International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The current publication presents an approach for the elaboration of a disposable microfluidic hollow micro-channel using 2 photon polymerization technology and Photonic Professional GT2 (Nanoscribe, Germany) equipment. The design of a 3D model of a microchannel is realized by the CAD analysis software – SOLIDWORKS. A suitable laminar flow is generated by using computational fluid dynamics (CFD) software. As a result, the critical points of the pressure, velocity, and wall shear stress into the microfluidic channel are obtained. A real prototype of the hollow microfluidic device is created, using a highly innovative technology of 3D nanoprinting by twophoton polymerization. Experimental studies with dilute erythrocyte suspensions are conducted to test the functionality of the developed prototype of nano 3D printed microchannel.

The present study aims to model and analyze the images of induced in vitro blood clots from healthy donors and patients with type 2 diabetes mellitus (T2DM). By using the BioFlux microfluidic system, blood clots are induced at varying shear rates, and for different fibrinogen concentrations: native and highly modified. The fiber diameter of blood clots is analyzed by the scanning electron microscope (SEM). The obtained images of blood clots are imported as input data into the Image J software environment, after which obtained results for the area, number, and fibrin fiber diameter of blood clots, are further processed in a program developed in IntelliJ IDEA. It is found that patients with T2DM at the native concentration of fibrinogen at all studied shear rates form more blood clots having a larger total area, in comparison with the control group. At the higher modified fibrinogen concentration with increasing shear rate, the group with T2DM forms a smaller number of blood clots with a larger area, compared to healthy donors. From the SEM images, it is found, that denser fibrin networks are formed with increased fibrinogen concentration, which contains numerous thick fibrin fibеrs in healthy and diabetic individuals.

The main focus of this research is on the elaboration of the combined experimental approach and image analysis (based on the specialized software environments) to the research of erythrocyte aggregation, which is evaluated by the microfluidic device BioFlux. To realize a precise evaluation of the erythrocyte aggregation index based on the obtained, during the experiment images, are applied image processing toolbox from ImageJ and an elaborated computer program in IntelliJ IDEA (integrated development environment) as well. The obtained results for the index of erythrocyte aggregation, based on the developed methodology, show a statistically significant difference between the two studied groups with preeclampsia and healthy pregnant women.

In this pilot study, microfluidic flow analysis and atomic force microscopy (AFM), are used, to determine microrheological properties of the blood – aggregation, and deformability of erythrocytes in women with preeclampsia (PE). The aggregation of red blood cells (RBCs) is evaluated with the microfluidic system BioFlux, by applying an experimental approach and image analysis created by the authors of this study. The elastic properties of erythrocytes are defined by Young’s modulus, using AFM. The aggregation index of erythrocytes and their elastic modulus are statistically significantly increased in patients with PE, in comparison to healthy normotensive pregnant women. In addition, it is found that the RBCs are less deformable and the interaction between them in aggregates is stronger in women with preeclampsia as compared with healthy pregnant women.

The present study offers an important technological approach for the development of a disposable microfluidic channel using 3D nanoprinter – Photonic Professional GT2 (Nanoscribe, Germany). This publication aims to present 3D modelling, simulation, and prototype of a 3D nanoprinted microfluidic device for the investigation of blood cells. The design of 3D model of a microchannel is realized by the 3D CAD analysis software – SOLIDWORKS. A suitable laminar flow is generated by using computational fluid dynamics (CFD) software. As a result, the critical points of the pressure, velocity and wall shear stress into the microfluidic channel are obtained. An actual physical prototype of the proposed microfluidic device is developed, using a highly innovative technology of 3D nanoprinting by two-photon polymerization. Experimental studies with dilute erythrocyte suspensions are conducted to test the functionality of the developed real-world prototype of nano 3D printed microchannel.

This study treats a study oriented to the basic synthesis of the conic convolute helicoid. On the base of the elaborated mathematical model, the written equations show a theoretical possibility, depending on the basic geometrical characteristics of the designed conic convolute worm, to generate the active flanks of the helical teeth as parts of these conical convolute helicoids. Analytical dependences of the cross-section and the axial section of the conic convolute surfaces are obtained. These relations, as well as the performed studies of the graphic images of these sections, precede the process of constructing the algorithms for computer synthesis and design of these conic helical surfaces. The realized studies of the graphic images of these sections are the basis of the algorithms for computer synthesis and design of these conical helical surfaces. The appearance of singular points on these surfaces is examined, which is of particular importance for their technological synthesis. Based on the developed algorithm, a computer program for the synthesis and visualization of conic helical surfaces is realized and illustrated.

This research deals with the study of some kinematic characteristics, which can be used to ensure the loading capacity of the rack drives, including its hydrodynamic component. A brief analysis of the spatial rack drives in terms of their load capacity is realized. When mutually enveloping tooth surfaces are synthesized, it is possible to appear singular contact points appear on the active tooth surfaces. Two kinds of singular points exist, depending on the normal vector to the meshed tooth surfaces in their common points: singular points of firstorder (called ordinary nodes), and singular points of second-order. Singular points of first order should be registered and eliminated from the mesh region since increased specific friction, worsen lubrication, and heat transfer are present, which result in a decreased loading
capacity of the gear set A special accent is placed on the registration and elimination of singular points on the tooth surfaces of the synthesized rack drives. Analytical expressions are written defining total transference velocity and its normal component to an instantaneous contact line at an arbitrary contact point.

The high current requirements for the characteristics determining the accuracy, reliability and efficient manufacturing of modern machines, apparatus and devices applicable in various fields of industry and transport in a big extend dictate the applied scientific methodology to the technological synthesis, design and production of gears. In the processes of synthesis and design of the different types of gear transmissions, the designer faces an extremely complex set of questions to solve, which together define the desired optimal construction.
In this case, an optimal design means a gear transmission that is capable of delivering preliminary defined kinematic and / or strength requirements at minimum design, production and operation costs (including the repair costs during their exploitation). This work presents a review of the methodology, developed by the authors, oriented towards the synthesis and design of spatial gear mechanisms (hyperboloid gear drives), realizing rotations transformation between crossed shafts. The main principles, on which the construction of adequate software programs are based for the synthesis of treated transmissions, are presented.