Research On Retinal Vein Injector For Robot-assistied Eye Microsurgey

Retinal vein occlusion is a common ophthalmic disease,which endanger human visual health seriously.There is no effective treatment due to technical limition.The retinal vein injector developed in this research is integrated into the end of eye microsurgey robot,and the method of injecting drugs directly into retinal blood vein is used to achieve the cure purpose.From the point of view of surgical experience,combined with the analysis of soft tissue interaction,a retinal vascular injector with high precision and micro-force perception ability is designed,and its feasibility is tested by experiment.The design of high precision mechanical structure is the basis of surgical injection.In this paper,the operation flow and requirement of the whole operation are analyzed,the movement space,accuracy and degree of freedom of the injector are determined,the injection mechanism which can enter the human eye for puncture is designed,the purpose of protecting the needle tip is realized through the needle tip release mechanism,and the requirement of the precision operation of the eye is achieved through the high precision driving device.The whole operation system achieves the straight line feed accuracy of 0.2 μ m and the end swing accuracy of 0.3 μm.Micro-force perception system is a necessary guarantee for doctors to operate safely.Based on the basic principle of FBG sensing,the method of filtering out temperature interference and measuring stress accurately is studied in this paper.A micro force sensing system integrated at the end of the surgical instrument is designed to measure the vascular force directly in the eye.The FBG calibration experimental platform is built,and the force calibration and related performance test experiments of FBG are completed.The highest force measurement accuracy of 0.2mN is realized.The analysis of force between needle and vein provides a theoretical basis for surgical operation.In this paper,an improved particle spring damping model of blood vessels is established according to the actual surgical experimental phenomena.The operation process is divided into four stages: vertical feed,horizontal feed,vascular puncture and feed after puncture.The force and displacement of blood vessels and needle tips in each stage are analyzed,the structure of injection needle is optimized,and a more reasonable surgical movement planning is put forward.The mechanical properties of pig eyes are measured by the related experiments of blood vessels and tissues.The actual vascular injection experiment is the key to verify the feasibility of this reaearch.In this paper,the retinal vascular drug injection system is built,and the work flow and control strategy of the whole system are planned.The retinal blood vessels of pig eyes and chicken embryos are successfully injected into medicine,and the minimum inject size of 120 μm blood vessels could be realized.The change of penetration force is analyzed,and the effect of feed speed,preloading and other factors on the difficulty of puncture are studied.It is proved that the retinal vascular injector can meet the functional requirement very well.