OBJECTIVE Carbon fiber electrodes may enable better long-term brain implants, minimizing the tissue response commonly seen with silicon-based electrodes. The small diameter fiber may enable high-channel count brain-machine interfaces capable of reproducing dexterous movements. Past carbon fiber electrodes exhibited both high fidelity single unit recordings and a healthy neuronal population immediately adjacent to the recording site. However, the recording yield of our carbon fiber arrays chronically implanted in the brain typically hovered around 30%, for previously unknown reasons. In this paper we investigated fabrication process modifications aimed at increasing recording yield and longevity. APPROACH We tested a new cutting method using a 532nm laser against traditional scissor methods for the creation of the electrode recording site. We verified the efficacy of improved recording sites with impedance measurements and in vivo array recording yield. Additionally, we tested potentially longer-lasting coating alternatives to PEDOT:pTS, including PtIr and oxygen plasma etching. New coatings were evaluated with accelerated soak testing and acute recording. MAIN RESULTS We found that the laser created a consistent, sustainable 257 ± 13.8 µm2 electrode with low 1 kHz impedance (19 ± 4 kΩ with PEDOT:pTS) and low fiber-to-fiber variability. The PEDOT:pTS coated laser cut fibers were found to have high recording yield in acute (97% > 100 µV pp , N = 34 fibers) and chronic (84% > 100 µV pp , day 7; 71% > 100 µV pp , day 63, N = 45 fibers) settings. The laser cut recording sites were good platforms for the PtIr coating and oxygen plasma etching, slowing the increase in 1 kHz impedance compared to PEDOT:pTS in an accelerated soak test. SIGNIFICANCE We have found that laser cut carbon fibers have a high recording yield that can be maintained for over two months in vivo and that alternative coatings perform better than PEDOT:pTS in accelerated aging tests. This work provides evidence to support carbon fiber arrays as a viable approach to high-density, clinically-feasible brain-machine interfaces.

中文翻译：

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超小型碳纤维电极记录位点优化，提高体内慢性记录产量。

目的 碳纤维电极可以实现更好的长期脑植入，最大限度地减少硅基电极常见的组织反应。小直径光纤可以实现能够再现灵巧运动的高通道数脑机接口。过去的碳纤维电极表现出高保真度的单个单元记录和紧邻记录位点的健康神经元群。然而，由于之前未知的原因，我们长期植入大脑的碳纤维阵列的记录产量通常徘徊在 30% 左右。在本文中，我们研究了旨在提高记录产量和寿命的制造工艺修改。方法 我们测试了一种使用 532 nm 激光的新切割方法，与传统剪刀方法相比，用于创建电极记录位点。我们通过阻抗测量和体内阵列记录产量验证了改进记录位点的功效。此外，我们还测试了 PEDOT:pTS 的可能更持久的涂层替代品，包括 PtIr 和氧等离子体蚀刻。通过加速浸泡测试和急性记录来评估新涂层。主要结果 我们发现，激光器创建了一致、可持续的 257 ± 13.8 µm2 电极，具有低 1 kHz 阻抗（PEDOT:pTS 为 19 ± 4 kΩ）和低光纤间变异性。发现 PEDOT:pTS 涂层激光切割光纤在急性（97% > 100 µV pp ，N = 34 根光纤）和慢性（84% > 100 µV pp ，第 7 天；71% > 100 µV pp ，第 7 天）中具有高记录产量，第 63 天，N = 45 根纤维）设置。激光切割记录位点是 PtIr 涂层和氧等离子体蚀刻的良好平台，在加速浸泡测试中与 PEDOT:pTS 相比，减缓了 1 kHz 阻抗的增加。意义 我们发现，激光切割碳纤维具有很高的记录产量，可以在体内维持两个月以上，并且替代涂层在加速老化测试中比 PEDOT:pTS 表现更好。这项工作提供了证据支持碳纤维阵列作为高密度、临床可行的脑机接口的可行方法。