Development Of Assembly And Testing System For Bioresorbable Stents

With the development of the society and the increasing demand for materials,cardiovascular diseases are attracting more and more attention from domestic and foreign experts.Coronary stent implantation is the main method for the treatment of cardiovascular diseases.Traditional coronary stent materials are mostly metal.Metal scaffolds will remain in the human body for a long time during the treatment stage,resulting in a variety of complications such as thrombosis and inflammation etc.Therefore,the focus is shifting to bioresorbable coronary stents which can be gradually absorbed by the human body and have better biocompatibility.Compared with traditional metal stents,the disadvantages of bioresorbable stents are mainly reflected in the imaging and radial support performance.Limited by the size of the stent,this paper designs an automation system of radiopaque markers and extrusion resistance test under the micro-scale.The effectiveness of the system is verified by experiments.The following results are obtained.:(1)Accomplish the hardware and mechanical structure properties of the bioresorbable stents assembly and test system.According to the assembly requirement of bioresorbable stents and precious metal radiopaque markers,the design scheme of radiopaque markers assembly system under the micro-scale is proposed.According to the experience of manual assembly,the automation assembly process scheme is proposed.The key assembly steps are analyzed theoretically.The precision of the assembly system is required,and the overall mechanical structure is designed.In this paper,the common testing methods of extrusion resistance are introduced.A local load testing method for the apposition and radial support force of the expanded support is proposed.According to the scaffolds and tubes in the laboratory,the assembly platform under the micro-scale was expanded to build the anti-extrusion test module.The key structures were designed and analyzed.(2)Complete the construction of electrical structure of the assembly and test system.The motion control card based on IPC and industrial camera are selected as the control scheme.The electric translation platform,camera,telecentric lens,pressure sensor,vacuum pump,solenoid valve and other components are selected and check.In the LabVIEW programming environment,the overall software architecture is divided into three modules: motion control,machine vision and pneumatic control.The human-computer interaction interface is designed.The automatic calibration,assembly and anti-extrusion testing process are finally determined.(3)Conduct an experimental study on the assembly platform based on the completed equipment above.Firstly,the force of end-effector and the parts to be adsorbed on the micro scale are theoretically analyzed and experimentally verified to determine the final adsorption and release scheme.The system precision including camera calibration accuracy,platform motion accuracy,endeffector calibration accuracy and image processing accuracy were tested.The test results show that the assembly system designed in this paper has a high precision and meets the design requirements.The automatic calibration and automatic assembly process were tested experimentally,and the microassembly system designed in this paper was evaluated from the perspective of assembly efficiency and assembly effect.The experiment proved that the equipment function was well realized.(4)Test the supports and pipes based on the anti-extrusion test platform above.The test results show that the device has good consistency.The finite element method was used to simulate the test process.Compared with the experimental results,the accuracy of the experimental results was further verified within the error range.And the possible causes of the error were analyzed.