Microelectrode array microdisc

Anion detection at microelectrodes has not been studied widely. Amongst the first was the work of de Beer et al. [ 111 ] who manufactured a nitrite sensor with a tip just a few microns in diameter, which could detect nitrite ions down to 1 pM. This proved to be suitable for profiling the concentrations of nitrite anion within biofilms less than 1-mm thick inside water treatment plants. Other workers have found that use of an interdigitated microelectrode array [ 112] allows measurement of iodide via monitoring of its redox peak down to sub-micromole levels, making it a suitable technique for analysing mineral water. Carbon nanotubes coated onto Pt microdiscs have been utilised to make a nitrite sensor [113,114] with detection levels of 0.1 pM. Sulphide has also been detected at nickel microdiscs (50 pm diameter) [115]. 

Figure 11.3 exhibits few examples of microelectrodes such as (a) microdisc electrode with diameter of 10 pm within a glass tube of 20 pm for amperometric measurements [5], (b) STM-Tip, which can measure with resolution in atomic dimension, (c) pH-sensitive microelectrode used in biological research, (d) microelectrode array for research [14], and (f) electrode array for glucose... 

A number of methods exist for fabricating microelectrode arrays [6] and a variety of array geometries are encountered with the most common being arrays of microdiscs and arrays of microbands. Microdiscs are most frequently arranged as a regularly distributed (i.e., a square or... 

The diamond growth can also be patterned to produce microelectrode array structures [18,19]. Several possible microstructures are possible, such as microbands, microdiscs, and microcolumns. Micropyramids are another microstructure that can be produced, and an image of such an array is shown in Fig. 5. The SEM image reveals a monolithic diamond-tip array. The tips are ca. 2 pm in base diameter and are equally positioned over the surface with a spacing of ca. 5 pm. 

Simm, A.O., Banks, C.E., Ward-Jones, S. et al. (2005) Boron-doped diamond microdisc arrays electrochemical characterisation and their use as a substrate for the production of microelectrode arrays of diverse metals (Ag, Au, Cu) via electrodeposition. Anflfyi f, 130, 1303. 

If we approximate each of the inert blocking particles as being discshaped and of the same size, the modelling of a PBE is only very slightly different from modelling a random array of microelectrodes. In the latter case we considered an array of electroactive discs on an inert surface whereas for a PBE we consider an array of inert discs on an electroactive surface. The simple solution then is to use exactly the same simulation model as for the random array of microdiscs except that the surface boundary conditions... 

---