Abstract：
Objective.Implanted neural microelectrodes are an important tool for recording from and stimulating the cerebral cortex. The performance of chronically implanted devices, however, is often hindered by the development of a reactive tissue response. Previous computational models have investigated brain strain from micromotions of neural electrodes after they have been inserted, to investigate design parameters that might minimize triggers to the reactive tissue response. However, these models ignore tissue damage created during device insertion, an important contributing factor to the severity of inflammation. The objective of this study was to evaluate the effect of electrode geometry, insertion speed, and surface friction on brain tissue strain during insertion.Approach. Using a coupled Eulerian-Lagrangian approach, we developed a 3D finite element model (FEM) that simulates the dynamic insertion of a neural microelectrode in brain tissue. Geometry was varied to investigate tip bluntness, cross-sectional shape, and shank thickness. Insertion velocities were varied from 1 to 8 m s-1. Friction was varied from frictionless to 0.4. Tissue strain and potential microvasculature hemorrhage radius were evaluated for brain regions along the electrode shank and near its tip.Main results. Sharper tips resulted in higher mean max principal strains near the tip except for the bluntest tip on the square cross-section electrode, which exhibited high compressive strain values due to stress concentrations at the corners. The potential vascular damage radius around the electrode was primarily a function of the shank diameter, with smaller shank diameters resulting in smaller distributions of radial strain around the electrode. However, the square shank interaction with the tip taper length caused unique strain distributions that increased the damage radius in some cases. Faster insertion velocities created more strain near the tip but less strain along the shank. Increased friction between the brain and electrode created more strain near the electrode tip and along the shank, but frictionless interactions resulted in increased tearing of brain tissue near the tip.Significance. These results demonstrate the first dynamic FEM study of neural electrode insertion, identifying design factors that can reduce tissue strain and potentially mitigate initial reactive tissue responses due to traumatic microelectrode array insertion.
摘要：
目的：＆＃xD;植入的神经微电极是记录和刺激大脑皮层的重要工具。长期植入设备的性能，然而,通常被反应性组织反应的发展所阻碍。以前的计算模型已经研究了神经电极在插入后的微运动引起的脑应变，以研究可能使反应性组织反应的触发因素最小化的设计参数。然而,这些模型忽略了设备插入过程中产生的组织损伤，炎症严重程度的重要因素。这项研究的目的是评估电极几何形状的影响，插入速度,以及插入过程中脑组织应变的表面摩擦。
方法：使用耦合的欧拉-拉格朗日(CEL)方法，我们开发了一个3D有限元模型（FEM），该模型模拟了神经微电极在脑组织中的动态插入。几何形状是不同的，以研究尖端的迟钝，横截面形状,和柄的厚度。插入速度从1m/s到8m/s不等。摩擦从无摩擦变化到0.4。评估了沿电极柄及其尖端附近的大脑区域的组织应变和潜在的微脉管系统出血半径。 结果。＆＃xD;更尖锐的尖端导致尖端附近的平均最大主应变较高，除了方形横截面电极上的最钝尖端，由于拐角处的应力集中，表现出很高的压缩应变值。电极周围潜在的血管损伤半径主要是柄直径的函数，具有较小的柄直径，导致电极周围的径向应变分布较小。然而,方柄与尖端锥形长度的相互作用引起了独特的应变分布，在某些情况下增加了损伤半径。更快的插入速度在尖端附近产生了更多的应变，但沿着柄部产生了更少的应变。大脑和电极之间摩擦的增加在电极尖端附近和沿着小腿产生了更多的应变，但是无摩擦的相互作用导致尖端附近脑组织的撕裂增加。
结论：这些结果证明了神经电极插入的首次动态有限元研究，确定设计因素可以减少组织应变，并可能减轻由于创伤性微电极阵列插入引起的初始反应性组织反应。 .
方法：使用耦合的欧拉-拉格朗日(CEL)方法，我们开发了一个3D有限元模型（FEM），该模型模拟了神经微电极在脑组织中的动态插入。几何形状是不同的，以研究尖端的迟钝，横截面形状,和柄的厚度。插入速度从1m/s到8m/s不等。摩擦从无摩擦变化到0.4。评估了沿电极柄及其尖端附近的大脑区域的组织应变和潜在的微脉管系统出血半径。 结果。＆＃xD;更尖锐的尖端导致尖端附近的平均最大主应变较高，除了方形横截面电极上的最钝尖端，由于拐角处的应力集中，表现出很高的压缩应变值。电极周围潜在的血管损伤半径主要是柄直径的函数，具有较小的柄直径，导致电极周围的径向应变分布较小。然而,方柄与尖端锥形长度的相互作用引起了独特的应变分布，在某些情况下增加了损伤半径。更快的插入速度在尖端附近产生了更多的应变，但沿着柄部产生了更少的应变。大脑和电极之间摩擦的增加在电极尖端附近和沿着小腿产生了更多的应变，但是无摩擦的相互作用导致尖端附近脑组织的撕裂增加。
结论：这些结果证明了神经电极插入的首次动态有限元研究，确定设计因素可以减少组织应变，并可能减轻由于创伤性微电极阵列插入引起的初始反应性组织反应。 .
