硅基电泳芯片非接触电导检测器

研制了一种集成于硅基电泳芯片分离沟道末端侧壁的新型二电极非接触电导检测器.讨论了影响电导检测响应灵敏度的相关因素;采用MEMS分析软件及等效电路模拟仿真,确定了检测器的相关参数,电极长度为550μm,宽度为15μm,间距为80μm,绝缘层厚度为1μm,电导检测工作频率为300 kHz.在加工技术中,选用SOI(sili-con on insulator)基片制作十字形微沟道及集成电导检测电极,采用深刻蚀和隔离技术使检测电极被完全隔离成孤岛,利用硼掺杂技术在分离沟道末端侧壁形成立体电极,获得了集成非接触电导检测电极的硅基电泳芯片.在外加Vpp为10 V、工作频率为300 kHz的正弦波激励下,进行了Na+无机阳离子浓度梯度实验以及Na+和Li+混合无机阳离子的电泳分离检测.结果表明,Na+浓度在1×10-9～1×10-4 mol/L范围内,电导响应信号随着离子浓度的增加而增大,检出限达到1×10-9 mol/L;Na+和Li+混合无机阳离子的分离度达到2.0,实现基线分离.     

侧壁四电极电容耦合非接触电导检测器(英文)

研制了一种集成于硅基电泳芯片分离沟道末端侧壁的新型四电极电容耦合非接触电导检测器.研究了该电导检测器的等效模型,对等效电路模型中的参数进行了公式推导,并讨论了影响电导检测响应灵敏度的相关因素.采用深刻蚀及离子注入加工技术制得了用于电导检测的立体电极.制作了基于锁相放大原理的信号处理电路,对该电导检测的频率响应及灵敏度进行了测试分析.实验结果表明,当激励信号频率为300 kHz时,该电导检测器具有最佳线性度;不同浓度Na+溶液响应电压差值为5 mV;检测限达到10-8mol/L;且成功实现了Na+和Li+混合无机阳离子的电泳分离在线检测.     

高效毛细管电泳/电导检测法测定饮用水中的阴离子

本实验采用四乙烯五胺作为毛细管电泳的电渗流抑制剂,以10mmol/L Tris(三羟甲基氨基甲烷)+10mmol/L H3BO3(硼酸)+0.2mmol/L EDTA(乙二胺四乙酸)+0.2%(V/V)四乙烯五胺为电泳运行液,负高压分离(-15kV),电导检测,对饮用水中的Cl-、NO3-、SO42-三种阴离子进行了直接分离测定,并考察了分离电压,pH值,电解质溶液的组成及浓度,电渗流抑制剂,有机添加剂组成等对分离的影响。建立高效、快速的饮用水无机阴离子高效毛细管电泳/电导检测的分析方法。     

高浓度有机废水处理中金属离子的离子色谱检测研究

提出了含盐有机废液的蒸发脱盐（焚烧）系统。建立了用离子色谱法测定高浓度有机废水中常见的碱金属、碱土金属离子含量的方法。选用IonPac CSl2A阳离子交换柱、20mmol／L甲磺酸流动相、抑制型电导检测，在14min内分别测定Na^＋、K^＋、Mg^2＋和Ca^2＋等4种阳离子。分析过程中通过C18预处理小柱直接进样，简化了样品处理过程。该方法具有灵敏度高、选择性强、操作简单等优点，适用于有机废液焚烧处理过程前后样品中碱金属、碱土金属离子含量的监测。     

新型铅离子选择电极的制备及应用

本文研究了以二（苯并[d]噻唑-2-硫基）甲烷为载体的新型的PVC膜铅离子选择电极的响应行为。室温下,所制得的电极对Ph2＋在1．0×10-3-1．0×10—2mol／L浓度范围内呈现能斯特响应,响应斜率为30．2mV／decade,检测下限为9．0×10-6mol／L。该膜电极响应较快,响应时间在1ls以内可连续使用两个月。电极具有良好的稳定性和重现性。在优化条件下,电极对Pb：‘具有较好的选择性。该电极可在≤20％（V／V）的甲醇水溶液中使用。制备的铅离子选择电极可作为准确滴定铅离子的电位滴定指示电极,并能用于膨化食品及汽车驶过的土中铅含量的直接测定,结果令人满意。     

基于组织液超滤提取的MEMS血糖检测传感器

基于超滤原理提取组织液、并对其进行后续葡萄糖检测,是实现长期血糖持续监测的一种有效途径．本文提出一种可用于组织液超滤提取及葡萄糖持续检测的传感器微系统．该系统主要由微流控底座和葡萄糖传感器芯片组成．其中微流控底座由PDMS微通道、SU一8单向阀等微加工器件组成,在压力作用下可完成组织液提取及将检测过的组织液排出的功能．采用体硅加工方法制作葡萄糖传感器芯片微型腔体及腔体底部的微孔膜,研制出具有扩散控制功能的三电极检测芯片,并在其上通过琼脂糖包埋方法固定葡萄糖氧化酶、基于电化学原理实现葡萄糖浓度的检测．实验结果表明,该系统可以实现液体的灵活提取,并且葡萄糖检测响应时间小于5s,在0．4V工作电压下线性测量范围达0．2～20mmol／L,灵敏度为9．76nA／（mmol·L-1）,相关系数为0．9954．多次测量5mmoL／L样本,差异系数3．48％．可见该传感系统具有较好的稳定性,并且体积小、易于集成,有望用于组织液灵活提取及其葡萄糖持续监测．     

离子色谱法测定面粉中的溴酸盐

采用离子色谱法测定面粉中的溴酸盐,选用Metmhm861型离子色谱仪,Metmsep Asupp 5—250阴离子分析柱,以3．2mmol／LNaCO3＋1．0mmol／LNaHCO3溶液为淋洗液（流动相）。标准曲线的线性范围为0．2～1．2mg／L（r=0．999807）,BrO3^-的检出限为0．02mg／L（进样阵积20μL）,相对标准偏差为1．173％,厢本方法测定面粉样品,加标回收率在91．9％以上。实验表明,本方法快速、准确,灵敏,重复性较好,结果令人满意。     

苯并咪唑在KOH溶液中对锌材的缓蚀性能

锌电极材料的优良缓蚀剂汞有剧毒,以苯并咪唑缓蚀剂取代汞有益于环保。采用失重法、电化学方法等研究了0．1mol／LKOH溶液中苯并咪唑对锌的缓蚀性能。结果表明：苯并咪唑能有效抑制锌的阳极氧化,从而抑制锌在碱液中的自腐蚀,属于阳极型缓蚀剂;当苯并咪唑浓度为10．0mmol／L时缓蚀效果最佳,缓蚀率可达96．68％;苯并咪唑...     

Ti/SnO_2 Sb_2O_3 MnO_2/PbO_2阳极的性能研究

制备了一种非贵金属阳极－Ｔｉ／ＳｎＯ２＋Ｓｂ２Ｏ３＋ＭｎＯ２／ＰｂＯ２,并用ＸＲＤ、ＳＥＭ进行了表征,计算出了电极的分形维数,测定了该电极在硫酸中的使用寿命和动力学参数,把该电极用于处理含酚废水和Ｐｂ电极进行对比．结果表明,节电３３％,转化率达９５％,是一种优良的电化学催化剂．     

Mn2O3纳米球的水热法合成及其应用

以CTAB作为模板剂,通过控制合适的浓度,得到尺度均匀的纳米级别的氧化锰颗粒,实验结果表明,当控制CTAB的浓度和反应物浓度在0．3mmol／L72．0．1mmol／L时,反应60min后得到的产物经过离心高温烘干后为均匀纳米球,形貌较为理想。将合成好的产物用于锂离子电池电极材料可得到较好的充放电效果。     

Improving the compatibility of contact conductivity detection with microchip electrophoresis using a bubble cell

A new approach for improving the compatibility between contact conductivity detection and microchip electrophoresis was developed. Contact conductivity has traditionally been limited by the interaction of the separation voltage with the detection electrodes because the applied field creates a voltage difference between the electrodes, leading to unwanted electrochemical reactions. To minimize the voltage drop between the conductivity electrodes and therefore improve compatibility, a novel bubble cell detection zone was designed. The bubble cell permitted higher separation field strengths (600 V/cm) and reduced background noise by minimizing unwanted electrochemical reactions. The impact of the bubble cell on separation efficiency was measured by imaging fluorescein during electrophoresis. A bubble cell four times as wide as the separation channel led to a decrease of only 3% in separation efficiency at the point of detection. Increasing the bubble cell width caused larger decreases in separation efficiency, and a 4-fold expansion provided the best compromise between loss of separation efficiency and maintaining higher field strengths. A commercial chromatography conductivity detector (Dionex CD20) was used to evaluate the performance of contact conductivity detection with the bubble cell. Mass detection limits (S/N = 3) were as low as 89 +/- 9 amol, providing concentration detection limits as low as 71 +/- 7 nM with gated injection. The linear range was measured to be greater than 2 orders of magnitude, from 1.3 to 600 microM for sulfamate. The bubble cell improves the compatibility and applicability of contact conductivity detection in microchip electrophoresis, and similar designs may have broader application in electrochemical detection as the expanded detection zone provides increased electrode surface area and reduced analyte velocity in addition to the reduction of separation field effects.     

POSS-(PMMA46)8浸渍涂覆商业PP隔膜的结构与性能

为了提高锂离子电池的安全性能,降低其界面阻抗,选用既具有优异耐热性能又与聚合物有良好相容性的POSS杂化聚甲基丙烯酸甲酯(POSS-(PMMA 46 ) 8)作为改性剂,通过在商业聚丙烯(PP)隔膜上浸渍POSS-(PMMA 46 ) 8制备改性商用PP隔膜,分析隔膜的力学性能、热收缩性能、界面性能、离子电导率及电化学性能。结果表明:当POSS-(PMMA 46 ) 8质量分数为40%时,复合膜的孔丰富均一,润湿性最佳,拉伸强度是未改性前的5.34倍,且在160℃/1h下具有较高的热稳定性。此复合膜电导率为1.35×10 -3 S/cm,与电极的界面阻抗由原来的743Ω降为152Ω;Li/改性隔膜/LiFePO 4扣式电池的充放电循环稳定性较好,低倍率下的电池容量与商业PP隔膜相当。     

A three-dimensional image reconstruction algorithm for electrical impedance tomography using planar electrode arrays

We present a three-dimensional non-iterative reconstruction algorithm developed for conductivity imaging with real data collected on a planar rectangular array of electrodes. Such an electrode configuration as well as the proposed imaging technique is intended to be used for breast cancer detection. The algorithm is based on linearizing the conductivity about a constant value and allows real-time reconstructions. The performance of the algorithm was tested on numerically simulated data and we successfully detected small inclusions with conductivities three or four times the background lying beneath the data collection surface. The results were fairly stable with respect to the noise level in the data and displayed very good spatial resolution in the plane of electrodes.     

Contact conductivity detection in poly(methyl methacrylate)-based microfluidic devices for analysis of mono- and polyanionic molecules

An on-column contact conductivity detector was developed for the analysis of various mono- and polyanionic compounds separated by electrophoresis chips fabricated in poly(methyl methacrylate) (PMMA) using hot embossing techniques from Ni electroforms. The detector consisted of a pair of Pt wires (127 microm diameter) with an end-to-end spacing of approximately 20 microm and situated within the fluidic channel. The waveform applied to the electrode pair was a bipolar pulse with a frequency of 5.0 kHz and was used to reduce the charging current from measurement so that the current recorded at the end of one pulse is more representative of the solution conductivity. Using the detector, separations of amino acids, peptides, proteins, and oligonucleotides were demonstrated. For the amino acids and peptides, free-solution zone electrophoresis was performed. A calibration plot for the amino acid alanine was found to be linear from approximately 10 to 100 nM in a carrier electrolyte consisting of 10 mM triethylamonium acetate. The concentration detection limit was found to be 8.0 nM, with the corresponding mass detection limit equal to 3.4 amol (injection volume = 425 pL). The protein separations with conductivity detection were performed using MEKC, in which the carrier electrolyte contained the anionic surfactant sodium dodecyl sulfate (SDS) above its cmc. Near baseline resolution was achieved in the PMMA microchip for a solution containing 8 different proteins. In the case of the DNA fragments, capillary electrochromatography was used with a C18-modified PMMA chip and a carrier electrolyte containing an ion-pairing agent.     

Fabrication of conductive human bio‐nanoelectrode from graphene oxide modified with polyvinyl alcohol

It is time for electrodes prepared from graphene oxide (GO) to replace the traditional electrodes. However, GO is an electrically insulating material. However, in this study, a conductive electrode was prepared from GO modification with glycerol (GL) under the esterification reaction at 90°C for 3 h with sulphuric acid as a catalyst under vacuum conditions. Polyvinyl alcohol (PVA) acts as a polymer host. It was mixed with GO and modification was carried out under heating conditions. The mixture of the GO/GL/PVA nanocomposite was rapidly cooled and poured into the electrode mould. Finally, it is placed in a desiccator at room temperature for two days. The characterisation (Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy) proved that the ester bond was formed and a complete distribution of GO/GL into the matrix of PVA was verified. The GO/GL/PVA nanocomposite was tested for electrocardiogram (ECG) electrodes. The biopic instrument was used to compare the behaviour of the GO/GL/PVA plastic electrode and the commercial one. The results indicated that the GO/GL/PVA plastic electrode efficiently detected ECG signals after two months with high conductivity and lower noise than the commercial electrode. The GO/GL/PVA plastic electrode has been reported for the first time in the literature.Inspec keywords: catalysts, scanning electron microscopy, filled polymers, nanofabrication, X‐ray diffraction, moulding, nanocomposites, graphene compounds, Fourier transform infrared spectra, nanomedicine, biomedical electrodes, electrocardiography, electrical conductivity, medical signal detection, bonds (chemical)Other keywords: graphene oxide, polyvinyl alcohol, electrode mould, electrocardiogram electrodes, conductive human bionanoelectrode, electrically insulating material, GO‐GL‐PVA nanocomposite, GO‐GL‐PVA plastic electrode, esterification reaction, sulphuric acid, catalyst, vacuum conditions, polymer host, heating conditions, desiccator, glycerol, Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, ester bond, biopic instrument, ECG signal detection, electrical conductivity, temperature 90.0 degC, time 3.0 hour, temperature 293 K to 298 K, time 2 day, CO     

Mg-Si-Sn基热电器件电极材料的优化选择与连接工艺

研究了采用不同放电等离子烧结(SPS)工艺获得的单质金属(Ni、Cu、Ag、Al)电极与Mg-Si-Sn基热电材料结合界面的微观形貌和成分分布特征, 测试了合金(Ni-Al、Cu-Al)、金属/合金复合电极材料的热膨胀系数、电导率和热导率等物性参数。实验结果表明: 通过SPS烧结可以有效实现电极材料与Mg-Si-Sn基材料的连接, 复合电极材料Ni-Al/Al(60:40)和Cu-Al/Cu(45:55)具有高的电导率和热导率, 并且热膨胀系数与Mg-Si-Sn基热电材料相匹配, 有可能成为Mg-Si-Sn基材料的较理想电极材料。     

A graphene-laminated electrode with high glucose oxidase loading for highly-sensitive glucose detection

Graphene oxide(GO) has received considerable attention for glucose detection because of high surface area, abundant functional groups, and good biocompatibility. Defects and functional groups of the GO are beneficial to immobilization of glucose oxidase(GOD), but sacrificing electron-transfer capability for highly-sensitive detection. In order to obtain high GOD loading and highly-sensitive detection of biosensors, we first designed and fabricated a graphene-laminated electrode by combining GO and edgefunctionalized graphene(FG) layers together onto glassy-carbon electrode. The graphene-laminated electrodes exhibited faster electron transfer rate, higher GOD loading of 3.80 × 10^-9 mol·cm^-2, and higher detection sensitivity of 46.71 μA·mM^-1·cm^-2 than other graphene-based biosensors reported in literature. Such high performance is mainly attributed to the abundant functional groups of GO, high electrical conductivity of FG, and strong interactions between components in the graphene-laminated electrodes.By virtue of their high enzyme loading and highly-sensitive detection, the graphene-laminated electrodes show great potential to be widely used as high-performance biosensors in the field of medical diagnosis.     

Capillary electrophoresis and contactless conductivity detection of ions in narrow inner diameter capillaries

Capillary electrophoresis and conductometry represent a combination of a high-resolution separation method with a sensitive detection principle for the analysis of ionic species. In this paper, results are reported that are obtained with a contactless conductivity detector. This device works without a galvanic contact of the electrolyte and the electrodes. The conductivity sensor is based on two metal tubes that act as cylindrical capacitors. These electrodes are both placed around a fused-silica capillary with a detection gap of 1 mm left in between. When a high audio or low ultrasonic oscillation frequency between 40 and 100 kHz is applied to one of the electrodes, a signal is produced as soon as an analyte zone with a different conductivity compared to the background electrolyte passes the detection gap. An amplifier and rectifier is connected to the other electrode where the signal is further processed. Limits of detection for lithium and fluoride are 4 and 13 ppb, respectively, with a linear range over 4 orders of magnitude from 90 ppb up to more than 1000 ppm for both anions and cations. Furthermore, it is demonstrated that for species with lower equivalent conductivities, such as organic ions, indirect conductivity detection is a sensitive alternative to indirect optical detection methods. Limits of detection of 50 ppb and below are obtained for organic acids.     

Impedance spectroscopy on xerogel layer for chemical sensing

This paper deals with a new approach for toluene detection in water based on conductivity measurement on a xerogel layer deposited on Si/SiO₂ electrode. The conductivity changes is evaluated by means of resistance and phase variation of absolute impedance of the TEOS xerogel layer in contact with small amounts of toluene in water. The electrical properties of such xerogel layer can be measured with impedance spectroscopy technique and modelised with electrical model. The molecule structure of such layer has been obtained with Fourier transformed infrared spectroscopy. For toluene detection, impedance spectroscopy shows a decrease of the membrane resistance over time and an increase of the phase. This decrease can be attributed to the conductivity and dielectric constant variation. A detection limit of 100 ppm and a dynamic range 100 ppm–0.7% are obtained in our experimental conditions.     

Stripping analysis of nanomolar perchlorate in drinking water with a voltammetric ion-selective electrode based on thin-layer liquid membrane

A highly sensitive analytical method is required for the assessment of nanomolar perchlorate contamination in drinking water as an emerging environmental problem. We developed the novel approach based on a voltammetric ion-selective electrode to enable the electrochemical detection of "redox-inactive" perchlorate at a nanomolar level without its electrolysis. The perchlorate-selective electrode is based on the submicrometer-thick plasticized poly(vinyl chloride) membrane spin-coated on the poly(3-octylthiophene)-modified gold electrode. The liquid membrane serves as the first thin-layer cell for ion-transfer stripping voltammetry to give low detection limits of 0.2-0.5 nM perchlorate in deionized water, commercial bottled water, and tap water under a rotating electrode configuration. The detection limits are not only much lower than the action limit (approximately 246 nM) set by the U.S. Environmental Protection Agency but also are comparable to the detection limits of the most sensitive analytical methods for detecting perchlorate, that is, ion chromatography coupled with a suppressed conductivity detector (0.55 nM) or electrospray ionization mass spectrometry (0.20-0.25 nM). The mass transfer of perchlorate in the thin-layer liquid membrane and aqueous sample as well as its transfer at the interface between the two phases were studied experimentally and theoretically to achieve the low detection limits. The advantages of ion-transfer stripping voltammetry with a thin-layer liquid membrane against traditional ion-selective potentiometry are demonstrated in terms of a detection limit, a response time, and selectivity.