Electrode microarray

FIGURE 4-28 Schematic representation of an interdigitated microarray electrode (a) and closely-spaced microdisk electrodes (b). 

FIGURE 6-20 Configuration of a penicillin sensor based on an microarray electrode coated with a pH-responsive polypyrrole. Vq = gate voltage VD = drain voltage ID = drain current PS = potentiostat CE and RE = counter and reference electrodes, respectively. (Reproduced with permission from reference 76.)... 

The microarray electrodes used for solid state electrochemistry are a slight variation of the transistor decribed in Sect. 5.2.2 The most appealing feature is the location of all the necessary electrodes on a single microchip, the reference electrode being provided by the application of a droplet of silver epoxy to one of the gold micro electrodes (Fig. 7). 

A poly(aniline boronic acid)-based conductimetric sensor for dopamine consisting of an interdigitated microarray electrode coated with poly(aniline boronic acid) has also been developed by the Fabre team. The sensor was found to show a reversible chemoresistive response to dopamine without interference by ascorbic acid from their mixtures.42... 

Figure 4.11 Effect of SAM formation on the cyclic voltammetry of ferrocenylmethyltrimethylam-monium on a polycrystalline gold electrode the supporting electrolyte is 0.5 M H2SO4, with a scan rate of 0.1 V s-1. Curve (a) is the reversible cyclic voltammogram obtained on bare gold, while curves (b)-(d) are obtained on the same electrode with different monolayers (for details see text). The symbols represent theoretical fits to a microarray electrode model. Reprinted with permission from H.O. Finklea, D.A. Snider, J. Fedyk, E. Sabatani, Y. Gafni and I. Rubinstein, Langmuir, 9,3660 (1993). Copyright (1993) American Chemical Society...

Recently, Colley et al. [104] studied the distribution of electrochemical activity in microarray electrodes. The array contained 50-pm diameter boron-doped regions spaced 250 pm apart in an intrinsic diamond disk. Reaction rate imaging was done in the substrate generation/tip collection mode. The electroactive boron doped regions were biased at a suitable potential to reduce the mediator, [Ru(NH3)6]3+, and the product of the reduction reaction was collected at the tip. Two-dimensional scans over different regions (Fig. 21) revealed wide variations in local electroactivity. 

A point electrode resembles a spot. It adopts a spherical-shaped concentration profile and potential distribution in the solution. As a result, such electrodes easily achieve a steady state and yield a steady-state current. This current is expected to be proportional to the characteristic length (radius) of the electrode. A typical point electrode is a disk electrode inlaid on an insulating plane. On the other hand, an ultrathin ring electrode shares characteristics of the point electrode and the line electrode. It appears as a point from a position distal from the electrode, but it resembles a curved line upon closer inspection. It exhibits a steady-state current because of the feature of the point electrode. Next, a plane electrode of interest is a microarray electrode, which is composed of point electrodes and line electrodes on a planar insulator. It is versatile in functionality by designing the geometrical arrangement. A mode of mass transport depends on whether elementary electrodes are a point or a line electrode. 

I. Methanol vapor-induced morphology and current-voltage characteristic changes in a cast-coated Nation film/interdigitated microarray electrode. J. Polym. Sci. B Polym. Phys. 2002, 40, 1103. 

Matsue, T. (1993) Electrochemical sensors using microarray electrodes. Trends in Analytical Chemistry TRAC, 12... 

K. Aoki and M. Tanaka. Time-dependence of diffusion-controlled currents of a soluble redox couple at interdigitated microarray electrodes, J. Electroanal. Chem. 266, 11-20 (1989). 

Nishizawa, M., et al. 1991. In situ characterization of copolymers of pyrrole and N-methylpyrrole at microarray electrodes. Synth Met 45 241. 

The oxidation or reduction of conducting polymers via enzyme reaction is another possible principle of the impedimetric biosensor. It was reported previously that the microarray electrode coated with the copolymer of pyrrole and N-methylpyrrole containing diaphorase worked as a switching device, which showed on-off response to the presence of NADH [187]. Bartlett and coworkers have expanded this... 

An interdigitated gold microarray electrode coated with Nation has recently been used to detect serotonin in human whole blood samples (20 pL) to monitor allergic response, during which serotonin is secreted into the bloodstream [111]. Results showed excellent agreement between electrochemically monitored serotonin... 

Nishizawa, M.. Matsue, T., and Uchida, I., Penicillin sensor based on a microarray electrode coated with pH-responsive polypyrrole, Atud. Chem., 64. 2462 (1992). 

Feldman BJ, D Alessandro A, Osterloh JD, Hata BH (1995) Electrochemical determination of low blood lead concentrations with a disposable carbon microarray electrode. Clin Chem 41 557-563. 

M. Nishizawa, T. Matsue, and I. Uchida, Fabrication of a pH-sensitive microarray electrode and applicability to biosensors. Sensors Actuators B 13-14 53 (1993). 

M. Nishizawa, M. Shibuya, T. Sawaguchi, T. Matsue, and 1. Uchida, Electrochemical preparation of ultrathin polypyrrole film at microarray electrodes, J. Phys. Chem. 95 9042 (1991). 

Arya, S.K., Chomokur, G., Venugopal, M., Bhansali, S., 2010. Dithiobis (succinimidylpropionate) modified gold microarray electrode based electrochemical immunosensor for ultrasensitive detection of cortisol. Biosens. Bioelectron. 25 (10), 2296—2301. 

Pesantez DE (2014) Microarray electrodes useful with analyte sensors and methods for making and using them. US 20140163346... 

Rianasari I, Walder L, Burchardt M, Zawisza I, Wittstock G (2008) Inkjet-printed thiol self-assembled monolayer structures on gold quality control and microarray electrode fabrication. Langmuir 24 9110-9117... 

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