151
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Dittami GM, Ayliffe HE, King CS, Rabbitt RD. A Multilayer MEMS Platform for Single-Cell Electric Impedance Spectroscopy and Electrochemical Analysis. JOURNAL OF MICROELECTROMECHANICAL SYSTEMS : A JOINT IEEE AND ASME PUBLICATION ON MICROSTRUCTURES, MICROACTUATORS, MICROSENSORS, AND MICROSYSTEMS 2008; 17:850-862. [PMID: 19756255 PMCID: PMC2743150 DOI: 10.1109/jmems.2008.921726] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The fabrication and characterization of a microchamber electrode array for electrical and electrochemical studies of individual biological cells are presented. The geometry was tailored specifically for measurements from sensory hair cells isolated from the cochlea of the mammalian inner ear. Conventional microelectromechanical system (MEMS) fabrication techniques were combined with a heat-sealing technique and polydimethylsiloxane micromolding to achieve a multilayered microfluidic system that facilitates cell manipulation and selection. The system allowed for electrical stimulation of individual living cells and interrogation of excitable cell membrane dielectric properties as a function of space and time. A three-electrode impedimetric system was incorporated to provide the additional ability to record the time-dependent concentrations of specific biochemicals in microdomain volumes near identified regions of the cell membrane. The design and fabrication of a robust fluidic and electrical interface are also described. The interface provided the flexibility and simplicity of a "cartridge-based" approach in connecting to the MEMS devices. Cytometric measurement capabilities were characterized by using electric impedance spectroscopy (1 kHz-10 MHz) of isolated outer hair cells. Chemical sensing capability within the microchannel recording chamber was characterized by using cyclic voltammetry with varying concentrations of potassium ferricyanide (K(3)Fe(CN)(6)). Chronoamperometric recordings of electrically stimulated PC12 cells highlight the ability of the platform to resolve exocytosis events from individual cells.
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Affiliation(s)
- Gregory M Dittami
- G. M. Dittami and R. D. Rabbitt are with the Department of Bioengineering, University of Utah, Salt Lake City, UT 84112 USA
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152
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Errachid A, Mills C, Pla-Roca M, Lopez M, Villanueva G, Bausells J, Crespo E, Teixidor F, Samitier J. Focused ion beam production of nanoelectrode arrays. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2008. [DOI: 10.1016/j.msec.2007.10.077] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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153
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Caban K. Overpotential deposition of copper on gold micro- and nanoelectrodes. J Solid State Electrochem 2008. [DOI: 10.1007/s10008-008-0603-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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154
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Molina A, Serna C, Martínez-Ortiz F, Laborda E. Potentiostatic voltammetry at spherical electrodes and microelectrodes in the presence of product. J Electroanal Chem (Lausanne) 2008. [DOI: 10.1016/j.jelechem.2008.01.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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155
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156
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Dumitrescu I, Unwin PR, Wilson NR, Macpherson JV. Single-Walled Carbon Nanotube Network Ultramicroelectrodes. Anal Chem 2008; 80:3598-605. [DOI: 10.1021/ac702518g] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ioana Dumitrescu
- Departments of Chemistry and Physics, University of Warwick, Coventry, CV4 7AL, U.K
| | - Patrick R. Unwin
- Departments of Chemistry and Physics, University of Warwick, Coventry, CV4 7AL, U.K
| | - Neil R. Wilson
- Departments of Chemistry and Physics, University of Warwick, Coventry, CV4 7AL, U.K
| | - Julie V. Macpherson
- Departments of Chemistry and Physics, University of Warwick, Coventry, CV4 7AL, U.K
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157
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Kennedy BM, Cunnane VJ. The degradation of electrochemically polymerised poly (3-aminophenol) films in sodium hydroxide solutions for the production of microelectrode ensembles. Electrochim Acta 2008. [DOI: 10.1016/j.electacta.2007.12.036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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158
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Anastassiou CA, Parker KH, O'Hare D. Scaling in Nonstationary Voltammetry Representations. J Phys Chem A 2007; 111:13053-60. [DOI: 10.1021/jp074585w] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Kim H. Parker
- Department of Bioengineering, Imperial College London, SW7 2AZ London, U.K
| | - Danny O'Hare
- Department of Bioengineering, Imperial College London, SW7 2AZ London, U.K
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159
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160
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161
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Mahon PJ, Feldberg SW. Simulations of cyclic voltammetric and chronoamperometric electrode responses at a disk electrode using combinations of spherical and cylindrical electrode geometries. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:10380-8. [PMID: 17725370 DOI: 10.1021/la701186k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Using geometric models based on one-dimensional transport at spheres and cylinders, three methods for improving the simulation of voltammetric behavior of a disk electrode have been explored. One method is based on the common assumption of equivalency between the limiting currents for a disk and a hemisphere under steady-state diffusion conditions. The second method involves the use of a partial-sphere geometry which is a better approximation that is suitable at the extreme diffusional limits achievable at a disk electrode of fully planar and steady-state transport. The third method, which is generally applicable, is a further refinement that uses a combination of appropriate one-dimensional spherical and cylindrical geometries. The results demonstrate that reasonably accurate approximations of disk behavior for several reaction mechanisms can be achieved in a fraction of the time required to compute the more rigorous two-dimensional model. We propose that the approximation serve primarily as a fast way to explore system behavior and establish approximate values of the relevant parameters. More accurate computations can then be performed using the two-dimensional model.
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Affiliation(s)
- Peter J Mahon
- Faculty of Life and Social Sciences, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia.
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162
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Wittstock G, Burchardt M, Pust SE, Shen Y, Zhao C. Scanning electrochemical microscopy for direct imaging of reaction rates. Angew Chem Int Ed Engl 2007; 46:1584-617. [PMID: 17285666 DOI: 10.1002/anie.200602750] [Citation(s) in RCA: 313] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Not only in electrochemistry but also in biology and in membrane transport, localized processes at solid-liquid or liquid-liquid interfaces play an important role at defect sites, pores, or individual cells, but are difficult to characterize by integral investigation. Scanning electrochemical microscopy is suitable for such investigations. After two decades of development, this method is based on a solid theoretical foundation and a large number of demonstrated applications. It offers the possibility of directly imaging heterogeneous reaction rates and locally modifying substrates by electrochemically generated reagents. The applications range from classical electrochemical problems, such as the investigation of localized corrosion and electrocatalytic reactions in fuel cells, sensor surfaces, biochips, and microstructured analysis systems, to mass transport through synthetic membranes, skin and tissue, as well as intercellular communication processes. Moreover, processes can be studied that occur at liquid surfaces and liquid-liquid interfaces.
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Affiliation(s)
- Gunther Wittstock
- Carl von Ossietzky Universität Oldenburg, Institut für Reine und Angewandte Chemie und Institut für Chemie und Biologie des Meeres, 26111 Oldenburg, Germany.
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163
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Aguiar F, Gallant A, Rosamond M, Rhodes A, Wood D, Kataky R. Conical recessed gold microelectrode arrays produced during photolithographic methods: Characterisation and causes. Electrochem commun 2007. [DOI: 10.1016/j.elecom.2006.11.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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164
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Shim JH, Kim J, Cha GS, Nam H, White RJ, White HS, Brown RB. Glass Nanopore-Based Ion-Selective Electrodes. Anal Chem 2007; 79:3568-74. [PMID: 17411008 DOI: 10.1021/ac061984z] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Glass nanopore-based all-solid-state ion-selective electrodes (ISEs) have been developed to probe the distribution of ionic species at micro- or submicrometer-length scales, e.g., mapping of ion flux through micrometer-sized pores. The all-solid-state ISE was fabricated by sealing a conically etched platinum wire (d = 25-microm; radius of etched tip <10 nm) into a soda lime glass capillary. A Pt disk was exposed by gentle polishing the glass and the disk etched to form a conical pore of submicrometer dimension (radius < approximately 500 nm; depth < approximately 30 microm). Ag was electroplated on the Pt electrode in the pore and gently chloridated to obtain a AgCl/Ag layer within the pore. The AgCl/Ag layer-coated ISE was used as a highly selective Cl- probe in scanning electrochemical microscope experiments to map the ion flux through a micropore. The same ISE was also used as the base transducer of the neutral carrier-doped solvent polymeric membrane. The optimized polymer membranes used for the glass nanopore-based all-solid-state ISE require a higher ratio of plasticizer/polymer (9/1) compared to those for conventional ISE (2/1). An ISE based on deposition of an IrO2 layer at the base of a glass nanopore electrode exhibited a highly sensitive response (79.7 +/- 2.3 mV/pH) to variations in pH and could be used for approximately 3 weeks.
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Affiliation(s)
- Jun Ho Shim
- Chemical Sensor Research Group, Department of Chemistry, Kwangwoon University, Seoul 139-701, Republic of Korea
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165
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SiC-C fiber electrode for biological sensing. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2007. [DOI: 10.1016/j.msec.2006.05.053] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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166
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Wittstock G, Burchardt M, Pust S, Shen Y, Zhao C. Elektrochemische Rastermikroskopie zur direkten Abbildung von Reaktionsgeschwindigkeiten. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200602750] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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167
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Gallardo I, Guirado G. Electrochemical mechanism of spiro and zwitterionic Meisenheimer compounds: A potential fluorescence molecular switching system. Electrochem commun 2007. [DOI: 10.1016/j.elecom.2006.08.054] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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168
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Hu J, Foord JS, Holt KB. Hot filament chemical vapour deposition of diamond ultramicroelectrodes. Phys Chem Chem Phys 2007; 9:5469-75. [DOI: 10.1039/b710241k] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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169
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Wang C, Shao X, Liu Q, Mao Y, Yang G, Xue H, Hu X. One step fabrication and characterization of platinum nanopore electrode ensembles formed via amphiphilic block copolymer self-assembly. Electrochim Acta 2006. [DOI: 10.1016/j.electacta.2006.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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170
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Etienne M, Anderson EC, Evans SR, Schuhmann W, Fritsch I. Feedback-Independent Pt Nanoelectrodes for Shear Force-Based Constant-Distance Mode Scanning Electrochemical Microscopy. Anal Chem 2006; 78:7317-24. [PMID: 17037938 DOI: 10.1021/ac061310o] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new generation of platinum nanoelectrodes for constant-distance mode scanning electrochemical microscopy (CD-SECM) has been prepared, characterized, and used for high spatial resolution electrochemical measurements and visualization of electrochemically induced concentration gradients in microcavities. The probes have long (1-2 cm), narrow quartz tips that were conically polished and have a Pt nanoelectrode that is slightly offset from center. Because of the size and location of the electrode on the probe, it does not exhibit SECM feedback while approaching the analyzed sample surfaces even to distances within a few hundred nanometers. The probe was positioned near the surface while scanning and performing electrochemical measurements through use of nonoptical shear force control of the tip-to-sample distance. Test structures consisted of cylindrically shaped microcavities that are 50 microm in diameter with three individually addressable electrodes: a gold disk at 8-microm depth, a crescent-shaped gold ring at 4-microm depth along the wall, and a top gold electrode at the rim. Different electrodes within the microcavity were used to reduce and oxidize redox species in 250 microL of a solution of 5 mM hexaamineruthenium(III) chloride and 0.1 M potassium chloride, protected from evaporation by mineral oil, while the SECM tip followed the topography of the structures and monitored the current from the oxidation of [Ru(NH3)6]2+. Electrochemically generated concentration profiles were obtained from these complex test structures that are not possible with any other SECM technology at this time.
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Affiliation(s)
- Mathieu Etienne
- Analytical Chemistry, Elektroanalytik & Sensorik, Ruhr-Universität Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany
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171
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Ghanem MA, Thompson M, Compton RG, Coles BA, Harvey S, Parker KH, O'Hare D, Marken F. Microwave Induced Jet Boiling Investigated via Voltammetry at Ring−Disk Microelectrodes. J Phys Chem B 2006; 110:17589-94. [PMID: 16942103 DOI: 10.1021/jp0637680] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
High intensity microwave radiation is (self-)focused at metal electrodes immersed in aqueous electrolyte solutions to generate highly localized superheating and convection effects. It is shown that, for an electrode pointing downward, low intensity microwave radiation causes density driven convective flow (upward), which at the onset of boiling abruptly switches to a fast jet of liquid moving away from the electrode surface (downward). This "jet-boiling" phenomenon allows extremely high rates of mass transport and mixing to be realized at the electrode surface. Cyclic voltammograms obtained at electrodes placed into a microwave field show very strong mass transport enhancement effects. Cyclic voltammograms recorded at a Pt/Pt ring-disk electrode system (r(1) = 25 microm, r(2) = 32 microm, r(3) = 32.4 microm) in the presence of microwave radiation are employed to further explore mass transport effects under microwave conditions. Mass transport coefficients, collection efficiencies, and temperatures are determined as a function of microwave intensity.
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172
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Sandison ME, Cooper JM. Nanofabrication of electrode arrays by electron-beam and nanoimprint lithographies. LAB ON A CHIP 2006; 6:1020-5. [PMID: 16874372 DOI: 10.1039/b516598a] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The fabrication of ordered nanoelectrode arrays using both electron-beam lithography and nanoimprint lithography is described. Arrays of nanoelectrodes with varying individual electrode diameters were produced and characterised electrochemically. Whilst both methods are highly reproducibile, nanoimprint lithography has the potential to produce devices rapidly and at low-cost. To our knowledge, this is the first report where nanoimprint lithography is employed for the production of nanoelectrode arrays for electroanalytical sensors.
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Affiliation(s)
- Mairi E Sandison
- Department of Electronics & Electrical Engineering, University of Glasgow, Glasgow, UK.
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173
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174
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Synthesis and electrochemical polymerization ofN-ethylcarbazole-bis-3,4-etyhlenedioxythiophene-N-ethylcarbazole comonomer. J Appl Polym Sci 2006. [DOI: 10.1002/app.25114] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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175
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Xie X, Stueben D, Berner Z. The Application of Microelectrodes for the Measurements of Trace Metals in Water. ANAL LETT 2005. [DOI: 10.1080/00032710500316050] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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176
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177
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Pagels M, Hall CE, Lawrence NS, Meredith A, Jones TGJ, Godfried HP, Pickles CSJ, Wilman J, Banks CE, Compton RG, Jiang L. All-Diamond Microelectrode Array Device. Anal Chem 2005; 77:3705-8. [PMID: 15924409 DOI: 10.1021/ac0502100] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report the development of all-diamond microelectrochemical devices, namely, a microelectrode array (MEA), in which a periodic array structure with well-defined diameters, distance, and hexagonal unit cell pattern is micromachined using a combination of state-of-the-art microwave-induced plasma growth and laser ablation shaping techniques to prepare and coat a patterned boron-doped diamond (BDD) substrate with an intrinsic diamond insulating layer. The active BDD element can be tuned to between 10 and 50 microm in diameter with a 10 times diameter center-to-center distance between two adjacent conducting elements, which are exactly coplanar to the dielectric surroundings. This type of device should enable applications in harsh conditions such as high temperature, high pressure, and resistive media under dynamic flow regimes.
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Affiliation(s)
- Markus Pagels
- Schlumberger Cambridge Research, Madingley Road, High Cross, Cambridge, CB3 0EL UK
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178
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Swaddle TW. Homogeneous versus Heterogeneous Self-Exchange Electron Transfer Reactions of Metal Complexes: Insights from Pressure Effects. Chem Rev 2005; 105:2573-608. [PMID: 15941222 DOI: 10.1021/cr030727g] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Thomas W Swaddle
- Department of Chemistry, University of Calgary, Alberta, Canada.
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179
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Turcu F, Hartwich G, Schäfer D, Schuhmann W. Ink-Jet Microdispensing for the Formation of Gradients of Immobilised Enzyme Activity. Macromol Rapid Commun 2005. [DOI: 10.1002/marc.200400464] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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180
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Burt DP, Cervera J, Mandler D, Macpherson JV, Manzanares JA, Unwin PR. Scanning electrochemical microscopy as a probe of Ag+ binding kinetics at Langmuir phospholipid monolayers. Phys Chem Chem Phys 2005; 7:2955-64. [PMID: 16189617 DOI: 10.1039/b506611e] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new method has been developed for measuring local adsorption rates of metal ions at interfaces based on scanning electrochemical microscopy (SECM). The technique is illustrated with the example of Ag+ binding at Langmuir phospholipid monolayers formed at the water/air interface. Specifically, an inverted 25 microm diameter silver disc ultramicroelectrode (UME) was positioned in the subphase of a Langmuir trough, close to a dipalmitoyl phosphatidic acid (DPPA) monolayer, and used to generate Ag+ via Ag electro-oxidation. The method involved measuring the transient current-time response at the UME when the electrode was switched to a potential to electrogenerate Ag+. Since the Ag+/Ag couple is reversible, the response is highly sensitive to local mass transfer of Ag+ away from the electrode, which, in turn, is governed by the interaction of Ag+ with the monolayer. The methodology has been used to determine the influence of surface pressure on the adsorption of Ag+ ions at a phospholipid (dipalmitoyl phosphatidic acid) Langmuir monolayer. It is shown that the capacity for metal ion adsorption at the monolayer increased as the density of surface adsorption sites increased (by increasing the surface pressure). A model for mass transport and adsorption in this geometry has been developed to explain and characterise the adsorption process.
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Affiliation(s)
- David P Burt
- Department of Chemistry, University of Warwick, Coventry, UK
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181
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Turcu F, Schulte A, Schuhmann W. Scanning electrochemical microscopy (SECM) of nanolitre droplets using an integrated working/reference electrode assembly. Anal Bioanal Chem 2004; 380:736-41. [PMID: 15517205 DOI: 10.1007/s00216-004-2818-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Scanning electrochemical microscopy (SECM) has been performed in the restricted space of nanolitre droplets with a robust and easy-to-handle coaxial electrode assembly centring a Pt microdisk in a circular Ag electrode. Straightforward and reproducible fabrication of the specially designed probe tips was achieved by using Tollens' reaction to chemically deposit a uniform and well-adhering layer of silver on the body of a glass-insulated Pt microdisk electrode. The suitability of the novel dual-electrode SECM tip for measurement in small volumes was evaluated by imaging an array of four Pt band microelectrodes in 500 nL electrolyte.
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Affiliation(s)
- Florin Turcu
- Analytische Chemie, Elektroanalytik & Sensorik, Ruhr-Universität Bochum, Universitätsstrasse 150, NC04/788, 44780 Bochum, Germany.
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182
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Guirado G, Fleming CN, Lingenfelter TG, Williams ML, Zuilhof H, Dinnocenzo JP. Nanosecond Redox Equilibrium Method for Determining Oxidation Potentials in Organic Media. J Am Chem Soc 2004; 126:14086-94. [PMID: 15506773 DOI: 10.1021/ja046946g] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A general, nanosecond equilibrium method is described for determining thermodynamically meaningful oxidation potentials in organic media for compounds that form highly reactive cation radicals upon one-electron oxidation. The method provides oxidation potentials with unusually high precision and accuracy. Redox ladders have been constructed of appropriate reference compounds in dichloromethane and in acetonitrile that can be used to set up electron-transfer equilibria with compounds with unknown oxidation potentials. The method has been successfully applied to determining equilibrium oxidation potentials for a series of aryl-alkylcyclopropanes, whose oxidation potentials were imprecisely known previously. Structure-property trends for oxidation potentials of the cyclopropanes are discussed.
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Affiliation(s)
- Gonzalo Guirado
- Department of Chemistry and the Center for Photoinduced Charge Transfer, University of Rochester, Rochester, New York 14627-0216, USA
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183
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Clegg AD, Rees NV, Klymenko OV, Coles BA, Compton RG. Marcus Theory of Outer-Sphere Heterogeneous Electron Transfer Reactions: Dependence of the Standard Electrochemical Rate Constant on the Hydrodynamic Radius from High Precision Measurements of the Oxidation of Anthracene and Its Derivatives in Nonaqueous Solvents Using the High-Speed Channel Electrode. J Am Chem Soc 2004; 126:6185-92. [PMID: 15137784 DOI: 10.1021/ja040014v] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The validity of Marcus theory for outer-sphere heterogeneous electron transfer for the electro-oxidation of a range of anthracene derivatives in alkyl cyanide solvents is investigated. The precision measurement of these fast electron transfers (k(0) >or= 1 cm s(-1)) is achieved by use of the high-speed channel electrode and, where necessary, fast-scan cyclic voltammetry. First, the solvent effect on the rate of electron transfer is studied by considering the first oxidation wave of 9,10-diphenylanthracene in the alkyl cyanide solvents: acetonitrile, propionitrile, butyronitrile, and valeronitrile. Second, the variation of k(0) for a series of substituted anthracenes is investigated by analyzing the voltammetric response of the one-electron oxidations of 9-phenylanthracene, 9,10-dichloroanthracene, 9-chloroanthracene, 9,10-dicyanoanthracene, 9-cyanoanthracene, 9-nitroanthracene, 9,10-diphenylanthracene, and anthracene in acetonitrile. It is shown that the rate of electron transfer of a single compound in different alkyl cyanides is determined by the longitudinal dielectric relaxation properties of the solvent, while differences in rate between the substituted anthracenes in acetonitrile can be quantitatively rationalized by considering their relative hydrodynamic radii. This makes possible the accurate prediction of electron-transfer rates for a molecule by interpolation of rate constants known for related molecules.
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Affiliation(s)
- Antony D Clegg
- Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom
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184
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Kovalcik KD, Kirchhoff JR, Giolando DM, Bozon JP. Copper ring–disk microelectrodes: fabrication, characterization, and application as an amperometric detector for capillary columns. Anal Chim Acta 2004. [DOI: 10.1016/j.aca.2003.11.052] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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185
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186
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Lord HL, Möder M, Popp P, Pawliszyn JB. In vivo study of triazine herbicides in plants by SPME. Analyst 2004; 129:107-8. [PMID: 14752550 DOI: 10.1039/b311997c] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The use of SPME for in vivo monitoring of herbicide levels in plant tissues is evaluated. Fibers are exposed to the plant tissue with the aid of buffer located at the fiber/tissue interface region. Following this extraction period the extracted amount is estimated by solvent desorption and LC-MS-MS.
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Affiliation(s)
- Heather L Lord
- Department of Chemistry, University of Waterloo, Waterloo, Canada.
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187
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Oxidation of mercury microelectrodes in complexing media in the presence and absence of supporting electrolyte:. J Electroanal Chem (Lausanne) 2003. [DOI: 10.1016/s0022-0728(03)00389-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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188
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Lord HL, Grant RP, Walles M, Incledon B, Fahie B, Pawliszyn JB. Development and Evaluation of a Solid-Phase Microextraction Probe for in Vivo Pharmacokinetic Studies. Anal Chem 2003. [DOI: 10.1021/ac0343230] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Heather L. Lord
- Department of Chemistry, University of Waterloo, Waterloo, ON N2L 3G1, Canada, Eli Lilly Canada Inc., 3650 Danforth Avenue, Scarborough, ON M1N 2E8, Canada, and Eli Lilly Corporate Center, Indianapolis, Indiana 46285
| | - Russell P. Grant
- Department of Chemistry, University of Waterloo, Waterloo, ON N2L 3G1, Canada, Eli Lilly Canada Inc., 3650 Danforth Avenue, Scarborough, ON M1N 2E8, Canada, and Eli Lilly Corporate Center, Indianapolis, Indiana 46285
| | - Markus Walles
- Department of Chemistry, University of Waterloo, Waterloo, ON N2L 3G1, Canada, Eli Lilly Canada Inc., 3650 Danforth Avenue, Scarborough, ON M1N 2E8, Canada, and Eli Lilly Corporate Center, Indianapolis, Indiana 46285
| | - Bev Incledon
- Department of Chemistry, University of Waterloo, Waterloo, ON N2L 3G1, Canada, Eli Lilly Canada Inc., 3650 Danforth Avenue, Scarborough, ON M1N 2E8, Canada, and Eli Lilly Corporate Center, Indianapolis, Indiana 46285
| | - Brian Fahie
- Department of Chemistry, University of Waterloo, Waterloo, ON N2L 3G1, Canada, Eli Lilly Canada Inc., 3650 Danforth Avenue, Scarborough, ON M1N 2E8, Canada, and Eli Lilly Corporate Center, Indianapolis, Indiana 46285
| | - Janusz B. Pawliszyn
- Department of Chemistry, University of Waterloo, Waterloo, ON N2L 3G1, Canada, Eli Lilly Canada Inc., 3650 Danforth Avenue, Scarborough, ON M1N 2E8, Canada, and Eli Lilly Corporate Center, Indianapolis, Indiana 46285
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189
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Abstract
The sample preparation step in an analytical process typically consists of an extraction procedure that results in the isolation and enrichment of components of interest from a sample matrix. Extraction can vary in degree of selectivity, speed, and convenience and depends not only on the approach and conditions used but on the geometric configurations of the extraction phase. Increased interest in sample preparation research has been generated by the introduction of nontraditional extraction technologies. These technologies address the need for reduction of solvent use, automation, and miniaturization and ultimately lead to on-site in situ and in vivo implementation. These extraction approaches are frequently easier to operate but provide optimization challenges. More fundamental knowledge is required by an analytical chemist not only about equilibrium conditions but, more importantly, about the kinetics of mass transfer in the extraction systems. Optimization of this extraction process enhances overall analysis. Proper design of the extraction devices and procedures facilitates convenient on-site implementation, integration with sampling, and separation/quantification, automation, or both. The key to rational choice, optimization, and design is an understanding of the fundamental principles governing mass transfer of analytes in multiphase systems. The objective of this perspective is to summarize the fundamental aspects of sample preparation and anticipate future developments and research needs.
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Affiliation(s)
- Janusz Pawliszyn
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.
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190
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Szunerits S, Garrigue P, Bruneel JL, Servant L, Sojic N. Fabrication of a Sub-Micrometer Electrode Array: Electrochemical Characterization and Mapping of an Electroactive Species by Confocal Raman Microspectroscopy. ELECTROANAL 2003. [DOI: 10.1002/elan.200390068] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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191
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Wittstock G, Wilhelm T. Characterization and manipulation of microscopic biochemically active regions by scanning electrochemical microscopy (SECM). ANAL SCI 2002; 18:1199-204. [PMID: 12458703 DOI: 10.2116/analsci.18.1199] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Preparation and characterization of microscopic biochemically active regions are important for the development of miniaturized bioanalytical systems with proteins, such as miniaturized enzyme electrode arrays. Scanning electrochemical microscopy (SECM) has emerged as an ideal tool for prototyping such systems. The technique is based on electrochemical conversions of dissolved species at a micrometer-sized probe electrode. It offers several mechanisms for local surface modifications under conditions compatible with conservation of protein functionality of enzymes and antibodies. The subsequent imaging of the immobilized activity provides direct information about local immobilized enzyme activities. The working modes of the techniques are illustrated by recent studies from this laboratory for the design and characterization of patterned enzyme layers covalently linked to gold surfaces via thiol self-assembly chemistry.
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Affiliation(s)
- Gunther Wittstock
- Carl von Ossietzky University Oldenburg, Department of Chemistry and Institute of Chemistry and Biology of the Marine Environment (ICBM), D-26 11 Oldenburg, Germany.
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192
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Ufheil J, Borgwarth K, Heinze J. Introduction to the principles of ultramicroheptodes in ring-disk interactions. Anal Chem 2002; 74:1316-21. [PMID: 11922299 DOI: 10.1021/ac010912z] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The use of ring-disk ultramicroelectrodes as tips as a means of extending the methodology of the scanning electrochemical microscope is described. Electrodes consisting of one centered disk with six interconnected disks surrounding it served as the ring-disk electrodes. Basic experiments illustrate the behavior in the feedback mode and the generation collection mode. The dependence on the electrodes' size, both potentials, the tip-sample distance, and the local properties of the underying sample were studied. When approaching an electrode to the surface of a sample, steady-state collection efficiencies between zero and unity were elegantly altered by adjusting the distance between tip and sample. The shielding factor could be varied between 0.25 and 0.82 the same way. Concerning feedback methods, the results presented illustrate the new principle of applying a precisely located external stimulus as a separate electrochemical means of analyzing the sample's response. Obviously, this technique can be extended to irreversible redox mediators, which are not treated here explicitly, but give this concept even greater flexibility. The interpretation of such data can be deduced directly from this contribution.
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Affiliation(s)
- Joachim Ufheil
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Germany
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193
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194
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Sun P, Zhang Z, Guo J, Shao Y. Fabrication of nanometer-sized electrodes and tips for scanning electrochemical microscopy. Anal Chem 2001; 73:5346-51. [PMID: 11721940 DOI: 10.1021/ac010474w] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A novel method for fabrication of nanometer-sized electrodes and tips suitable for scanning electrochemical microscopy (SECM) is reported. A fine etched Pt wire is coated with polyimide, which was produced by polymerization on the Pt surface initiated by heat. This method can prepare electrodes with effective radii varying from a few to hundreds of nanometers. Scanning electron microscopy, cyclic voltammetry, and SECM were used to characterize these electrodes. Well-defined steady-state voltammograms could be obtained in aqueous or in 1,2-dichloroethane solutions. This method produced the nanoelectrodes with exposed Pt on the apex, and they can also be employed as the nanotips for SECM investigations. Different sizes of Pt nanotips made by this method were employed to evaluate the kinetics of the redox reaction of Ru(NH3)6(3+) on the surface of a large Pt electrode by SECM, and the standard rate constant kappa0 of this system was calculated from the best fit of the SECM approach curve. This result is similar to the values obtained by analysis of the obtained voltammetric data.
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Affiliation(s)
- P Sun
- Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry of the Chinese Academy of Sciences, Jilin
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195
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196
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197
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Bozon JP, Giolando DM, Kirchhoff JR. Development of Metal-Based Microelectrode Sensor Platforms by Chemical Vapor Deposition. ELECTROANAL 2001. [DOI: 10.1002/1521-4109(200107)13:11<911::aid-elan911>3.0.co;2-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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198
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Kranz C, Friedbacher G, Mizaikoff B, Lugstein A, Smoliner J, Bertagnolli E. Integrating an ultramicroelectrode in an AFM cantilever: combined technology for enhanced information. Anal Chem 2001; 73:2491-500. [PMID: 11403290 DOI: 10.1021/ac001099v] [Citation(s) in RCA: 255] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present a novel approach to develop and process a microelectrode integrated in a standard AFM tip. The presented fabrication process allows the integration of an electroactive area at an exactly defined distance above of the end of a scanning probe tip and the subsequent remodeling and sharpening of the original AFM tip using a focused ion beam (FIB) technique (See ref 1 for patent information). Thus, the functionality of scanning electrochemical microscopy (SECM) can be integrated into any standard atomic force microscope (AFM). With the demonstrated approach, a precisely defined and constant distance between the microelectrode and the sample surface can be obtained, alternatively to the indirect determination of this distance usually applied in SECM experiments. Hence, a complete separation of the topographical information and the electrochemical signal is possible. The presented technique is a significant step toward electrochemical imaging with submicrometer electrodes as demonstrated by the development of the first integrated frame submicroelectrode.
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Affiliation(s)
- C Kranz
- Institute of Analytical Chemistry, Vienna University of Technology, Wien, Austria.
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199
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Bieniasz L, Britz D. Chronopotentiometry at a microband electrode: simulation study using a Rosenbrock time integration scheme for differential–algebraic equations and a direct sparse solver. J Electroanal Chem (Lausanne) 2001. [DOI: 10.1016/s0022-0728(01)00391-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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200
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Theory and practice of electrochemical titrations with dual microband electrodes. J Electroanal Chem (Lausanne) 2001. [DOI: 10.1016/s0022-0728(00)00426-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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