薄层油膜在电解质溶液中的导电机制转变

薄层油膜在电解质中的电位变化是一个电化学过程，采用组合式微电极研究了薄层油膜在5％Na2SO4溶液中导电机制转变行为。结果表明：薄层油膜在电解质溶液中存在导电机制由电子导体向离子导体转变现象，表现为薄层油膜在浸泡初期，电位随时间变化发生正移，当浸泡一段时间后，薄层油膜的电位开始随时间变化发生负移，理论分析说明：当油膜为电子导体时，所测得的电位值实际上反应了电解质溶液中的氧化剂在油膜／电解质界面发生还原反应时的平衡电位，当油膜为离子导体时，所测得的电位值实际上反应了金属在金属／油膜界面发生氧化反应时的平衡电位，因此，采用组合式微电极，通过对薄层油膜电位的精确测量，可以研究高阻薄膜（如薄层油膜）在电解质溶液中导电机制转变。     

Electropolymerization of N‐hydroxyethylcarbazole on carbon fiber microelectrodes

N‐Hydroxyethylcarbazole (EtOHCz) was electropolymerized on carbon fiber microelectrodes (CFMEs). The polyEtOHCz‐modified CFME was characterized with FTIR‐ATR, scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. The polymer/CFME electrode exhibited the capacitive behavior and also good stability up to 2.0 V. The presence of hydoxylic group of the monomer seems to be an advantage on polymerization because of the unpaired electrons of oxygen, which would make ease at first stage for the adsorbtion on carbon fiber. The estimated value of the low‐frequency redox capacitance (C_LF) was found to increase with increasing dc potential. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Ag/AgCl微电极束的制作及其原位检测焊缝局部腐蚀的效果

金属焊接件焊缝处易优先发生腐蚀,单个微电极难以测量焊接件同一时刻、不同位置的局部腐蚀行为。自制了Ag/AgCl微电极束,用其测试了X80钢焊接件在天然海水和模拟的咸淡水(0.1 mol/L NaCl溶液)中以及X65-316L焊接件在模拟的酸性海洋大气环境(0.1 mol/L,pH=2的NaCl溶液)中的电位分布,预测了焊材的局部腐蚀行为。结果表明:制作的Ag/AgCl微电极束性能稳定,用其测定X80焊接件和X65-316L焊接件在不同环境中的电位分布,可准确推测腐蚀发生的位置。     

用于电刺激的植入式铂黑微电极

传统的植入式电刺激微电极表面积小,电极／组织界面阻抗高,并且电荷存储容量（CSC）小,这些都会增加植入式系统的功耗并影响电刺激效果．提出了一种在电极点电镀铂黑的方法来增加微电极的有效面积（ESA）．通过在超声波浴下使用脉冲电流电镀的方法,可以极大地增加微电极的ESA,降低界面阻抗并增加CSC和电荷注入容量．铂黑微电极的几何特性和电学特性分别由扫描电子显微镜（SEM）和电化学分析仪测定,并与未镀铂黑的电极特性进行了对比,对铂黑镀层的机械稳定性也做了相应的测试．实验结果表明,铂黑镀层的纳米结构使铂黑电极相比普通铂电极界面阻抗降低了1／16,CSC扩大13倍．在5min的室温超声波衰减实验中,阴极电荷存储容量（CSCc）仅减小20％．     

三维微柱阵列电极的电化学性能(英文)

随着MEMS技术的发展,对微纳尺寸器件的需求日益凸显,微能源的研究变得尤为重要,而微型超级电容器则是其中一种基于电化学电容实现储能的微型能量存储器件.设计了一种基于氧化钌功能薄膜的三维微柱阵列电极,并进行了相关的扫描电镜(SEM)、循环伏安(CV)和交流阻抗谱(EIS)测试.测试表明在2 mm×2 mm的硅片上,直径为50μm、高为100μm的三维微柱阵列电极的比电容为2.43 F/cm2,具有良好的电化学性能.与同容量的二维平面电极相比,基于三维结构的微型超级电容器具有明显的小尺寸优势.     

镍黄铁矿电化学生物氧化过程的分解机理(英文)

应用表面粘附和没有粘附Acidithiobacillus ferrooxidans的镍黄铁矿粉末微电极进行电化学测试,以说明镍黄铁矿氧化分解的机理。循环伏安CV结果显示,在-0.2V的低电位区域,在镍、铁离子析出时镍黄铁矿转变为中间相Fe4.5-yNi4.5-xS8-z;当电位在-0.2V到0.2V区间时,有不稳定的紫硫镍矿Fe3Ni3S4和FeNi2S4形成并在表面伴有元素硫的产生;当电位增加到0.2V以上时,不稳定相将全部分解;在高电位0.7V时,析出的亚铁离子被氧化为高铁离子。嗜酸氧化亚铁硫杆菌Acidithiobacillus ferrooxidans的存在使峰电位增高,反应起始电位负移,并对表面形成的元素硫有氧化去除作用。这一过程可通过-0.75到-0.5V电位区间发生的的还原反应证实。生物浸出和电化学实验结果均表明当pH2时溶液酸度的增加对氧化过程有轻度的阻碍作用。     

聚吡咯氧化石墨烯修饰的神经微电极阵列

利用电化学方法,在多通道神经微电极阵列芯片上制备聚吡咯氧化石墨烯薄膜材料,并对该材料的电化学行为进行了分析。对神经微电极阵列芯片采用计时电压法探究,确定了定向修饰聚吡咯氧化石墨烯薄膜的最佳电沉积条件。微电极阵列芯片为多通道实时检测神经细胞的电生理和电化学信号提供了一种新的器件,但其检测灵敏度、信噪比需进一步的提高。将聚吡咯氧化石墨烯的平面微电极阻抗值降低了92.1%,且提高了对多巴胺循环伏安响应的灵敏度,对神经电生理信号和电化学信号的检测具有重要意义。     

视网膜前假体中柔性凸起微电极的研制

采用聚对二甲苯（Parylene C）作为结构材料,借助微细加工技术设计并制作了按6×6矩阵排布的柔性凸起微电极阵列．微电极直径为80μm,引线线宽40μm,电极间距为280μm,引线间距为80μm．电极位点高度约为10μm,呈明显的圆滑凸起结构特征．电极和引线表面均平整光滑,轮廓清晰,结构完好．阻抗测试结果表明：随着频率的增加,凸起微电极的阻抗呈下降趋势,显示出明显的高通特性;1kHz时凸起微电极的阻抗约为10kΩ,较具有相同基底面积的平面电极约低30％,有助于提高电极的信噪比,可望用于视网膜前假体中．柔性凸起微电极制作工艺简单,利于高效率批量制作并提高微电极的集成度．     

Electrochemical impedance spectroscopy and morphological analyses of pyrrole, phenylpyrrole and methoxyphenylpyrrole on carbon fiber microelectrodes

In this study, N-pyrrole (Py), N-phenylpyrrole (PhPy), and 1[4-methoxyphenyl]-1H-pyrrole (MPhPy) homopolymers were synthesized electrochemically onto carbon fiber microelectrodes (CFMEs). The influences of the substituent effect on electrochemical impedance spectroscopy (EIS) were studied comparatively. All the monomers were electrodeposited in 0.05 M tetraethyl ammonium perchlorate (TEAP)/dichloromethane (CH₂Cl₂) solution and characterized by cyclic voltammetry (CV), Fourier transform infrared reflectance spectrophotometry (FTIR-ATR), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The morphological study reveals that the polymers were deposited as a continuous and well adhered film to surface of the CFME. An equivalent electrical circuit for three different monomers on CFMEs was proposed and experimental data were simulated to obtain the numerical values of circuit components. All results support the high quality film deposition that resulted in desired electronic properties due to the electron donating behaviors of substituent group of phenyl and methoxy.     

Study of the powder/membrane interface by using the powder microelectrode technique I. The Pt-black/Nafion® interfaces

The polarization behavior of a Pt microdisk electrode, a platinized Pt microdisk electrode and a Pt-black powder microelectrode immersed in sulfuric acid solution, in contact with a moist Nafion® membrane were studied by cyclic voltammetry. The experimental results reveal that the surface diffusion of the adsorbed species plays an important role in determining the kinetics of interfacial reactions taking place at the powder/Nafion® membrane interface. The weakly adsorbed hydrogen atoms diffuse significantly faster than the strongly adsorbed hydrogen and the oxygen-containing surface species. Surface active sites in the range of tens of microns from the powder/Nafion® interface can be involved in interfacial reactions. The apparent coefficients of diffusion of various surface species were estimated from the variation of peak current with scan rate of potential. The apparently higher irreversibility of electrode reaction observed at the powder/membrane composite electrode is explained by considering mechanism of current generation of this type of electrode.