Evaluation of Carbon Nanotube Electrodes for Neural Stimulation

描述（由申请人提供）：本项目的目标是使用脑深部电刺激（DBS）作为测试用例，评价碳纳米管（CNT）作为神经刺激的低阻抗、小电极。电极-组织界面的较低阻抗导致较低的功耗，因为需要较小的电压来实现相同的电荷注入。低功耗延长了电池寿命，并减小了电池的尺寸，从而减小了植入设备的尺寸。刺激电极的尺寸受到有效刺激所需的最小电荷注入和电极-组织界面的阻抗的限制。同样，电极的尺寸是由电极产生的插入损伤和可以刺激的体积的特异性的重要因素。更低的阻抗和更小的电极将导致更少的损坏电极和更小和更持久的电池的组合。我们将使用定量体外测量比较CNT电极与AIROF和传统铂电极的性能。我们期望在水电解窗口中使可逆电荷注入容量Qinj（以μ C/cm 2计）比相同尺寸的Pt电极增加230%并且超过AIROF电极200%，或者将电极的尺寸从标准的0.06cm 2减小到0.026cm 2，同时保持相同的电荷注入容量，或者其组合。我们预计与铂电极相比阻抗Z降低65%，与相同尺寸的AIROF电极相比阻抗Z降低40%。本项目的具体目标是：（1）量化碳纳米管形态（长度，密度，取向）对电荷注入和界面阻抗的影响，并确定那些增加电荷注入和降低界面阻抗的组合。电荷注入能力将通过测量体外电流脉冲刺激期间的电压瞬变来确定，并且电荷注入机制将通过循环伏安法来确定。将通过电化学阻抗谱法在体外测量界面阻抗。(2)使用来自目标#1的最佳电极配置，评估CNT表面的化学改性，例如氧官能团，例如，=O和-COOH，以进一步增加电荷注入容量并降低阻抗。(3)在体外用大鼠神经组织测试目标#2的前5种电极配置的神经胶质反应，并评估存在神经组织时CNT电极的性能（Qinj，Z，功耗），并将性能与铂和AIROF电极进行比较。此外，电极将在溶液中进行慢性脉冲测试，以评估电荷注入容量和界面阻抗的稳定性。该项目的成果将是一个全面的体外评估碳纳米管，生长与铂催化剂，作为高效的神经刺激电极。如果实现，它将导致神经刺激电极更小，限制插入损伤，消耗更少的功率，从而减小尺寸并增加电池的寿命。 公共卫生相关性：用于神经刺激的基于碳纳米管的电极将允许创建神经电极以减轻帕金森病、原发性震颤的症状，以及潜在的其他神经刺激应用。这些电极将更小，对大脑造成的伤害更小，并且功耗更低，因此电池将持续更长时间，需要更换的频率更低。

DESCRIPTION (provided by applicant): The goal of this project is to evaluate carbon nanotubes (CNTs) as lower impedance, smaller electrodes for neurostimulation, using deep brain stimulation (DBS) as a test case. Lower impedance of the electrode-tissue interface results in lower power consumption, as a smaller voltage is required to achieve the same charge injection. Low power consumption extends battery life and decreases the size of the batteries and thus of the implanted device. The size of stimulating electrodes is limited by the minimum charge injection required for effective stimulation and the impedance of the electrode-tissue interface. As well, the size of the electrode is an important factor in the insertion damage created by the electrode and the specificity of the volume that can be stimulated. Lower impendence and smaller electrodes will lead to less damaging electrodes and a combination of smaller and longer lasting batteries. We will compare the performance of CNT electrodes to AIROF and traditional platinum electrodes using quantitative in vitro measurements. We expect to increase the reversible charge injection capacity, Qinj, (in ¿C/cm2) by 230% over the same-sized Pt electrode and exceed AIROF electrodes by 200% in the water electrolysis window, or to reduce the size of the electrode from a standard 0.06 cm2 to 0.026 cm2 while maintaining the same charge injection capacity, or a combination thereof. We expect to reduce the impedance, Z, by 65% vs a platinum electrode and 40% vs an AIROF electrode of the same size. The specific aims of this project are: (1) Quantify the effect of CNT morphology (length, density, orientation) on charge injection and interfacial impedance, and identify those combinations that increase charge injection and reduce interfacial impedance. The charge injection capacity will be determined by measuring voltage transients during in vitro current pulse stimulation, and the charge injection mechanisms will be determined by cyclic voltammetry. The interfacial impedance will be measured in vitro by electrochemical impedance spectroscopy. (2) Using the best electrode configuration from Aim #1, evaluate chemical modification of the CNT surface, such as oxygen functional groups, e.g., =O and -COOH, to further increase the charge injection capacity and decrease the impedance. (3) Test the top 5 electrode configurations from Aim #2 in vitro with rat neural tissue for a glial response and assess the CNT electrode performance (Qinj, Z, power consumption) in the presence of neural tissue and compare the performance to platinum and AIROF electrodes. Further, the electrodes will undergo chronic pulse testing in solution to evaluate the stability of charge injection capacity and interfacial impedance. The outcome of this project will be a comprehensive in vitro assessment of carbon nanotubes, grown with a platinum catalyst, as highly efficient neural stimulation electrodes. If realized, it will lead to neural stimulation electrodes that are smaller, limiting insertion damage, and consume less power, thereby reducing the size and increasing the lifetime of batteries. PUBLIC HEALTH RELEVANCE: Carbon nanotube-based electrodes for neural stimulation will allow the creation of neural electrodes to alleviate symptoms of Parkinson's disease, Essential tremor, and potentially other neural stimulation applications. These electrodes will be smaller, causing less damage to the brain, and have lower power consumption, so batteries will last longer and need to be replaced less frequently.