Polymer Sandwich and IDA Configurations

In this section we discuss the interesting work reported by Murray and coworkers on the application of the polymer sandwich and IDA techniques for determining electron diffusion coefficients in materials exhibiting redox conduction. The twin electrode geometries favored by these researchers are illustrated in Fig. 1.94. 

Note that current flowing through the thin polymer film for both the sandwich and IDA geometries is related to the electron flux via 

FIGURE 1.94. Schematic representation of the twin-microelectrode polymer sandwich arrangement for determining electron-hopping diffusion coefficients. 

FIGURE 1.95. Schematic representation of the interdigitated array (IDA) arrangement for determining electron-hopping diffusion coefficients in the steady state, (a) the IDA configuration, (b) Polymer-overcoated IDA. (c) Finger dimensions, (d) A different perspective of the polymer-overcoated IDA device. 

We first consider concentration gradient experiments. These are similar in concept to the overcoated ring disk experiment described in the previous section. These experiments can be conducted in either a 

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