Monitoring of piezoelectric scanners micro-displacement.

Meta robots: development of physical and technical principles for ensuring micro-movement of objects in scanning probe microscopy, which is implemented with the help of piezoelectric scanners

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Scanning probe microscopy (SPM) is one of the most difficult modern methods for studying the properties of the surface of a solid. Nowadays, practically every research in the field of surface physics and microtechnology cannot be done without the use of SPM methods.

The principles of scanning probe microscopy can be used as the basic basis for the development of technology for the creation of solid-state structures on a nanoscale scale (1 nm = 10 A). First of all, technological practice of the creation of man-made objects destroys the nutrition of the vicarious principles of atomic folding during the preparation of industrial viruses. Such an approach opens up prospects for the implementation of devices that can accommodate a large number of individual atoms in one’s warehouse.

The scanning tunneling microscope (STM), the first of the family of probe microscopes, was discovered in 1981 by Swiss scientists G. Binnig and G. Rohrer. In their robots, they showed that it is possible to achieve a simple and effective way of tracking surfaces with high spatial resolution, right down to atomic order. The correct knowledge of this technique was obtained after visualization of the atomic structure on the surface of a number of materials, such as spores, and reconstructed surfaces of silicon. In 1986, for the development of the tunnel microscope, G. Binnigu and G. Poper were awarded the Nobel Prize in Physics. Following the tunnel microscope, within a short hour, an atomic force microscope (AFM), a magnetic force microscope (MSM), an electric force microscope (ESM), an optical microscope (BOM), close to the same and many other okay, that similar principles of work may exist and the name scanning probe microscopes.

1. Basic principles of robotic probe microscopes that can be scanned.

In scanning probe microscopes, the investigation of the microrelief and local structures of the surface is carried out using a special method of preparing probes of the holotype type. The radius of rounding of the working part of such probes (vist) is approximately ten nanometers in size. It is typical for the distance between the probe and the surface of the stains in probe microscopes to be in the order of magnitude 0.1 – 10 nm.

p align="justify"> The operation of probe microscopes is based on different types of physical interaction between the probe and the atoms on the surface of the particles. Thus, the operation of the tunnel microscope is based on the detection of the passage of the tunnel stream between the metal head and the eye to be carried out; Various types of force interactions underlie the operation of atomic force, magnetic force and electric force microscopes.

Let's take a look at the dark rice, powered by different probe microscopes. Let the interaction of the probe with the surface be characterized by a specific parameter R. Because it is enough to cut and the length of the parameter is mutually unambiguous R in front of the stand there is a probe - a P = P(z), then this parameter can be used to organize the feedback system (OS), which controls the position between the probe and the probe. In Fig. Figure 1 schematically shows the fundamental principle of organizing the folding joint of a scanning probe microscope.

Small 1. Scheme of the system of the gateway of the probe microscope

The gate system maintains the parameter value R steady, equal in size Ro, which is specified by the operator. As soon as the probe is inserted, the surface changes (for example, increases), a change (increase) of the parameter is required R. The OS system generates a differential signal proportional to the value. P= P - Po, which is reduced to the required value and fed to the final element IE. The final element produces a resonant signal by bringing the probe close to the surface or by removing further parts until the signal becomes zero. In this way, it is possible to obtain a probe with high accuracy. In regular probe microscopes, the accuracy of the probe-surface alignment reaches ~0.01 Å. When the probe is moved from the surface of the sample, the interaction parameter is changed R covered with surface relief. The OS system responds to changes, so when the probe moves in the X,Y area, the signal on the final element appears proportional to the surface topography.

To capture SPM images, a special process of image scanning is required. When scanned, the probe immediately collapses over the surface of the line (row), and the value of the signal on the tip element, proportional to the surface relief, is recorded in the computer memory. Then the probe rotates at the exit point and moves to the next scanning row (frame layout) and the process is repeated again. Recordings in this manner, when scanned, the return signal is processed by the computer, and then the surface relief is imaged. Z = f(x, y) Will work on additional computer graphics skills. In order to study the surface topography, probe microscopes allow one to study various surface properties: mechanical, electrical, magnetic, optical and many others.

7. Suspension of a scanning probe microscope for the investigation of biological objects

7. Suspension of a scanning probe microscope for the observation of biological objects.

7.1. Robot goals 2

7.2. Information for tab 3

7.4. Methodical additions 31

7.5. Safety equipment 32

7.6. Zavdannya 32

7.7. Control nutrition 32

7.8. Literature 32

The laboratory work was developed by the Nizhny Novgorod State University named after. N.I. Lobachevsky

7.1.Robot goals

The study of the morphological parameters of biological structures is an important task for biologists, since the size and shape of these structures largely indicate their physiological powers. Comparing morphological data with functional characteristics, it is possible to obtain valuable information about the role of living cells in maintaining the physiological balance of the human or animal body.

Previously, biologists and physicians were rarely able to analyze their preparations using optical and electron microscopes. These investigations gave a clear picture of the morphology of the cells, fixed, barbed, and thin metal coatings, trimmed with a sawing path. It was impossible to trace the morphology of living objects and their changes under the influx of different officials, but it would have been even more difficult.

Scanning probe microscopy (SPM) has revealed new possibilities in studied cells, bacteria, biological molecules, and DNA in the minds as close as possible to native ones. SPM makes it possible to monitor biological objects without special fixatives or barvnikov, in the open air, or near rare media.

Currently, SPM is used in a wide variety of disciplines, both in fundamental scientific research and in applied high-tech developments. Many scientific and advanced institutes of the region are equipped with probe microscopy equipment. In connection with this, the demand for high-class specialists is steadily growing. For the satisfaction of the company NT-MDT (Zelenograd, Russia) has developed a specialized primary scientific laboratory of scanning probe microscopy. NanoEducator.

SPM NanoEducator Specially designed for laboratory work by students. This device is aimed at the student audience: it is entirely controlled from a separate computer, has a simple and basic interface, animation support, transfers step-by-step mastered techniques, a variety of complex adjustments and inexpensive expenses no materials.

In this laboratory robot you will learn about scanning probe microscopy, get to know its basics, understand the design and operating principles of the initial SPM NanoEducator, learn to prepare biological preparations for surveillance, take your first SPM images of a complex of lactic acid bacteria, and learn the basics of processing and reporting the results of vimirvania.

7.2.Information for payout 1

Laboratory work consists of several stages:

1. The preparation of the sample is decided by each student individually.

2. The first image is removed from one device under the control of the display, and then the student traces his image independently.

3. Processing of experimental data by each student must be done individually.

Butt for investigation: lactic acid bacteria on the surface of the glass.

Before starting work, it is necessary to select a probe with the most characteristic amplitude-frequency response (the same symmetrical maximum), and take an image of the surface of the sample that is being monitored.

The laboratory robot is responsible for including:

1. theoretical part (videos on the control diet).

2. results of the experimental part (description of the investigations carried out, abstraction of the results and development of findings).

1. Methods for tracking the morphology of biological objects.

2. Scanning probe microscope:

SPM design;

Types of SPM: STM, AFM;

SPM data format; Visualization of SPM data.

3. Preparation of samples for SPM follow-up:

morphology and structure of bacterial cells;

preparation of preparations for the development of morphology from SPM stagnation.

4. Familiarity with the design and control program of the NanoEducator SPM.

5. Trimming the SPM image.

6. Processing and analysis of captured images. Kilkisna characterized by SPM image.

Methods for studying the morphology of biological objects

The characteristic diameter of cells is 10  20 µm, bacteria from 0.5 to 3  5 µm, which is 5 times the fraction per found particle visible with the naked eye. Therefore, the first diagnosis of cells became possible only after the advent of optical microscopes. For example, the XVII century. Antonio van Leeuwenhoek produced the first optical microscope, until which people did not suspect the existence of pathogenic microbes and bacteria [Lit. 7-1].

Optical microscopy

Difficulties in the treatment of cells are associated with the fact that the stench of barn-free and open spaces is due to the fact that the restoration of their basic structures was possible only after the introduction of barn-berries into practice. Barvniki ensured sufficient image contrast. Using an optical microscope, objects can be separated, separated from each other by 0.2 µm, then. The smallest objects that can be separated in an optical microscope are bacteria and mitochondria. The images of other elements of the cells are created by the effects inspired by the chylous nature of the light.

To prepare preparations that can be stored for a long time, the cells are treated with a fixing agent in order to immobilize and preserve them. On the other hand, fixation increases the availability of cells to barnworms, because Clint macromolecules are held together by cross-links, which stabilizes and secures them in their original position. Most often, aldehydes and alcohols act as fixatives (for example, glutaraldehyde or formaldehyde form covalent bonds with free amino groups of proteins and cross-link liquid molecules). After fixing the tissue, be sure to cut the tissue into very thin sections (1 to 10 µm thick), which are then placed on a slide. With this method of preparation, the structure of cells or macromolecules can be damaged; the most important method is freezing. Cut frozen tissue with a microtome placed in a cold chamber. After preparing the cabbage slices, prepare them. Mainly for this purpose, organic marigolds (malachite greens, black sudan, etc.) are used. The skin from them is characterized by its sporidity to the cellular components, for example, hematoxylin has a sporidity with negatively charged molecules, which allows DNA to be detected in the cells. Since this molecule is present in the cell in an insignificant quantity, it is best to use fluorescence microscopy.

Fluorescence microscopy

Fluorescent barnberries fade lightly in one vine and give way to light in other, larger vines. If such a speech is washed away with light, then a filter is used for analysis, which allows the light to pass through. And, which corresponds to the light that is produced by the barnberry, the fluorescent molecule can be detected by the light on a dark field . The high intensity of light that is produced is a characteristic feature of such molecules. Such a microscope is similar to a basic optical microscope, but the light from the light is passed through two sets of filters - one for filtering part of the light before the image and the other for filtering the light removed from the image zrazka. The first filter is designed in such a way that it lets through only the light of the last century, so that it awakens the singing fluorescent barnberry; At the same time, another filter blocks the falling light and lets in the light until the fluorescence is detected.

Fluorescence microscopy is often used to identify specific proteins or other molecules that become fluorescent after being covalently bound to fluorescent molecules. For this purpose, call two barvniks to vikorist - fluorescein, which gives an intense yellow-green fluorescence when awakened by a light blue light, and rhodamine, which produces dark red fluorescence after being awakened by yellow green light. Using stasis agents for preparation and fluorescein and rhodamine, it is possible to isolate a variety of different molecules.

Dark-film microscopy

The easiest way to see the details of the cell structure is to use light to highlight the different components of the cell. In a dark-field microscope, the illuminator is directed from the side, and only the scattered light is illuminated into the lens of the microscope. Apparently, the cell looks like a lightened object on a dark field. One of the main advantages of dark-field microscopy is the ability to prevent the destruction of cells during the process of migration. As a rule, political ruins are discovered quite quickly and are difficult to avoid in real time. In this case, you can use time-lapse (time-lapse) micro-cinema or video recording. The last frames, when separated in an hour, or when created with normal speed, the picture of real scenes will speed up.

In recent years, the development of video cameras and related image processing technologies have significantly increased the capabilities of optical microscopy. Finally, this stagnation was overcome by difficulties due to the peculiarities of human physiology. The stinks of the one who:

1. The eye of the most advanced minds does not register even the faintest light.

2. The eye cannot record small differences in light intensity on a bright aphid.

The first problem with these problems was solved after the addition of high-sensitive video cameras to the microscope. This made it possible to protect the skin for three hours at low light levels, including a trivial influx of bright light. Image processing systems are especially important for the use of fluorescent molecules in living cells. The fragments of the image are captured by the video camera in the form of electronic signals, which can then be converted into numerical signals, sent to a computer and then subjected to additional processing to capture the received information.

High contrast, achievable with computer-assisted interference microscopy, makes it possible to detect even smaller objects, such as microtubules, whose diameter is less than one tenth xvili light (0.025 µm). The edges of the microtubules can be examined using additional fluorescence microscopy. However, in both cases there are inevitable diffraction effects that greatly change the images. The diameter of the microtubules is determined (0.2 µm), which does not allow cutting the edges of the microtubules into a bundle of several microtubules. For this purpose, an electron microscope is required, which is placed far beyond the limits of visible light.

Electron microscopy

Interactions between the two and between permissions are saved for electronics. However, for an electron microscope, the resolution is very low due to the diffraction difference. The amount of energy of the electron changes due to the increase in its fluidity. In an electron microscope with a voltage of 100,000, the electron voltage reaches 0.004 nm. In accordance with the theory, the separation distance of such a microscope ranges from 0.002 nm. However, in reality, due to the small value of the numerical apertures of electronic lenses, current electron microscopes have allowed the aperture to be 0.1 nm. It is difficult to prepare a zrace, yogo pushzhennya vipromіnyuvannyam vuttnovo to Normalnnu Rozdilnu, a yak for the bioologian Op'Kktvs to become 2 nm (approximately in 100 Vishav, NIZH at the Svitlovoy Miroscope).

Dzherel elektroniv transmits an electron microscope (EM) This is a cathode thread, spread out at the top of the cylindrical column of the curl about two meters. To prevent the dispersion of electrons when they interact with air molecules, a vacuum is created at the column. The electrons that are released by the cathode filament are accelerated by the nearest anode and penetrate through the critical opening, forming an electron pass that passes at the bottom of the column. The installation of a colony on the singing surface contains ring magnets that focus the electron beam, similar to glass lenses that focus the light beam in an optical microscope. The sample is placed through the airlock in the middle of the column on the path of the electron beam. Some of the electrons at the moment of passing through the glass dissipate, similar to the intensity of speech in this section, the excess electrons are focused and form an image (similar to the formation of an image in an optical microscope) on a photographic plate or phosphorescent screen.

One of the biggest disadvantages of electron microscopy is that biological samples require special processing. First, fix the stem with glutaraldehyde, and then with osmic acid, which binds and stabilizes the suspended ball of lipids and proteins. Otherwise, electrons produce low-penetrating properties, which have to work through thin layers, and for this purpose they become watery and leak resins. Thirdly, to enhance the bloom, the particles are sprinkled with salts of important metals, such as osmium, uranium and lead.

In order to remove the trivial image of the surface, you need to use the scanning electron microscope (SEM), electrons are detected, which dissipate or proliferate on the surface of the glass. In this case, the image is fixed, dried and coated with a thin splatter of solid metal, and then scanned with a narrow beam of electrons. In this case, the number of electrons that are released when the surface is crushed is estimated. The following values ​​are selected to control the intensity of the other exchange, which collapses simultaneously with the first one and forms images on the monitor screen. Allowed the method to be close to 10 nm and it does not stagnate for the implantation of internal cellular organs. The number of electrons that are measured by this method is determined by the penetrating production of electrons or their energy.

The main and essential disadvantages of all these methods are the trifle, foldability and high cooking quality of the dough.

Scan probe microscopy

In a scanning probe microscope (SPM), instead of an electronic exchange or optical exchange, a sharp probe, a head, is used, which scans the surface of the image. Figuratively speaking, we can say that when an optical or electron microscope looks around, the SPM gets dirty. As a result, it is possible to obtain three-dimensional images of objects in different media: vacuum, wind, environment.

Special designs of SPMs, adapted for biological research, allow one-hour scanning of living cells in various rare media, as well as fixed preparations on the surface, under optical conditions.

Scanning probe microscope

The name of the scanning probe microscope reflects the principle of its operation - scanning the surface of the sample, which results in the flow stage of interaction between the probe and the surface. The size of the scanning area and the number of points N X N Y can be set. The larger the point is specified, the greater the separation of the surface images. The position between the signal reading points is called the scanning edge. The scanned surface is to blame for the smaller details on the surface that are being twisted. The probe of the probe in the process of the scanning (div. Mal. 7 -1) is likely, the lilaco at the right -time effort (at the straight of the Shvidsky scannan), rested on the advance of Liniy, to the perpendicular intensity (the intense scanning scannel is intense).

Small 7 1. Schematic illustration of the scanning process
(the signal is read during the forward stroke of the scanner)

Depending on the nature of the signal being read, scanning microscopes have different purposes:

atomic force microscope (AFM), which reads the forces of interatomic interactions between probe atoms and sample atoms;

tunnel microscope (STM), reads the tunnel stream that flows between the conductive tissue and the probe to be carried out;

magnetic force microscope (MFM), which measures the interaction forces between the probe coated with magnetic material and the image, which reveals magnetic power;

An electrostatic force microscope (ESM) allows you to obtain a picture of the distribution of the electrical potential of the surface of the image. The probes, the tip of any coatings, are vicorized with a thin cast (gold or platinum).

SPM design

The SPM consists of the following main components (Fig. 7 -2): a probe, piezoelectric drives for moving the probe X, Y, Z over the surface of the image being tracked, a collar and a computer for controlling the scanning process and capturing the image.

Figure 7 2. Scheme of a scanning probe microscope

Probe sensor - Component of a power probe microscope that scans the specimen. The probe sensor is placed with a cantilever (spring console) of rectilinear (I-like) or tricutaneous (V-like) types (Small 7 -3), at the end of which there is a sharp probe (Small 7 -3), which can form a cone or pyramidal form . The other end of the cantilever sticks to the lining (the so-called chip). Probe sensors are made from silicon or silicon nitride. The main characteristic of the cantilever is the force constant (hardness constant), which varies from 0.01 N/m to 1020 N/m. To monitor biological objects, “soft” probes are used with a hardness of 0.01  0.06 N/m.

Small 7 3. Images of pyramidal AFM probe sensors
Using an electron microscope:
a – I-like type, b – V-like type, c – pyramid on the tip of the cantilever

P'ezoelectric drives or scanners - for controlled movement of the probe over the eye or the eye itself, or the probe at small distances. In piezoelectric drives, piezoceramic materials are used, which change their dimensions when electrical voltage is added to them. The process of changing geometric parameters under the infusion of an electric field is called the reversal piezoelectric effect. The most expanded plastic material is lead zirconate titanate.

The scanner is a porous-ceramic design that ensures movements in three coordinates: x, y (at the lateral plane of the eye) and z (vertically). There are a number of types of scanners, the widest being the tripod and tube parts (Fig. 7-4).

Small 7 4. Scanner designs: a) – tripod; b) – pipe parts

In a tripod scanner, displacement by three coordinates ensures the creation of an orthogonal structure by three independent ceramic-ceramic rods.

In an empty tube scanner, the piezoelectric tube bends in the XZ and ZY planes and is compressed or compressed along the Z axis when conductive voltage is applied to the electrodes, which ensures the displacement of the tube. Electrodes for controlling the arm at the XY plane are rotated on the outer surface of the tube; to control the movements of Z on X and Y, equal voltages are supplied to the electrodes.

Lanzyug zvorotnogo zv'yazku - A set of SPM elements, in addition to which, when scanning, the probe is placed on a fixed surface on the surface of the specimen (Fig. 7 -5). During the scanning process, the probe can be placed on sections of the surface of the sample with a different relief, in which case the position Z of the probe-probe changes, and the value of the interaction of the probe-probe will also change.

Small 7 5. Scheme of the gateway of a scanning probe microscope

As the probe approaches the surface, the probe-to-probe interaction forces increase and the signal to the recording device increases. V(t), Kotriy appears in units of voltage. The comparator equalizes the signal V(t) with reference voltage V support it vibrates a distorting signal V correspondent. Correction signal V correspondent is fed to the scanner and the probe is introduced into the image. The reference voltage is the voltage that corresponds to the signal of the recording device when the probe appears at the target position of the display. By supporting the probe-exposure during scanning, the coupling system maintains the specified force of probe-exposure interaction.

Small 7 6. Trajectory of the aerial probe during the process of support by the system of the return coupling of the constant force of probe-probe interaction

Rice. 7 -6 shows the trajectory of the probe's rotation towards the probe while saving the stationary force of the probe-spike interaction. As the probe appears above the hole, a voltage is applied to the scanner, and when the scanner is pressed, the probe is lowered.

The liquidity of the lancet coupling between changing the probe-plug station (probe-plug interaction) is determined by the lancet constant at the toggle coupling K. Significance K depend on the design features of a particular SPM (design and characteristics of the scanner, electronics), the SPM operating mode (the size of the scanning area, the scanning fluidity, etc.), as well as the features of the surface being monitored (the scale of features, the relief, terialu too).

Riznovidi SPM

Scanning tunnel microscope

With an STM recording device (Mal. 7 -7), a tunnel stream flows between the metal probe, which varies depending on the potential on the surface of the sample and the topography of its surface. The probe has a sharp sharpened head, the radius of the rounded tip can reach several nanometers. As a material for the probe, consider vicorized metals with high hardness and chemical resistance: tungsten or platinum.

Small 7 7. Scheme of a tunnel probe sensor

A voltage is applied between the probe and the conductive wire. When the tip of the probe appears with a winder close to 10A in front of the sample, the electrons from the sample begin to tunnel through the gap at the probe and in the opposite direction, depending on the voltage sign (Fig. 7 - 8).

Small 7 8. Schematic representation of the interaction between the tip of the probe and the glass

The tunnel flow, which is responsible for this, appears to be a registering device. Yogo size I T proportional supply of voltage to the tunnel contact V and lie exponentially from the protrusion from the head to the tip d.

In this manner, small changes are made from the tip of the probe to the d indicate exponentially large changes in the tunnel flow I T(transfers, what is the voltage V maintains the unchangeable). As a result, the sensitivity of the tunnel probe sensor is sufficient to detect height changes of less than 0.1 nm and, therefore, to capture images of atoms on the surface of a solid.

Atomic force microscope

The largest probe sensor of atomic force interaction is a spring cantilever (cantilever - console) with a probe extended at its end. The size of the large cantilever, which results from the force interaction between the probe and the probe (Fig. 7 - 9), is controlled by additional optical registration schemes.

The principle of operation of a force sensor is based on a range of atomic forces that operate between the atoms of the probe and the atoms of the sample. When changing the force of the probe, the magnitude of the cantilover displacement changes, and such a change is measured by the optical registration system. Thus, an atomic force sensor is a hot probe with high sensitivity, which allows you to record the forces of interaction between close atoms.

For small periods of connection between the force of the probe and the probe F and enhancement of the cantilever tip x is indicated by Hooke's law:

de k - Force constant (hardness constant) of the cantilever.

For example, a cantilever with a constant k on the order of 1 n/m, then under the influence of the probe-particle interaction force on the order of 0.1 nanonewton, the value of the cantilever expansion is approximately 0.1 nm.

To detect such small movements, an optical sensor is used (Fig. 7-9), which consists of a conductor laser and a multi-section photodiode. When the cantilever is bent, the output of the new laser channel is shifted towards the center of the photodetector. Thus, the value of the cantilever can be determined by changing the brightness of the upper (T) and lower (B) halves of the photodetector.

Figure 7 9. Power sensor diagram

The strength of the interaction forces between the probe and the probes at the probe and probe stand

When the probe is close to the eye, the kidney is attracted to the surface due to the presence of forces that attract (van der Waals forces). As the probe gets further closer to the particle, the electron shell of the atoms at the end of the probe and the atoms on the surface of the glass begin to overlap, which leads to the appearance of a force that increases. With further changes, the force that rises becomes dominant.

Deposit of power or interatomic interaction F between the atoms R looks like:

.

Constanti aі b that stage show mі n lie in the type of atoms and type of chemical bonds. For van der Waals forces m=7 ta n=3. The level of F(R) is clearly shown in Fig. 7-10.

Small 7 10. The intensity of the interaction force between atoms from the surface

Format of SPM-data, visualization of SPM-data

Data on the surface morphology, taken for observation on an optical microscope, is presented in the form of a larger image of the surface section. The information that is captured by the additional SPM is recorded in the form of a two-dimensional array of integers A ij . Skin value ij This is indicated by a spot on the surface at the boundaries of the scanning field. The graphically displayed array of numbers is called SPM scanned images.

Image scans can be two-dimensional (2D) or tri-dimensional (3D). With 2D visualization of a skin point on the surface Z= f(x,y) set the color tone to the same height as the surface point (Fig. 7 - 11 a). With 3D visualization of the surface image Z= f(x,y) will be in an axonometric perspective with an additional emphasis on the pixels and line relief. The most effective way of 3D painting is to highlight the surface of the brain with a dot dzherel, drawn at the first point in the space above the surface (Fig. 7-11 b). Which allows you to emphasize the small features of the relief.

Small 7 11. Human blood lymphocytes:
a) 2D images; b) 3D images with backlights

Preparation of samples for SPM follow-up

Morphology and structure of bacterial cells

Bacteria are single-celled microorganisms that have a varied shape and folded structure, which indicates the diversity of their functional activities. Bacteria are characterized by the following basic shapes: spherical (kulasta), cylindrical (rod-like), coily and thread-like [Ref. 7-2].

Koki (bacteria of the round form) – long-term growth of the surrounding individuals are divided into micrococci (lying cocas), diplococci (coca coci), streptococci (coca lances), staphylococci (which look like grapevines), tetracoci ennya) ) that sarcini (packages of 8 or 16 coques).

Stick-like – bacteria grow in the form of single cells, diplobacteria or streptobacteria.

Twisted – vibrations, spiri and spirochetes. Vibrions look like slightly curved sticks, and spiri have a twisted shape with a few spiral curls.

The size of bacteria ranges from 0.1 to 10 microns. The bacterial cell consists of a capsule, a cell wall, a cytoplasmic membrane and cytoplasm. The cytoplasm contains nucleotides, ribosomes and inclusions. Some bacteria are supported by flagella and villi. A number of bacteria create supercaps. Depending on the outer transverse size of the thigh, the super-cheeks give it a spindle-like shape.

To study the morphology of bacteria on an optical microscope, native (surviving) preparations and fixed smears prepared with aniline barn are prepared. There are special preparation methods for identifying flagella, cell walls, nucleotides and various cytoplasmic inclusions.

SPM examination of the morphology of bacterial cells does not require infusion of the drug. SPM allows the shape and size of bacteria to be determined at a high level. With a carefully prepared preparation and a vicoristic probe with a small radius of rounding, flagella can be detected. At the same time, through the great rigidity of the cell wall, bacteria cannot “break through” the internal cell structures, as can be done on other human cells.

Preparation of preparations for SPM examination of morphology

For the first trial using SPM, it is recommended to choose a biological preparation that does not require complex preparation. In general, readily available and non-pathogenic lactic acid bacteria are found in the brine of sauerkraut or fermented milk products.

For SPM observation in the air, it is necessary to carefully fix the object to be observed on the surface of the pad, for example, on a curved slide. In addition, the strength of the bacteria in the suspension must be such that the cells do not stick when deposited on the lining, and the space between them is not too large, so that when scanning it is possible to take a sample of the object in one frame c. It’s important to remember to select the correct cooking mode. If you apply a drop of rubbish to remove bacteria onto the lining, then their deposition and adhesion will occur. The main parameters for this calculation are the concentration of cells in the plant and the time of sedimentation. The concentration of bacteria in the suspension is determined according to the optical calamutity standard.

In this case, we only have one parameter – the hour of incubation. The more the drops are visible on the glass, the more the strength of the bacterial cells will be revealed. At the same time, if the drops begin to dry out, the drug will become heavily contaminated with the components of the mixture that have precipitated. I sprinkle the rub to remove bacterial cells (rozsil), apply on the surface, rub 5-60 quilins (depending on the deposit). Then, without letting the droplets dry, rinse thoroughly with distilled water (wetting the preparation with tweezers in the bottle several times). After drying, the preparation is ready for drying the SPM.

For the butt, preparations of lactic acid bacteria were prepared from the rose brine of sauerkraut. The hour for vitrimation of the droplets in rose brine on the curved surface was chosen as 5 minutes, 20 minutes and 1 year (the drops had already begun to dry out). SPM - footage presented on Mal. 7-12, Small 7 -13,
Small 7-14.

It is clear from the little ones that from this point of view the optimal incubation hour is 510 minutes. Extended exposure to the surface of the lining causes the bacterial cells to stick together. Whenever the droplets of rubbish begin to dry out, beware of depositing the rock components on the surface, which are impossible to remove.

Small 7 12. Images of lactic acid bacteria on a curved glass,
take away the SPM for help.

Small 7 13. Images of lactic acid bacteria on a curved glass,
take away the SPM for help. Incubation hour: 20 min.

Small 7 14. Images of lactic acid bacteria on a curved glass,
take away the SPM for help. Incubation hour is 1 year.

Using one of the selected preparations (Fig. 7-12), we tried to look at what lactic acid bacteria are and what form is typical for them in this period. (Mal. 7 -15)

Small 7 15. AFM – images of lactic acid bacteria on a curved glass.
Incubation hour is 5 minutes.

Small 7 16. AFM – image of a lancet of lactic acid bacteria on a curved glass.
Incubation hour is 5 minutes.

Rozsolu is characterized by a rod-like form of bacteria and a lancet-shaped growth.

Small 7 17. View of the basic program of the initial SPM NanoEducator.
Toolbar

Vikorist tools using the initial SPM NanoEducator program determined the size of bacterial cells. The stinks were stacked approximately 0.5×1.6 µm
up to 0.8×3.5 microns.

The results can be compared with the data obtained from the origin of bacteria Bergey [Lit. 7-3].

Lactic acid bacteria are transferred to lactobacilli (Lactobacillus). The flaps look like sticks and are of the correct shape. The sticks are long, sometimes coco-like, and have short lanterns. Dimensions 0.5 – 1.2 X 1.0 – 10 microns. Superechka does not approve; in single bursts, they squirm for the shell of the peritrichial flagella. Widely wide in the middle part, they are especially often narrowed in grub products of cooked and algae origin. Lactic acid bacteria enter the normal microflora of the grass tract. Everyone knows that sauerkraut, along with vitamins and cinnamon, helps to improve the intestinal microflora.

Design of a scanning probe microscope NanoEducator

Rice. 7 -18 views of the current appearance of the visualization head SPM NanoEducator And I will identify the main elements so that they can be analyzed during the hour of work.

Small 7 18. External view of the imaging head of the NanoEducator SPM
1- base, 2- trim arm, 3- Interaction sensor, 4-screw fixing the sensor,
5-screw for manual movement, 6-screw for moving the scanner from the glass to the horizontal plane, 7-screw for the cover with a video camera

Rice. 7 -19 shows the design of the vimiruval head. On the stand 1 there is a removable scanner 8 with a trimach of the sample 7 a mechanism for bringing the sample to the probe 2 based on the clock motor. At the beginning SPM NanoEducator The image is attached to the scanner and the image is scanned using an indestructible probe. The connection of probe 6, attached to the force interaction sensor 4, can be adjusted using the additional manual screw 3. The forward selection of the place is followed by the additional screw that 9.

Small 7 19. Design of SPM NanoEducator: 1 – base, 2 – feed mechanism,
3 – manual adjustment screw, 4 – interaction sensor, 5 – sensor fixing screw, 6 – probe,
7 – image trimach, 8 – scanner, 9, 10 – screw for moving the scanner from the image

Chief SPM NanoEducator consists of cables connected to the imaging head, the SPM controller and the supporting computer. The microscope is connected to the video camera. The signal from the interaction sensor, after being converted into a booster, goes to the SPM controller. Robot control SPM NanoEducator Operates from a computer through an SPM controller.

Force interaction sensor and probe

At the ready NanoEducator vibration sensor in sight of the ceramic ceramic tube l=7 mm, diameter d=1.2 mm thick wall h=0.25 mm, rigidly fixed at one end. A conductive electrode is applied to the inner surface of the tube. Two electrically insulated cylindrical electrodes are applied to the outer surface of the tube. A tungsten wire with a diameter of
100 microns (Small 7 -20).

Small 7 20. Design of the universal sensor for the NanoEducator device

The long end of the drill, which is used as a probe, is sharpened electrochemically, the radius of rounding is 0.2  0.05 µm. The probe makes electrical contact with the internal electrode of the tube, connected to the grounded housing of the device.

The presence of two external electrodes on the piezoelectric tube allows the force interaction sensor (mechanical impact sensor) to vibrate one part of the piezoelectric tube (upper, in line with Fig. 7 -21), and the other part of the vikorist is like a p'ezovibrator. A variable electrical voltage is supplied to the oscillator at a frequency equal to the resonant frequency of the power sensor. The amplitude of the sound with a large extension of the probe is maximum. The yak is visible from Mal. 7 -22, in the process of hammering, the probe moves away from the equal position by the value A, equal to the amplitude of its disturbing mechanical vibrations (to set parts of the micrometer), while on the other part of the cutting (to the chipping sensor) There is a changeable electrical voltage due to the proportional displacement of the probe and it seems to fit.

When the probe is close to the surface of the sample, the probe begins to stick out to the sample during the process of crushing. To reduce the amplitude-frequency characteristic (AFC), the sensor's movement to the left is equal to the AFC, which is far above the surface (Fig. 7 -22). Since the frequency of the vibration is subject to a constant and equal frequency of vibration, then when the probe is close to the surface, the amplitude of the vibration changes and becomes equal A. This amplitude of the vibration It is registered from another part of the cut.

Small 7 21. The principle of operation of a piezoelectric tube
as a force interaction sensor

Small 7 22. Changing the frequency of the power sensor
when close to the surface of the eye

Scanner

The method of organizing micro-displacement that is used in the device NanoEducator, bases on a metal membrane pressed around the perimeter, with a resin plate glued to the surface (Mal. 7 -23 a). Changing the size of the plastic plate under the influence of the voltage that controls it will lead to the membrane violating. Having pushed such membranes along three perpendicular sides of the cube and connected their centers with metal staples, you can remove a 3-coordinate scanner (Fig. 7-23 b).

Small 7 23. Principle of operation (a) and design (b) of the scanner attached to the NanoEducator

Leather element 1, fastenings on the faces of cube 2, with the addition of a new electrical voltage, you can transfer the fastenings to a new piece 3 in one of three mutually perpendicular straight lines - X, Y or Z. As can be seen from the little piece, all three and got together at one point 4. From any proximity, you can note that this point moves behind three coordinates X, Y, Z. To this point, the stand 5 is attached to the trimmer of the frame 6. In this way, the frame moves along three coordinates under the action of three independent tension rods. At the edges NanoEducator The maximum movement of the image becomes close to 5070 µm, which means the maximum scanning area.

Mechanism for automated advancement of the probe to the mucus (retention of the mucous membrane)

The range of movement of the Z-axis scanner should be approximately 10 µm, so before starting the scan it is necessary to bring the probe close to the target. For this purpose, the reduction mechanism, a diagram of which is shown in Fig. 7-19. Dvigun 1 Crokovy when serving on the eogo electrichny izpulsіv gutifs 2 І Movish bar 3 s 3 zontia 4, closely submarine vid Zrazka 5, stanned on the scanner 6. The value of one croc is become close to 2 μm.

Small 7 24. Scheme of the mechanism for bringing the probe to the surface of the eye

The fragments of the cutting mechanism significantly outweigh the size of the required probe-displacement during the scanning process, in order to avoid deformation of the applied probe during one-hour operation of the cutting motor and moving yum scanner along the Z axis following the advanced algorithm:

1. The folding system is turned on and the scanner is “retracted”, which lowers the indicator at the bottom extreme position.

2. The mechanism for inserting the probe starts working once and then stops.

3. The reversal system is turned on, and the scanner smoothly raises the probe, and the probe-spectrum interaction is simultaneously analyzed.

4. If there is daily interaction, the process is repeated from point 1.

If a non-zero signal appears when the scanner is being pulled up, the system of the coupling system will push the scanner up and fix the value of the interaction at a given level. The magnitude of the force interaction at which there will be a tip of the probe and the scanning process will take place, in the device NanoEducator characterized by the parameter Suppressed amplitude (AmplitudeSuppression) :

A = A o . (1- Amplitude Suppression)

Taking SPM images

After clicking the program NanoEducator The main program window appears on the computer screen (Mal. 7-20). The robot prints a trace from the menu item File and choose something new Vidkriti or else new or additional buttons on the toolbar (, ).

Select commands File new means the transition until the SPM of the vimirs is carried out, and the selection of the team File Vidkriti means a transition to review and processing of previously removed data. The program allows you to view and process data in parallel with the views.

Small 7 25. Golovne vikno program NanoEducator

After the victory of the team File new A dialog box appears on the screen, which allows you to select or create a working folder in which the results of the in-line editing will be recorded. During the process of editing, all data is removed and sequentially recorded in files named ScanData+i.spm, de index i resets to zero when you start the program and increases with each new change. Filey ScanData+i.spm are placed in the working folder, which is installed before the start of the world. It is possible to select a different working folder at the time of the virtualization. For which you need to press the button , displayed on the toolbar of the main window of the program and select a menu item Change working folder.

To save the results of the stream viewer, you need to press the button Save the yak In the scan window, in the dialog box, select a folder and indicate the name of the file whose file ScanData+i.spm, which serves as a temporary file for saving data during the editing process, will be renamed based on the given file name. After processing, the file will be saved in a working folder, indicated before being deleted. If you don’t cancel the operation of saving the results of the dimming, then at the time of launching the program, the results recorded in the time files ScanData+i.spm, will be sequentially overwritten (if the working folder has not been changed). About the detection of time-sensitive files of the results of modification in the working father, advances are seen before closing and after launching programs. Changing the working folder before performing the experiment allows you to protect the results of the previous experiment from being deleted. Standard ScanData You can change this by selecting a working folder from the window. The folder selection window is clicked when the button is pressed , displayed on the toolbar of the main window of the program. You can also save the results of curing Scan browser, through seeing the necessary files and saving them to the selected folder.

It is possible to export results captured using the additional NanoEducator device into ASCII format and Nova format (NTMDT company), which can be imported by the NT MDT Nova program, Image Analysis and other programs. The ASCII format exports images of scans, data on their cross-sections, and results of vibrating spectroscopy. To export data you need to click the button Export, displayed in the toolbar of the main window of the program, or select Export at the menu item File In this window, select the appropriate export format. Data for processing and analysis can be sent directly to the previously launched Image Analysis program.

After closing the dialogue window, the panel will appear on the screen
(Mal. 7 -26).

Small 7 26. Panel keruvannya fitted

On the left side of the panel there are arranged buttons for selecting the SPM configuration:

SSM- Scanning force microscope (SFM)

STM- Scanning tunnel microscope (STM).

Conducting vimirs on the initial SPM NanoEducator involves the following operations:

1. Installation of vision

UVAGA! Before inserting the probe, it is necessary to remove the sensor from the probe to avoid damaging the probe.

There are two ways to attach the symbol:

on a magnetic table (in which case the images are attached to the magnetic pad);

on double-sided adhesive strip.

UVAGA! To install a label on a double-sided adhesive strip, you need to unscrew the trimmer from the stands (so as not to damage the scanner), and then screw it back in until it stops slightly.

If there is a magnetic fastening, the replacement part may come out without pushing out the part.

2. Installation of the probe sensor

UVAGA! Install the sensor with the trace probe first after installing the trace.

Having selected the required probe sensor (trim the sensor by the metal edges of the base) (div. Mal. 7 -27), loosen the fixing screw of the probe sensor 2 on the crown of the vibrating head, insert the sensor at the trimach socket until it stops, tighten the fixing screw behind the anniversary page I break it until it's light.

Small 7 27. Installation of the probe sensor

3. Select location scan

When selecting for the design of the extension, use the screw to move the x-axis table, moved in the lower part of the attachment.

4. Advance the probe to the eye

The operation of the front extension is not obligatory for the skin test; it is necessary to pay attention to the size of the distance between the eye and the ends of the probe. The forward approach operation should be carried out when the distance between the tip of the probe and the surface of the specimen moves 0.51 mm. If the automated probe is brought up to the target from a large distance between them, the process will take quite an hour.

Use the manual screw to lower the probe, visually checking that it is positioned between it and the surface of the eye.

5. Pobudova resonant curve and setting the operating frequency

This operation necessarily involves the beginning of the skin infection and, until the dock is broken, proceeds to further stages of the elimination of blocking. In addition, during the process of canceling the code, situations arise that require repeating the same operation (for example, once you lose contact).

It is obvious that the resonance is heard by pressing the button on the panel of the device. This operation transfers the amplitude of the probe’s vibrations when changing the frequency of the vibrations, which are set by the generator. For which you need to press the button RUN(Mal. 7 -28).

Small 7 28. How to operate by searching for resonance and setting the operating frequency:
a) – automatic mode; b) – manual mode.

In mode Auto The generator frequency is automatically set to the same frequency as the maximum amplitude of the probe oscillation. A graph that demonstrates a change in the amplitude of the probe in a given frequency range (Fig. 7-28a) allows you to monitor the shape of the resonant peak. Because the resonant peak does not have enough expression, because the amplitude at the resonance frequency is small ( less than 1V), then it is necessary to change the parameters of the vibration and re-select the resonant frequency.

For whom the mode is assigned Manual. When you select this mode from the window Value of resonant frequency appears as an additional panel
(Mal. 7 -28b), which allows you to customize the following parameters:

Probe voltage, what is set by the generator. It is recommended to set this value to the minimum (all the way to zero) and not more than 50 mV.

Amplitude enhancement factor ( Increased amplitude). If the amplitude is insufficient, the probe is pierced (<1 В) рекомендуется увеличить коэффициент Increased amplitude.

To start the operation, search for resonance, you need to press the button Start.

Mode Manual allows you to manually change the selected frequency by moving the green cursor to the graphic behind the mouse, and also clarify the nature of the change in the amplitude of the sound in a narrow range of values ​​near the selected frequency (for which you need to install a jumper Manual mode at the camp Exactly press the button Start).

6. Mutual burying

To ensure mutual interaction, a procedure is developed for controlled proximity of the probe and the connection with an additional automated approach mechanism. This procedure is carried out by pressing the button on the treatment panel with the device. During the hour of operation with SCM, this button becomes available after completing the operation and setting the resonant frequency. Vikno SSM, Pіdvedennya(Min. 7 -29) place the elements of the cerium on the probe leads, as well as the indicators of the parameters that allow you to analyze the process of the procedure.

Small 7 29. Display of the probe insertion procedure

At the window Pіdvedennya The analyst can keep an eye on the following values:

scanner details ( ScannerZ) along the Z axis to the maximum possible, taken as one. The amount of scanner uplift is characterized by the level of filling of the left indicator with color, which indicates the zone in which the scanner is currently located: green color - working zone, blue - working zone position, red - scanner in progress the seam must be close to the surface of the eye, which may cause deformation of the probe . Sometimes the program shows a sound advance;

amplitude of the probe So the amplitude of this vibration without force interaction is taken as one. The value of the aqueous amplitude of the probe is shown on the right indicator of the level of filling with a burgundy color. Horizontal mark on the indicator Amplitude of the probe indicates that when passing through any analysis, the scanner will be automatically displayed in the operating position;

number of crops ( Shyeah), following a given direction: Pіdvedennya - proximity, Vіdvedennya - vidalennya.

Before the process of lowering the probe begins, it is necessary:

Check the correctness of the proximity parameters settings:

Coefficient of strengthening of the lancet of the collar link Powerful OS insertions on the values 3 ,

Convert to what parameter Smotheringamplitude (Strength) The value is close to 0.2 (div. small 7 -29). In the other option, press the button Force and at the window Setting the communication parameters (Fig. 7-30) set values Smotheringamplitude Rivne 0.2. For a more delicate presentation of the parameter value Smotheringamplitude maybe buti less .

Check the correctness of the settings in the parameters window Parameters, side Submission parameters.

Both interactions can be indicated by the left indicator ScannerZ. Outside the scanner (the entire indicator ScannerZ filling with a blue color), as well as the surface of filling with a burgundy color indicator Amplitude of the Kolivan probe(Mal. 7 -29) indicate the existence of mutual relations. After checking the resonance and setting the operating frequency, the amplitude of the strong vibrations of the probe is set to one.

As soon as the scanner is turned off, I won’t turn it on until the hour is approaching, and the program displays the notification: “Make a deal!” The probe is very close to the eye. Change the settings for your physical education course. If you want to leave in a safe place, it is recommended to slow down the following procedures:

a. change one of the parameters:

increase the amount of interaction, parameter Smotheringamplitude, or

increase the value Powerful OS, or

increase the shutdown time between the proximity steps (parameter Integration hour on the page Submission parameters vikna Parameters).

b. increase the distance between the probe and the eye (for this operation, described in paragraph and operation Resonance, after which turn to the next procedure Pіdvedennya.

Small 7 30. Window for setting the value of probe interaction and expression

After storing the interaction, a notification appears “ Pіdvedennya Wikonan".

If you need to move closer by one click, press the button. In this case, the criterion is determined first, and then the criteria for depositing the interaction are verified. To click on the roc, you need to press the button. To complete the withdrawal operation, you must press the button for quick withdrawal

Or press the button for full input. If necessary, press the button to move forward one cycle at a time. In which case the criterion is determined first, and then the criteria for depositing mutual interaction are verified

7. Scanuvannya

After completing the finalization procedure ( Pіdvedennya) This storage becomes available for scanning (the button next to the toolbar panel window).

Having pressed this button (look at the scanning window in Fig. 7 -31), the operator begins immediately until the modification is carried out and the results of the modification are removed.

Before scanning, you need to set the scanning parameters. These parameters are grouped on the right side of the top panel of the window Skanuvannya.

First, after starting the program, the stinks are installed:

Square scanuvannya - Region (Xnm*Ynm): 5000*5000 nm;

Number of pointsalignment along axes- X, Y: NX=100, NY=100;

Shlyakh skanuvannya - Directly means direct scanning. The program allows you to select the direct scanning axis (X or Y). When starting the program, the program is installed Directly

After setting the scanning parameters, you must press the button Zastosuvati buttons to confirm the entered parameters Start for the cob scan.

Small 7 31. Easy control of the process and display of SFM scanning results

7.4.Methodical additions

First print the robot on a scanning probe microscope NanoEducator after reading the user manual [Lit. 7-4].

7.5.Safety techniques

To operate the device, a voltage of 220 V is used. The operation of the NanoEducator scanning probe microscope is carried out in accordance with the PTE and PTB of electrical installations with voltages up to 1000 V.

7.6.Zavdannya

1. Prepare independent biological samples for observation using the SPM method.

2. Consider the practical design of the NanoEducator attachment.

3. Get to know the NanoEducator program.

4. Take first SPM images under the control of the computer.

5. Perform processing and analysis of the captured image. What forms of bacteria are present in your culture? What determines the shape and size of bacterial cells?

6. Take the result of Burgee bacteria and compare the results with the descriptions there.

7.7.Control food

1. What are the methods for tracking biological objects?

2. What is scanning probe microscopy? What principle lies at its basis?

3. Name the main components of the SPM and their functions.

4. What is the piezoelectric effect and how does it stand out in SPM? Describe the different designs of scanners.

5. Describe the basic design of the NanoEducator device.

6. Describe the force interaction sensor and the principle of its operation.

7. Describe the mechanism for bringing the probe to the tip of the NanoEducator device. Explain the parameters that determine the strength of the interaction between the probe and the probe.

8. Explain the principle of scanning and robotic system of the turning link. Tell us about the criteria for choosing scanning parameters.

7.8.Literature

Lit. 7 1. Paul de Cruy. Mysteries for bacteria. M. Terra. 2001.

Lit. 7 2. A guide to practical lessons in microbiology. Edited by Egorov N.S. M: Nauka, 1995.

Lit. 7 3. Hoult J., Craig N., P. Sneath, J. Staley, S. Williams. // Origin of bacteria Bergi. M.: Svit, 1997. T. No. 2. P. 574.

Lit. 7 4. Pos_bnik koristuvach prladu NanoEducator.objects. Nizhny Novgorod. Science and Education Center...

The first devices that made it possible to monitor nanoobjects and transfer them were scanning probe microscopes - an atomic force microscope and a scanning tunnel microscope, which operate on a similar principle. Atomic force microscopy (AFM) was developed by G. Binnig and G. Rohrer, who were awarded the Nobel Prize for their research in 1986. The creation of an atomic force microscope, capable of detecting the forces of gravity and movement that occur between neighboring atoms, made it possible to “smash and rub” nanoobjects.

Malyunok 9. The principle of a robotic scanning probe microscope. The dotted line shows the progress of the laser. Other explanations in the text.

The basis of the AFM (div. Fig. 9) is a probe made of silicon and is a thin cantilever plate (it is called a cantilever, from the English word “cantilever” - console, beam). At the end of the cantilever (length 500 μm, width 50 μm, thickness 1 μm) there is a very sharp spike (length 10 μm, radius of rounding from 1 to 10 nm), which ends in a group of one or several atoms (div. Fig. 10).

Malyunok 10. Electronic microphotos of one and the same probe, divided into small (top) and large increases.

When the microprobe is moved along the surface of the surface, the tip of the spike rises and falls, mirroring the microrelief of the surface, similar to how a gramophone head moves around the recorder. At the protruding end of the cantilever (above the spike, div. Fig. 9) there is a mirrored area where the laser head falls and where it beats. When a spike descends and rises on uneven surfaces, the impacted membrane is breathed, and this vibration is recorded by a photodetector, and the force by which the spike is attracted to adjacent atoms is detected by a photodetector.

The photodetector and photodetector data are integrated into the coupling system, which can ensure, for example, a constant magnitude of the interaction force between the microprobe and the surface of the sample. As a result, it is possible to determine the volumetric relief of the surface of the image in real time. The separation distance of the AFM method is approximately 0.1-1 nm horizontally and 0.01 nm vertically. The image of coliform bacteria, taken using a probe microscope and scanned, is shown in Fig. eleven.

Malunok 11. Intestinal coli bacterium ( Escherichia coli). The image was obtained using a scanning probe microscope. The length of the bacteria is 1.9 microns, the width is 1 microns. The thickness of the flagella is 30 nm and 20 nm, similar.

Another group of probing microscopes that scan, to create a relief on the surface, is known as the quantum-mechanical “tunnel effect.” The essence of the tunnel effect lies in the fact that the electric stream between the sharp metal head and the surface, which is spread out at a distance of about 1 nm, begins to lie below this surface - the less you stand, the more streams there are. If a voltage of 10 V is applied between the base and the surface, this “tunnel” flow can be adjusted from 10 pA to 10 nA. Vividly this strum and keeping it stable, you can keep it constant and stand between the naked and the surface. This allows for a volumetric surface profile (div. small 12). Instead of an atomic force microscope, a tunnel microscope that scans can only scan the surfaces of metals or conductors.

Malyunok 12. The head of the tunnel microscope, which scans, is located at a stationary position (div. arrows) above the balls of atoms on the traced surface.

A scanning tunnel microscope can be rotated to move any atom to a point selected by the operator. For example, if the voltage between the head of the microscope and the surface of the sample is slightly greater than the required surface, then the closest atom of the sample turns into an ion and “jumps” to the head. After slightly moving the head and changing the voltage, you can squeeze the atom “striped” back onto the surface of the eye. It is also possible to manipulate atoms and create nanostructures, etc. surface structures range in size on the order of a nanometer. Back in the 1990s, IBM's satellite scientists showed what was possible by charging 35 atoms of xenon to their company's name on a nickel fee (Fig. 13).

Figure 13. Folded from 35 atoms of xenon on a nickel payment under the name of the IBM company, assembled by the company's scientists for the scanning probe microscope in 1990.

With the help of a probe microscope, it is possible to destroy atoms and create changes in their self-organization. For example, if there is a drop of water on a metal plate to displace the thiols, then the microscope probe will be sensitive to such an orientation of these molecules, in which their two carbohydrate tails will be formed on the plate. As a result, it is possible to create a monoball of thiol molecules that stick to the metal plate (extraordinary Fig. 14). This method of creating a monosphere of molecules on a metal surface is called “particle nanolithography.”

Figure 14. In the dark – cantilever (gray-steel) of a scanning probe microscope above a metal plate. On the right is a larger image of the area (outlined in white by the small left hand) under the cantilever probe, with a schematic showing of a thiol molecule with purple carbohydrate tails arranged in a monoball near the tip of the probe. Adapted from Scientific American, 2001, Sept, p. 44.

Enter

At the present time, the scientific and technological field is rapidly developing - nanotechnology, which supports a wide range of fundamental and applied research. This is a fundamentally new technology, which poses problems in various fields such as communications, biotechnology, microelectronics and energy. Today, more than a hundred young companies are developing nanotechnological products that will enter the market in the next two or three years.

Nanotechnologies will become leading technologies in the 21st century and will facilitate the development of the economy and social sphere of marriage, and they may become a revolutionary new industrial revolution. In the past two hundred years, progress in the industrial revolution was achieved at the cost of wasting about 80% of the Earth's resources. Nanotechnologies will allow us to significantly change the consumption of resources and will not involve too much of the middle ground; they will play a significant role in the life of mankind, as, for example, the computer has become an invisible part of people’s lives.

Progress in nanotechnology was stimulated by the development of experimental tracking methods, the most informative methods being scanning probe microscopy, and especially the expansion of light for Nobel laureates 198 6 - to Professor Heinrich Rohrer and Dr. Gerd Binnig.

There is a world of fascination in such simple methods of visualizing atoms, as well as the possibility of manipulating them. Many pre-Slednitsky groups began to construct their own devices and experiment in this direction. As a result of the development of a number of simple adjustment schemes, various methods were developed for visualizing the results of probe-surface interaction, such as lateral force microscopy, magnetic force microscopy, rheumatic microscopy strategies of magnetic, electrostatic, electromagnetic interactions. There has been intensive development of the method of near-field optical microscopy. Methods of direct, controlled infusion in the probe-surface system have been developed, for example, nanolithography - changes are injected on the surface under the influence of electrical, magnetic infusions, plastic deformations, and light in the probe-surface system. Technologies have been created for the production of probes from specified geometric parameters, with special coatings and structures for visualization of various surface properties.

Scanning probe microscopy (SPM) is one of the most important modern methods for studying the morphology and local properties of the surface of a solid body with a high spaciousness. Over the past 10 years, scanning probe microscopy has been transformed into an exotic technique, accessible only to a limited number of pre-survey groups, widely expanded, and a tool for tracking surface authorities has successfully become established. Nowadays, practically every research in the field of surface physics and fine-fuel technologies cannot be done without the use of SPM methods. The development of scanning probe microscopy also served as the basis for the development of new methods in nanotechnology - the technology of creating structures on a nanometer scale.

1. Historical background

To monitor other objects, the Dutchman Anton van Leeuwenhoek used a microscope in the 17th century to reveal the light of microbes. Their microscopes were incomplete and gave an increase of 150 to 300 times. Finally, his successors perfected this optical apparatus, laying the foundation for rich discoveries in biology, geology, and physics. However, in the 19th century (1872), the German optician Ernst Karl Abbe showed that through diffraction of light the separate part of the microscope (then there is a minimum distance between objects, unless they are angry in one image) is surrounded by a dove of light thread (0.4 – 0, 8 µm). Tim himself spared a lot of opticians, who were trying to develop more thorough microscopes, but disappointed biologists and geologists, who lost hope of trying to find a way to increase the value of more than 1500x.

The history of the creation of the electron microscope is a miraculous example of how science and technology are developing independently, and can, by exchanging information that has been captured, create a new powerful scientific instrument. follow-up The pinnacle of classical physics was the theory of the electromagnetic field, which explained the expansion of light, the rise of electric and magnetic fields, the flow of charged particles in these fields as the expansion of electromagnetic fields. Hvili's optics developed an intelligent phenomenon of diffraction, the mechanism of image formation and a group of factors that indicate light microscopy. The success of theoretical and experimental physics is due to the discovery of the electron with its specific powers. Along with this, it would seem, independent developments led to the creation of the foundations of electronic optics, one of the most important programs of the 1930s. In direct reference to this possibility, one can take into account the hypothesis about the Hwyllian nature of the electron, proposed in 1924 by Louis de Broglie and experimentally confirmed in 1927 by K. Davisson and L. Germer in the USA and by J. Thomson in England. Tim himself was prompted by an analogy, which allowed him to follow the laws of cow optics. H. Bush discovered that with the help of electric and magnetic fields it is possible to form electronic images. The first one has two decades and 20 centuries. Necessary technical changes were made. The industrial laboratories that worked on the electron-electronic oscillograph provided vacuum technology, stable high-voltage devices and jets, and good electronic emitters.

In 1931, R. Rudenberg filed a patent application for an electron microscope, which shines through, and in 1932, M. Knoll and E. Ruska created the first such microscope, which used frozen magnetic lenses for focusing electrons. This device was used as a frontier for the current optical electron microscope (OPEM). (Ruska went on to win the Nobel Prize in Physics for 1986.) In 1938, Ruska and B. von Borris produced a prototype of an industrial OPEM for the Siemens-Halske company in Nimecchina; This device allows you to reach a resolution of 100 nm. A few years later, A. Prebus and J. Hiller initiated the first high-level OPEM at the University of Toronto (Canada).

The wide possibilities of OPEM immediately became obvious. This industrial production was launched simultaneously by the Siemens-Halske company in Germany and the RCA corporation in the USA. In the late 1940s, such devices began to be produced by other companies.

REM in its newest form was founded in 1952 by Charles Otli. True, the earliest versions of such a device were inspired by Knoll at Germany in the 1930s and by Zvorikin and his colleagues at the RCA corporation in the 1940s, but rather the adaptation of these devices would serve as the basis for low-tech more thoroughly, so that the development of the industrial variant of REM has been completed mid-1960s. The number of people living with such a simple device with volumetric images and an electronic output signal has expanded due to the fluidity of the vibration. At present, there are a dozen commercial REM devices on three continents and tens of thousands of such devices that are being tested in laboratories around the world. .5 million volts. RTM buv Founded by G. Binnig and R. Rohrer in 1979 in Zurich, the creation of RTM Binnig and Rohrer (at the same time with Ruska) won the Nobel Prize.

In 1986, Rohrer and Bunning discovered a probe microscope that scans. Since its launch, STM has been widely adopted by various specialties, embracing almost all natural sciences disciplines, from fundamental research in physics, chemistry, biology to specific technological advances. iv. The principle of STM is so simple, and the potential is so great that it is impossible to transfer its influx to science and technology until the next one.

As it turned out, in practice, any interactions of the hot probe with the surface (mechanical, magnetic) can be transformed using additional devices and computer programs on the surface.

The installation of a scanning probe microscope consists of several functional blocks shown in Fig. 1. First of all, the microscope itself is equipped with a pressure manipulator for the examination of the probe, which turns the tunnel stream into a voltage and a blood motor for drawing the image; block of analog-to-digital and digital-to-analog converters and high-voltage boosters; block keruvannya with a crocodile engine; a board with a signal processor that processes the insurance signal; a computer that collects information and provides an interface with the computer. Structurally, the DAC and ADC unit is installed in the same housing with the power supply unit. The board with a signal processor (DSP - Digital Signal Processor) ADSP 2171 from Analog Devices is installed in the ISA expansion slot of a personal computer.

A detailed view of the mechanical system of the microscope is shown in Fig. 2. The mechanical system includes a base with a pseudomanipulator and a system for smooth feeding of the sample on a rotary motor with a gearbox and two vibrating vibrating heads for robot operation in the scanning tunnel and atomic force microscope modes ii. The microscope allows you to obtain stable atomic data on traditional test surfaces without drying out additional seismic and acoustic filters.

2. Principles of robotic scanning probe microscopes

In scanning probe microscopes, the observation of the microrelief of the surface and local structures is carried out using an additional special procedure for preparing the probes at the top of the head. The working part of such probes (vistra) measures approximately ten nanometers. It is typical for the distance between the probe and the surface of the stains in probe microscopes to be in the order of magnitude 0.1 – 10 nm. p align="justify"> The operation of probe microscopes is based on different types of interaction between the probe and the surface. Thus, the operation of the tunnel microscope is based on the detection of the passage of the tunnel stream between the metal head and the eye to be carried out; Various types of force interactions underlie the operation of atomic force, magnetic force and electric force microscopes. Let's take a look at the dark rice, powered by different probe microscopes. The interaction of the probe with the surface is characterized by a certain parameter P. Since the sharpness and unambiguous significance of the parameter P is due to the rise of the probe probe, then this parameter can be used for organizing the return coupling system (OS) to control Position yourself between the probe and the eye. In Fig. 3 schematic indications of the fundamental principle of organizing the gateway of the SPM.

The gate system keeps the value of the P parameter constant, equal to the value set by the operator. As soon as the probe-surface position is changed, the P parameter is changed. The OS system generates a differential signal, proportional to the value ΔP = P - P, which is reduced to the required value and fed to the end element IE. The final element produces a resonant signal by bringing the probe close to the surface or by removing further parts until the signal becomes zero. With this method, it is possible to obtain a probe-image with great accuracy. When the probe is moved from the surface of the sample, the interaction parameter P is determined by the surface relief. The OS system responds to changes, so when the probe moves in the X, Y area, the signal on the final element appears proportional to the surface topography. To capture SPM images, a special process of image scanning is required. When scanned, the probe immediately collapses over the surface of the line (row), and the value of the signal on the tip element, proportional to the surface relief, is recorded in the computer memory. Then the probe rotates at the exit point and moves to the next scanning row (frame layout) and the process is repeated again. Recordings in this manner, at the hour of scanning, the turn-off signal is processed by a computer, and then the surface relief image will be generated using additional computer graphics. In order to study the surface topography, probe microscopes allow one to study various surface influences: mechanical, electrical, magnetic, optical and others.

3. Scanning elements (scanners) of probe microscopes

3.1 Scanning elements

For the operation of probe microscopes, it is necessary to control the working position of the probe probe and detect the displacement of the probe in the plane of the specimen with high accuracy (equivalent to angstrom frequencies). This task is carried out with the help of special manipulators - scanning elements (scanners). The scanning elements of probe microscopes are prepared from piezoelectric materials - materials that have piezoelectric power. P'ezoelectrics change their size in response to the external electric field. The level of the turning effect for crystals is written in the form:

where u is the strain tensor, E is the electric field components, d is the components of the piezoelectric coefficient tensor. The type of piezoelectric coefficient tensor is determined by the type of symmetry of the crystals.

In various technical applications, a wide range of technologies have been developed using poisoceramic materials. Pezoceramics are a polarized polycrystalline material produced by agglomeration of powders from crystalline ferroelectrics. Polarization of ceramics is carried out in this way. The ceramics are heated above the Curie temperature (for most ceramic ceramics, the temperature is less than 300C), and then completely cooled in a strong (about 3 kV/cm) electric field. After cooling, the ceramic ceramics are induced by polarization and begin to change their dimensions (increase or change according to the mutual direction of the polarization vector and the vector of the external electric field).

In wide-width scanning probe microscopy, the tubular parts of the piezoelements appeared (Fig. 4). They allow you to handle large displacements of objects with relatively low voltages to control. The tubular parts of the petrochemical elements are empty thin-walled cylinders made from petroceramic materials. Electrodes that look like thin balls of metal are applied to the outer and inner surfaces of the tube, and the ends of the tube are left uncoated.

Due to the difference in potentials between the internal and external electrodes, the tube changes its dimensions. In this case, the late deformation under the influence of the electric radial field can be recorded in the form:

de l - Dovzhina tube in an undeformed mill. Absolutely sub-cutting one

where h is the thickness of the cutting wall, V is the difference in potentials between the internal and external electrodes. Thus, with the same voltage V, the pressure of the tube will be greater, the greater the pressure and the smaller the thickness of the wall.

Connecting three tubes into one tube allows for precise movements of the microscope probe in three mutually perpendicular directions. Such a scanning element is called a tripod.

The disadvantages of such a scanner are the foldability of the design and the strong asymmetry of the design. Today, the most widely used scanning probe microscopy is scanners manufactured on the basis of a single tubular element. The hidden appearance of a tubular scanner and the diagram of the arrangement of electrodes are presented in Fig. 5. The tube material aligns radially with the polarization vector.

The internal electrode is suitable. The external electrode of the scanner separates the curing cylinder into four sections. When an antiphase voltage is applied to the proximal section of the external electrode (or the internal one), the tube section is shortened in the place where the direct field is avoided by the direct polarization, and there they are straight on the prostrate side. This is to connect the tube directly to the main line. In this way, scanning is carried out in the X, Y area. Changing the potential of the internal electrode in all external sections leads to a straightening or shortening of the tube along the Z axis. In this way, it is possible to organize a tricoordinate scanner on the basis one pipes. Real scanning elements often have a folding structure, and the principles of their work are lost by themselves.

Scanners based on bimorphic resin elements have also become increasingly widespread. Bimorph consists of two piezoelectric plates, glued together in such a way that the polarization vectors in the skin of them are in the opposite direction (Fig. 6). How to apply voltage to bimorph electrodes, as shown in Fig. 6 then one of the plates will expand, and the other will shrink, leading to the collapse of the entire element. In real designs of bimorphic elements, a difference in potentials is created between the internal and external electrodes so that in one element the field is aligned with the direction of the polarization vector, and in the other there is a direct ovane protilenno.

The development of bimorph under the influx of electric fields forms the basis for the work of bimorph piezoscanners. By combining three bimorphic elements in one design, it is possible to implement a tripod based on bimorphic elements.

If the external electrodes of the bimorphic element are separated from the same sector, it is possible to organize the rotation of the probe along the Z axis at the X, Y plane of one bimorphic element (Fig. 7).

Effectively, by applying antiphase voltage to the proximal pairs of sections of external electrodes, it is possible to ignite the bimorph so that the probe collapses in the area X, Y (Fig. 7 (a, b)). And by changing the potential of the internal electrode in relation to all sections of the external electrodes, the bimorph can be suppressed by moving the probe in the direction Z (Fig. 7(c, d)).

3.2 Nonlinearity of ceramic ceramics

Despite a number of technological advantages over crystals, ceramic ceramics have some shortcomings that negatively affect the operation of the moving elements. One of these shortcomings is the non-linearity of electrical power. In Fig. 8 as a butt, the value of the displacement of the cut in the straight line Z is determined according to the value of the applied field. In the opposite direction (especially with large ceramic fields), ceramic ceramics are characterized by a nonlinear degree of deformation in the field (or in the voltage that controls it).

Thus, the deformation of ceramic ceramics is a combined function of the external electric field:

For small grain fields, the given deposit can be presented in the following form:

u = d* E+ α* E*E+…

where d and α are linear and quadratic moduli of the piezoelectric effect.

Typical values ​​of field E, for which nonlinear effects begin to appear, become close to 100 V/mm. Therefore, for the correct operation of the elements to be scanned, force the ceramic fields to be vicorized in the area of ​​linearity of the ceramics (E< Е) .

scanning probe electron microscope

3.3 Strengthening of ceramic ceramics and hysteresis of ceramic ceramics

Another disadvantage of ceramic ceramics is called creep - delayed reaction to a change in the value of the control electric field.

The creep is brought to the point that SPM images are careful not to create geometrical changes associated with this effect. The creep is especially strong at the hour when scanners are released at a given point before local extinctions and at the beginning stages of the scanning process. To change the creep rate of ceramics, time-to-hour adjustments are required in certain processes, which can often compensate for scanner delays.

Another disadvantage of ceramic ceramics is the ambiguity of the direction of the change in the electric field (hysteresis).

This leads to the point that, even under very high voltages, the ceramic ceramics appear at various points along the trajectory in a position directly in the direction of the flow. To turn off the SPM imaging process, due to the hysteresis of the ceramic ceramics, the registration of information when scanning images is selected on one of the beds.

4. Devices for precision movement of the probe and the image

4.1 Mechanical gearboxes

One of the important technical problems in scanning probe microscopy is the need for precise movement of the probe and the formation of the working space of the microscope and the selection of the additional section no surface. To complete this problem, there are different types of devices that enable the movement of objects with high precision. A wide range of different mechanical gearboxes has been created, in which the rough movement of the output shaft is indicated by the fine movement of the object being displaced. Methods for reducing movement may vary. There is a wide range of important devices in which the reduction in the amount of displacement occurs due to the difference in the difference between the shoulders of the important ones. The diagram of an important gearbox is shown in Fig. 9.

Mechanical importance allows the reduction of displacement to be adjusted with a coefficient

In this way, the greater the distance between shoulder L and shoulder L, then the process of approaching the probe and the eye can be more accurately controlled.

Also, the designs of microscopes widely use mechanical gearboxes, in which the reduction of movement is achieved by the difference between the stiffness coefficients of two successively connected spring elements (Fig. 1). 0). The structure consists of a rigid base, a spring and a spring beam. The stiffness of the spring k and the spring beam are selected in such a manner that the mind is formed: k< K .

Reduction coefficient of the traditional spring element stiffness coefficient:

In this way, the more the stiffness of the beam is set to the stiffness of the spring, then the displacement of the working element of the microscope can be more accurately controlled.

4.2 Electric motors

Blood electric motors (SMO) are electromechanical devices that convert electrical impulses into discrete mechanical displacements. An important advantage of electric motors is that they ensure that the position of the rotor is unambiguously aligned with the input pulses of the stream, so that the rotation of the rotor is determined by the number of pulses that are controlled. In SHED, the moment that turns is created by magnetic fluxes, the collapsing poles of the stator and rotor, which are obviously oriented one after the other.

The simplest design is that of motors made of permanent magnets. They arise from the stator, which contains the windings, and the rotor, which contains permanent magnets. In Fig. Figure 11 shows a simplified design of the electric motor.

The rotor poles, which are drawn, have a rectilinear shape and are moved parallel to the axis of the motor. Indications for a small engine include 3 pairs of rotor poles and 2 pairs of stator poles. The motor has 2 independent windings, each of which is wound on two parallel stator poles. The engine readings show a value of 30 degrees. When the power is turned on, one of the windings, the rotor, will not occupy such a position in which the different poles of the rotor and stator are opposite each other. For uninterrupted wrapping, it is necessary to turn on the windings alternately.

In practice, electric motors are built up, which power the folding structure and provide 100 to 400 motors per rotor revolution. Since such a motor operates in pairs with threaded connections, then with a thread size of 0.1 mm, the accuracy of the positioning of the object is ensured on the order of 0.25 - 1 microns. To increase accuracy, additional mechanical gearboxes are used. The power of electrical heating allows the efficient use of SHED in automated probe proximity systems and imaging of scanning probe microscopes.

4.3 Blood drives

It is possible to ensure good insulation of devices from external vibrations and the need to operate probe microscopes in vacuum washes imposes serious stress on the drying of mechanical devices for moving the probe and the image. In connection with this, the connection has become very wide in probe microscopes, devices with the arrangement of piezoelectric converters have been developed, allowing for remote control of the movement of objects.

One of the designs of a rotary inertial motor is shown in Fig. 12. Place this device on the base (1), on which the piezoelectric tube (2) is attached. The tube carries electrodes (3) on the outer and inner surfaces. A split spring (4) is fixed at the end of the tube, which is a cylinder with adjacent pellets. The spring has a trimach of the object (5) installed - tighten the cylinder with a polished surface. The object that moves can be secured behind a spring or cap nut, which allows the device to operate in any orientation in the space.

The device operates as usual. To move the object's trimach in the direction of the Z axis to the cutting electrodes, a saw-shaped pulse voltage is applied (Fig. 13).

On the flat front of the saw-like voltage, the tube is smoothly compressed or compressed in position due to the polarity of the voltage, and finally, together with the spring and trimmer of the object, it is displaced onto the stand:

At the moment the saw-like voltage is released, the tube rotates at the exit position with accelerations a, so that it reaches the maximum value:

de - resonant frequency of the late collapsing tube. When Vikonanna Umovi F< ma (m – масса держателя объекта, F - сила трения между держателем объекта и разрезной пружиной), держатель объекта, в силу своей инерционности, проскальзывает относительно разрезной пружины. В результате держатель объекта перемещается на некоторый шаг К Δl относительно исходного положения. Коэффициент К определяется соотношением масс деталей конструкции и жесткостью разрезной пружины. При смене полярности импульсов управляющего напряжения происходит изменение направления движения объекта. Таким образом, подавая пилообразные напряжения различной полярности на электроды пьезотрубки, можно перемещать объект в пространстве и производить сближение зонда и образца в сканирующем зондовом микроскопе .

5. Protection of probe microscopes from external injections

5.1 Protection from vibration

To protect devices from external vibrations, use different types of vibration-insulating systems. Intellectually they can be divided into passive and active. The main idea behind the passive vibration-insulating system is in the future. The amplitude of the disturbing vibrations of the mechanical system decreases rapidly due to the increased difference between the frequency of the exciting force and the external resonant frequency of the system (a typical amplitude-frequency characteristic (AFC) of the collateral system is shown in Fig. 14).

Therefore, external influxes with frequencies > practically practically do not produce any significant influx on the covalent system. Ozhe, yakshcho romstiti vimiruvalnu head of probe microscope on the vіbro -ovyuchu platform submarine submarine Pidvis (Fig. 15), then go to the miroscope case, pass the lichen of the colivanni with frequencies, close to resonant frequency of the vіbroizoluyuchuyuyu systems. Set the air frequency of the SPM heads to 10 – 100 kHz, by choosing the resonant frequency of the vibration-insulating system to be low (about 5 – 10 Hz), you can effectively protect the device from external vibrations. By extinguishing the vibration at high resonant frequencies of the vibration-insulating system, dissipative elements with viscous friction are introduced.

Thus, to ensure effective protection, it is necessary that the resonant frequency of the vibration-insulating system be as low as possible. It is important to practically implement even low frequencies.

To protect SPM heads, active systems for suppressing external vibrations are successfully used. Such devices have electromechanical systems with a negative coupling, which ensures a stable position of the vibration-insulating platform in space (Fig. 16).

5.2 Protection against acoustic noise

Another factor is vibration of the design elements of probe microscopes and acoustic noise of various natures.

The peculiarity of acoustic transients are those in which the acoustic strands immediately flow onto the structural elements of the SPM heads, which causes the probe to oscillate until it reaches the surface of the sample. To protect the SPM from acoustic transients, a variety of drying bags are used, which allows one to significantly reduce the level of acoustic transients in the working space of the microscope. The most effective protection against acoustic disturbances is to place the vibrating head of the probe microscope near the vacuum chamber (Fig. 17).

5.3 Stabilization of thermal drift of the probe position above the surface

One of the important problems of SPM is the stabilization of the probe above the surface of the sample being monitored. The main reason for the instability of the probe is the change in the temperature of the medium or the heating of the design elements of the probe microscope during the hour of operation. Changes in solid temperature lead to thermal spring deformations. Such deformations are often observed in probe microscopes. To change the thermal drift, stabilize the temperature control of the SPM vibrating heads or introduce temperature-compensating elements into the design of the heads. The idea of ​​thermocompensation is common in the past. Whatever the design of the SPM, it is possible to supply a set of elements with different thermal expansion coefficients (Fig. 18(a)).

To compensate for thermal drift, compensating elements are introduced into the design of the SPM vibrating heads so that different expansion coefficients are created so that the sum of the temperature expansions at the different arms of the structure is equal to zero:

ΔL = ∑ ΔL = ΔT ∑αl0

The simplest way to change the thermal drift of the probe position along the Z axis is to introduce SPM elements into the design to compensate for the same material and the same characteristic dimensions as the main structural elements (Fig. 18 (b)). When changing the temperature of this design, the pressure of the probe at the Z direction will be minimal. To stabilize the position of the probe in the X, Y plane, the vibrating heads of microscopes are prepared as axially symmetrical structures.

6. Forming and processing SPM image

6.1 Scanning process

The process of scanning the surface in a probe microscope, which is being scanned, is similar to the flow of an electron on the screen in the electron tube of a TV set. The probe collapses along the line (rows) along the straight line, and then at the turning straight line (row row), and then moves to the advancing row (frame row) (Fig. 19). The probe moves behind the scanner in small pieces under the action of saw-like voltages, which are formed by digital-analog converters. Registration of information about the surface relief is carried out, as a rule, on a straight pass.

The information captured using a probe scanning microscope is stored in an SPM frame - a two-dimensional array of integers a (matrix). The physical location of these numbers is determined by the same value as was digitized during the scanning process. The skin value of the pair of indices ij is indicated by a small point on the surface between the scanning field. The coordinates of surface points are calculated by simply multiplying the corresponding index by the distance between the points where information is recorded.

As a rule, SPM frames are square matrices of size 2 (mostly 256x256 and 512x512 elements). Visualization of SPM frames is carried out using computer graphics, mainly in the form of trivial (3D) and double-dimensional 2D bright images. In 3D rendering, the surface image will be shown in an axonometric perspective using pixels or lines. In addition, there are different ways of illuminating pixels, which indicate different heights and surface topography. The most effective way to paint a 3D painting is to illuminate the surface with a dotted dzherel, drawn at the first point of the space above the surface (Fig. 20). In this case, it becomes possible to speak out about the small-scale unevenness of the relief. Also, using computer processing and graphics, scaling and wrapping of 3D SPM images is realized. When 2D visualization of the skin surface point is set to the same color. The most widely used are gradient palettes, in which the shading of the image is varied by the tone of the song color corresponding to the height of the surface point.

Local SPM vibrancy is associated with the registration of the deposits of monitored quantities in various parameters. For example, depending on the magnitude of the electrical flow through the probe-surface contact with the applied voltage, the dependence of various parameters of the force interaction between the probe and the surface from the probe-probe interface, etc. This information is stored in the form of vector arrays or in the form of a 2 x N matrix. For their visualization, a set of standard functions is transferred to the software of microscopes ій.

6.2 Imaging methods

When studying the power of objects using probe microscopy methods, which scan, the main result of scientific research is, as a rule, trivial images of the surface of these objects. The adequacy of the interpretation of the image depends on the qualifications of the specialist. At the same time, when processing an image, a low level of traditional techniques is used, which should be known before analyzing the image. The scanning probe microscope marks the moment of intensive development of computer technology. Therefore, in the meantime, I will record trivial images from the new Vikoristan digital methods of saving information, developed for computers. This led to significant difficulty in analyzing this image sample, but it was necessary to sacrifice the photographic brush to the methods of electron microscopy. The information captured using a probe microscope is represented in the computer as a two-dimensional matrix of integers. The skin number in this matrix depends on the scanning mode, it can be the values ​​of the tunnel stream, the values ​​of the hysteria, or the values ​​of more folding functions. If we show this matrix to people, then we cannot remove the same bonding phenomenon about the traced surface. Well, the first problem is to transform the numbers into a visual one that is easy to figure out. To fight like this. The numbers in the output matrix lie in the range of minimum and maximum values. Which range of integer numbers is assigned to the color palette. In this way, the skin value of the matrix is ​​displayed at the color point on the rectangular image. A series of places, in which there are significant meanings, become the coordinates of a point. As a result, we get a picture, where, for example, the height of the surface is conveyed by color - like a geographical map. There are probably dozens of colors on the map, but in our picture there are hundreds and thousands of them. For ease of identification, points that are close in height should be conveyed in similar colors. It may appear, and this is usually the case, that the range of output values ​​is larger than the number of possible colors. In this case, there is a loss of information, and an increase in the number of colors is not a way out of this situation, leaving the possibility of the human eye limiting. Additional processing of information is required, and the processing may vary depending on the order. Who needs to see the whole picture in detail, but who wants to look at the details. For this purpose different methods are used.

6.3 Revelation of a stationary nakhil

Images of the surface, taken with the help of probe microscopes, begin to appear as a dark field. This may be due to a number of reasons. First of all, the damage may result from inaccurate installation of the probe; Otherwise, there may be a connection with temperature drift, which can lead to displacement of the probe to the point of view; thirdly, the piezoscanner may move due to nonlinearity. A great deal of effort is wasted on the image in the SPM frame, so that other details of the image are not visible. To remove this defect, an operation is performed to remove the permanent wound. For which, at the first stage, the approximating area is found by the method of least squares

P(x,y), which has minimal impact on the surface relief Z = f(x,y), then the given area is taken from the ZZM image. It is necessary to completely destroy it in different ways depending on the nature of the disease.

If the SPM image has been removed from the image of the image of the probe, then it is necessary to completely rotate the area to the corner, which indicates the area between the normal to the area and the whole Z; at which surface coordinates Z = f(x, y) are recreated accordingly to the spatial rotation. However, with this transformation it is possible to draw the image of the surface from the appearance of a rich-valued function Z = f (x, y). If the thermal drift has affected the understanding, then the procedure can be reduced to the identification of Z – the coordinates of the Z plane – the coordinates of the SPM image:

The result is an array with a smaller range of values, and other details of the image are displayed in a large number of colors, becoming more prominent.

6.4 Troubleshooting problems related to scanner imperfections

The imperfection of the scanner's power leads to the fact that SPM images are subject to low specific conditions. Often, imperfections of the scanner, such as irregularities in the forward and reverse motion of the scanner (hysteresis), cryptocurrencies and nonlinearity of the ceramic ceramics, are compensated by hardware and the choice of optimal scanning modes. However, regardless of this, the ZZM image is a misconception, which is important to put on the hardware level. In the image, fragments of the scanner in the plane of the image infuse the position of the probe above the surface, the SPM images are a superposition of the real relief and the actual surface of a different (and often greater) order.

To solve this kind of problem using the least squares method, we find an approximated surface of a different order P(x,y), which has a minimal effect on the output function Z = f(x,y), and then this surface is derived from One SPM image:

Another type of interaction with non-linearity and non-orthogonality is the movement of the scanner at the X, Y plane. This is to achieve the same geometric proportions in different parts of the SPM image surface. To eliminate such problems, follow the SPM correction procedure using an additional file of correction coefficients, which is created when test structures are scanned with a specific scanner in a well-known relief.

6.5 SPM image filtration

The noise of the equipment (mainly the noise of highly sensitive input boosters), instability of the probe-scanner contact during scanning, external acoustic noise and vibrations lead to the SPM images being in order with the core information I'm in the noise warehouse. Partial noise of the SPM image can be removed by software.

6.6 Median filtration

Median filtering gives good results when detecting high-frequency transient errors in EPM frames. This is a non-linear method of processing, the essence of which can be explained as follows. Select the working filter window, which consists of nxn points (for significance, take a 3 x 3 window to place 9 points (Fig. 24)).

During the filtering process, the window moves around the frame from point to point, and the procedure ends. The values ​​of the amplitude of the SPM image at the points of this window are calculated according to the scale, and the values ​​that stand at the center of the sorted row are entered to the central point of the window. Then the selected point is always selected, and the sorting procedure is repeated. Thus, heavy dropouts and failures with such sorting always appear at the edge of the array that is being sorted, and do not disappear from the filtered image. With this kind of edge trimming, the frame is stripped of unfiltered areas that appear at the end of the image.

6.7 Methods for updating the surface using SPM images

One of the disadvantages common to all methods of scanning probe microscopy is the end size of the working part of the probes that are being analyzed. This is to achieve a significant improvement in the spatial resolution of microscopes and significant differences in SPM images when scanning a surface with uneven relief, aligned with the characteristic dimensions of the working part of the probe.

In fact, the SPM image is captured by the “neck” of the probe and the monitored surface. The process of “shaping” the probe shape with a surface relief is illustrated in a one-dimensional view in Fig. 25.

This problem can often be resolved by the SPM imaging method, which is based on computer processing of SPM data on the specific shape of the probes. The most effective method of surface renewal is the method of numerical deconvolution, which is a vicoristic shape of the probe, experimentally obtained by scanning test structures (with a well-known surface relief) structures.

It is important to note that the external surface of the image can only be achieved by combining two minds: during the scanning process, the probe touches all points on the surface, and at the same time, the probe touches only one point on the surface. If the probe during the scanning process cannot reach several sections of the surface (for example, if the sections of the relief are exposed to overhang), then the relief will be less frequently updated. Moreover, the more points on the surface the probe is used for scanning, the more reliably the surface can be reconstructed.

In practice, SPM imaging and experimentally determined the shape of the probe with two-dimensional arrays of discrete values, for which the similar and poorly determined value. Therefore, instead of calculating similar discrete functions in practice, with numerical deconvolution of the SPM, it is possible to visualize the minimum distance between the probe and the surface when scanning from the average average height .

At what height to the surface relief at this point can be taken the minimum distance between the probe point and the reference point of the surface for this position of the probe on the surface. In its physical place, this mentality is equivalent to the mental zeal of others, the provon allows you to search the point of the probe's surface with a more adequate method, which significantly speeds up the time of reconstructing the relief.

To calibrate and determine the shape of the working part of the probes, special test structures with known parameters of the surface topography are used. Views of the widest test structures and their characteristic images, taken using an atomic force microscope, are presented in Fig. 26 and fig. 27.

The calibration grid in the form of sharp spikes allows you to properly define the tip of the probe, while the straight-cut burrs help to renew the shape of the butt surface. The combined results of scanning these gratings can completely reshape the working part of the probes.

7. Suchasni SPM

1) Scanning probe microscope SM-300

Purposes for the modification of morphological features and structure of pore spaces. The SM-300 (Fig. 28) provides an optical positioning microscope, which eliminates the need to search the area of ​​interest. The color optical image of the sample is displayed with slight enhancements on the computer monitor. The intersection on the optical image indicates the position of the electron exchange. Based on the intersection, you can create a positioning check to define the area that is of interest for raster analysis

Small 28. SPM SM-300 electron microscope. The optical positioning unit is connected to a computer, which ensures its hardware independence from the microscope that is scanning.

CAPACITY SM - 300

· Guaranteed separate production 4 nm

· Unique optical positioning microscope (additional)

· Intuitively intuitive Windows ® software

· Complete computer control of the raster microscope and day-by-day imaging

· Standard TV production with digital signal processing

· Computerized low vacuum system (optional)

· All traces that fit on one position of the applique axis (12 mm)

· Elemental X-ray microanalysis in low and high vacuum modes (additional)

· The power of work in the minds of normal room lighting

· Follow-up of non-conducting signals without their prior preparation

· 5.5 nm separation in low vacuum mode

· Programmable control of mode switching

· Selectable chamber vacuum range 1.3 - 260 Pa

· Displaying images on a computer monitor screen

· Sequential V-backward Robinson sensor

2) High-split scanning probe microscope Supra50VP with INCA Energy+Oxford microanalysis system.

The appendix (Fig. 29) is intended for carrying out research in all fields of material science, in the field of nanotechnology and biotechnology. The device allows you to process large-sized samples, in addition, it supports the robotic mode in the mind of a grinding vise to trace non-conducting samples without preparation. Small 29. SPM Supra50VP

PARAMETERS:

Prestressing voltage 100 V – 30 kV (field cathode)

Max. increase to x 900000

Overhead separation – up to 1 nm (at 20 kV)

Vacuum mode with variable pressure from 2 to 133 Pa

Acute voltage – from 0.1 to 30 kV

Motorized table with five steps of freedom

Separate EDX detector 129 eV on the Ka(Mn) line, speed up to 100,000 imp/s

3) LEO SUPRA 25 modernized microscope with a “GEMINI” column and a field emitter (Fig. 30).

– Divided for research into galusi nanoanalysis

– Can connect both EDX and WDX systems for microanalysis

- Separate construction 1.5 nm at 20 kV, 2 nm at 1 kV.

Visnovok

Over the years, probe microscopy has allowed us to achieve unique scientific results in various fields of physics, chemistry and biology.

While the first scanning probe microscopes were indicator devices for clear investigations, the current scanning probe microscope is a device that integrates up to 50 different investigation techniques. It is possible to create displacement tasks in the probe-sample system with an accuracy of up to 0.1%, design the probe form factor, carry out precision measurements and achieve large dimensions (up to 200 µm at the scanning area and 15 – 20 µm per hundredth) and, whereby, secure submolecular dose.

Scanning probe microscopes have become one of the most sought after classes of scientific research equipment in the light market. New designs of fixtures are constantly being created, specialized to various additions.

The dynamic development of nanotechnology will require further expansion of the capabilities of previous technology. High-tech companies around the world are working on the development of pre-modern and technological nanocomplexes, which includes a group of analytical methods, such as: spectroscopy of a combination of roses Yuvannaya light, luminescent spectroscopy, X-ray spectroscopy for elemental analysis, micro-beam optical methods. The systems gain intense intellectual capabilities: the ability to recognize and classify images, see the necessary contrasts, gain the ability to model results, and the computational effort is provided by supercomputers. Yuteriv.

The technology that is being fragmented may have potential, but in the end it will undermine scientific results. Expanding the capabilities of this technology itself on the basis of tasks of a high level of complexity, which requires the preparation of high-class fakhivs who can effectively use these devices and systems.

List of references

1. Nevolin V.K. Fundamentals of tunnel-probe technology / V.K. Nevolin, - M.: Nauka, 1996, - 91 p.

2. Kulakov Yu. A. Electron microscopy / Yu. A. Kulakov, - M.: Zannanya, 1981, - 64 p.

3. Volodin A.P. Scanning microscopy / A. P. Volodin, - M.: Nauka, 1998, - 114 p.

4. Scanning probe microscopy of biopolymers / Edited by I. V. Yaminsky, - M.: Naukoviy Svit, 1997, - 86 p.

5. Mironov U. Fundamentals of scanning probe microscopy / U. Mironov, – M.: Tekhnosphere, 2004, – 143 pp.

6. Rikov S. A. Scanning probe microscopy of conductor materials / S. A. Rikov, - St. Petersburg: Nauka, 2001, - 53 p.

7. Bikov V. A., Lazarev M. I. Scanning probe microscopy for science and industry / V. A. Bikov, M. I. Lazarev // Electronics: science, technology, business, – 1997, – No. 5, – p. 7 – 14.