Electrochemical and biological performance of chronically stimulated conductive hydrogel electrodes
Electrochemical and biological performance of chronically stimulated conductive hydrogel electrodes
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DOI：
10.1088/1741-2552/ab7cfc
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发表时间：
2020-04-01
影响因子：
4
通讯作者：
Shepherd, Robert K.
中科院分区：
文献类型：
--
作者：
Dalrymple, Ashley N.;Robles, Ulises A.;Shepherd, Robert K.
客观的。评估导电水凝胶 (CH) 涂层在慢性体内刺激后的电化学特性、生物反应和表面特征。方法。将有涂层的 CH 或无涂层的光滑铂 (Pt) 电极阵列植入大鼠的耳蜗中，并在 5 周内用超过 5700 万个双相电流脉冲进行刺激。在刺激前后以及刺激程序期间在体内测量电化学阻抗谱（EIS）、电荷存储容量（CSC）、电荷注入极限（CIL）和电压瞬态（VT）阻抗。记录电诱发的听觉脑干反应以监测神经功能。外植后，对耳蜗进行组织学检查，并使用扫描电子显微镜检查电极。主要结果。在电刺激程序之前和之后，CH 涂层电极表现出优于 Pt 电极的台式电化学优势。在体内，在整个刺激程序中，CH 涂层电极也比 Pt 电极具有显着优势，表现出更高的 CSC (p = 0.002)、更大的 CIL (p = 0.002) 和更低的 VT 阻抗 (p < 0.001)。 CH 组表现出更大的组织反应 (p = 0.003)，组织囊内有少量颗粒材料沉积。任何耳蜗的听觉神经元密度都没有损失，神经反应阈值也没有变化。对电极表面的检查表明，大多数 CH 电极表现出一些涂层损失；然而，没有证据表明下面的铂有腐蚀。意义。 CH 涂层电极在台式和体内表现出显着的电化学优势，尽管组织反应增加和涂层损失，但仍保持神经功能。虽然需要进一步研究来了解涂层损失的原因，但 CH 电极为神经假体的使用提供了希望。
Objective. Evaluate electrochemical properties, biological response, and surface characterization of a conductive hydrogel (CH) coating following chronic in vivo stimulation. Approach. Coated CH or uncoated smooth platinum (Pt) electrode arrays were implanted into the cochlea of rats and stimulated over a 5 week period with more than 57 million biphasic current pulses. Electrochemical impedance spectroscopy (EIS), charge storage capacity (CSC), charge injection limit (CIL), and voltage transient (VT) impedance were measured on the bench before and after stimulation, and in vivo during the stimulation program. Electrically-evoked auditory brainstem responses were recorded to monitor neural function. Following explant, the cochleae were examined histologically and electrodes were examined using scanning electron microscopy. Main results. CH coated electrodes demonstrated a bench-top electrochemical advantage over Pt electrodes before and after the electrical stimulation program. In vivo, CH coated electrodes also had a significant advantage over Pt electrodes throughout the stimulation program, exhibiting higher CSC (p= 0.002), larger CIL (p = 0.002), and lower VT impedance (p < 0.001). The CH cohort exhibited a greater tissue response (p= 0.003) with small deposits of particulate material within the tissue capsule. There was no loss in auditory neuron density or change in neural response thresholds in any cochleae. Examination of the electrode surface revealed that most CH electrodes exhibited some coating loss; however, there was no evidence of corrosion in the underlying Pt. Significance. CH coated electrodes demonstrated significant electrochemical advantages on the bench-top and in vivo and maintained neural function despite an increased tissue response and coating loss. While further research is required to understand the cause of the coating loss, CH electrodes provide promise for use in neural prostheses.