A tubular nested dual piezoelectric scanning probe microscope and scanning imaging method

Abstract

The present invention belongs to the technical field of scanning probe microscopes, and in particular relates to a tubular nested dual piezoelectric scanning probe microscope and a scanning imaging method. The microscope includes a mirror body, a signal acquisition module, and a computer. The mirror body and the signal acquisition module are electrically connected. The mirror body includes a fixedly connected imaging module, a driving module, and a base in the vertical direction from top to bottom. The imaging module includes a scanning head frame, a sample rack, and a scanning unit. The sample rack and the scanning unit are relatively arranged in the scanning head frame; the driving module includes an inner nested driving unit and a tubular external piezoelectric body that are nested inside and outside. The inner nested driving unit drives the scanning unit to advance the needle. The two ends of the tubular external piezoelectric body are respectively fixedly connected to the base and the scanning head frame. The tubular external piezoelectric body swings the scanning unit to retract the needle through inertia. The present invention can avoid the occurrence of needle collision as much as possible, improve the quality and stability of imaging, and improve experimental efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of scanning probe microscopes, and in particular relates to a tubular nested dual piezoelectric scanning probe microscope and a scanning imaging method. Background Art

[0002] Strong magnetic fields can affect the orientation and motion of electron and nuclear spins within matter, facilitating research into the structure, properties, and interactions of matter. High-magnetic field research can probe properties such as magnetism, superconductivity, and spin states, driving the development of materials science and condensed matter physics. Therefore, using scanning probe microscopy (SPM) to observe and study magnetic materials, magnetic nanostructures, quantum spin states, and superconductor properties in high magnetic fields can help us further explore the microscopic mechanisms of magnetic materials and quantum phenomena, and promote the development of magnetic materials science and nanotechnology.

[0003] When the sharp probe of a scanning probe microscope (SPM) approaches the sample surface until the distance between the tip and the sample surface is as small as nanometers, the SPM can scan the sample surface by using the tunneling effect or the force between the probe and the sample. Among them, the microscope that scans the sample surface by using the tunneling effect is called a scanning tunneling microscope (STM), and the microscope that scans the sample surface by using the force between the probe and the sample is called an atomic force microscope (AFM).

[0004] Taking the scanning tunneling microscope (STM) as an example, in many existing STM microscope bodies, the resonance of the scanning frame and the noise of the electromechanical components will cause mechanical vibrations. The turbulent cooling water in the water-cooled magnetic field will also cause strong environmental vibrations. Thermal drift and thermal fluctuations will also occur during operation and be transmitted to the scanning unit of the microscope body. These interference factors will directly or indirectly interfere with the piezoelectric element, and the advancement or withdrawal of the probe is often directly driven by the piezoelectric element. These interference factors will cause the STM probe to accidentally contact the sample surface during the advancement process, the scanning imaging process, or the moment of withdrawal, that is, the probe strikes. The strike will not only blur or distort the high-resolution atomic-level imaging during the scanning imaging process, affecting the precise observation of the sample surface features, but will also cause damage to the probe tip and change the morphology and structure of the sample, greatly affecting experiments conducted using the STM and greatly reducing experimental efficiency. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art and provide a tubular nested dual piezoelectric scanning probe microscope, which can avoid the occurrence of needle collision as much as possible, improve the quality and stability of imaging, and enhance experimental efficiency.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A tubular nested dual piezoelectric scanning probe microscope includes a mirror body, a signal acquisition module, and a computer. The mirror body and the signal acquisition module are electrically connected. The mirror body includes, from top to bottom in the vertical direction, a fixedly connected imaging module, a driving module, and a base. The imaging module includes a scanning head frame, a sample rack, and a scanning unit. The sample rack and the scanning unit are relatively arranged in the scanning head frame; the driving module includes an inner nested driving unit and a tubular external piezoelectric body arranged in an inner and outer nested manner. The inner nested driving unit drives the scanning unit to advance the needle. The two ends of the tubular external piezoelectric body are respectively fixedly connected to the base and the scanning head frame. The tubular external piezoelectric body drives the scanning unit to retract the needle through inertial swing.

[0008] Preferably, the scanning unit includes a tubular scanning piezoelectric body, a first sliding rod and a probe holder, the tubular scanning piezoelectric body includes a fixed end and a movable end, the fixed end of the tubular scanning piezoelectric body is fixedly arranged at the bottom of the inner cavity of the scanning head frame, a through hole is opened at the bottom of the scanning head frame corresponding to the fixed end of the tubular scanning piezoelectric body, both ends of the tubular scanning piezoelectric body are open and the inside is hollow, the first sliding rod is nested inside the tubular scanning piezoelectric body, and the two ends of the first sliding rod are respectively recorded as the first end and the second end, the first end of the first sliding rod is close to the sample holder, and the second end of the first sliding rod is away from the sample holder, and the probe holder is fixedly arranged on the first end of the first sliding rod; the inner nested driving unit drives the first sliding rod to advance the needle.

[0009] Preferably, the nested driving unit includes a tubular nested piezoelectric body and a second sliding rod, the tubular nested piezoelectric body includes a fixed end and a movable end, the fixed end of the tubular nested piezoelectric body is fixedly set on the base, the movable end of the tubular nested piezoelectric body is open and hollow inside, the second sliding rod is nested inside the tubular nested piezoelectric body and extends from the movable end of the tubular nested piezoelectric body, the two ends of the second sliding rod are respectively recorded as the first end and the second end, the first end of the second sliding rod is close to the second end of the first sliding rod, and the second end of the second sliding rod is away from the second end of the first sliding rod; the first end of the second sliding rod enters and exits the fixed end of the tubular scanning piezoelectric body.

[0010] Preferably, the distance between the inner wall of the tubular nested piezoelectric body and the inner wall of the tubular external piezoelectric body is greater than 0.

[0011] Preferably, the scanning unit further includes a first elastic pressing portion, which is fixedly arranged on an outer wall of the first sliding rod and is pressed by the first sliding rod and the tubular scanning piezoelectric body.

[0012] Preferably, the nested drive unit further includes a second elastic extrusion portion, the second elastic extrusion portion is fixedly arranged on the outer wall of the second sliding rod, and the second sliding rod is squeezed by the second sliding rod and the tubular nested piezoelectric body.

[0013] Preferably, the outer wall of the first sliding rod is in line contact with the inner wall of the tubular scanning piezoelectric body.

[0014] The present invention also provides a scanning imaging method, using the above-mentioned tubular nested bi-piezoelectric scanning probe microscope, comprising the following steps:

[0015] S1, the needle insertion process adopts needle insertion method 1: the signal acquisition module sends a needle insertion signal to the tubular nested piezoelectric body, and the movable end of the tubular nested piezoelectric body extends upward in the vertical direction, driving the second sliding rod to rise and enter the tubular scanning piezoelectric body from the fixed end of the tubular scanning piezoelectric body, and then pushes the first sliding rod to rise, so that the probe on the probe holder continuously approaches the sample on the sample holder. When the signal acquisition module collects the tunnel current, the movable end of the tubular nested piezoelectric body stops extending upward, the needle insertion process ends, and the scanning imaging process begins;

[0016] S2, scanning and imaging process: the signal acquisition module sends a scanning signal to the tubular scanning piezoelectric element, and the movable end of the tubular scanning piezoelectric element drives the probe holder provided at the first end of the first sliding rod to move in the XY plane, and the probe scans and images the sample surface;

[0017] S3, after the scanning imaging is completed, the needle retraction process begins: at the beginning of the current needle retraction cycle, the signal acquisition module first sends a retraction signal to the tubular external piezoelectric element for a first time interval Δt1, and the active end of the tubular external piezoelectric element drives the imaging module to slowly and uniformly retract downward in the vertical direction; then the signal acquisition module sends an acceleration rise signal to the tubular external piezoelectric element for a second time interval Δt2, and the active end of the tubular external piezoelectric element drives the imaging module to accelerate upward in the vertical direction, and the first sliding rod moves downward relative to the tubular scanning piezoelectric element through inertial swing;

[0018] The acceleration rising signal sent by the signal acquisition module ends, the current needle withdrawal cycle also ends, and the distance between the probe holder and the sample holder increases by L.

[0019] Preferably, in S1: if the signal acquisition module still does not collect tunnel current when the movable end of the tubular nested piezoelectric body 221 is extended to the first top dead center, the second needle insertion method is adopted, including steps 1a to 4a:

[0020] Step 1a: The signal acquisition module sends a retraction signal to the tubular inner-nested piezoelectric body, and the movable end of the tubular inner-nested piezoelectric body slowly and uniformly retracts downward in the vertical direction to a first bottom dead point;

[0021] Step 2a: The signal acquisition module sends a uniform extension signal to the tubular inner-nested piezoelectric element for a third time interval Δt3, and the movable end of the tubular inner-nested piezoelectric element slowly and uniformly extends upward in the vertical direction;

[0022] In step 3a, the signal acquisition module sends an accelerated retraction signal to the tubular inner-nested piezoelectric element for a fourth time interval Δt4. The movable end of the tubular inner-nested piezoelectric element accelerates and retracts downward in the vertical direction, while the second sliding rod decelerates and moves upward in the vertical direction due to inertia. At the moment when the signal acquisition module stops sending the accelerated retraction signal to the tubular inner-nested piezoelectric element, the speed of the second sliding rod's upward deceleration is zero.

[0023] Step 4a: Repeat the needle insertion method 1. If the signal acquisition module detects tunneling current, the movable end of the tubular inner-nested piezoelectric element stops extending upward, the needle insertion process ends, and the scanning imaging process begins. If the signal acquisition module still does not detect tunneling current when the movable end of the tubular inner-nested piezoelectric element extends to the first top dead center, the process returns to step 1a.

[0024] If the second elastic extrusion portion moves to the first limit spacing α below the movable end of the tubular nested piezoelectric body, and the movable end of the tubular nested piezoelectric body is extended to the upper first stop point, the signal acquisition module still does not collect the tunnel current, then the needle insertion method three is adopted: the signal acquisition module sends a stop needle insertion signal to the tubular nested piezoelectric body, and the movable end of the tubular nested piezoelectric body no longer moves. At the same time, the signal acquisition module sends a retraction signal to the tubular external piezoelectric body, and the movable end of the tubular external piezoelectric body drives the imaging module to retract slowly and uniformly downward in the vertical direction; the second sliding rod enters the tubular scanning piezoelectric body from the fixed end of the tubular scanning piezoelectric body, and then pushes the first end of the first sliding rod to continuously approach the sample on the sample holder until the signal acquisition module collects the tunnel current, and the movable end of the tubular external piezoelectric body stops retracting, the needle insertion process ends, and the scanning imaging process begins.

[0025] Preferably, in S3: before the start of the first needle withdrawal cycle, it also includes a needle withdrawal preparation stage: the signal acquisition module sends a retraction signal to the tubular nested piezoelectric body, and when the active end of the tubular nested piezoelectric body retracts to the first bottom dead point, the needle withdrawal preparation stage ends; the needle withdrawal process includes n consecutive needle withdrawal cycles, where n is a positive integer.

[0026] The beneficial effects of the present invention are:

[0027] (1) The scanning probe microscope of the present invention can avoid the occurrence of needle collisions as much as possible during the entire experimental process, thereby improving the quality and stability of imaging and enhancing the experimental efficiency.

[0028] (2) In the scanning probe microscope of the present invention, the imaging module is set as a relatively independent part, and is supplemented by a special structure in the nested driving unit and the scanning unit, which ensures that the probe on the probe holder in the scanning unit is always perpendicular to the sample holder at all times. This avoids the situation where the probe damages the sample surface during the subsequent scanning and imaging process due to the skew of the probe, and the imaging quality is sometimes good and sometimes bad, which further improves the efficiency of scanning and imaging.

[0029] (3) In the scanning probe microscope of the present invention, both the needle insertion process and the scanning imaging process are greatly weakened or even completely offset by the elastic potential energy and frictional heat generated by the internal nested driving unit and scanning unit to reduce the interference that eventually reaches the probe holder. Therefore, even if the probe advances toward the sample due to interference, it will only advance a very small distance, minimizing the occurrence of the probe tip colliding with the sample surface, thereby extending the service life of the probe and avoiding damage to the sample.

[0030] (4) The needle withdrawal process in the scope of the present invention is divided into a needle withdrawal preparation stage and a needle withdrawal stage. First, the needle withdrawal preparation stage allows the tubular internally embedded piezoelectric element to retract, clearing obstacles in the vertical direction for the subsequent needle withdrawal stage; then, in the subsequent needle withdrawal stage, the needle withdrawal is completed through n consecutive needle withdrawal cycles; wherein each needle withdrawal cycle relies solely on the tubular external piezoelectric element and utilizes the inertia generated by sudden reverse acceleration to withdraw the needle. The needle withdrawal speed is extremely fast and will not cause a needle collision. During the needle withdrawal process, a needle collision will only occur at the moment when the needle withdrawal actually begins, corresponding to the moment when the active end of the tubular external piezoelectric element accelerates and extends upward in the vertical direction in the first needle withdrawal cycle of the needle withdrawal stage of the present invention, and at this moment, the probe holder is moving in a direction away from the sample holder relative to the sample holder, so a needle collision will not occur at all during the needle withdrawal process of the present invention.

[0031] (5) In the scanning probe microscope of the present invention, the internally nested driving unit and the tubular external piezoelectric body are nested inside and outside, which greatly improves the space utilization rate in the microscope body and makes the structure in the microscope body more compact. At the same time, it is different from the piezoelectric body in the prior art, which is responsible for both needle insertion and needle withdrawal. Once the piezoelectric body fails, the entire experiment cannot be carried out. In the present invention, the internally nested driving unit and the tubular external piezoelectric body each have their own functions, which are responsible for needle insertion and needle withdrawal respectively. Damage to any one piezoelectric body will not directly affect the normal operation of other piezoelectric bodies, and the faulty piezoelectric body can be easily identified based on the cause of the failure.

[0032] (6) The present invention not only completely avoids the existing technology of "using a hook to connect the inertial motor and the scanning head", but also fully utilizes the "utilization of inertia during sudden acceleration to withdraw the needle", which has always been considered to have many shortcomings and needs to be improved. The technical defect overcomes the prejudice of the existing technology, ensures efficient needle withdrawal, and also utilizes the inertia during sudden acceleration during the needle insertion process, which ensures the smooth needle insertion process and ensures the safety and reliability of the needle insertion process; the special structure of the embedded drive unit and the scanning unit in the mirror body also effectively controls the process and displacement of the probe holder close to the sample holder through friction.

[0033] (7) A scanning imaging method of the present invention can significantly reduce the interference within the scanning tunneling microscope, avoid the occurrence of needle collisions as much as possible, improve the quality and stability of imaging, and enhance experimental efficiency.

[0034] (8) A scanning imaging method of the present invention sets four needle insertion methods during the needle insertion process. Needle insertion method 2, needle insertion method 3 and needle insertion method 4 are further backup methods of the previous needle insertion method, and on the basis of the previous needle insertion method, the probe is brought closer to the sample to ensure that the needle insertion process is smooth, safe and reliable, and each needle insertion method is safe and controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the internal structure of the probe microscope of the present invention;

[0036] Figure 2 for Figure 1 AA section view in;

[0037] Figure 3 for Figure 1 BB cross-sectional view in;

[0038] Figure 4 Scanning imaging for existing technologies;

[0039] Figure 5 This is the scanning imaging of the present invention.

[0040] The actual correspondence between the reference numerals and component names of the present invention is as follows:

[0041] 1. Imaging module; 11. Scanning head frame; 12. Sample holder; 13. Scanning unit; 131. Tubular scanning piezoelectric element; 132. First sliding rod; 133. First elastic extrusion portion; 134. Probe holder;

[0042] 2. Driving module; 21. Tubular external piezoelectric element; 22. Internally nested driving unit; 221. Tubular internally nested piezoelectric element; 222. Second sliding rod; 223. Second elastic extrusion portion;

[0043] 3. Base. DETAILED DESCRIPTION

[0044] Any equivalent replacement of the technical features of the technical solution of the present invention and any solution derived by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0045] For the convenience of description, the scanning probe microscope in the present invention is a scanning tunneling microscope.

[0046] When an electric field (hereinafter referred to as driving voltage) is applied to piezoelectric bodies, their shape or size will change. This is the prior art. In the present invention, the piezoelectric body is tubular or cylindrical, with a movable end and a fixed end at its two ends. Because the fixed end of the piezoelectric body is usually fixed on other components, when the piezoelectric body is deformed, it can be regarded as the movable end of the piezoelectric body being deformed relative to the fixed end of the piezoelectric body (such as stretching, contracting or swinging).

[0047] Example 1

[0048] The present invention discloses a tubular nested bi-piezoelectric scanning probe microscope comprising a microscope body, a signal acquisition module, and a computer. The microscope body and the signal acquisition module are electrically connected, and the signal acquisition module and the computer are electrically connected. The main innovation of the present invention lies in the microscope body; the signal acquisition module and the processing module are not shown in the accompanying drawings.

[0049] The mirror structure of the scanning tunneling microscope of this embodiment is as follows Figures 1 to 3 As shown, the vertical direction includes, from top to bottom, a fixedly connected imaging module 1, a driving module 2 and a base 3. The imaging module 1 includes a scanning head frame 11, a sample holder 12 and a scanning unit 13. The sample holder 12 and the scanning unit 13 are relatively arranged in the scanning head frame 11; the driving module 2 includes an inner nested driving unit 22 and a tubular external piezoelectric body 21 that are nested inside and outside. The two ends of the tubular external piezoelectric body 21 are fixedly connected to the base 3 and the scanning head frame 11 respectively. The inner nested driving unit 22 drives the scanning unit 13 to advance the needle, and the tubular external piezoelectric body 21 drives the scanning unit 13 to retract the needle through inertial swing.

[0050] The outermost part of the imaging module 1 is the scanning head frame 11, which is made of a rigid alloy. The interior of the scanning head frame 11 is hollow, and a sample holder 12 is fixedly arranged at the top of the inner cavity of the scanning head frame 11. The sample holder 12 is used to place the sample; the scanning unit 13 is arranged at the bottom of the inner cavity of the scanning head frame 11.

[0051] Specifically, the scanning unit 13 includes a tubular scanning piezoelectric element 131, a first sliding rod 132, and a probe holder 134. The scanning piezoelectric element 131 has a fixed end and a movable end, respectively. The fixed end of the scanning piezoelectric element 131 is fixedly mounted at the bottom of the inner cavity of the scanning head frame 11. The scanning piezoelectric element 131 in the present invention is an XY piezoelectric scanning tube, with the vertical direction being the Z-axis. The movable end of the scanning piezoelectric element 131 can swing within the XY plane based on different electrical signals emitted by the signal acquisition module. The scanning piezoelectric element 131 is open at both ends and hollow inside. A first sliding rod 132 is nested within the tubular scanning piezoelectric element 131, with the length of the first sliding rod 132 aligning with the length of the scanning piezoelectric element 131. The two ends of the first sliding rod 132 are designated as the first end and the second end, respectively. The second end of the first sliding rod 132 is distal from the sample holder 12, while the first end of the first sliding rod 132 is proximal to the sample holder 12. A probe holder 134 is provided on the first end of the first sliding rod 132 for placing probes, the specific probes of which are determined by the sample and imaging requirements. A through hole is provided at the bottom of the scanning head frame 11, corresponding to the fixed end of the scanning piezoelectric element 131.

[0052] When the movable end of the scanning piezoelectric body 131 swings in the XY plane, the probe holder 134 can be driven to move in the XY plane, that is, the probe on the probe holder 134 scans and images the sample surface on the sample holder 12 .

[0053] Optionally, a window is provided on the side wall of the scanning head frame 11 to facilitate replacement of samples and probes.

[0054] The tubular external piezoelectric element 21 is open at both ends and hollow inside. It has a fixed end and a movable end. The fixed end is fixedly connected to the base 3, while the movable end is fixedly connected to the bottom of the scanning head frame 11. The movable end of the tubular external piezoelectric element 21 can expand and contract vertically based on the electrical signals emitted by the signal acquisition module. In other words, the through hole at the bottom of the scanning head frame 11 connects the inner cavity of the tubular external piezoelectric element 21 with the inner cavity of the scanning piezoelectric element 131.

[0055] The inner nested driving unit 22 is arranged in the inner cavity of the tubular external piezoelectric body 21. The inner nested driving unit 22 includes a tubular inner nested piezoelectric body 221 and a second sliding rod 222. The two ends of the tubular inner nested piezoelectric body 221 are respectively a fixed end and a movable end. The fixed end of the tubular inner nested piezoelectric body 221 is fixedly set on the base 3, and the movable end of the tubular inner nested piezoelectric body 221 is close to the second end of the first sliding rod 132. The interior of the tubular inner nested piezoelectric body 221 is hollow and the movable end is open. The second sliding rod 222 is nested inside the tubular inner nested piezoelectric body 221 and extends from the movable end of the tubular inner nested piezoelectric body 221. The length direction of the second sliding rod 222 is the same as the length direction of the tubular inner nested piezoelectric body 221; the two ends of the second sliding rod 222 are respectively recorded as the first end and the second end, the second end of the second sliding rod 222 is away from the second end of the first sliding rod 132, and the first end of the second sliding rod 222 is close to the second end of the first sliding rod 132. The movable end of the tubular inner-nested piezoelectric body 221 can be extended and retracted in the vertical direction according to different electrical signals sent by the signal acquisition module. The outer wall of the tubular inner-nested piezoelectric body 221 does not contact the inner wall of the tubular outer-mounted piezoelectric body 21.

[0056] Optionally, the scanning unit 13 also includes a first elastic extrusion portion 133, which is fixedly arranged on the outer wall of the first sliding rod 132, and contacts the inner wall of the tubular scanning piezoelectric body 131, and is squeezed by the first sliding rod 132 and the tubular scanning piezoelectric body 131; at the same time, the outer wall of the first sliding rod 132 is in line contact or surface contact with the inner wall of the tubular scanning piezoelectric body 131.

[0057] Optionally, the projection of the first sliding rod 132 on the XY plane is a polygon, and the outer wall of the first sliding rod 132 is in line contact with the inner wall of the tubular scanning piezoelectric body 131 , and the number of contact lines is greater than two.

[0058] Optionally, the nested drive unit also includes a second elastic extrusion portion 223, which is fixedly arranged on the outer wall of the second sliding rod 222, and contacts the inner wall of the tubular nested piezoelectric body 221, and is squeezed by the second sliding rod 222 and the tubular nested piezoelectric body 221; at the same time, the outer wall of the second sliding rod 222 is in line contact or surface contact with the inner wall of the tubular nested piezoelectric body 221.

[0059] Optionally, the projection of the second sliding rod 222 on the XY plane is a polygon, and the outer wall of the second sliding rod 222 is in line contact with the inner wall of the tubular nested piezoelectric body 221, and the number of contact lines is greater than two.

[0060] In this embodiment, if Figure 2As shown, the projection of the first sliding rod 132 on the XY plane is a rectangle, and the edges at the four corners of the rectangle are in line contact with the inner wall of the tubular scanning piezoelectric body 131. At the same time, the first elastic pressing portion 133 is provided on one side of the first sliding rod 132 and in contact with the inner wall of the tubular scanning piezoelectric body 131. The first elastic pressing portion 133 is squeezed by the first sliding rod 132 and the tubular scanning piezoelectric body 131; Figure 3 As shown, the projection of the second sliding rod 222 on the XY plane is a rectangle, and the edges of the four vertices of the rectangle are in line contact with the inner wall of the tubular nested piezoelectric body 221 respectively. At the same time, the second elastic extrusion portion 223 is arranged on a side surface of the second sliding rod 222 and in contact with the inner wall of the tubular nested piezoelectric body 221. The second elastic extrusion portion 223 is squeezed by the second sliding rod 222 and the tubular nested piezoelectric body 221.

[0061] Optionally, the first elastic extrusion portion 133 and the second elastic extrusion portion 223 are both spring sheets.

[0062] Let the maximum distance between two points of the projection figure of the second sliding rod 222 in the XY plane be d2, let the inner diameter of the tubular scanning piezoelectric body 131 be d1, and let the diameter of the through hole at the bottom of the scanning head frame 11 be d3, then 0<d2<d1 and 0<d2<d3, and the first end of the second sliding rod 222 can move in and out of the fixed end of the tubular scanning piezoelectric body 131 in the vertical direction.

[0063] The following describes in detail the needle insertion process, scanning imaging process, and needle withdrawal process of the probe in the scope:

[0064] 1. Needle insertion process

[0065] 1.1 Needle insertion method 1

[0066] After the tubular nested piezoelectric body 221 receives the needle advancement signal sent by the signal acquisition module, the movable end of the tubular nested piezoelectric body 221 continues to extend upward in the vertical direction. During this process, the first end of the second sliding rod 222 continues to rise and enters the interior of the tubular scanning piezoelectric body 131 from the fixed end of the tubular scanning piezoelectric body 131; when the first end of the second sliding rod 222 contacts the second end of the first sliding rod 132, the first sliding rod 132 is pushed by the second sliding rod 222 to continue to rise in the vertical direction, that is, the probe on the probe rack 134 continues to approach the sample on the sample rack 12 until the signal acquisition module collects the tunnel current, and then the computer sends a stop needle advancement signal to the tubular nested piezoelectric body 221 through the signal acquisition module. At this time, the tubular nested piezoelectric body 221 stops moving, the needle advancement process ends, and the probe on the probe rack 134 no longer approaches the sample on the sample rack 12, and enters the scanning imaging process.

[0067] 1.2 Needle insertion method 2

[0068] If the needle is inserted using the first needle insertion method, but the signal acquisition module still does not collect the tunnel current when the movable end of the tubular nested piezoelectric body 221 is extended to the first upper dead point, the computer then sends a retraction signal to the tubular nested piezoelectric body 221 through the signal acquisition module, and the movable end of the tubular nested piezoelectric body 221 slowly and uniformly retracts downward to the first lower dead point in the vertical direction, and there is static friction between the outer wall of the second sliding rod 222 and the inner wall of the tubular nested piezoelectric body 221; then the signal acquisition module sends a uniform extension signal to the tubular nested piezoelectric body 221 and continues for a third time. During time interval Δt3, the movable end of the tubular inner-nested piezoelectric element 221 slowly and uniformly extends upward in the vertical direction, creating static friction between the outer wall of the second sliding rod 222 and the inner wall of the tubular inner-nested piezoelectric element 221. Finally, the signal acquisition module sends an accelerated retraction signal to the tubular inner-nested piezoelectric element 221 for a fourth time interval Δt4. This causes the movable end of the tubular inner-nested piezoelectric element 221 to accelerate downward and retract vertically, while the second sliding rod 222, due to inertia, continues to decelerate upward in the vertical direction. Dynamic friction between the outer wall of the second sliding rod 222 and the inner wall of the tubular inner-nested piezoelectric element 221 occurs. At the moment the signal acquisition module stops sending the accelerated retraction signal to the tubular inner-nested piezoelectric element 221, the speed of the second sliding rod 222's upward deceleration is zero. At this point, the length of the portion of the first end of the second sliding rod 222 extending relative to the movable end of the tubular inner-nested piezoelectric element 221 increases.

[0069] The signal acquisition module then sends a needle insertion signal to the tubular nested piezoelectric body 221, and the movable end of the tubular nested piezoelectric body 221 continuously extends upward in the vertical direction. During this process, the first end of the second sliding rod 222 continuously rises and enters the interior of the tubular scanning piezoelectric body 131 from the fixed end of the tubular scanning piezoelectric body 131; when the first end of the second sliding rod 222 contacts the second end of the first sliding rod 132, the first sliding rod 132 is pushed by the second sliding rod 222 to continuously rise in the vertical direction, that is, the probe on the probe holder 134 continuously approaches the sample on the sample holder 12 until the signal acquisition module collects the tunnel current, and then the computer sends a stop needle insertion signal to the tubular nested piezoelectric body 221 through the signal acquisition module. At this time, the tubular nested The sleeve piezoelectric body 221 stops moving, the needle insertion process ends, the probe on the probe holder 134 no longer approaches the sample on the sample holder 12, and enters the scanning imaging process; if the signal acquisition module still does not collect the tunnel current when the movable end of the tubular nested piezoelectric body 221 is extended to the first upper dead point, the needle insertion method 2 is repeated, and the length of the protruding part of the first end of the second sliding rod 222 relative to the movable end of the tubular nested piezoelectric body 221 is continued to be increased until the second elastic extrusion portion 223 moves to the first limit spacing α below the movable end of the tubular nested piezoelectric body 221, and the needle insertion method 2 is stopped. At this time, the length of the protruding part of the first end of the second sliding rod 222 relative to the movable end of the tubular nested piezoelectric body 221 has reached the maximum length L MAX.

[0070] In this embodiment, α=5 μm.

[0071] Under normal circumstances, needle insertion can be completed by using needle insertion method one. However, under special circumstances, that is, "the movable end of the tubular nested piezoelectric body 221 is extended to the first upper dead point, and the signal acquisition module still does not collect the tunnel current", the first upper dead point is the maximum length that the movable end of the tubular nested piezoelectric body 221 can be extended. The reason for this situation may be that after the last experiment, the distance between the second end of the first sliding rod 132 and the first end of the second sliding rod 222 is too far, or the distance between the probe holder 134 and the sample holder 12 is too far. When special circumstances arise, the present invention can use needle insertion method two, which is equivalent to continuously increasing the length of the protruding part of the first end of the second sliding rod 222 relative to the movable end of the tubular nested piezoelectric body 221 by inertial swing on the basis of needle insertion method one, so as to ensure that the needle insertion process is successfully completed, that is, the signal acquisition module can collect the tunnel current. At the same time, in order to ensure the safety and controllability during the needle insertion process, the present invention sets a "until the second elastic extrusion portion 223 moves to the first limit distance α below the movable end of the tubular inner nested piezoelectric body 221, that is, the length of the protruding portion of the first end of the second sliding rod 222 relative to the movable end of the tubular inner nested piezoelectric body 221 has reached the maximum length L MAX The second needle insertion method "is stopped" is to ensure that the second elastic extrusion portion 223 is always squeezed by the second sliding rod 222 and the tubular inner nested piezoelectric body 221, so that the second sliding rod 222 does not deflect.

[0072] The inertial swing in the second needle insertion method occurs between the nested piezoelectric body 221 and the second sliding rod 222 in the driving module 2, rather than directly on the first sliding rod 132, making the process of increasing the "length of the protruding part of the first end of the second sliding rod 222 relative to the movable end of the tubular nested piezoelectric body 221" safe and controllable.

[0073] 1.3 Needle insertion method three

[0074] If the needle is inserted using the second needle insertion method, but the second elastic extrusion portion 223 moves to the first limit spacing α below the movable end of the tubular inner nested piezoelectric body 221, and the movable end of the tubular inner nested piezoelectric body 221 extends to the upper first stop point, the signal acquisition module still does not collect the tunnel current, then the computer sends a stop needle insertion signal to the tubular inner nested piezoelectric body 221 through the signal acquisition module, and the movable end of the tubular inner nested piezoelectric body 221 no longer moves, that is, the movable end of the tubular inner nested piezoelectric body 221 does not extend or retract, and the length of the protruding portion of the first end of the second sliding rod 222 relative to the movable end of the tubular inner nested piezoelectric body 221 still maintains the maximum length L MAXAt the same time, the tubular external piezoelectric element 21 receives the retraction signal from the signal acquisition module, and the movable end of the tubular external piezoelectric element 21 slowly and uniformly retracts downward in the vertical direction, causing the entire imaging module 1 to slowly and uniformly descend in the vertical direction. During this process, the first end of the second sliding rod 222 enters the interior of the tubular scanning piezoelectric element 131 from the fixed end of the tubular scanning piezoelectric element 131. When the first end of the second sliding rod 222 contacts the second end of the first sliding rod 132, the probe on the probe holder 134 continuously approaches the sample on the sample holder 12 until the signal acquisition module detects the tunneling current. At this point, the computer sends a stop retraction signal to the tubular external piezoelectric element 21 through the signal acquisition module, causing the tubular external piezoelectric element 21 to stop moving, the needle insertion process ends, and the probe on the probe holder 134 no longer approaches the sample on the sample holder 12, entering the scanning imaging process.

[0075] When the movable end of the tubular external piezoelectric body 21 retracts vertically downward to the second bottom dead point, the needle insertion method 3 is stopped; the shortest length of the tubular external piezoelectric body 21 is the point where the movable end of the tubular external piezoelectric body 21 retracts to the second bottom dead point.

[0076] Needle insertion method three is equivalent to further increasing the length of the first end of the second sliding rod 222 entering the interior of the tubular scanning piezoelectric body 131 on the basis of needle insertion method two, so as to increase the length of the part of the first end of the first sliding rod 132 extending relative to the movable end of the tubular scanning piezoelectric body 131, so as to ensure that the needle insertion process is successfully completed, that is, the signal acquisition module can collect the tunnel current.

[0077] 1.4 Needle insertion method 4

[0078] Because the movable end of the tubular external piezoelectric body 21 can only retract to the second lower dead point when it retracts downward in the vertical direction, the length of the first end of the first sliding rod 132 relative to the protruding part of the movable end of the tubular scanning piezoelectric body 131 increased by the third needle insertion method is very limited. Therefore, in the extremely extreme case that the signal acquisition module cannot collect the tunnel current by the third needle insertion method, it is necessary to use the fourth needle insertion method as a backup needle insertion method.

[0079] If the needle is inserted using the third needle insertion method, and the active end of the tubular external piezoelectric body 21 retracts downward in the vertical direction and retracts to the second lower dead point, the signal acquisition module still does not collect the tunnel current, then the computer sends a stop retraction signal to the tubular external piezoelectric body 21 through the signal acquisition module, and the active end of the tubular external piezoelectric body 21 is at the second lower dead point. At the same time, the signal acquisition module sends a retraction signal to the tubular scanning piezoelectric body 131, and the active end of the tubular scanning piezoelectric body 131 continues to retract downward in the vertical direction until it reaches the third lower dead point. The block then sends a needle-advancement signal to the tubular scanning piezoelectric body 131, and the movable end of the tubular scanning piezoelectric body 131 continues to extend upward slowly and uniformly in the vertical direction, driving the probe on the probe holder 134 to continuously approach the sample on the sample holder 12. During this process, if the signal acquisition module collects the tunnel current, the signal acquisition module sends a stop needle-advancement signal to the tubular scanning piezoelectric body 131. At this time, the tubular nested piezoelectric body 221 stops moving, the needle-advancement process ends, and the probe on the probe holder 134 no longer approaches the sample on the sample holder 12, and enters the scanning imaging process.

[0080] If the signal acquisition module still does not detect any tunneling current when the movable end of the tubular scanning piezoelectric element 131 extends vertically to the third upper dead center, the signal acquisition module sends a retraction signal to the tubular scanning piezoelectric element 131. The movable end of the tubular scanning piezoelectric element 131 continues to retract vertically downward until it reaches the third lower dead center. The signal acquisition module then sends a uniform extension signal to the tubular external piezoelectric element 21 for a fifth time interval Δt5. The movable end of the tubular scanning piezoelectric element 131 stops moving at the third lower dead center and continues to extend vertically upward slowly and uniformly. Finally, the signal acquisition module sends an accelerated retraction signal to the tubular external piezoelectric element 21 for a sixth time interval Δt6. The movable end of the tubular external piezoelectric element 21 accelerates and retracts vertically downward. The first sliding rod 132 continues to decelerate vertically upward due to inertia, and dynamic friction occurs between the outer wall of the first sliding rod 132 and the inner wall of the tubular scanning piezoelectric element 131. When the signal acquisition module finishes sending the accelerated retraction signal to the tubular external piezoelectric body 21, the speed of the first sliding rod 132's upward deceleration movement is 0; at this time, the length of the extended portion of the first end of the first sliding rod 132 relative to the active end of the tubular scanning piezoelectric body 131 increases.

[0081] Then the signal acquisition module sends a needle-entry signal to the tubular scanning piezoelectric body 131, and the movable end of the tubular scanning piezoelectric body 131 continuously extends upward in the vertical direction, driving the probe on the probe holder 134 to continuously approach the sample on the sample holder 12. During this process, if the signal acquisition module collects a tunnel current, the signal acquisition module sends a stop needle-entry signal to the tubular scanning piezoelectric body 131. At this time, the tubular nested piezoelectric body 221 stops moving, the needle-entry process ends, and the probe on the probe holder 134 no longer approaches the sample on the sample holder 12, and enters the scanning imaging process; if the tubular When the active end of the tubular scanning piezoelectric body 131 is extended in the vertical direction to the third top dead center, if the signal acquisition module still does not collect the tunnel current, the needle insertion method 4 is repeated, and the length of the protruding portion of the first end of the first sliding rod 132 relative to the active end of the tubular scanning piezoelectric body 131 is continued to be increased until the first elastic extrusion portion 223 moves to the second limit spacing β below the active end of the tubular nested piezoelectric body 221, and the needle insertion method 4 is stopped. At this time, the length of the protruding portion of the first end of the first sliding rod 132 relative to the active end of the tubular scanning piezoelectric body 131 has reached the maximum length L MAX ′.

[0082] In this embodiment, β=2 μm.

[0083] Optionally, when the length of the extended portion of the first end of the first sliding rod 132 relative to the movable end of the tubular scanning piezoelectric body 131 has reached the maximum length L MAX ', if the signal acquisition module still does not collect the tunnel current, the computer will report an error to the technician and notify the technician to inspect the components in the mirror body.

[0084] Because the main function of the tubular scanning piezoelectric body 131 is that its movable end drives the probe holder 134 to scan in the XY plane, although the tubular scanning piezoelectric body 131 also has the function of extending and retracting in the Z-axis direction, its extension range is very limited, and the third upper dead point and the third lower dead point are very close. If you want to directly drive the probe to approach the sample by extending the tubular scanning piezoelectric body 131 until the signal acquisition module collects the tunnel current, it is impossible to do so.

[0085] Because the fourth needle insertion method is based on the third needle insertion method, although the signal acquisition module has not yet collected the tunnel current at this time, the probe may collect the tunnel current if it approaches the sample to a very small distance. In addition, considering that the probe holder 134 is directly fixed on the first end of the first sliding rod 132, in the fourth needle insertion method, although the length of the protruding part of the first end of the first sliding rod 132 relative to the movable end of the tubular scanning piezoelectric body 131 is increased by inertial swing, in the fourth needle insertion method of the present invention, the tubular scanning piezoelectric body 131 is first extended to "test" whether the tunnel current can be collected. If the tubular scanning piezoelectric body 131 has been extended to the third upper dead point and the tunnel current has not been collected, it means that when the tubular scanning piezoelectric body 131 has been retracted to the third lower dead point, the distance between the probe tip and the sample surface is still relatively large. We can safely use the inertial swinging method to increase the length of the protruding part of the first end of the first sliding rod 132 relative to the active end of the tubular scanning piezoelectric body 131. In this process, the needle will not be hit due to the inertial swinging. Then, by extending the tubular scanning piezoelectric body 131, we can "test" whether the tunnel current can be collected, and repeat this process to gradually increase the length of the protruding part of the first end of the first sliding rod 132 relative to the active end of the tubular scanning piezoelectric body 131. However, in order to ensure that the first sliding rod 132 will not be skewed during the needle insertion process, the first elastic squeezing part 133 must always be squeezed by the first sliding rod 132 and the tubular scanning piezoelectric body 131. Therefore, a restriction condition is set in the present invention, that is, the first elastic squeezing part 223 moves to the second limit spacing β below the active end of the tubular nested piezoelectric body 221, and the needle insertion method four is stopped.

[0086] In the nested drive unit 22, a contact surface or line exists between the outer wall of the second sliding rod 222 and the inner wall of the tubular nested piezoelectric body 221. Due to the presence of the second elastic pressing portion 223, which is simultaneously squeezed by the second sliding rod 222 and the tubular nested piezoelectric body 221, the second sliding rod 222 is subjected to balanced forces at all locations in the XY plane. The second sliding rod 222 is also fixed in position by multiple contact surfaces or lines, ensuring that the entire length of the second sliding rod 222 is parallel to the Z-axis. During the needle insertion process, in addition to its own gravity and friction, only the first end of the second sliding rod 222 is subject to the vertical downward external force exerted by the second end of the first sliding rod 132. If the external force exerted by the second end of the first sliding rod 132 is not vertically downward but forms an acute angle with the vertical downward direction, this external force will also be decomposed into a first vertically downward force component and a second force component in the XY plane. The second component of force will pass through the contact surface or contact line of the outer wall of the second sliding rod 222, or the contact surface between the second elastic extrusion portion 223 and the inner wall of the tubular nested piezoelectric body 221, and will eventually be applied to the inner wall of the tubular nested piezoelectric body 221; and this part of the force applied to the inner wall of the tubular nested piezoelectric body 221 will change the degree of extrusion of the second elastic extrusion portion 223 to restore the force balance of the second sliding rod 222 at various locations on the XY plane, so the length direction of the entire second sliding rod 222 is still parallel to the Z-axis direction and will not produce an angle with the Z-axis direction. The probe on the probe holder 134 is also always perpendicular to the sample holder 12, that is, the second sliding rod 222 in the present invention will never be skewed during the needle insertion process.

[0087] Similarly, if the scanning head frame 11 is not skewed, the first sliding rod 132 of the present invention will not be skewed during the needle insertion process. In the scanning unit 13, a contact surface or contact line exists between the outer wall of the first sliding rod 132 and the inner wall of the tubular scanning piezoelectric body 131. At the same time, due to the presence of the first elastic extrusion portion 133, and the fact that the first elastic extrusion portion 133 is simultaneously squeezed by the first sliding rod 132 and the tubular scanning piezoelectric body 131, the first sliding rod 132 is subjected to balanced forces at all locations on the XY plane. The first sliding rod 132 is also fixed in position by multiple contact surfaces or contact lines, ensuring that the entire length of the first sliding rod 132 is parallel to the Z-axis. During the needle insertion process, in addition to its own gravity and friction, only the second end of the first sliding rod 132 will be affected by the vertical upward external force applied by the first end of the second sliding rod 222. If the external force applied by the first end of the second sliding rod 222 is not vertically upward, but forms an acute angle with the vertical upward direction, then the external force will also be decomposed into a third component force vertically downward and a fourth component force in the XY plane. The fourth component of force will pass through the contact surface or contact line of the outer wall of the first sliding rod 132, or the contact surface between the first elastic extrusion portion 133 and the inner wall of the tubular scanning piezoelectric body 131, and will eventually be applied to the inner wall of the tubular scanning piezoelectric body 131; and this part of the force applied to the inner wall of the tubular scanning piezoelectric body 131 will change the degree of extrusion of the first elastic extrusion portion 133 to restore the force balance of the first sliding rod 132 at various locations on the XY plane, so that the length direction of the entire first sliding rod 132 is still parallel to the Z-axis direction and will not form an angle with the Z-axis direction, and the probe on the probe holder 134 is always perpendicular to the sample holder 12.

[0088] Because the imaging module 1 is a relatively independent unit, all components within the imaging module 1 are also relatively independent. Even if the movable end of the tubular external piezoelectric element 21 tilts during its vertical downward retraction in needle insertion method three or needle insertion method four, all components within the entire imaging module 1 will also tilt in the same manner, and the probe on the probe holder 134 will always be perpendicular to the sample holder 12. In this case, even if the entire length of the second sliding rod 222 is parallel to the Z-axis, the external force applied by the first end of the second sliding rod 222 to the second end of the first sliding rod 132 is also tilted relative to the length of the first sliding rod 132. However, combined with the analysis in the previous paragraph, we know that this force applied to the inner wall of the tubular scanning piezoelectric element 131 will restore force balance at various locations on the first sliding rod 132 in the XY plane by changing the degree of compression of the first elastic extrusion portion 133, so that the probe on the probe holder 134 is always perpendicular to the sample holder 12.

[0089] In summary, in the scope of the present invention, during the needle insertion process and the scanning imaging process, the probe on the probe holder 134 is always perpendicular to the sample on the sample holder 12, and will not be skewed on the sample plane. This avoids the situation where the probe damages the sample surface and the imaging quality fluctuates during the subsequent scanning and imaging process due to the skew of the probe, which further improves the efficiency of scanning and imaging.

[0090] Needle insertion methods two, three, and four are further backup methods of the previous needle insertion method, respectively, to ensure that the needle insertion process is smooth, safe and reliable, and each needle insertion method is safe and controllable; furthermore, no matter whether the propagation path of interference factors such as mechanical vibration, environmental vibration, thermal drift, thermal fluctuation, etc. first enters the nested drive unit 22 and then passes through the nested drive unit 22 to the scanning unit 13; or directly passes into the scanning unit 13, they will be greatly weakened or even completely offset, so that the interference that finally reaches the probe frame 134 is greatly reduced or even disappears. When "the propagation path of the mechanical vibration is to first enter the inner nested driving unit 22 and then be transmitted to the scanning unit 13 through the inner nested driving unit 22", the mechanical vibration must pass through the second sliding rod 222 and the first sliding rod 132 in sequence, and finally be transmitted to the probe of the probe holder 134. However, in this propagation path, the energy of the mechanical vibration will be converted into the elastic potential energy of the first elastic squeezing part 133, the elastic potential energy of the second elastic squeezing part 222, and even the heat generated by friction in the process of the first sliding rod 132 approaching the sample holder 12; therefore, the part of the mechanical vibration energy that is finally converted into the kinetic energy that causes the probe holder 134 to suddenly accelerate uncontrollably and approach the sample holder 12 is very small, or even zero. When the "propagation path of the mechanical vibration is directly transmitted to the scanning unit 13", the mechanical vibration must also pass through the first sliding rod 132 and finally be transmitted to the probe of the probe holder 134. However, in this propagation path, the energy of the mechanical vibration will be converted into the elastic potential energy of the first elastic squeezing part 133, or even the heat generated by friction when the first sliding rod 132 approaches the sample holder 12; therefore, the part of the mechanical vibration energy that is finally converted into the kinetic energy that causes the probe holder 134 to suddenly accelerate uncontrollably and approach the sample holder 12 is also very small, and may even be 0.

[0091] During the needle insertion process, the mirror body of the present invention can also significantly reduce the interference amplitude transmitted to the probe frame 134 by interference factors such as mechanical vibration, environmental vibration, thermal drift, thermal fluctuation, etc., enhance the stability of the needle-like tunnel junction, improve the quality and stability of scanning imaging, minimize the occurrence of needle collision, extend the service life of the probe, and avoid damage to the sample.

[0092] 2. Scanning imaging process

[0093] During the scanning imaging process, the probe tip and the sample surface still maintain a certain distance.

[0094] After the tubular scanning piezoelectric body 131 receives the scanning signal sent by the signal acquisition module, the movable end of the tubular scanning piezoelectric body 131 drives the first sliding rod 132 to move in the XY plane. The movement of the first end of the first sliding rod 132 in the XY plane can synchronously drive the probe holder 134 to move in the XY plane, so that the probe on the probe holder 134 scans and images the sample surface on the sample holder 12. After the scanning and imaging process is completed, the tubular scanning piezoelectric body 131 receives the reset signal sent by the signal acquisition module, and the movable end of the tubular scanning piezoelectric body 131 returns to the vertical direction. After the length direction of the entire tubular scanning piezoelectric body 131 is parallel to the Z axis, the needle retraction process begins.

[0095] 3. Needle withdrawal process

[0096] The needle withdrawal process includes a needle withdrawal preparation stage and a needle withdrawal stage in sequence. The needle withdrawal stage includes n consecutive needle withdrawal cycles, where n is a positive integer.

[0097] When the needle retraction begins, the signal acquisition module sends a retraction signal to the tubular inner nested piezoelectric body 221. When the movable end of the tubular inner nested piezoelectric body 221 retracts to the first bottom dead point, the needle retraction preparation phase ends and the needle retraction phase begins.

[0098] The shortest length of the tubular inner-nested piezoelectric body 221 is the length when the movable end of the tubular inner-nested piezoelectric body 221 retracts to the first bottom dead point.

[0099] During the needle withdrawal preparation stage, static friction always occurs between the outer wall of the second sliding rod 222 and the inner wall of the tubular embedded piezoelectric body 221 .

[0100] In any needle withdrawal cycle during the needle withdrawal phase:

[0101] First, the signal acquisition module sends a retraction signal to the tubular external piezoelectric body 21 and lasts for a first time interval Δt1. The movable end of the tubular external piezoelectric body 21 retracts slowly and uniformly downward in the vertical direction, and the entire imaging module 1 descends slowly and uniformly in the vertical direction. There is static friction between the outer wall of the first sliding rod 132 and the inner wall of the tubular scanning piezoelectric body 131.

[0102] The signal acquisition module then sends an acceleration signal to the tubular external piezoelectric element 21 for a second time interval Δt2. The active end of the tubular external piezoelectric element 21 accelerates and extends vertically upward. Inside the imaging module 1, the first sliding rod 132, due to inertia, continues to decelerate downward in the vertical direction. Dynamic friction occurs between the outer wall of the first sliding rod 132 and the inner wall of the tubular scanning piezoelectric element 131. When the signal acquisition module stops sending the acceleration signal to the tubular external piezoelectric element 21, the downward deceleration speed of the first sliding rod 132 reaches zero, marking the end of the current needle retraction cycle and the beginning of the next. This continues until n needle retraction cycles have been completed, concluding the needle retraction phase and the process.

[0103] At the end of each needle withdrawal cycle, the distance between the probe holder 134 and the sample holder 12 increases by L, that is, in each needle withdrawal cycle, the needle withdrawal distance is L. When the current needle withdrawal process ends, the needle withdrawal distance is nL.

[0104] In this embodiment, L=1 μm, and n=100.

[0105] During a needle withdrawal process, the number of consecutive needle withdrawal cycles n is determined by the technician. Usually n will not be too large. When n is too large, the following problems may occur:

[0106] ① This may cause the second end of the first sliding rod 132 to collide with the first end of the second sliding rod 222. If there are still unexecuted needle withdrawal cycles to be executed during the current needle withdrawal process, the distance between the probe holder 134 and the sample holder 12 will not increase, and the second end of the first sliding rod 132 will repeatedly collide with the first end of the second sliding rod 222. This not only wastes experimental time and reduces experimental efficiency, but also may cause components within the imaging module 1 to loosen due to these multiple meaningless collisions.

[0107] Even if the second end of the first sliding rod 132 and the first end of the second sliding rod 222 do not collide, if n is too large, it means that the distance between the probe holder 134 and the sample holder 12 will be too far during the next experiment. This will lead to the special situation mentioned above, where using only the needle insertion method may not ensure the successful completion of the needle insertion process. In other words, if n is too large, not only will the needle withdrawal process of the current experiment be prolonged, but it will also increase the time for the next needle insertion process, reducing experimental efficiency.

[0108] Therefore, when setting the value of n, technicians must not only comprehensively consider preventing the second end of the first sliding rod 132 from colliding with the first end of the second sliding rod 222, but also consider whether the distance between the probe holder 134 and the sample holder 12 is too far during the next needle insertion process.

[0109] Optionally, during the needle withdrawal process, when the second end of the first sliding rod 132 collides with the first end of the second sliding rod 222 , the current needle withdrawal cycle is terminated, and the current needle withdrawal process is also terminated.

[0110] The needle withdrawal process in the scope of the present invention is divided into a needle withdrawal preparation stage and a needle withdrawal stage. First, the tubular internally nested piezoelectric body 221 is retracted in the needle withdrawal preparation stage to clear obstacles in the vertical direction for the subsequent needle withdrawal stage; then, in the subsequent needle withdrawal stage, the needle withdrawal is completed through n consecutive needle withdrawal cycles; each needle withdrawal cycle relies solely on the tubular external piezoelectric body 21 and utilizes the inertia generated by sudden reverse acceleration to withdraw the needle, and the needle withdrawal speed is extremely fast.

[0111] There are also existing technologies that use the inertia during sudden acceleration to advance or retract the needle in the scope. Although this method of advancing or retracting the needle is very fast, if the inertial force is not restricted, it can easily cause the probe in the scanning head to hit the needle when it approaches the sample. Therefore, "using the inertia during sudden acceleration to advance or retract the needle" has always been considered a defect that needs to be overcome. In subsequent improvement schemes, a hook is used in the scope to connect the inertial motor and the scanning head. This can limit the advancement or retraction displacement of the scanning head through the hook while utilizing the inertial force, reducing the probability of needle collision. However, because the inertial motor often has a large step size and low limiting accuracy, needle collision is still common. In addition, the appearance of the hook not only increases the mechanical vibration in the scope, but also increases the way for the mechanical vibration in the scope to be transmitted to the probe.

[0112] The present invention not only completely avoids the use of "using a hook to connect the inertial motor and the scanning head", but also overcomes the prejudice of the prior art:

[0113] ① The inertia during sudden acceleration is still used to withdraw the needle, ensuring efficient needle withdrawal; the inertia during sudden acceleration is also used during the needle insertion process to ensure the smooth insertion process and at the same time ensure the safety and reliability of the needle insertion process.

[0114] ② Because the nested drive unit 22 and the scanning unit 13 are not connected all the time, but only when the probe holder 134 is actually pushed close to the sample holder 12, there is contact between the nested drive unit 22 and the scanning unit 13. By reducing the contact time, the probability of mechanical vibration being transmitted to the scanning unit 13 through the nested drive unit 22 is reduced.

[0115] ③ The structure inside the nested drive unit 22 and the scanning unit 13 of the present invention can adjust the non-vertical external force by itself, ensuring that the probe on the probe holder 134 is always perpendicular to the sample holder 12 during the entire needle insertion process and the start of the scanning imaging process; it can also use the elastic potential energy and the internal energy generated by friction to greatly weaken or even completely offset the interference that eventually reaches the probe holder 134.

[0116] ④ The structure inside the nested driving unit 22 and the scanning unit 13 of the present invention effectively controls the process and displacement of the probe holder 134 approaching the sample holder 12 through friction.

[0117] The needle withdrawal process of the present invention will not cause a needle collision. During the needle withdrawal process, a needle collision will only occur at the moment when the needle withdrawal actually begins, which corresponds to the moment when the movable end of the tubular external piezoelectric body 21 accelerates and extends upward in the vertical direction during the first needle withdrawal cycle of the needle withdrawal stage of the present invention. At this moment, regardless of whether there are interference factors such as mechanical vibrations transmitted to the imaging module 1 through the movable end of the tubular external piezoelectric body 21, and regardless of the force and direction of the interference factors, at this moment, the probe holder 134 moves in a direction away from the sample holder 12 relative to the sample holder 12, so the needle withdrawal process of the present invention will not cause a needle collision at all.

[0118] The driving voltage during the needle withdrawal process of the present invention is relatively small and the applicable temperature range is wide.

[0119] Corresponding to the analysis above regarding the needle insertion process, the imaging module 1 is a relatively independent component. Even during the needle withdrawal process, if the movable end of the tubular external piezoelectric element 21 tilts while vertically retracting downward or extending upward, all components within the entire imaging module 1 will also tilt in the same manner, and the probe on the probe holder 134 will remain perpendicular to the sample holder 12. In other words, the imaging module 1 is configured as a relatively independent component, supplemented by the internally nested drive unit 22 and scanning unit 13, ensuring that the probe on the probe holder 134 in the scanning unit 13 remains perpendicular to the sample holder 12 at all times.

[0120] In the scanning probe microscope of the present invention, the internally nested drive unit 22 and the tubular external piezoelectric body 21 are nested inside and outside, which greatly improves the space utilization rate in the microscope body and makes the structure in the microscope body more compact. At the same time, unlike the piezoelectric body in the prior art, which is responsible for both needle insertion and needle withdrawal, once the piezoelectric body fails, the entire experiment cannot be carried out. In the present invention, the internally nested drive unit 22 and the tubular external piezoelectric body 21 each perform their respective duties, respectively responsible for needle insertion and needle withdrawal. Damage to any one piezoelectric body will not directly affect the normal operation of other piezoelectric bodies, and the faulty piezoelectric body can be easily identified based on the cause of the failure (such as sudden inability to withdraw the needle, etc.). Because the probability of needle insertion method three and needle insertion method four being used is extremely small, the probability of the tubular external piezoelectric body 21 participating in these two needle insertion methods is also extremely small.

[0121] In the scanning probe microscope body of the present invention, the probe on the probe holder 134 can be ensured to be always perpendicular to the sample holder 12 during the needle insertion process and the start of the scanning imaging process, thereby avoiding damage to the probe tip and the sample surface due to contact and collision during the scanning imaging process, and avoiding the situation where the imaging quality is sometimes good and sometimes bad during the scanning imaging process, which further improves the efficiency of scanning imaging.

[0122] In the scanning probe microscope body of the present invention, both the needle insertion process and the scanning imaging process are achieved by using the elastic potential energy and frictional heat generated by the nested drive unit 22 and the scanning unit 13 to greatly weaken or even completely offset the interference that eventually reaches the probe holder 134. This ensures that even if the probe advances toward the sample due to interference, it will only advance a very small distance, minimizing the occurrence of the probe tip colliding with the sample surface, thereby extending the probe's service life and avoiding damage to the sample.

[0123] In the scanning probe microscope body of the present invention, the needle withdrawal process is not only fast but also will never cause the needle to be hit.

[0124] In summary, the scanning probe microscope of the present invention can avoid the occurrence of needle collisions as much as possible during the entire experimental process, thereby improving the quality and stability of imaging and enhancing the experimental efficiency.

[0125] like Figure 4 The existing technology is a scanning probe microscope that uses a hook to connect the inertial motor and the scanning head. Figure 5 From the scanning imaging of the present invention, it can be seen that the clarity of the imaging of the scanning probe microscope of the present invention is significantly higher than that of the imaging of the prior art; and the overall clarity of the imaging of the present invention is similar, that is, the imaging quality of the present invention is relatively stable, while the imaging of the prior art is slightly clearer in some places and very blurry in some places, that is, the imaging quality of the prior art is very unstable.

[0126] Example 2

[0127] The present invention also provides a scanning imaging method, using a tubular nested bi-piezoelectric scanning probe microscope as described in Example 1, comprising the following steps:

[0128] S1, the needle insertion process adopts the needle insertion method 1: when the signal acquisition module sends a needle insertion signal to the tubular nested piezoelectric body 221, the movable end of the tubular nested piezoelectric body 221 continuously extends upward in the vertical direction, causing the second sliding rod 222 to rise and enter the tubular scanning piezoelectric body 131 from the fixed end of the tubular scanning piezoelectric body 131, and then push the first sliding rod 132 to rise, then the probe on the probe holder 134 continuously approaches the sample on the sample holder 12, until the signal acquisition module collects the tunnel current, the movable end of the tubular nested piezoelectric body 221 stops extending upward, the needle insertion process ends, and enters the scanning imaging process.

[0129] S2, scanning and imaging process: when the signal acquisition module sends a scanning signal, the movable end of the tubular scanning piezoelectric body 131 drives the probe holder 134 set at the first end of the first sliding rod 132 to move in the XY plane, and the probe scans and images the sample surface.

[0130] S3, after the scanning imaging is completed, the needle retraction process begins: at the beginning of the current needle retraction cycle, the signal acquisition module first sends a retraction signal to the tubular external piezoelectric body 21 for a first time interval Δt1, and the movable end of the tubular external piezoelectric body 21 drives the imaging module 1 to slowly and uniformly retract downward in the vertical direction; then the signal acquisition module sends an acceleration rise signal to the tubular external piezoelectric body 21 for a second time interval Δt2, and the movable end of the tubular external piezoelectric body 21 drives the imaging module 1 to accelerate upward in the vertical direction, and the first sliding rod 132 moves downward relative to the tubular scanning piezoelectric body 131 through inertial swing;

[0131] When the acceleration rising signal sent by the signal acquisition module ends, the current needle withdrawal cycle ends, and the distance between the probe holder 134 and the sample holder 12 increases by L.

[0132] Optionally, in S1, if the signal acquisition module still fails to collect tunnel current when the movable end of the tubular nested piezoelectric body 221 is extended to the first top dead center, the second needle insertion method is adopted, including steps 1a to 4a:

[0133] Step 1a: The signal acquisition module sends a retraction signal to the tubular inner nested piezoelectric body 221, and the movable end of the tubular inner nested piezoelectric body 221 slowly and uniformly retracts downward in the vertical direction to a first bottom dead point;

[0134] Step 2a: The signal acquisition module sends a uniform extension signal to the tubular inner-nested piezoelectric body 221 for a third time interval Δt3, and the movable end of the tubular inner-nested piezoelectric body 221 slowly and uniformly extends upward in the vertical direction.

[0135] In step 3a, the signal acquisition module sends an accelerated retraction signal to the tubular nested piezoelectric body 221 and continues for a fourth time interval Δt4. The movable end of the tubular nested piezoelectric body 221 accelerates and retracts downward in the vertical direction, and the second sliding rod 222 decelerates and moves upward in the vertical direction due to inertia. At the moment when the signal acquisition module stops sending the accelerated retraction signal to the tubular nested piezoelectric body 221, the speed of the second sliding rod 222 decelerating upward is 0.

[0136] Step 4a, repeat the needle insertion method 1. If the signal acquisition module collects the tunnel current, the movable end of the tubular nested piezoelectric body 221 stops extending upward, the needle insertion process ends, and the scanning imaging process begins. If the movable end of the tubular nested piezoelectric body 221 extends to the first upper dead point, the signal acquisition module still does not collect the tunnel current, then return to step 1a.

[0137] Optionally, in S1, when the second elastic extrusion portion 223 moves to the first limit spacing α below the movable end of the tubular nested piezoelectric body 221, and the movable end of the tubular nested piezoelectric body 221 is extended to the upper first stop point, the signal acquisition module still does not collect the tunnel current, then the needle insertion method three is adopted: the signal acquisition module sends a stop needle insertion signal to the tubular nested piezoelectric body 221, and the movable end of the tubular nested piezoelectric body 221 no longer moves. At the same time, the signal acquisition module sends a retraction signal to the tubular external piezoelectric body 21, and the movable end of the tubular external piezoelectric body 21 drives the imaging module 1 to retract slowly and uniformly downward in the vertical direction; the second sliding rod 222 enters the tubular scanning piezoelectric body 131 from the fixed end of the tubular scanning piezoelectric body 131, and pushes the first end of the first sliding rod 132 to continuously approach the sample on the sample holder 12 until the signal acquisition module collects the tunnel current, the movable end of the tubular external piezoelectric body 21 stops retracting, the needle insertion process ends, and the scanning imaging process begins.

[0138] Optionally, in S1, when the movable end of the tubular external piezoelectric body 21 retracts vertically downward to the second bottom dead point, and the signal acquisition module still does not collect the tunnel current, the needle insertion method 3 is stopped and the needle insertion method 4 is adopted, including steps 1b to 4b:

[0139] Step 1b: The signal acquisition module sends a stop retraction signal to the tubular external piezoelectric element 21, and the movable end of the tubular external piezoelectric element 21 is located at the second bottom dead center. At the same time, the signal acquisition module sends a retraction signal to the tubular scanning piezoelectric element 131, and the movable end of the tubular scanning piezoelectric element 131 retracts vertically to the third bottom dead center.

[0140] In step 2b, the signal acquisition module sends a needle-advancement signal to the tubular scanning piezoelectric body 131. The movable end of the tubular scanning piezoelectric body 131 drives the probe holder 134 to extend upward at a uniform speed in the vertical direction, driving the probe on the probe holder 134 to continuously approach the sample on the sample holder 12. If the signal acquisition module detects a tunneling current, the signal acquisition module sends a needle-advancement-stopping signal to the tubular scanning piezoelectric body 131. The tubular nested piezoelectric body 221 stops moving, the needle-advancement process ends, and the scanning imaging process begins. If the movable end of the tubular scanning piezoelectric body 131 extends vertically to the third upper dead point and the signal acquisition module still does not detect a tunneling current, the signal acquisition module sends a retraction signal to the tubular scanning piezoelectric body 131. The movable end of the tubular scanning piezoelectric body 131 retracts vertically downward to the third lower dead point.

[0141] Step 3b: The signal acquisition module sends a uniform extension signal to the tubular external piezoelectric body 21 for a fifth time interval Δt5, and the movable end of the tubular external piezoelectric body 21 uniformly extends upward in the vertical direction;

[0142] In step 4b, the signal acquisition module sends an accelerated retraction signal to the tubular external piezoelectric element 21 for a sixth time interval Δt6. The movable end of the tubular external piezoelectric element 21 accelerates and retracts downward in the vertical direction, while the first sliding rod 132 decelerates and moves upward in the vertical direction due to inertia. When the signal acquisition module stops sending the accelerated retraction signal to the tubular external piezoelectric element 21, the speed of the first sliding rod 132's upward deceleration is zero.

[0143] Step 5b, return to step 2b, if the length of the first end of the first sliding rod 132 relative to the active end of the tubular scanning piezoelectric body 131 has reached the maximum length L MAX ′, if the signal acquisition module still fails to collect the tunnel current, the computer will report an error to the technician.

[0144] In S3, before the first needle retraction cycle begins, a needle retraction preparation phase is also included: the signal acquisition module sends a retraction signal to the tubular inner nested piezoelectric element 221. The needle retraction preparation phase ends when the movable end of the tubular inner nested piezoelectric element 221 retracts to the first bottom dead center. The needle retraction process includes n consecutive needle retraction cycles, where n is a positive integer.

[0145] The scanning imaging method of the present invention can significantly reduce interference within the scanning tunneling microscope, minimize needle collisions, improve imaging quality and stability, and enhance experimental efficiency. Four needle insertion methods are provided during the needle insertion process. Methods 2, 3, and 4 are further backup methods of the previous method, and based on the previous method, they bring the probe closer to the sample to ensure a smooth, safe, and reliable needle insertion process. Each method is safe and controllable.

[0146] The technology, shape, and structure not described in detail in the present invention are all well-known technologies.

[0147] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A tubular nested bi-piezoelectric scanning probe microscope, comprising a microscope body, a signal acquisition module, and a computer, wherein the microscope body and the signal acquisition module are electrically connected, and characterized in that: The mirror body includes, in a vertical direction from top to bottom, a fixedly connected imaging module (1), a driving module (2) and a base (3), wherein the imaging module (1) includes a scanning head frame (11), a sample holder (12) and a scanning unit (13), and the sample holder (12) and the scanning unit (13) are relatively arranged in the scanning head frame (11); the driving module (2) includes an inner nested driving unit (22) and a tubular external piezoelectric body (21) which are arranged in an inner and outer nested manner, the inner nested driving unit (22) drives the scanning unit (13) to advance the needle, and the two ends of the tubular external piezoelectric body (21) are fixedly connected to the base (3) and the scanning head frame (11) respectively, and the tubular external piezoelectric body (21) swings the scanning unit (13) to withdraw the needle by inertia; The scanning unit (13) includes a tubular scanning piezoelectric body (131), a first sliding rod (132) and a probe frame (134), wherein the tubular scanning piezoelectric body (131) includes a fixed end and a movable end, wherein the fixed end of the tubular scanning piezoelectric body (131) is fixedly arranged at the bottom of the inner cavity of the scanning head frame (11), and a through hole is provided at the bottom of the scanning head frame (11) corresponding to the fixed end of the tubular scanning piezoelectric body (131), and the tubular scanning piezoelectric body (131) is open at both ends and hollow inside, and the first The sliding rod (132) is nested inside the tubular scanning piezoelectric body (131), and the two ends of the first sliding rod (132) are respectively recorded as a first end and a second end. The first end of the first sliding rod (132) is close to the sample holder (12), and the second end of the first sliding rod (132) is away from the sample holder (12). The probe holder (134) is fixedly arranged on the first end of the first sliding rod (132); the inner nested driving unit (22) drives the first sliding rod (132) to advance the needle; The inner nested driving unit (22) includes a tubular inner nested piezoelectric body (221) and a second sliding rod (222), the tubular inner nested piezoelectric body (221) includes a fixed end and a movable end, the fixed end of the tubular inner nested piezoelectric body (221) is fixedly arranged on the base (3), the movable end of the tubular inner nested piezoelectric body (221) is open and hollow inside, the second sliding rod (222) is nested inside the tubular inner nested piezoelectric body (221) and extends from the movable end of the tubular inner nested piezoelectric body (221), the two ends of the second sliding rod (222) are respectively recorded as the first end and the second end, the first end of the second sliding rod (222) is close to the second end of the first sliding rod (132), and the second end of the second sliding rod (222) is away from the second end of the first sliding rod (132); the first end of the second sliding rod (222) enters and exits from the fixed end of the tubular scanning piezoelectric body (131); The scanning unit (13) further comprises a first elastic extrusion portion (133), the first elastic extrusion portion (133) being fixedly arranged on the outer wall of the first sliding rod (132), and the first elastic extrusion portion (133) being squeezed by the first sliding rod (132) and the tubular scanning piezoelectric body (131); The inner nested driving unit (22) further includes a second elastic extrusion portion (223), the second elastic extrusion portion (223) being fixedly arranged on the outer wall of the second sliding rod (222), and the second sliding rod (222) being squeezed by the second sliding rod (222) and the tubular inner nested piezoelectric body (221).

2. The tubular nested bi-piezoelectric scanning probe microscope according to claim 1, characterized in that: The distance between the outer wall of the tubular internally nested piezoelectric body (221) and the inner wall of the tubular externally positioned piezoelectric body (21) is greater than 0.

3. The tubular nested bi-piezoelectric scanning probe microscope according to claim 1, characterized in that: The outer wall of the first sliding rod (132) is in line contact with the inner wall of the tubular scanning piezoelectric body (131).

4. A scanning imaging method, using a tubular nested bi-piezoelectric scanning probe microscope as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: S1, the needle insertion process adopts the needle insertion method 1: the signal acquisition module sends a needle insertion signal to the tubular nested piezoelectric body (221), and the movable end of the tubular nested piezoelectric body (221) extends upward in the vertical direction, driving the second sliding rod (222) to rise and enter the tubular scanning piezoelectric body (131) from the fixed end, and then pushes the first sliding rod (132) to rise, so that the probe on the probe holder (134) continuously approaches the sample on the sample holder (12), until the signal acquisition module collects the tunnel current, the movable end of the tubular nested piezoelectric body (221) stops extending upward, the needle insertion process ends, and the scanning imaging process begins; S2, scanning imaging process: the signal acquisition module sends a scanning signal to the tubular scanning piezoelectric body (131), and the movable end of the tubular scanning piezoelectric body (131) drives the probe holder (134) provided at the first end of the first sliding rod (132) to move in the XY plane, and the probe scans and images the sample surface; S3, after the scanning imaging is completed, the needle retraction process begins: when the current needle retraction cycle begins, the signal acquisition module first sends a retraction signal to the tubular external piezoelectric body (21) and lasts for a first time interval △t1, and the active end of the tubular external piezoelectric body (21) drives the imaging module (1) to retract slowly and uniformly in the vertical direction; then the signal acquisition module sends an acceleration rise signal to the tubular external piezoelectric body (21) and lasts for a second time interval △t2, and the active end of the tubular external piezoelectric body (21) drives the imaging module (1) to extend upward in the vertical direction at an accelerated speed, and the first sliding rod (132) moves downward relative to the tubular scanning piezoelectric body (131) through inertial swing; The acceleration rising signal sent by the signal acquisition module ends, the current needle withdrawal cycle also ends, and the distance between the probe holder (134) and the sample holder (12) increases by L.

5. A scanning imaging method according to claim 4, characterized in that: In S1: If the signal acquisition module still fails to collect the tunnel current when the movable end of the tubular nested piezoelectric body (221) is extended to the first top dead center, the second needle insertion method is adopted, including steps 1a to 4a: Step 1a, the signal acquisition module sends a retraction signal to the tubular inner nested piezoelectric body (221), and the movable end of the tubular inner nested piezoelectric body 221 slowly and uniformly retracts downward to a first bottom dead point in the vertical direction; Step 2a, the signal acquisition module sends a uniform extension signal to the tubular inner nested piezoelectric body (221) for a third time interval Δt3, and the movable end of the tubular inner nested piezoelectric body (221) slowly and uniformly extends upward in the vertical direction; Step 3a, the signal acquisition module sends an accelerated retraction signal to the tubular inner nested piezoelectric body (221) for a fourth time interval Δt4, the movable end of the tubular inner nested piezoelectric body (221) accelerates and retracts downward in the vertical direction, and the second sliding rod (222) decelerates and moves upward in the vertical direction due to inertia; at the moment when the signal acquisition module finishes sending the accelerated retraction signal to the tubular inner nested piezoelectric body (221), the speed of the second sliding rod (222) decelerating and moving upward is 0; Step 4a, repeating the needle insertion method 1, if the signal acquisition module collects the tunnel current, the movable end of the tubular inner nested piezoelectric body (221) stops extending upward, the needle insertion process ends, and the scanning imaging process begins. If the signal acquisition module still does not collect the tunnel current when the movable end of the tubular inner nested piezoelectric body (221) extends to the first top dead center, then returning to step 1a; If the second elastic extrusion portion (233) moves to the first limit spacing α below the movable end of the tubular inner nested piezoelectric body (221), and the movable end of the tubular inner nested piezoelectric body (221) is extended to the upper first stop point, and the signal acquisition module still does not collect the tunnel current, the needle insertion method three is adopted: The signal acquisition module sends a stop needle insertion signal to the tubular internally nested piezoelectric body (221), and the movable end of the tubular internally nested piezoelectric body (221) stops moving. At the same time, the signal acquisition module sends a retraction signal to the tubular externally mounted piezoelectric body (21), and the movable end of the tubular externally mounted piezoelectric body (21) drives the imaging module (1) to retract slowly and uniformly downward in the vertical direction. The second sliding rod (222) enters the tubular scanning piezoelectric body (131) from the fixed end thereof, and then pushes the first end of the first sliding rod (132) to continuously approach the sample on the sample holder (12), until the signal acquisition module collects the tunnel current, at which point the movable end of the tubular externally mounted piezoelectric body (21) stops retracting, the needle insertion process ends, and the scanning imaging process begins.

6. A scanning imaging method according to claim 4 or 5, characterized in that: In S3: before the first needle withdrawal cycle begins, a needle withdrawal preparation phase is also included: the signal acquisition module sends a retraction signal to the tubular inner nested piezoelectric body (221), and when the movable end of the tubular inner nested piezoelectric body (221) retracts to the first bottom dead point, the needle withdrawal preparation phase ends; the needle withdrawal process includes n consecutive needle withdrawal cycles, where n is a positive integer.

Images