The use of scanning probe and capillary microscopy in international collaboration
The scientific collaboration of the probe microscopy group of Lomonosov Moscow State University and the scientific group from the Sharif University of Technology (Tehran, IRI) in the framework of the Russian-Iranian project was extremely fruitful. For three years of the project the original results on local surface modification in thin films due to the use of scanning capillary microscopy were obtained. Also, a device for combined probe and capillary microscopy has been developed.
Nano- and microcapillaries have been widely used in patch clamps and microinjection techniques. It is in electrophysical measurements carried out with individual cells that capillaries found their first applications. Since then, capillary-based nanofluidic devices have acted as probes for local electrochemical analysis, scanning capillary microscopy, determination of surface charge, and manipulations with a nano-liter volume of liquid. The available works on capillary microscopy are mainly devoted to overcoming limitations of the method: the scanning speed is still relatively low, and the resolution obtained is not always sufficient for ultra-precise measurements [3, 4].
It was shown  that ions with redox potential can be retained inside the capillary due to the applied voltage between the electrode in the capillary and the electrode in solution, and then delivered by a pulse to a specific region of the sample.
We previously demonstrated that capillary microscopy can measure the level of hydrogen peroxide near the surface of a cell . Experiments on chemical nanolithography were carried out and measurements were made in the capillary microscopy mode using a FemtoScan Xi scanning probe microscope .
In the third year of the project we have achieved the following key indicators to initiate local chemical reactions using probe microscopy.
To conduct experimental studies, the installation of a combined atomic force and scanning capillary microscope, shown in Fig. 1, was developed.
Chemical lithography and oxidation experiments were performed with the following materials: titanium, silicon, graphite, graphene and conductive polymers.
A controlled local chemical reaction was carried out with atomic-size surface areas, inorganic molecules and macromolecules. Nanolithography methods for the implementation of a chemical reaction using nanoclusters and nanoparticles of gold and silver have been optimized.
The dependences of the local chemical reaction size versus the external interaction parameters (the pulse amplitude of the applied voltage between the probe and the surface), the pulse duration, the increase rate of the pulse fronts and environmental parameters) were determined.
A controlled local chemical reaction and modification was carried out in the natural conditions – air and aquatic environment. Experiments in the aquatic environment were carried out in a buffer solution using capillary microscopy.
To achieve the key project aims, the scanning probe microscopy installation was optimized, in particular, the feedback system in the scanning probe microscope has been improved.
Precision scanning systems for chemical reactions have been developed. Impulse exposure parameters have been optimized for the effective initiation of a local chemical reaction.
Practical recommendations how to use local chemical reactions in the creation of chemical and biological sensors, as well as how project results can be applied in nanoindustry and high technology have been developed.
Using remote control of FemtoScan scanning probe microscope via the Internet, a researcher, Ph.D. Meshkov G.B. held a remote master class on image processing and scanning settings for the Iranian group under the guidance of Reza Ejtehadi, a professor at the Sharif University of Technology (Tehran).
Remote control by a scanning probe microscope has been performed using the FemtoScan Online software in the multi-user master client interface. The master determines and sets all the scanning and measurement parameters, while all the obtained experimental data is simultaneously transmitted to the computers of all connected users. The master can delegate all his rights to one of the clients and such client becomes the master, and the master becomes the client. For communication between the participants during the experiment, the FemtoScan Online software integrates a messaging service – built-in chat. This helps to effectively conduct technical support, consultations and workshops. During implementation of lengthy experiments, it becomes possible to monitor the measurement process and carry out the correction of experimental parameters from different places: laboratories, classrooms or home. As a result, the effectiveness of individual and collective work increases significantly. ■