Department of Biomedical Engineering, Florida International University, Miami, FL, United States of America.
J Neural Eng. 2017 Dec;14(6):066014. doi: 10.1088/1741-2552/aa814d.
A neural interface system has been developed that consists of an implantable stimulator/recorder can with a 15-electrode lead that trifurcates into three bundles of five individual wire longitudinal intrafascicular electrodes. This work evaluated the mechanical fatigue resistance of the branched lead and distributed electrode system under conditions designed to mimic anticipated strain profiles that would be observed after implantation in the human upper arm.
Custom test setups and procedures were developed to apply linear or angular strain at four critical stress riser points on the lead and electrode system. Each test was performed to evaluate fatigue under a high repetition/low amplitude paradigm designed to test the effects of arm movement on the leads during activities such as walking, or under a low repetition/high amplitude paradigm designed to test the effects of more strenuous upper arm activities. The tests were performed on representative samples of the implantable lead system for human use. The specimens were fabricated using procedures equivalent to those that will be used during production of human-use implants. Electrical and visual inspections of all test specimens were performed before and after the testing procedures to assess lead integrity.
Measurements obtained before and after applying repetitive strain indicated that all test specimens retained electrical continuity and that electrical impedance remained well below pre-specified thresholds for detection of breakage. Visual inspection under a microscope at 10× magnification did not reveal any signs of damage to the wires or silicone sheathing at the stress riser points.
These results demonstrate that the branched lead of this implantable neural interface system has sufficient mechanical fatigue resistance to withstand strain profiles anticipated when the system is implanted in an arm. The novel test setups and paradigms may be useful in testing other lead systems.
已经开发出一种神经接口系统，该系统由一个可植入的刺激器/记录器和一个 15 电极导联组成，该导联分为三个束，每个束包含五个单独的线纵向束内电极。本研究评估了分支导联和分布式电极系统在模拟预期应变曲线条件下的机械疲劳阻力，这些应变曲线将在人体上臂植入后观察到。
开发了定制的测试设置和程序，以在导联和电极系统的四个关键应力集中点施加线性或角应变。每项测试都是为了在高重复/低幅度范式下进行疲劳评估，该范式旨在测试手臂运动对活动期间（如行走）或低重复/高幅度范式下（旨在测试更剧烈的上臂活动）对导联的影响。在代表人体使用的植入式导联系统的样本上进行了测试。使用与生产人体使用植入物时等效的程序制造样本。在测试程序前后，对所有测试样本进行电气和目视检查，以评估导联的完整性。
在施加重复应变前后获得的测量结果表明，所有测试样本都保持了电连续性，并且电阻抗远低于检测断裂的预定阈值。在 10×放大倍数下通过显微镜进行的目视检查未显示在应力集中点处的电线或硅树脂护套有任何损坏迹象。
这些结果表明，这种可植入神经接口系统的分支导联具有足够的机械疲劳阻力，可以承受系统植入手臂时预期的应变曲线。新颖的测试设置和范式可能有助于测试其他导联系统。
