Optimization Design And Implantation Mechanics Of PEG-DEX Coated Flexible Neural Electrode

Neural electrodes are designed to record neuron signals,exert electrical stimulations,and conduct medical treatment.However,large mechanical mismatch between traditional hard substrate material(e.g.,silicon)and soft brain tissue is inclined to cause inevitable tissue rejection and inflammation.Hence,flexible neural implants based on soft polymers have gradually become the mainstream in clinical applications.Flexible neural implant is difficult to insert into brain tissue due to bending.To facilitate smooth implantations,resorbable coatings have been used,acting as a stiff prop during penetrations.Optimizing design strategies is another way to reduce mechanical mismatch and realize long-term stable work of neural electrodes.From the perspective of manufacturing techniques and implantation mechanics,this study aims at optimizing dimensional and non-dimensional parameters of flexible neural implant coating.Specifically,an improved melt injection molding protocol is developed to process a type of composite coating(material: polyethylene glycol,dexamethasone)for polyimide based flexible neural implant.An in vitro testing system is developed,using rat brain tissue,0.6%agarose gel,and silicone rubber respectively as brain phantoms.Based on the system,impacts of machining qualities of masters on implantationinduced injuries at different insertion speed is quantitively evaluated.The simulation accuracy of different brain phantoms is also quantitatively compared.Next,non-dimensional design parameters including fabricating techniques,implantation methods and material selections are further optimized.The mechanical model of coating implantation is established to optimize the cross-section size of coatings.The main conclusions of this research are as follows:...