Puncture Performance Of Micro-textured Electrode On Brain Tissue Under Low Frequency Vibration

Deep brain stimulation is an effective treatment for neurological diseases such as Parkinson’s.During the surgery,a cannulated electrode is directly punctured into the brain tissue.This process generates significant insertion force before the puncture and frictional force between the electrode and brain tissue during the puncture.These forces increase with the depth of the puncture,causing deformation and damage to the brain tissue and affecting the targeting accuracy of the procedure.In this study,we took advantage of the frictionreducing effects of micro-textures on surfaces to optimize laser processing parameters and investigate the wetting and friction properties of textured surfaces.We designed and fabricated two types of grooved micro-textured electrodes,and their puncture performance was evaluated through puncture tests,leading to the identification of the optimal frictionreducing texture configuration.By leveraging vibration-assisted puncture technology,we proposed a method that combines micro-texturing techniques with low-frequency vibrations to reduce the insertion force between the electrode and brain tissue,further minimizing puncture frictional force.The main research findings are as follows:(1)To obtain a grooved micro-texture with excellent comprehensive performance,a morphology quality factor was introduced to quantify the texture morphology.Through single-factor laser processing tests,appropriate ranges for laser processing parameters were determined using the width and morphology quality factor as evaluation criteria.An orthogonal test combined with grey relational analysis was used to optimize multiple evaluation criteria(width,depth,and recast layer)simultaneously,resulting in the optimal laser processing parameters: a scanning speed of 350 mm/s,a power of 1 W,and a modulation frequency of 65 k Hz.After verification,the maximum grey relational degree value was 0.881,and the width,depth,and recast layer thickness of the grooved texture were 21.153 μm,8.187 μm,and 26.030 μm,respectively.(2)To investigate the wetting and friction properties of textured surfaces,we aimed to identify texture configurations and spacings with excellent friction-reducing performance.In order to investigate the change of wettability of the micro-textured surface,the rectangular area method was proposed to obtain the rule that the size,spacing and morphology of the micro-textured affect the wettability of the surface,and the spacing of the weave with excellent wettability was determined to be 0.1mm by contact angle test.The friction of the micro-textured surface was reduced by 56.3% compared to that of the smooth specimens.The friction reduction mechanism of the micro-textured surface was revealed:the micro-textured surface reduces the direct contact area with the brain tissue block,and it traps the lubricating fluid to form a liquid film on the surface.(3)In order to better investigate the electrode puncture performance,the electrodebrain tissue interaction was analysed to provide theoretical guidance for the puncture test;a micro-textured electrode puncture platform was used,two types of grooved micro-textured electrodes were prepared,and the puncture test was carried out using fresh pig brain as the test material.The results show that the friction reduction performance of the linear interlaced grooved micro-textured electrodes is excellent with or without lubrication and at speeds of 3-7 mm/s.The growth rate of the puncture friction increases with increasing speed,which provides a basis for the selection of the puncture speed for subsequent tests.(4)Based on low-frequency vibration-assisted puncture technology,we designed and built a low-frequency vibration puncture platform.By changing the amplitude and frequency,single-factor vibration puncture tests were conducted using insertion force and puncture friction force growth rate as evaluation criteria.The results show that the penetration force in 24 out of 25 vibration punctures and the friction growth rate in 16 out of 25 vibration punctures are lower than that of micro-textured electrode punctures without vibration,which shows that low frequency vibration-assisted microfabricated electrode punctures can not only effectively reduce the penetration force but also further reduce the penetration friction.A grey correlation analysis was used to determine the optimum combination of vibration parameters of 150 Hz and 1 μm,with a maximum grey correlation value of 0.918 and growth rates of 7.43 m N and 1.03 m N/mm for puncture force and puncture friction respectively.