Design And Experimental Study Of Piezo Ultrasonic Microdissection Based On Flexible Guide Mechanism

Piezoelectric ultrasonic microdissection as a technique for small damage to tissue cells and high precision of separation has been widely used in the pathological section microdissection experiment.However,existing microdissection devices have many shortcomings.For example,the lateral vibration of the cutting instrument tip is large,the cutting precision is low,and it is easy to cause additional damage to the tissue.The cutting track is rough and the separation effect is poor.At the same time,in the face of different types,size,thickness of the experimental objects,cutting parameters are not adjustable.In order to solve this problem,a new model of piezo ultrasonic micro-cutting device is proposed,which can reduce or restrain the harmful vibration in the cutting process,improve the cutting precision and reduce the additional damage,so as to realize efficient,accurate and safe requirements for micro-cutting.The main research contents are as follows:Firstly,according to the characteristics of micro-cutting experiments,the system platform is designed,the required functions of it are analyzed and the overall framework structure of the system is proposed.According to the technical requirements of each functional module,each device and module are selected and debugged.In order to meet the special experimental operation requirements of the system,some devices and drive circuits are customized.Through the integration and debugging of each module,the system operation interface is written to realize automatic or semi-automatic operation tasks.Secondly,the research on bio-microdissection technology and methods at home and abroad is carried out,and the advantages and disadvantages of piezo ultrasonic microdissection technology are analyzed.Combining the mechanism of biological tissue fracture and the principle of piezoelectric ultrasonic micro-cutting,the motion control parameters,experimental conditions and ceramic drive parameters of the cutting process were analyzed and parameters were established.Thirdly,in order to solve the problems of large lateral harmful vibration and unstable cutting precision of the existing cutting instrument,combined with the analysis of flexible hinge characteristics,a micro-cutting instrument based on the three-dimensional flexible guiding mechanism is proposed.The finite element simulation optimization design and theoretical calculations have established the parameters and materials of the hinge and key components.In order to verify the feasibility of the device,the modal analysis is performed to calculate the resonant frequency and the modal order.The movement of the two models'needle tip is researched under the same conditions.The results of the harmonic response analysis show that the cutting instrument has smaller lateral harmful vibration than the ordinary one,and the axial output performance is more stable.Fourthly,the parts are processed and assembled for the designed cutting device model,including cutter selection and piezo ceramic package design.In order to meet the device amplitude and frequency adjustment,the device adaptability is wider,and the cutter driver circuit is customized and packaged and debugged.In order to verify the actual performance of the device,the displacement frequency response curve of the tip is obtained by comparing the two sets of tests results.The results show that the flexible guide mechanism cutter tip has less harmful lateral displacement(<1?m)and the displacement output amplitude is more stable,which meets the requirements of safe and efficient experiment.Finally,in order to verify the feasibility and practicability of the device and system,the technical process of microdissection operation was developed,and the 5 ?m mouse liver pathological paraffin section was studied.Through series of comparison experiments,the optimum cutting parameters of insertion depth 2 ?m,cutting speed 100 ?gm/s,cutting angle 45°,and vibration frequency 21 KHz were obtained.In addition,the angle between the cutting force direction and the tangential direction of the trajectory is also an important parameter affecting the trajectory quality.The results show that the experimental results obtained when the two directions are consistent are the best,which meets the requirements of high-precision and micro-damage biological tissue micro-cutting experiments.