Research and Development, Pulse Technologies Inc., Quakertown, PA, 18951, USA.
Biomedical Engineering Department, University of Connecticut, Storrs, CT, 06269, USA.
Sci Rep. 2022 Aug 17;12(1):13966. doi: 10.1038/s41598-022-18161-4.
Long-term implantable neural interfacing devices are able to diagnose, monitor, and treat many cardiac, neurological, retinal and hearing disorders through nerve stimulation, as well as sensing and recording electrical signals to and from neural tissue. To improve specificity, functionality, and performance of these devices, the electrodes and microelectrode arrays-that are the basis of most emerging devices-must be further miniaturized and must possess exceptional electrochemical performance and charge exchange characteristics with neural tissue. In this report, we show for the first time that the electrochemical performance of femtosecond-laser hierarchically-restructured electrodes can be tuned to yield unprecedented performance values that significantly exceed those reported in the literature, e.g. charge storage capacity and specific capacitance were shown to have improved by two orders of magnitude and over 700-fold, respectively, compared to un-restructured electrodes. Additionally, correlation amongst laser parameters, electrochemical performance and surface parameters of the electrodes was established, and while performance metrics exhibit a relatively consistent increasing behavior with laser parameters, surface parameters tend to follow a less predictable trend negating a direct relationship between these surface parameters and performance. To answer the question of what drives such performance and tunability, and whether the widely adopted reasoning of increased surface area and roughening of the electrodes are the key contributors to the observed increase in performance, cross-sectional analysis of the electrodes using focused ion beam shows, for the first time, the existence of subsurface features that may have contributed to the observed electrochemical performance enhancements. This report is the first time that such performance enhancement and tunability are reported for femtosecond-laser hierarchically-restructured electrodes for neural interfacing applications.
长期植入式神经接口设备能够通过神经刺激来诊断、监测和治疗许多心脏、神经、视网膜和听力障碍，并感应和记录来自神经组织的电信号。为了提高这些设备的特异性、功能性和性能，作为大多数新兴设备基础的电极和微电极阵列必须进一步小型化，并且必须具有卓越的电化学性能和与神经组织的电荷交换特性。在本报告中，我们首次表明，飞秒激光分级重构电极的电化学性能可以进行调整，以产生前所未有的性能值，这些性能值大大超过了文献中的报道值，例如，与未重构电极相比，电荷存储容量和比电容分别提高了两个数量级和 700 多倍。此外，还建立了激光参数、电极的电化学性能和表面参数之间的相关性，虽然性能指标表现出相对一致的增加行为，但随着激光参数的增加，表面参数往往呈现出不太可预测的趋势，从而否定了这些表面参数与性能之间的直接关系。为了回答是什么驱动了这种性能和可调性，以及增加电极的表面积和粗糙度是否是导致观察到的性能提高的关键因素的问题，使用聚焦离子束对电极进行的横截面分析首次表明，可能存在亚表面特征有助于观察到的电化学性能增强。本报告首次报道了飞秒激光分级重构电极在神经接口应用中的这种性能增强和可调性。
