Scientists have come close to creating nanorobots. There are materials for this: nanoparticles, nanotubes, graphene, various proteins. All of them are very fragile - to study them, new, more advanced microscopes are needed that do not damage the device during the research process.
Nanorobots can be useful in many areas of human life, primarily in medicine. Imagine tiny smart devices that quietly work inside us, control various parameters, transmitting data in real time directly to the doctor's smartphone. Such a robot must be made of a biocompatible material that is not rejected by the body, it also needs a power source and memory.
The battery will not help here, since it increases the size of the device, and it is not easy to find a biocompatible material for it. The problem is solved with the help of piezoelectrics - materials that generate energy when mechanically applied to them, such as compression. There is also the opposite effect - in response to the action of an electric field, structures made of piezoelectric materials change their shape.
Biocompatible piezoelectric nanorobots can be launched into blood vessels, and they convert their pulsation into electricity. Another option is to power the devices by moving joints and muscles. But then nanorobots will not be able to act constantly, unlike those in the vessels.
In any case, for nanorobots, it is necessary to select suitable materials and determine exactly how much pressure must be applied to the device so that an electrical impulse occurs in it.
Atomic Relations
A three-dimensional image of an object or surface at the nanoscale is obtained using an atomic force microscope. It works as follows: atoms in any substance interact with each other, and in different ways, depending on the distance. At large distances, they attract, but as they approach, the electron shells of the atoms repel each other.
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“A probe needle with a tip of 1-30 nanometers in diameter approaches the sample surface. As soon as it gets close enough, the atoms of the probe and the object under study will begin to repel. As a result, the elastic arm, to which the needle is attached, will bend,”says Arseniy Kalinin, lead developer at NT-MDT Spectrum Instruments.
The needle moves along the surface, and any height differences change the bend of the console, which is recorded by an ultra-precise optical system. As the probe passes over the surface, the software records the entire relief and builds a 3D model of it. As a result, a picture is formed on the computer screen, which can be analyzed: to measure the overall roughness of the sample, the parameters of objects on the surface. Moreover, this is done in a natural environment for the samples - liquid, vacuum, at different temperatures. The horizontal resolution of the microscope is limited only by the diameter of the tip of the probe, while the vertical accuracy of good instruments is tens of picometers, which is less than the size of an atom.
The needle of an atomic force microscope probes the sample / ITMO University Press Service.
For 30 years of development of atomic force microscopy, scientists have learned to determine not only the surface relief of the sample, but also the properties of the material: mechanical, electrical, magnetic, piezoelectric. And all these parameters can be measured with the highest accuracy. This has greatly contributed to the progress of materials science, nanotechnology and biotechnology.
Biologists are in business too
Measurement of piezoelectric parameters is a unique feature of an atomic force microscope. For a long time, it was used only for the study of solid-state piezoelectrics. The fact is that biological objects are quite soft; the tip of the probe easily damages them. Like a plow, it plows the surface, displaces and deforms the sample.
Recently, physicists from Russia and Portugal figured out how to make an atomic force microscope needle that would not damage a biological sample. They developed an algorithm according to which the probe, when moving from one point to another, moves away from the surface just enough so as not to interact with it in any way. Then he touches the subject under study and rises again, heading to the next point. Of course, the needle can still press a little on the surface, but this is an elastic interaction, after which an object, be it a protein molecule or a cell, is easily restored. In addition, the force of pressure is controlled by a special program. This technology makes it possible to study a biocompatible piezoelectric structure without damaging it.
“The new method is applicable to any atomic force microscope, provided there is specially designed high-speed electronics that processes the piezoelectric response from the console and software that converts the data into a map. A slight voltage is applied to the needle. The electric field acts on the sample, and the probe reads its mechanical response. The feedback is similar, so we can figure out how to squeeze an object so that it responds with the desired electrical signal. This gives the researcher a tool to search and study new biocompatible food sources,”explains Kalinin.