Experimental investigation on bubble growth and detachment characteristics on vertical microelectrode surface under electrode-normal magnetic field in water electrolysis

The effects of current density and electrode-normal magnetic fields on the growth and detachment characteristics of a single bubble on vertical microelectrode surface have been investigated. A high-speed camera was used to capture the bubble evolution behavior and the bubble contact characteristic parameters were extracted and analyzed with OpenCV-Python program. The results reveal that an apparent bubble coalescence behavior occurs at low current densities and can be gradually inhibited with increasing current density. With the increase of current density, the bubble growth rate, departure diameter, working electrode potential and potential fluctuations increase, while the bubble growth time first increases and then decreases continuously. The upper microelectrode surface is more easily covered than the lower microelectrode surface. The whole microelectrode can be completely covered when the current density exceeds a certain limit with and without magnetic fields. The external magnetic fields can obviously promote the bubble detachment behavior within a relatively large current density range.     

微细盘状电极制备及其微细电解加工研究

基于电化学腐蚀加工方法,提出了一种微细盘状电极的制备方法。先采用平板阴极电化学腐蚀法,将毛坯加工成圆柱状微细电极,再对圆柱电极端部进行绝缘保护,进一步腐蚀制备得到微细盘状电极。利用微细圆柱电极、盘状电极和盘状群电极,在厚1 mm的304不锈钢片上进行电解加工对比实验,结果证明采用微细盘状电极电解加工微小孔,其加工定域性有明显改善,侧壁间隙减小,且降低了孔锥度。     

锂离子电池正极材料锂钒氧的制备及表征

以Li2CO3和V2O5为原料，采用固相法制备了锂离子电池正极材料LihV3O8，并通过XRD、SEM、粉末微电极循环伏安、恒流充放电及交流附抗等测试手段对其物理性能和电化学性能进行了表征。结果表明：所合成产物旱棒状，衍射特征峰与LiV3O8标准谱图基本一致，为单一物相．层状结构。产物具有较好的可逆性．初始容量为238．7mAh·g^-1，15次循环容量衰减至201．6mAh-g^-1，容量保持率为84．46％。粉末微电极循环伏安结果表明：Li^＋的嵌入脱出过程机理不同，嵌入是一个多相转变过程。计算得到材料的电导率为2．74×10^-5S．cm^-1     

Connection‐Strength Estimation of Neuronal Networks by Fitting for Izhikevich Model

Recently, there has been abundant research using multineuron recording, but there are many problems with extracting the features from the obtained spike time series, which are huge in volume and complex. Here we introduce a new method of estimating synaptic connection strengths between neurons by fitting to the Izhikevich model by maximum likelihood estimation. We demonstrate that our method can estimate connection strengths from spike time series given by a simulated neural ensemble and can estimate nonconnectivity between two independent cultured neuronal networks. These results suggest that our method is applicable to network and plasticity analysis of neuronal networks.     

Single nanowire assembled by liquid dielectrophoresis for on-chip technologies

ABSTRACT

Study on dynamic tensile properties and atomic chain fabrication of single nanowire, for understanding its dynamic tensile properties and unique physical properties of atomic chain to fabricate atom scale devices, is one of frontier research issues in nano-scale science. However, how to assemble single nanowire on a tensible micro-structure becomes one of the most difficult problems, which severely restricts the development of this research field. In this paper, after the ultrahigh tensible microelectrode chip is fabricated by micro-electromechanical systems technology, hexamethyldisilazane is utilized to improve hydrophobicity of the chip, and then a micro-droplet dielectrophoresis experimental platform and technology is developed to assemble single nanowire on the sensible microelectrode. Experimental results show that accurate and efficient assembly of single Cu nanowire is realized, which contributes greatly to the further research of dynamic tensile properties and atomic chain fabrication. And for guiding the assembly experiments, finite element technology is also utilized to analyze the local micro electro-field around the microelctrodes during dieletrophoresis experiments.     

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．     

pH measurement in the vicinity of a cathode evolving hydrogen gas using an antimony microelectrode

An antimony microelectrode was prepared by quenching a molten Sb–Sb2O3 mixture (2% Sb2O3). The local pH in the vicinity of a cathode evolving hydrogen gas was directly measured using the microelectrode. The local pH during electrolysis of KCl-glycine aqueous solutions was increased by proton consumption; however, the increment decreased with increasing concentrations of glycine, a buffering agent. The diffusion-limiting current density of hydrogen evolution involving proton reduction was controlled by the concentrations of the proton-donating species: protonated-glycine +H3NCH2COOH and H3O+ ions. A plot of the current density against the sum of the concentrations gives a single straight line passing through the origin. The phenomena are discussed in terms of electrodeposition processes of base metals.     

一种低温无硼无铅生料乳浊釉的研究

研究了一种无硼无铅生料乳浊釉，并讨论了影响乳浊度的一些因素     

Numerical simulations of phenomena observed at hot microelectrodes: Inlaid microdisk

In this paper we describe numerical simulations of a number of physico-chemical phenomena observed at disk microelectrodes polarized with a high frequency ac waveform. These phenomena include resistive heating of an electrolyte solution surrounding a microelectrode, electrothermal flow of the solution and electrochemical mass transport of dissolved redox species. The main purpose of doing these simulations was to provide the required theoretical background to the previously obtained experimental data. It is shown that the simulated linear flow rate of the solution is proportional to the voltage across the solution resistance in the power four and inversely proportional to the radius of the microelectrode. Thus this supports the idea that the convection at hot microelectrodes is driven primarily by the electrothermal flow. Simulations of the Faradaic current agree semi-quantitatively with the experimental observations. We have identified possible reasons for the observed discrepancy between the two sets of data.     

神经记录用硅基多通道微电极探针的设计与制造

为了从中枢神经系统记录电信号,半导体加工技术已经被用于微电极探针的制造.介绍了一种硅基探针的设计和制造工艺流程.我们已经制造出15 μm厚,3 mm长,100μm宽的记录用探针,每根探针含有7个记录点,间隔120 μm.在制造过程中使用微机械系统(MEMS)工艺中常用的硅表面微加工工艺:等离子增强化学气相淀积(PECVD),感应耦合等离子刻蚀(ICP)以及硅的各向异性刻蚀等.测试结果给出了探针的强度和阻抗特性.