On Drug Injection Instrement For Robot-Assisted Retinal Vein Injecttion

Retinal vein occlusion is one of the common retinal vascular diseases,causing severe vision loss and even blindness.There is no effective treatment for this disease in clinical practice.In recent years,an innovative surgical retinal vein injection that directly injects thrombolytic drugs into the blocked retinal vein to dissolve the thrombus brings new light to patients.Due to the scale and fragility of the retinal anatomy,and the surgeon’s limited positioning accuracy and force perception,retinal vein injection is still a challenging and risky process.Surgical robots have high positioning accuracy and good stability,which provides a good solution for the realization of retinal vein injection surgery.A drug injection instrument for intravenous retinal injection was designed based on the operation of intravenous retinal vein injection.It can achieve retinal venipuncture,automatic injection of thrombolytic drugs.And with force sensing function,real-time sensing of the contact force between the instrument and the retinal tissue.The feasibility of the method was verified by in vitro animal experiments with dual-arm robots.Firstly,the research of high precision injection device is carried out,which lays the foundation for the realization of retinal venous injection surgery.This paper introduces the ophthalmic microsurgical robot system,and determines the precision,motion space,degree of freedom and function of the drug injection device used for retinal intravenous injection.A retinal intravenous drug injection instrument was designed to be used with a dual-arm robot.The drug injection instrument was composed of a high-precision driving mechanism and a double-stiffness cascade microneedle.The driving mechanism realizes the functions of microneedle rotation and positioning,linear feeding,and automatic injection.For clinical scenarios,the diameter of the target blood vessel is usually less than 200μm,and the outer diameter of the tip of the microneedle is only 80μm.The packaging of injection equipment is complete,the external parts are easy to disinfect,and the microneedle is convenient to replace,which is in line with the operation habits of surgeons.Then a three-dimensional micro-force sensing system was built to escort the operation of retinal venous injection.According to the principle of fiber Bragg grating sensor,three fiber Bragg grating sensors were integrated into the microneedle to achieve high precision contact force sensing.Integrated calibration platform,a direct calibration method is used to calibrate the lateral force,an indirect calibration method is used to calibrate the axial force.The RMS errors of the measured and actual forces in the three directions are 0.24 m N,0.18 m N,and1.71 m N,respectively.The RMS error of the two-dimensional force and the three-dimensional force are 0.3m N and 1.73 m N,respectively.Finally,the feasibility of intravenous retinal vein injection with drug injection instrument was verified by animal experiments in vitro.Planning the surgical procedure of retinal vein injection.With the help of a two-arm robot,the retinal vein of isolated porcine eyeballs and the blood vessels of the 12-day chicken embryo were injected into the experiment.The results showed that the drug injection instrument could successfully detect the puncture phenomenon and inject the t-PA solution into the blood vessels.During the experiment,the three-dimensional contact force between the instrument and the tissue can be sensed in real-time.The average venipuncture force of isolated porcine eyeballs in 15 groups was9.98 m N.The mean vascular puncture force of chicken embryos in 17 groups was 12.05 m N.Through the research of this subject,the robot-assisted retinal vein injection is realized.The high-precision driving mechanism and double-rigidity cascade microneedle of the injection device realize the function of retinal intravenous injection.The three-dimensional micro-force sensing system senses the contact force between the instrument and the tissue in real-time to ensure the safe operation of operation.In vitro animal experiments lay the foundation for the next stage of active animal experiments and clinical surgery.