Mao Yuyang, Pechenizkiy Ivan, Stieglitz Thomas, Doll Theodor
BioMaterial Engineering, Department of Otorhinolaryngology, Hannover Medical School, Carl Neuberg-Str. 1, 30625 Hannover, Germany.
Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering-IMTEK & BrainLinks-BrainTools Center, University of Freiburg, 79110 Freiburg, Germany.
Micromachines (Basel). 2021 Jun 8;12(6):669. doi: 10.3390/mi12060669.
The most common failure mode of implantable neural implants has been delamination of layers in compound structures and encapsulations in a wet body environment. Current knowledge of failure mechanisms of adhesion and its standardized test procedures are lacking and must be established. This study demonstrated a combined experimental and numerical method to investigate the residual stresses from one of the most common encapsulation materials, silicone rubber (polydimethylsiloxane-PDMS) during the coating process at elevated temperatures. Measured shrinkage of test specimen correlates well to a modified shrinkage model using thermal-mechanical finite element method (FEM) simulation. All simulated interfacial stresses show stress concentration at the PDMS coating front depending on curing temperature and coating thickness, while Griffith's condition estimated the delamination of the coating front. This study emphasizes the understanding of the interfacial delamination giving the possibility to predict failure mode of neural interface.
可植入神经植入物最常见的失效模式是复合结构中层的分层以及在潮湿身体环境中的封装。目前缺乏关于粘附失效机制及其标准化测试程序的知识，必须加以确立。本研究展示了一种结合实验和数值的方法，以研究在高温涂层过程中，一种最常见的封装材料硅橡胶（聚二甲基硅氧烷 - PDMS）产生的残余应力。使用热 - 机械有限元方法（FEM）模拟，测试样品的测量收缩率与修正的收缩模型相关性良好。所有模拟的界面应力都显示，根据固化温度和涂层厚度，在PDMS涂层前沿存在应力集中，而格里菲斯条件估计了涂层前沿的分层情况。本研究强调对界面分层的理解，从而有可能预测神经接口的失效模式。
