In Vitro Processing Experimental Research Of Laser Welding For Biological Tissue

Laser Biological Tissue Welding is a potential technology instead of traditional suture, with a lot of advantages, like well operation, short time of surgery, quick healing of wound, little inflammation, small scar. But, so far, most of the laser biological tissue researches are focused on the chronic tissue studies after laser cure and lack of systematical analysis for the influence law of tissue welding effect. Meanwhile, the repetition rate of laser welding technology is low and the mechanism of tissue fusion is unclear because of too much welding parameters and big difference of biological tissue. This dissertation combines ANSYS numerical stimulation and testing research to explore the welding fusion effect on skin tissue cut by the laser parameter (such as power, spot size, model of output, scanning route), besides, the mechanism of laser biological tissue welding and optimization methods of parameters have been given to improve its repetition rate and security.Firstly, this dissertation introduces the character of skin, and summarizes systematically the interaction effect and the theory of heat transmission in skin tissue, which provide selectable and controllable parameters for the research of laser tissue welding testing.Secondly, based on the theory of biological tissue heat transmission, a double-layer model is established via ANSYS and Gauss heat resource is add. This dissertation discuses the temperature field effect of tissue under different parameters which include power, beam diameter and scanning route.At last, combining the results of ANSYS numerical stimulation, the skin tissue fusion test is conducted in the laser tissue welding testing platform designed by ourselves. In the testing study, the laser power, beam diameter, output mode, scanning route and additive are all considered to explore their practical effect in tissue fusion. Welding mechanism of laser tissue welding and optimization methods of parameters are given based on the numerical stimulation and testing research.The main reason for that biological tissue cut gets fusion under laser irradiation is because high temperature conducted by photo-thermal effect make collagen and protein degenerate and coagulate. BSA can improve the healing rate of tissue cut; compared to continuous laser, big power pulsing laser can reduce welding time by 30～40%, which improves welding efficiency; when the pulsing power is 5W, spot radius is 0.2mm, welding velocity is 200mm/s, time is 12min, the combined parameters can realize high repetition rate and stronger tensile strength for the tissue cut processed by BSA.