Abstract:

Electric welding of living tissue is used in almost many areas of surgery. The operation time, blood loss, and the likelihood of postoperative complications decrease. It is convenient to use it where it is difficult or impossible to use threads, clips, staples. Welding is carried out at frequencies from 100 kHz to 15 MHz. At high frequencies, the current flows on the surface of the conductor. This phenomenon is called surface or skin effect. Uneven distribution of current in biological tissue during welding can cause defects in the weld. Computer simulation makes it possible to determine the current density, electric field strength, tissue temperature during welding, considering the surface effect. Computer simulation was carried out in MATLAB and SolidWorks environments. Modeling in MATLAB allows you to more fully consider all the features of the processes. Modeling in SolidWorks is convenient to use in the design of electric welding tools, the development of welding technologies, because the creation of technical documentation, mechanical, electromagnetic, and thermal modeling are performed in the same environment. The article provides a review of the literature on modeling the surface effect when welding living tissues. To reduce the influence of the surface effect, tools with a special shape of the electrodes are used. The minimum thickness of the tissue to be welded can be tens of microns. Therefore, the effect of the proximity of the electrodes also has a significant effect on the current density. The lowest current densities are inside the electrodes and tissue and at the end of the electrodes. The maximum current densities are 10 times higher than the minimum ones. This is due to skin and proximity effects. The maximum temperature in the middle of the tissue is several times higher than the minimum temperature at the edges of the electrodes. The research results can be useful in the design of equipment, tools, and technologies for welding living tissues. Computer simulation allows, in many cases, to abandon experiments on experimental animals and speeds up research and equipment design.

Keywords: Living tissue welding, superficial, skin, proximity effects