Interdigitated microelectrode electrode arrays

Figure 7 shows the detection principle of an impedimetric IME biosensor for bacterial detection [8]. It is based on measurements of electrochemical faradic impedance in the presence of [Fe(CN)6] " as a redox probe. When a bare interdigitated microelectrode is immersed into an electrolyte solution containing the redox couple and a small-amplitude AC potential (5 mV) is applied to the electrode, the faradic process of oxidation and reduction of the redox couple occurs, and then electrons are transferred between the two sets of array electrodes through the redox couple (Fig. 7a). When antibodies are immobilized onto the electrode surface (Fig. 7b) they form a layer that can inhibit the electron transfer between the electrodes, and thus an increase in the electron transfer resistance can be expected. If bacterial cells attach to the antibody-modified electrode surface (Fig. 7c), the intact cells can create a further barrier for...

Figure 10.1 Classification of microelectrodes (A) random array, (B) ordered array, (C) paired electrode, schematic representation of a double band assembly, (D) interdigitated array, schematic presentation of IDA electrodes vertically arranged (E) linear array, (F) three-dimensional array, Utah electrode array (reprints from reference (28)). (for colour version see colour section at the end of the book).

Figure 6. Generation/collection experiments for different fixed collector potentials in an interdigitated array of microelectrodes coated with poly(I) in CH3CN/O.I 14 [n-Bu4N]PF6. The potential of the collector electrodes is held at 0.0 V, -0.50 V, -0.59 V, -0.62 V, or -0.80 V vs. Ag+/Ag while the potential of the generator electrodes is swept between 0.0 V and -0.9 V vs. Ag+/Ag at 20 mV/s.

Figure 7. Cyclic voltammetry of an interdigitated array of microelectrodes coated with poly(I) in CH3CN/0.I H [n-Bu NlPFg (a) The potential of all eight electrodes is scanned together at 10 mV/s. (b) The potential of electrodes 2,4,6, and 8 is scanned at 10 mV/s while the potential of electrodes 1,3,5, and 7 is held at 0 V vs. Ag+/Ag.

Great activity has also been evidenced in microlithographically fabricated arrays of microelectrodes, which are typically formed in one plane on an insulating substrate [7,8,13,34-45] for experiments involving either an array of electrodes held at a common potential [37,40,42,43], or an array of noninteracting electrodes held at two or more different applied potentials [42,44], or an array of interdigitated electrodes held at two different potentials [13,34,36,38,39,45-47]. Arrays have significantly better analytical detection limits than continuous electrodes of the same overall dimensions, due to enhanced mass transport fluxes that arise from an increase in the spatial dimensionality of mass transport due to the alternation of electrode zones with pas-... 

Using the interdigitated arrays (IDAs) described above, the conductivity cells consist either of the IDA of microelectrode pairs (width/gap of 10 /rm) or the compact two electrodes of area 0.36 mm (gap of 300 /am). Conductivity microelectrode cells were tested... 

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