Nanoelectrode array

Nano-electrode arrays can be formed through nano-structuring of the electrocatalyst on an inert electrode support. Indeed, if the current of the analyte reduction (oxidation) on a blank electrode is negligible compared to the activity of the electrocatalyst, the former can be considered as an insulator surface. Hence, for the synthesis of nanoelectrode arrays one has to carry out material nano-structuring. Recently, an elegant approach [140] for the electrosynthesis of mesoporous nano-structured surfaces by depositioning different metals (Pt, Pd, Co, Sn) through lyotropic liquid crystalline phases has been proposed [141-143],... 

A.A. Karyakin, E.A. Puganova, I.A. Budashov, I.N. Kurochkin, E.E. Karyakina, V.A. Levchenko, V.N. Matveyenko, and S.D. Varfolomeyev, Prussian Blue based nanoelectrode arrays for H202 detection. Anal Chem. 76, 474-478 (2004). 

Figure 3.16 Different steps in the fabrication of MWNT nanoelectrode arrays, (a) metal film deposition, (b) catalyst deposition, (c) plasma-enhanced chemical vapor deposition for CNT growth, (d) dielectric encapsulation with Si02, (e) planarization with a chemical mechanical polishing to expose the ends of the carbon nanotubes, (f) electrochemical characterization. Readapted from Ref [6].

Figure3.17 (a) and (b) CV measurements in 1 mM ofFe(CN)6 and 1 M KCI with the high-density MWNT nanoelectrode array (2 X lO electrodes/cm ) and low density one (with about 7x 10 electrodes/cm ), respectively, (c) and (d) showthescanningelectron images for the high and low density arrays. Readapted from Ref [4] with permission. Copyright, 2004, RSC.

There is increasing interest in preparing Ti02 nanomembranes both for advanced photocatalytic processes in the field of air and water purification, purification of drinking water, novel membrane for high temperature PEM fuel cells,Li-ion batteries,advanced nanoelectrode arrays (NEA) and nanofiltration and pervaporation. ... 

An other interesting strategy is the modification of the surface of the electrodes with multiwalled carbon nanotubes (MWNTs) or single-walled carbon nanotubes (SWNTs) [13,32]. The MWNTs are grown on the electrodes covered with a nickel catalyst film by plasma-enhanced chemical vapour deposition and encapsulated in Si02 dielectrics with only the end exposed at the surface to form an inlaid nanoelectrode array [13]. In the other case, commercial SWNTs are deposited on SPE surface by evaporation [32], The carbon nanotubes are functionalised with ssDNA probes by covalent attachment. This kind of modification shows a very efficient hybridisation and, moreover, the carbon nanotubes improve the analytical signal. 

J.E. Koehne, H. Chen, A.M. Cassell, Q. Ye, J. Han, M. Meyyappan and J. Li, Miniaturised multiplex label-free electronic chip for rapid nucleic acid analysis based on carbon nanotube nanoelectrode arrays, Clin. Chem., 50... 

Scheme 2. Fabrication and oxidative pretreatment of carbon nanoelectrode arrays for functionalization. From reference 69.

This section highlights two trends in nanobiosensing. First, the use of nanofiuid-ics [321, 322] in biosensing and, second, the use of nanoelectrodes [307] and nanoelectrode arrays [323] will be briefiy discussed. 

N. V., Streeter, I., and Baron, R. (2008) Design, fabrication, characterisation and application of nanoelectrode arrays. Chemical Physics Letters, 459 (1-5), 1-17. 

A more defective form of sp carbon fibers, carbon nanotubules (CNTbs), grown by pyrolytic deposition of carbon into anodized aluminum oxide (AAO) nanochannels, are also used as nanoelectrode arrays for electrochemical sensors. Small graphitic crystallites are deposited on the inner surface of the nanochannels. Since the crystallites do not extend very long (less than micrometers) and are structurally discontinued, the resistance is orders of magnitude higher than CNFs... 

For many practical applications, hundreds to thousands of UMEs or NEs need to be connected in parallel to a common micro or macro contact [78]. With sufficient spacing between neighbors, each UME or NE is capacitively, resistively, and diffusively independent and behaves similar to a single UME or NE. The collective signal from such microelectrode arrays (MEAs) or nanoelectrode arrays (NBAs) is therefore many orders of magnitude larger and can be measured easily with a simple system. 

Figure 14.10 Processing procedure for fabricating CNF nanoelectrode arrays with metal film deposition, catalyst deposition, plasma-enhanced chemical vapor deposition (PECVD), tetraethoxysilane (TEOS) chemical vapor deposition (CVD), chemical mechanical polishing (CMP), and the setup for electrochemical (EC) characterization. (Adapted with permission from ref. 43. Copyright 2004 Royal Society of Chemistry.)...

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