涂层修饰的柔性神经电极力学综合性能评估

Evaluation on Mechanical Comprehensive Performance of Flexible Neural Electrodes Modified by Coatings

目的对带有涂层修饰的柔性神经电极进行力学综合性能的评估,为电极及涂层参数的优化设计提供依据。方法对接触、植入以及微动阶段建立简化力学模型,以聚酰亚胺为电极材料,PEG为涂层材料,PDMS模具注塑法为涂层涂覆方法,设置40、80、120、160、200μm涂层厚度梯度,对3个因素(临界载荷、最大形变、脑组织最大应变)进行综合对比评估。结果厚度增加会引起临界载荷增大、最大形变减小以及脑组织最大应变减小,同时也会导致脑组织应变区域增大。均衡3个因素考虑,选择200μm作为涂层最佳厚度,在该厚度下,临界载荷为17.9 m N,最大形变为10.1μm,脑组织最大应变为0.011 4。结论涂层厚度对神经电极的力学性能有较大影响,在具体情况下可通过设置多个力学性能因素的影响因子选择最优参数。涂层的最优参数选择可提高电极的性能,对神经电极的临床应用具有重要意义。

Objective To evaluate mechanical comprehensive performance of the flexible neural electrode with coating modification,so as to provide references for optimal design of the electrode and coating parameters.Methods Simplified mechanical models were established for the contact phase, implantation phase and micromotion phase.The electrode material was polyimide,the coating material was PEG,and PDMS mold injection method was selected as the coating method.The coating thickness gradients were set as 40,80,120,160 and 200 μm,respectively,and the three factors( the critical load,the maximum total deformation and the maximum strain of brain tissues) were comprehensively evaluated.Results As the thickness increased,the critical load increased,the maximum total deformation and the maximum strain of brain tissues decreased,but meanwhile,the strain area of brain tissues increased.For consideration of equilibrium for three factors,200 μm was chosen as optimal thickness of the coating.At this thickness,the critical load was 17.9 mN,the maximum total deformation was 10.1 μm,and the maximum strain of brain tissues was 0.011 4.Conclusions The coating thickness had a great influence on mechanical properties of the neural electrode.The optimal parameters could be selected by setting influencing factors from the mechanical performance factors under specific case.The optimal parameter selection of coating can improve the electrode performance,which is of great significance for clinical application of the neural electrode.