Chronic dopamine (DA) monitoring is a critical enabling technology to identify the neural basis of human behavior. Carbon fiber microelectrodes (CFM), the current gold standard electrode for in vivo fast scan cyclic voltammetry (FSCV), rapidly loses sensitivity due to surface fouling during chronic neural testing. Periodic voltage excursions at elevated anodic potentials regenerate fouled CFM surfaces but they also chemically degrade the CFM surfaces. Here, we compare the dimensional stability of 150 μm boron-doped ultrananocrystalline diamond (BDUNCD) microelectrodes in 1X PBS during 'electrochemical cleaning' with a similar-sized CFM. Scanning electron microscopy and Raman spectroscopy confirm the exceptional dimensional stability of BDUNCD after 40 h of FSCV cycling (~8 million cycles). The fitting of electrochemical impedance spectroscopy data to an appropriate circuit model shows a 2x increase in charge transfer resistance and an additional RC element, which suggests oxidation of BDUNCD electrode surface. This could have likely increased the DA oxidation potential by ~34% to +308 mV. A 2x increase in BDUNCD grain capacitance and a negligible change in grain boundary impedance suggests regeneration of grains and the exposure of new grain boundaries, respectively. Overall, DA voltammogram signals were reduced by only ~20%. In contrast, the CFM is completely etched with a ~90% reduction in the DA signal using the same cleaning conditions. Thus, BDUNCD provides a robust electrode surface that is amenable to repeated and aggressive cleaning which could be used for chronic DA sensing.

中文翻译：

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使用尺寸稳定的超纳米晶金刚石微电极实现对多巴胺的长期监测。

慢性多巴胺（DA）监测是一项重要的技术，可以识别人类行为的神经基础。碳纤维微电极（CFM）是目前用于体内快速扫描循环伏安法（FSCV）的金标准电极，由于在慢性神经测试过程中表面结垢而迅速失去了敏感性。阳极电位升高时的周期性电压偏移会重新生成结垢的CFM表面，但也会化学降解CFM表面。在这里，我们比较了使用类似尺寸的CFM在“电化学清洗”过程中在1X PBS中的150μm掺硼超纳米晶金刚石（BDUNCD）微电极的尺寸稳定性。扫描电子显微镜和拉曼光谱证实了FSCV循环40小时（约800万次循环）后BDUNCD具有出色的尺寸稳定性。电化学阻抗谱数据与适当的电路模型的拟合显示电荷转移电阻增加了2倍，附加的RC元素表明BDUNCD电极表面发生了氧化。这可能会使DA氧化电位增加了约34％，达到+308 mV。BDUNCD晶粒电容增加2倍，且晶界阻抗的变化可忽略不计，分别表明晶粒再生和新晶界暴露。总体而言，DA伏安图信号仅减少了约20％。相比之下，在相同的清洁条件下，CFM会被完全蚀刻，DA信号降低约90％。因此，BDUNCD提供了坚固的电极表面，可以进行反复的积极清洁，可用于慢性DA感测。