| With the improvement of people’s living standard,the change of life style and the quickening pace of life,more and more people are suffering from cardiovascular disease,which has become the number one killer of the people’s health.At present,the main method of treating the cardiovascular disease is endovascular stent implantation.Now,the most widely used stent is drug eluting stent.Compared with the bare metal stent,drug eluting stent significantly reduced the incidence of restenosis in the stent.The preparation and selection of the coating materials are the key to ensure the clinical effect of the drug eluting stent.The coating type and quality will seriously affect the compatibility of the stent,the integrity of the stent in the process of implanting and the drug release rate in the late,and these factors will directly affect the incidence of the restenosis in the stent.Spraying method and the material of coating are the key factors to determine the coating quality.This paper redesign and improve the laboratory original spraying device,optimize the coating technology and use the medical 316 L stainless steel sheet to make some corresponding verifications.The results shows that the device and coating technology can achieve good results.The main contents and results of this paper are as follows.1.Improvement and optimization of ultrasonic atomizing spraying device.This paper redesign the load support platform,which includes two sets of 57 stepper motor as transmission control platform,and STM32 is selected as the core processor to control the motions of the platform,and the 7 inch capacitive touch screen is used to control the platform by writing the corresponding program.The operation of the touch screen is simple,convenient and easy to control the transmission platform;the adjustable selection of ultrasonic power driver circuit realizes the power of atomization adjustable,and different coating materials select the appropriate power to obtain the best effect.This paper redesign the shell of the device and the organic glass is used as the top shell.2.The best coating technology of ultrasonic atomization device was explored.Firstly,the pretreatment of medical 316 L stainless steel sheet was carried out before spraying: First,sheet is beneficiated by mechanical polishing with aluminum oxide;then the sheet is acid pickled for different time by chromic acid.Last,we find the best time of acid pickling is 20 min by measuring the contact angle and observing with the atomic force microscopy.Then,this paper designed 9 groups’ orthogonal experiments and then we sprayed the sheets according to the parameters of each group.Last,we find the best parameters of spraying according to the observation and analysis of scanning electron microscopy and atomic force microscopy.The best spraying parameters is that the horizontal forward speed V1 is 4mm/s,and the rotation speed V2 is 9r/s,and the number of processing engineering n is 25.3.We sprayed the sheets with two kinds of coating,which are chitosan and chitosan + heparin mixed coating,in accordance with the best spraying parameters.We compared the sheet without the coating and the sheets with coating,finding that later has a better hydrophilicity;then we also did some biocompatibility experiments and found that the sheets coated by the device which is designed by the writer have a better biocompatibility.To sum up,this paper optimizes the design of the ultrasonic atomization device and it can be more effective in coating spraying,and through the experiments we found the best spray parameters,and the results showed that the sheets coating sprayed by the device have good biocompatibility. |
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