of the invention

[0004] Based on this, it is necessary to provide a piezoelectric ceramic excitation device with high spatial resolution, an atomic force microscope, a surface force field detection device and a detection method in order to address the problem of low spatial resolution of the atomic force microscope mentioned above.

[0005] A piezoelectric ceramic excitation device, the piezoelectric ceramic excitation device comprising:

[0006] A first piezoelectric ceramic, a second piezoelectric ceramic component and a first gasket;

[0007] The first piezoelectric ceramic, the first gasket and the second piezoelectric ceramic component are stacked, and the first gasket is arranged between the first piezoelectric ceramic and the second piezoelectric ceramic components;

[0008] The first piezoelectric ceramic is used to receive a first electrical signal and to perform longitudinal flexural vibration under the excitation of the first electrical signal;

[0009] The second piezoelectric ceramic component is used to receive a second electrical signal group and perform lateral torsional vibration under the excitation of the second electrical signal group.

[0010] In one embodiment, the second piezoelectric ceramic component includes a third piezoelectric ceramic and a fourth piezoelectric ceramic, the third piezoelectric ceramic and the fourth piezoelectric ceramic are placed opposite to and spaced apart from each other, the second electrical signal group includes a third electrical signal and a fourth electrical signal with opposite phases, the third piezoelectric ceramic is used to receive the third electrical signal, the fourth piezoelectric ceramic is used to receive the fourth electrical signal, and the third piezoelectric ceramic and the fourth piezoelectric ceramic are spaced apart from the first piezoelectric ceramic via the first gasket.

[0011] In one embodiment, the third piezoelectric ceramic and the fourth piezoelectric ceramic are disposed on a surface of the first gasket away from the first piezoelectric ceramic, and are spaced apart at two opposite edges of the first gasket.

[0012] An atomic force microscope, comprising: a piezoelectric ceramic excitation device as described in any one of the above;

[0013] The probe component is connected to the piezoelectric ceramic excitation device, and the probe component can receive the vibration mode of the piezoelectric ceramic excitation device and vibrate under the excitation of the vibration mode.

[0014] In one embodiment, the probe component includes a probe and a probe seat, the probe includes a cantilever beam, a needle tip and a probe substrate respectively connected to the cantilever beam, and the probe can be freely extended relative to the probe seat;

[0015] The probe seat can receive the vibration mode of the piezoelectric ceramic excitation device, and transmit the vibration mode through the probe substrate and the cantilever beam to excite the needle tip to vibrate.

[0016] In one embodiment, the first piezoelectric ceramic is fitted to the probe seat, and the first gasket and the second piezoelectric ceramic component are sequentially stacked on the surface of the first piezoelectric ceramic.

[0017] In one embodiment, the second piezoelectric ceramic component is disposed in contact with the probe seat, and the first gasket and the first piezoelectric ceramic are sequentially stacked on the surface of the second piezoelectric ceramic.

[0018] A surface force field detection device comprises: a force detection component, a position detection component, and a feedback control component;

[0019] The force detection component comprises a signal generator and any one of the above-mentioned atomic force microscopes, wherein the signal generator is connected to the atomic force microscope and is used to provide an electrical signal to the atomic force microscope to drive the probe component to vibrate;

[0020] The position detection component is used to monitor the vibration of the probe component on the surface of the sample to be tested to obtain a transverse frequency shift signal and a longitudinal frequency shift signal;

[0021] The feedback control component is used to feedback control the vibration of the probe component on the surface of the sample to be measured according to the transverse frequency offset signal or the longitudinal frequency offset signal to obtain the surface force field distribution;

[0022] Among them, the position detection component includes a laser emitter, a photodetector and a phase-locked amplifier. The laser emitter emits laser light, which is reflected into the photodetector through the cantilever beam of the atomic force microscope; the photodetector is used to receive the laser light reflected by the cantilever beam and use the laser light to convert the vibration signal into an electrical signal; the phase-locked amplifier is used to receive the electrical signal for modulation and demodulation to obtain the lateral frequency offset signal and the longitudinal frequency offset signal.

[0023] A detection method for detecting the surface force field distribution of a sample to be tested by the above-mentioned surface force field detection device, the detection method comprising:

[0024] Acquire a first electrical signal and a second electrical signal group;

[0025] The first piezoelectric ceramic is stimulated to perform longitudinal flexural vibration according to the first electrical signal, and the second piezoelectric ceramic component is stimulated to perform lateral torsional vibration according to the second electrical signal group.

[0026] The probe component follows the longitudinal flexural vibration of the first piezoelectric ceramic and the transverse torsional vibration of the second piezoelectric ceramic component to generate a combined transverse and longitudinal vibration;

[0027] The force field distribution on the surface of the sample to be tested is detected contactlessly by utilizing the combined vibration of the probe components.

[0028] In one embodiment, the non-contact detection of the force field distribution on the surface of the sample to be tested by the combined vibration of the probe component includes:

[0029] Detecting the vibration mode of the cantilever beam of the probe component to obtain a transverse vibration signal and a longitudinal vibration signal;

[0030] Modulating and demodulating the transverse vibration signal and the longitudinal vibration signal to obtain a vibration frequency offset signal of a transverse force and a vibration frequency offset signal of a longitudinal force between the needle tip and the surface of the sample to be measured;

[0031] The lateral force and the longitudinal force between the needle tip and the surface of the sample to be tested are calculated according to the vibration frequency offset signal of the lateral force and the vibration frequency offset signal of the longitudinal force, thereby obtaining the surface force field distribution of the sample to be tested.

[0032] The above-mentioned piezoelectric ceramic excitation device, atomic force microscope, surface force field detection device and detection method adopt a piezoelectric ceramic stacking method, and use different electrical signals to excite different piezoelectric ceramics in the piezoelectric ceramic excitation device, so that the piezoelectric ceramic excitation device can simultaneously perform a combined lateral and longitudinal vibration. The piezoelectric ceramic excitation device can make the atomic force microscope needle tip perform a combined lateral and longitudinal vibration. The dynamic stiffness of the needle tip during vibration is larger than the static stiffness, and the needle tip is not easy to adsorb to the surface, so that the needle tip and the sample to be tested can perform real-time measurement of the non-contact interaction force in the lateral and longitudinal directions. In addition, the method of simultaneously measuring the non-contact interaction force in the lateral and longitudinal directions can increase the spatial resolution of the atomic force microscope, thereby realizing the accurate analysis of the surface force field of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic structural diagram of a piezoelectric ceramic excitation device according to an embodiment;

[0034] Figure 2 A schematic diagram of the structure of a detection unit in an atomic force microscope according to an embodiment;

[0035] Figure 3 It is a structural schematic diagram of a detection unit in an atomic force microscope in another embodiment;

[0036] Figure 4 is a schematic structural diagram of a surface force field detection device according to an embodiment;

[0037] Figure 5 The figure is a flow chart of a surface force field detection method according to an embodiment. DETAILED DESCRIPTION

[0038] In order to facilitate the understanding of the present invention, a more comprehensive description of the piezoelectric ceramic excitation device, atomic force microscope, surface force field detection device and detection method will be given below with reference to the relevant drawings. The preferred embodiments of the piezoelectric ceramic excitation device, atomic force microscope, surface force field detection device and detection method are given in the drawings. However, the piezoelectric ceramic excitation device, atomic force microscope, surface force field detection device and detection method can be implemented in many different forms and are not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the piezoelectric ceramic excitation device, atomic force microscope, surface force field detection device and detection method more thorough and comprehensive.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used in the specification of the piezoelectric ceramic excitation device and the atomic force microscope, the surface force field detection device and the detection method herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0040] Please also read Figure 1 and Figure 2 In one embodiment, a piezoelectric ceramic excitation device 100 is provided, and the piezoelectric ceramic excitation device 100 includes a first piezoelectric ceramic 102, a second piezoelectric ceramic component 103, and a first gasket 101. The first piezoelectric ceramic 102, the first gasket 101, and the second piezoelectric ceramic component 103 are stacked, and the first gasket 101 is arranged between the first piezoelectric ceramic 102 and the second piezoelectric ceramic component 103. The first piezoelectric ceramic 102 is used to receive a first electrical signal and perform longitudinal flexural vibration under the excitation of the first electrical signal; the second piezoelectric ceramic component 103 is used to receive a second electrical signal group and perform lateral torsional vibration under the excitation of the second electrical signal group.

[0041] Specifically, in the above-mentioned piezoelectric ceramic excitation device 100, a first gasket 101 is placed between the first piezoelectric ceramic 102 and the second piezoelectric ceramic component 103. The material of the first gasket 101 is an insulating material, for example, it can be rubber, plastic, ceramic, glass, mica, etc., so that the first piezoelectric ceramic 102 and the second piezoelectric ceramic component 103 are electrically insulated to avoid electrical connection or short circuit between the two. In addition, the first gasket 101 is also used for pasting to fix the first piezoelectric ceramic 102 and the second piezoelectric ceramic component 103. The first piezoelectric ceramic 102 is placed in close contact with the first gasket 101. Further, the first gasket 101 can be attached to the entire surface of the first piezoelectric ceramic 102 close to the second piezoelectric ceramic component 103, and the second piezoelectric ceramic component 103 is arranged on the surface of the first gasket 101 away from the first piezoelectric ceramic 102.

[0042] The first piezoelectric ceramic 102 is used to receive a first electrical signal, and the first electrical signal is preferably a sinusoidal electrical signal, so that the first piezoelectric ceramic 102 can perform longitudinal flexural vibration. The second piezoelectric ceramic component 103 is used to receive a second electrical signal group, and the second electrical signal group includes two electrical signals with the same frequency, pulse width, and amplitude, but opposite phases. Preferably, the second electrical signal group can be a group of sinusoidal electrical signals with opposite phases that meet the above conditions. Sinusoidal electrical signals are the most common waveform of all electrical signals and are also the easiest to generate. It can be said to be the basis of all forms of electrical signals. The results obtained using sinusoidal electrical signals are highly versatile and universal.

[0043] Optionally, protective components may be provided at both ends of the piezoelectric ceramic excitation device, which can not only prevent the piezoelectric ceramic excitation device from being damaged but also provide electrical insulation.

[0044] The above-mentioned piezoelectric ceramic excitation device adopts a piezoelectric ceramic stacking method and uses different electrical signals to excite different piezoelectric ceramics in the piezoelectric ceramic excitation device, so that the piezoelectric ceramic excitation device simultaneously performs a combined transverse and longitudinal vibration. The piezoelectric ceramic excitation device is installed in an atomic force microscope, which can make the tip of the atomic force microscope perform a combined transverse and longitudinal vibration. The dynamic stiffness of the tip during vibration is larger than the static stiffness, and the tip is not easy to adsorb to the surface, so that the tip and the sample to be tested can perform real-time measurement of the non-contact interaction force in the transverse and longitudinal directions. The method of simultaneously measuring the non-contact interaction force in the transverse and longitudinal directions can increase the spatial resolution of the atomic force microscope, thereby realizing the precise analysis of the surface force field of the material.

[0045] Further, in one embodiment, the second piezoelectric ceramic component 103 may include a third piezoelectric ceramic 1032 and a fourth piezoelectric ceramic 1034, and the third piezoelectric ceramic 1032 and the fourth piezoelectric ceramic 1034 are arranged opposite to each other and spaced apart. The second electrical signal group includes a third electrical signal and a fourth electrical signal with opposite phases, and the third piezoelectric ceramic 1032 is used to receive the third electrical signal, and the fourth piezoelectric ceramic 1034 is used to receive the fourth electrical signal. The third piezoelectric ceramic 1032 and the fourth piezoelectric ceramic 1034 are spaced apart from the first piezoelectric ceramic 102 through the first gasket 101.

[0046] Specifically, the first piezoelectric ceramic 102 may be a complete block piezoelectric ceramic, and the second piezoelectric ceramic assembly 103 may include two separate, opposite and spaced parts, one of which is the third piezoelectric ceramic 1032 and the other is the fourth piezoelectric ceramic 1034 .

[0047] Optionally, the third piezoelectric ceramic 1032 and the fourth piezoelectric ceramic 1034 are two small pieces of completely identical block-shaped piezoelectric ceramics. Of course, it can be understood that the third piezoelectric ceramic 1032 and the fourth piezoelectric ceramic 1034 can also be two small pieces of piezoelectric ceramics with slight differences, as long as lateral torsional vibration can be achieved. As an embodiment, the sinusoidal electrical signals received by the third piezoelectric ceramic 1032 and the fourth piezoelectric ceramic 1034 are respectively opposite in phase, so that the expansion and contraction directions of the third piezoelectric ceramic 1032 and the fourth piezoelectric ceramic 1034 are opposite. It can be understood that when the third piezoelectric ceramic 1032 is stretched, the fourth piezoelectric ceramic 1034 is contracted, and vice versa, so that the two form a lateral torsional vibration, that is, the second piezoelectric ceramic component 103 can perform lateral torsional vibration.

[0048] Further, the first gasket 101 is bonded to the first piezoelectric ceramic 102, and the edges of the first gasket 101 and the first piezoelectric ceramic 102 overlap. That is, the area and shape of the surface where the first gasket 101 contacts the first piezoelectric ceramic 102 are completely consistent. This can most effectively make the third piezoelectric ceramic 1032 and the fourth piezoelectric ceramic 1034 electrically insulated from the first piezoelectric ceramic 102. The third piezoelectric ceramic 1032 and the fourth piezoelectric ceramic 1034 are stacked and bonded to the first gasket 101, and are spaced apart from the first piezoelectric ceramic 102 by the first gasket 101.

[0049] In another embodiment, the third piezoelectric ceramic 1032 and the fourth piezoelectric ceramic 1034 are disposed on a surface of the first gasket 101 away from the first piezoelectric ceramic 102 , and are spaced apart at two opposite edges of the first gasket 101 .

[0050] Specifically, the third piezoelectric ceramic 1032 and the fourth piezoelectric ceramic 1034 are placed on two opposite edges of the surface of the first gasket 101 away from the first piezoelectric ceramic 102. A certain gap is left between the third piezoelectric ceramic 1032 and the fourth piezoelectric ceramic 1034, that is, they are arranged at intervals, so that different electrical signals received by the two will not affect each other. Being placed at the edge position of the first gasket 101 makes the vibration mode generated by the third piezoelectric ceramic 1032 and the fourth piezoelectric ceramic 1034 more balanced and efficient during the transmission process, and is easy to process.

[0051] In one embodiment, an atomic force microscope is also provided. The atomic force microscope includes the piezoelectric ceramic excitation device 100 in any of the above embodiments and a probe component 200, wherein the probe component 200 is connected to the piezoelectric ceramic excitation device 100, and the probe component 200 can receive the vibration mode of the piezoelectric ceramic excitation device 100 and vibrate under the excitation of the vibration mode.

[0052] Specifically, the piezoelectric ceramic excitation device 100 generates vibrations, which are transmitted to the probe component 200 connected thereto, so that the probe component 200 can vibrate and scan and detect the sample to be tested. Since the atomic force microscope includes the piezoelectric ceramic excitation device 100, it has the advantages of the piezoelectric ceramic excitation device 100.

[0053] The piezoelectric ceramic excitation device in the above-mentioned atomic force microscope adopts a piezoelectric ceramic stacking method, and uses different electrical signals to excite different piezoelectric ceramics in the piezoelectric ceramic excitation device, so that the piezoelectric ceramic excitation device can simultaneously perform a combined lateral and longitudinal vibration. The piezoelectric ceramic excitation device can make the atomic force microscope needle tip perform a combined lateral and longitudinal vibration. The dynamic stiffness of the needle tip during vibration is larger than the static stiffness, and the needle tip is not easy to adsorb to the surface, so that the needle tip and the sample to be tested can perform real-time measurement of the non-contact interaction force in the lateral and longitudinal directions. In addition, the method of simultaneously measuring the non-contact interaction force in the lateral and longitudinal directions can increase the spatial resolution of the atomic force microscope, thereby realizing the accurate analysis of the surface force field of the material.

[0054] Further, in one embodiment, the probe component 200 includes a probe 210 and a probe base 220, the probe 210 includes a cantilever beam 212, a needle tip 214 and a probe substrate 216 respectively connected to the cantilever beam 212, and the probe 210 can be freely extended relative to the probe base 220. The probe base 220 can receive the vibration mode of the piezoelectric ceramic excitation device 100, and transmit the vibration mode through the probe substrate 216 and the cantilever beam 212 to excite the needle tip 214 to vibrate.

[0055] Specifically, in the present embodiment, the piezoelectric ceramic excitation device 100 is fitted with one side of the probe seat 220 in the probe component 200, and the other side of the probe seat 220 is connected to the probe 210. In the probe 210, the probe substrate 216 is connected to the cantilever beam 212, and the top of the cantilever beam 212 includes a needle tip 214, which is used to detect the interaction force between the sample to be tested and the needle tip. It can be seen that the vibration generated by the piezoelectric ceramic excitation device 100 is first transmitted to the probe seat 220, and then transmitted to the probe substrate 216 through the probe seat 220, and then transmitted to the cantilever beam 212, and then transmitted to the needle tip 214 to make the needle tip 214 vibrate. The cantilever beam 212 can be freely extended relative to the probe seat 220 so that the needle tip 214 can perform a full range of mobile scanning above the sample to be tested.

[0056] Preferably, the frequency of the first electrical signal is the longitudinal resonance frequency of the cantilever beam 212, and the frequency of the second electrical signal group is the transverse resonance frequency of the cantilever beam 212. Vibrating at the resonance frequency of the cantilever beam will improve the vibration efficiency.

[0057] As an implementable approach, Figure 2As shown, the piezoelectric ceramic excitation device 100 includes a first piezoelectric ceramic 102 and a second piezoelectric ceramic component 103, both of which can transmit vibration to the probe component 200. Therefore, the first piezoelectric ceramic 102 and the probe seat 220 can be selected to be arranged in a close fit, and the first gasket 101 and the second piezoelectric ceramic component 103 are sequentially stacked on the surface of the first piezoelectric ceramic 102. That is, the first piezoelectric ceramic 102 is arranged between the second piezoelectric ceramic component 103 and the probe seat 220, so as to achieve the transmission of vibration to the needle tip 214.

[0058] In addition, as another possible implementation method, please also refer to Figure 3 , the second piezoelectric ceramic component 103 in the piezoelectric ceramic excitation device 100 and the probe seat 220 in the probe component 200 can be laminated, and the first gasket 101 and the first piezoelectric ceramic 102 are sequentially laminated on the surface of the second piezoelectric ceramic 103. In this way, the second piezoelectric ceramic component 103 is located between the first piezoelectric ceramic 102 and the probe seat 220, and this lamination method can also transmit vibration, and finally make the needle tip 214 vibrate bidirectionally.

[0059] In one embodiment, a second gasket 111 is provided between the piezoelectric ceramic excitation device 100 and the probe component 200. The second gasket 111 mainly serves as electrical insulation. When the piezoelectric ceramic excitation device 100 receives an electrical signal, the electrical signal is insulated by providing the second gasket 111 to prevent the electrical signal from flowing into the probe component 200. In addition, the second gasket also serves as an adhesive to fix the piezoelectric ceramic excitation device 100 and the probe component 200.

[0060] See also Figure 4 In one embodiment, a surface force field detection device is also provided. The detection device includes: a force detection component 310, a position detection component 320 and a feedback control component 330.

[0061] Among them, the force detection component 310 includes a signal generator 312 and an atomic force microscope in any of the above-mentioned embodiments, the signal generator 312 is connected to the atomic force microscope, and is used to provide an electrical signal to the atomic force microscope to drive the probe component 200 to vibrate; the position detection component 320 is used to monitor the vibration of the probe component 200 on the surface of the sample to be tested to obtain a lateral frequency offset signal and a longitudinal frequency offset signal; the feedback control component 330 is used to feedback control the vibration of the probe component 200 on the surface of the sample to be tested according to the lateral frequency offset signal or the longitudinal frequency offset signal to obtain the distribution of the surface force field.

[0062] Specifically, the signal generator 312 in the force detection component 310 provides different electrical signals to the piezoelectric ceramic excitation device 100 of the atomic force microscope, so that the piezoelectric ceramic excitation device 100 can perform lateral and longitudinal combined vibrations and transmit the vibrations to the probe component 200. The position detection component 320 is used to cause the cantilever beam 212 of the probe component 200 to be disturbed during the vibration process after the probe component 200 interacts with the sample to be tested. When the laser is irradiated on the end of the cantilever beam 212, the vibration state of the reflected light will also change due to the force disturbance of the cantilever beam 212, which causes the frequency offset to be generated. The phase-locked amplifier 326 demodulates the lateral frequency offset signal and the longitudinal frequency offset signal respectively for subsequent processing. The feedback control component 330 is used to use the longitudinal vibration signal as a feedback signal in the feedback system as an internal adjustment signal, control the longitudinal frequency offset signal at a set value, and drive the probe component 200 to move appropriately so that the sample and the probe component 200 maintain a certain force.

[0063] The above-mentioned surface force field detection device uses different electrical signals to excite different piezoelectric ceramics in the piezoelectric ceramic excitation device, so that the piezoelectric ceramic excitation device simultaneously performs a combined lateral and longitudinal vibration. The piezoelectric ceramic excitation device is installed in an atomic force microscope, which can make the tip of the atomic force microscope perform a combined lateral and longitudinal vibration. The dynamic stiffness of the tip during vibration is larger than the static stiffness, and the tip is not easy to adsorb to the surface, so that the tip and the sample to be tested can perform real-time measurement of the non-contact interaction force in the lateral and longitudinal directions. In addition, the test device adopts a method of simultaneously measuring the non-contact interaction force in the lateral and longitudinal directions, which can increase the spatial resolution of the atomic force microscope, thereby realizing accurate analysis of the surface force field of the material.

[0064] In one embodiment, the position detection component 320 includes a laser emitter 322, a photodetector 324, and a lock-in amplifier 326. The laser emitter 322 emits laser light, which is reflected by the cantilever beam 212 of the atomic force microscope into the photodetector 324. The photodetector 324 is used to receive the laser light reflected by the cantilever beam 212 and convert the vibration signal into an electrical signal using the laser light. The lock-in amplifier 326 is used to receive the electrical signal for modulation and demodulation to obtain the lateral frequency shift signal and the longitudinal frequency shift signal.

[0065] Specifically, in the initial state, the vibration of the cantilever beam 212 is vibrated according to the frequency of the electrical signal, but when the needle tip 214 begins to generate a force with the sample to be tested, the vibration frequency begins to change. At this time, the vibration of the cantilever beam 212 is detected by the red laser spot emitted by the laser emitter 322 irradiated on the front end of the cantilever beam 212, and reflected to the photodetector 324. The photodetector 324 converts the lateral vibration signal and the longitudinal vibration signal into an electrical signal output, and uses the phase-locked amplifier 326 to modulate and demodulate the lateral vibration signal and the longitudinal vibration signal in two directions respectively, and obtains the vibration frequency offset signals Δf1 and Δf2 in each vibration direction under the force of the needle tip-sample surface. Ignoring the coupling effect between the response signals of the two vibration directions, the forces on the needle tip in different directions can be calculated respectively according to the frequency offset signal, thereby obtaining the lateral and longitudinal surface force field distribution of the fixed point.

[0066] In one embodiment, see Figure 5 , a detection method for detecting the surface force field distribution of a sample to be tested by using the surface force field detection device in the above embodiment is also provided, the detection method comprising:

[0067] Step S502: Acquire a first electrical signal and a second electrical signal group.

[0068] Specifically, the first electrical signal and the second electrical signal group may be generated by signal generators of different types, or may be generated by the same signal generator.

[0069] Step S504, according to the first electrical signal, the first piezoelectric ceramic is stimulated to perform longitudinal flexural vibration, and according to the second electrical signal group, the second piezoelectric ceramic component is stimulated to perform lateral torsional vibration, so that the probe component follows the longitudinal flexural vibration of the first piezoelectric ceramic and the lateral torsional vibration of the second piezoelectric ceramic component to generate a combined lateral and longitudinal vibration.

[0070] Specifically, the first piezoelectric ceramic receives the first electrical signal and performs longitudinal flexural vibration according to the frequency of the first electrical signal. The second piezoelectric ceramic assembly receives the second electrical signal group and performs lateral torsional vibration according to the frequency of the second electrical signal group. The second piezoelectric ceramic assembly may include a third piezoelectric ceramic and a fourth piezoelectric ceramic, so the second electrical signal group also includes a group of two types of electrical signals with the same frequency, pulse width, and amplitude but opposite phases, namely, the third electrical signal and the fourth electrical signal. When the third piezoelectric ceramic receives the third electrical signal, the fourth piezoelectric ceramic receives the fourth electrical signal with the opposite phase, so when the third piezoelectric ceramic stretches according to the frequency of the third electrical signal, the fourth piezoelectric ceramic contracts instead, so that the two form a lateral torsional vibration.

[0071] Furthermore, the first piezoelectric ceramic generates longitudinal flexural vibration, and the second piezoelectric ceramic component generates transverse torsional vibration, and the two combine to generate transverse and longitudinal combined vibration, which is transmitted to the probe component used for detection, so that the probe component vibrates in accordance with the combined vibration.

[0072] Step S506: utilizing the combined vibration of the probe component to non-contactly detect the force field distribution on the surface of the sample to be tested.

[0073] Specifically, when the probe component is not close to the sample to be tested, the probe component vibrates at the frequency of the electrical signal. Once the probe component begins to exert force on the sample to be tested, the frequency of the probe component begins to change. Based on the change in the frequency offset before and after, the force field distribution of the horizontal and vertical surfaces of the fixed point on the surface of the sample to be tested can be calculated.

[0074] The above-mentioned surface force field detection method uses different electrical signals to excite different piezoelectric ceramics in the piezoelectric ceramic excitation device, so that the piezoelectric ceramic excitation device simultaneously performs a combined lateral and longitudinal vibration. The piezoelectric ceramic excitation device is installed in an atomic force microscope, which can make the tip of the atomic force microscope perform a combined lateral and longitudinal vibration. The dynamic stiffness of the tip during vibration is larger than the static stiffness, and the tip is not easy to adsorb to the surface, so that the tip and the sample to be tested can perform real-time measurement of the non-contact interaction force in the lateral and longitudinal directions. In addition, the test device adopts a method of simultaneously measuring the non-contact interaction force in the lateral and longitudinal directions, which can increase the spatial resolution of the atomic force microscope, thereby realizing accurate analysis of the surface force field of the material.

[0075] In one embodiment, step S506 includes: detecting the vibration mode of the cantilever beam of the probe component to obtain a lateral vibration signal and a longitudinal vibration signal; modulating and demodulating the lateral vibration signal and the longitudinal vibration signal to obtain a vibration frequency offset signal of the lateral force between the needle tip and the surface of the sample to be tested and a vibration frequency offset signal of the longitudinal force; calculating the lateral force and the longitudinal force between the needle tip and the surface of the sample to be tested based on the vibration frequency offset signal of the lateral force and the vibration frequency offset signal of the longitudinal force, thereby obtaining the surface force field distribution of the sample to be tested.

[0076] Specifically, in the initial state, the vibration of the cantilever beam is carried out according to the frequency of the electrical signal, but when the needle tip begins to generate a force with the sample to be tested, the vibration frequency begins to change. At this time, the vibration of the cantilever beam is detected by the red laser spot emitted by the laser emitter irradiating the front end of the cantilever beam and reflected to the photodetector. The photodetector converts the lateral vibration signal and the longitudinal vibration signal into electrical signal output, and uses a phase-locked amplifier to modulate and demodulate the lateral vibration signal and the longitudinal vibration signal in two directions respectively, and obtains the vibration frequency offset signal in each vibration direction under the force of the needle tip-sample surface. Ignoring the coupling effect between the response signals of the two vibration directions, the force on the needle tip in different directions can be calculated separately according to the vibration frequency offset signal, thereby obtaining the lateral and longitudinal surface force field distribution of the fixed point of the sample to be tested.

[0077] In another embodiment, a specific process of how to obtain a force field distribution in a single direction is involved, wherein the process after step S506 includes: using the longitudinal vibration signal as a control feedback signal, comparing the vibration frequency offset signal of the longitudinal force with a first preset value, making the vibration frequency offset signal of the longitudinal force equal to the first preset value, so that the longitudinal force field remains in a constant state; detecting the change of the lateral force when the longitudinal force field remains in a constant state, and then obtaining the lateral force field distribution of the sample to be tested.

[0078] The lateral vibration signal is used as a control feedback signal, and the vibration frequency offset signal of the lateral force is compared with a second preset value, so that the vibration frequency offset signal of the lateral force is equal to the second preset value, so that the lateral force field remains in a constant state; when the lateral force field remains in a constant state, the change of the longitudinal force is obtained, and then the longitudinal force field distribution of the sample to be tested is obtained.

[0079] In the atomic force microscope system, after the vibration form of the cantilever beam is input through the photoelectric detector, the longitudinal vibration signal or the transverse vibration signal will be used as a control feedback signal in the feedback system as an internal adjustment signal, by comparing the vibration frequency offset signal of the longitudinal force with the first preset value, so that the vibration frequency offset signal of the longitudinal force is equal to the first preset value; or the vibration frequency offset signal of the transverse force is compared with the second preset value, so that the vibration frequency offset signal of the transverse force is equal to the second preset value, so as to drive the cantilever beam to move appropriately, so that the sample to be tested and the needle tip maintain a certain force. Among them, the longitudinal force field is kept in a constant state, and the data obtained by the needle tip detection is the transverse force between the needle tip and the sample to be tested, and the transverse force field distribution of the sample to be tested is obtained according to the difference in the transverse force. Similarly, the transverse force field can also be kept in a constant state, so as to obtain the longitudinal force field distribution of the sample to be tested. The first preset value and the second preset value can be set according to the accuracy of the probe detection.

[0080] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0081] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An atomic force microscope, characterized in that: The atomic force microscope comprises: A probe component (200), the probe component (200) being connected to a piezoelectric ceramic excitation device (100), and the probe component (200) being capable of receiving a vibration mode of the piezoelectric ceramic excitation device (100) and vibrating under the excitation of the vibration mode; A piezoelectric ceramic excitation device (100), the piezoelectric ceramic excitation device (100) comprising a first piezoelectric ceramic (102), a second piezoelectric ceramic component (103) and a first gasket (101); The first piezoelectric ceramic (102), the first gasket (101) and the second piezoelectric ceramic component (103) are stacked, the second piezoelectric ceramic component (103) is fitted with a probe seat (220) in the probe component (200), the first gasket (101) is arranged between the first piezoelectric ceramic (102) and the second piezoelectric ceramic component (103), and the first gasket (101) and the first piezoelectric ceramic (102) have edges that overlap; The second piezoelectric ceramic component (103) comprises a third piezoelectric ceramic (1032) and a fourth piezoelectric ceramic (1034), wherein the third piezoelectric ceramic (1032) and the fourth piezoelectric ceramic (1034) are arranged on a surface of the first gasket (101) away from the first piezoelectric ceramic (102), and are arranged at intervals on two opposite edges of the first gasket (101); The first piezoelectric ceramic (102) is used to receive a first electrical signal and to perform longitudinal flexural vibration under the stimulation of the first electrical signal; The second piezoelectric ceramic component (103) is used to receive a second electrical signal group and perform lateral torsional vibration under the excitation of the second electrical signal group; A second gasket (111) is provided between the piezoelectric ceramic excitation device (100) and the probe component (200), and the second gasket (111) is used to fix the piezoelectric ceramic excitation device (100) and the probe component (200).

2. The atomic force microscope according to claim 1, characterized in that: The third piezoelectric ceramic (1032) and the fourth piezoelectric ceramic (1034) are arranged opposite to each other and spaced apart from each other. The second electrical signal group includes a third electrical signal and a fourth electrical signal with opposite phases. The third piezoelectric ceramic (1032) is used to receive the third electrical signal, and the fourth piezoelectric ceramic (1034) is used to receive the fourth electrical signal. The third piezoelectric ceramic (1032) and the fourth piezoelectric ceramic (1034) are spaced apart from the first piezoelectric ceramic (102) by the first gasket (101).

3. The atomic force microscope according to claim 1, characterized in that: The probe component (200) comprises a probe (210) and a probe seat (220), the probe (210) comprising a cantilever beam (212), a needle tip (214) and a probe substrate (216) respectively connected to the cantilever beam (212), and the probe (210) can be freely extended relative to the probe seat (220); The probe seat (220) can receive the vibration mode of the piezoelectric ceramic excitation device (100), and transmit the vibration mode through the probe substrate (216) and the cantilever beam (212) to excite the needle tip (214) to vibrate.

4. The atomic force microscope according to claim 3, characterized in that: The first piezoelectric ceramic (102) is arranged in close contact with the probe seat (220), and the first gasket (101) and the second piezoelectric ceramic component (103) are sequentially stacked on the surface of the first piezoelectric ceramic (102).

5. The atomic force microscope according to claim 3, characterized in that: The first gasket (101) and the first piezoelectric ceramic (102) are sequentially stacked on the surface of the second piezoelectric ceramic component (103).

6. A surface force field detection device, characterized in that: include: A force detection component (310), a position detection component (320), and a feedback control component (330); The force detection component (310) comprises a signal generator (312) and the atomic force microscope according to any one of claims 1 to 5, wherein the signal generator (312) is connected to the atomic force microscope and is used to provide an electrical signal to the atomic force microscope to drive the probe component (200) to vibrate; The position detection component (320) is used to monitor the vibration of the probe component (200) on the surface of the sample to be tested, so as to obtain a transverse frequency offset signal and a longitudinal frequency offset signal; The feedback control component (330) is used to feedback control the vibration of the probe component (200) on the surface of the sample to be tested according to the transverse frequency offset signal or the longitudinal frequency offset signal to obtain a surface force field distribution; The position detection component (320) includes a laser emitter (322), a photodetector (324) and a phase-locked amplifier (326); the laser emitter (322) emits laser light which is reflected by the cantilever beam (212) of the atomic force microscope into the photodetector (324); the photodetector (324) is used to receive the laser light reflected by the cantilever beam (212) and convert the vibration signal into an electrical signal using the laser light; the phase-locked amplifier (326) is used to receive the electrical signal for modulation and demodulation to obtain the lateral frequency offset signal and the longitudinal frequency offset signal.

7. A detection method for detecting the surface force field distribution of a sample to be tested using the surface force field detection device according to claim 6, characterized in that: The detection method comprises: Acquire a first electrical signal and a second electrical signal group; The first piezoelectric ceramic is stimulated to perform longitudinal flexural vibration according to the first electrical signal, and the second piezoelectric ceramic component is stimulated to perform lateral torsional vibration according to the second electrical signal group. The probe component follows the longitudinal flexural vibration of the first piezoelectric ceramic and the transverse torsional vibration of the second piezoelectric ceramic component to generate a combined transverse and longitudinal vibration; The force field distribution on the surface of the sample to be tested is detected contactlessly by utilizing the combined vibration of the probe components.

8. The detection method according to claim 7, characterized in that: The method of utilizing the combined vibration of the probe component to non-contactly detect the force field distribution on the surface of the sample to be tested comprises: Detecting the vibration mode of the cantilever beam of the probe component to obtain a transverse vibration signal and a longitudinal vibration signal; Modulating and demodulating the transverse vibration signal and the longitudinal vibration signal to obtain a vibration frequency offset signal of a transverse force and a vibration frequency offset signal of a longitudinal force between the needle tip and the surface of the sample to be measured; The lateral force and the longitudinal force between the needle tip and the surface of the sample to be tested are calculated according to the vibration frequency offset signal of the lateral force and the vibration frequency offset signal of the longitudinal force, thereby obtaining the surface force field distribution of the sample to be tested.

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