Ward Matthew P, Rajdev Pooja, Ellison Casey, Irazoqui Pedro P
Weldon School of Biomedical Engineering, Purdue University, MJIS 2083, 206 S Martin Jischke Drive West Lafayette, IN 47907 USA.
Brain Res. 2009 Jul 28;1282:183-200. doi: 10.1016/j.brainres.2009.05.052. Epub 2009 May 30.
Several variations of microelectrode arrays are used to record and stimulate intracortical neuronal activity. Bypassing the immune response to maintain a stable recording interface remains a challenge. Companies and researchers are continuously altering the material compositions and geometries of the arrays in order to discover a combination that allows for a chronic and stable electrode-tissue interface. From this interface, they wish to obtain consistent quality recordings and a stable, low impedance pathway for charge injection over extended periods of time. Despite numerous efforts, no microelectrode array design has managed to evade the host immune response and remain fully functional. This study is an initial effort comparing several microelectrode arrays with fundamentally different configurations for use in an implantable epilepsy prosthesis. Specifically, NeuroNexus (Michigan) probes, Cyberkinetics (Utah) Silicon and Iridium Oxide arrays, ceramic-based thin-film microelectrode arrays (Drexel), and Tucker-Davis Technologies (TDT) microwire arrays are evaluated over a 31-day period in an animal model. Microelectrodes are compared in implanted rats through impedance, charge capacity, signal-to-noise ratio, recording stability, and elicited immune response. Results suggest significant variability within and between microelectrode types with no clear superior array. Some applications for the microelectrode arrays are suggested based on data collected throughout the longitudinal study. Additionally, specific limitations of assaying biological phenomena and comparing fundamentally different microelectrode arrays in a highly variable system are discussed with suggestions on how to improve the reliability of observed results and steps needed to develop a more standardized microelectrode design.
几种微电极阵列变体被用于记录和刺激皮层内神经元活动。绕过免疫反应以维持稳定的记录界面仍然是一项挑战。公司和研究人员不断改变阵列的材料成分和几何形状，以便找到一种能实现长期稳定的电极-组织界面的组合。通过这个界面，他们希望获得质量一致的记录以及在较长时间内用于电荷注入的稳定、低阻抗路径。尽管付出了诸多努力，但没有一种微电极阵列设计能够避免宿主免疫反应并保持完全功能。本研究初步比较了几种具有根本不同配置的微电极阵列，用于植入式癫痫假体。具体而言，在动物模型中对NeuroNexus（密歇根州）探针、Cyberkinetics（犹他州）硅和氧化铱阵列、陶瓷基薄膜微电极阵列（德雷塞尔大学）以及Tucker-Davis Technologies（TDT）微丝阵列进行了为期31天的评估。通过阻抗、电荷容量、信噪比、记录稳定性和引发的免疫反应对植入大鼠体内的微电极进行比较。结果表明，微电极类型内部和之间存在显著差异，没有明显更优的阵列。基于纵向研究收集的数据，提出了微电极阵列的一些应用。此外，还讨论了在高度可变系统中检测生物现象和比较根本不同的微电极阵列的具体局限性，并就如何提高观察结果的可靠性以及开发更标准化微电极设计所需的步骤提出了建议。
