Electrode carbon-fiber micro

Acetylcholineesterase and choline oxidase Carbon-fiber micro-electrode for determination of ACh and choline, mounted in a glass capillary tube. Enzyme was immobilized on the surface of the carbon fiber with albumin. Electrode was dip-coated with Nafion. Evaluation of selectivity and dynamic range, at a fixed potential of 1.2 V versus Ag-AgCl. Calibration graph for ACh and Ch was rectilinear between 0.1 and 3mM. Interference from ascorbic acid was not observed in the range 0.1 to 0.3 mM. [79]... 

Carbon fiber electrode - Edison produced the first carbon fibers by carbonization of cotton threads in 1879. Today polyacrylonitrile (as well as Rayon and various other organic precursors) is the most common precursor for carbon fiber formation [i]. Carbonization of polyacrylonitrile is carried out at 1500 °C to give highly electrically conducting fibers with 5-10 pm diameter. Fibers carbonized at up to 2500 °C are more graphitic with a carbon content of >99%. Carbon fiber-based materials have found many applications due to their exceptionally high tensile strength. In electrochemistry carbon fiber -> micro electrodes are very important in analytical detection [ii] and for in vivo electrochemical studies [iii]. Carbon fiber textiles are employed in - carbon felt electrodes. 

To fulfill both the requirement of CFME for the practical applications and the necessity of Au substrate to assemble so-called promoters to construct the third-generation biosensor, Tian el al. have combined the electrochemical deposition of Au nanoparticles (Au-NPs) onto carbon fiber microelectrodes with the self-assembly of a monolayer on these Au-NPs to facilitate the direct electron transfer of SOD at the carbon fiber micro-electrode. The strategy enabled a third-generation amperometric 02 biosensor to be readily fabricated on the carbon fiber microelectrode. This CFME-based biosensor is envisaged to have great potential for the detection of 02 in biological systems [158]. 

In order to form dopamine sensing devices, N-vinylcarbazole polymers were electrochemically coated onto xm sized carbon fibers [216]. As solutions, lithium perchlorate/acetonitrile, sodium perchlorate/acetonitrile, and tetraethylammonium tetratluoroborate/acetonitrile were used. In this way, dopamine sensing layers on the carbon fiber micro-electrodes were formed. 

Runnels P.L., Joseph J.D., Logman M.J., Wightman R.M. (1999) Effect of pH and surface functionalities on the cyclic voltammetric responses of carbon-fiber micro-electrodes. Anal Chem 71 2782-2789. 

Carbon fiber electrodes ( 100 nm dia.) were also used to characterize the diffusion between adjacent stream zones at the interface between a micro fluidic system (16 channels 50 im wide, 57 im deep, separated by a 22- im wall) and a large volume using 10 mM ferrocyanide and amperometric detection [756]. It was reported that when the carbon fiber electrode was used in a PDMS chip, the in-channel format gave better peak symmetry than the end-channel format [757]. 

On the other side, Zhang et al. [78] have prepared and characterized a carbon fiber cone nanometric sized ultramicroelectrodes equipped with an integrated micro Ag AgCl reference electrode. The introduction of such integrated Ag AgCl electrode located at the bottom edge of the carbon fiber tip led to the determination of dopamine in extremely small volumes. This leads to the conclusion that such electrode system may be used for in vivo and/or single cell studies. 

An electrochemical reaction, the reduction of benzoquinone, is exemplarily described. An electrochemical micro structured reactor is divided into a cathode and anode chamber by a Nafion hollow-fiber tube. The anode chamber is equipped with a platinum electrode and the cathode chamber contains the analyte and carbon or zinc electrodes. Current density and flow rate are controlled to maximize current efficiency as determined by analysis of the formed hydroquinone by an electrochemical detector. Hydroquinone is extracted subsequently in a micro extractor from the resulting product stream [84],... 

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