Mass transport electrically active complex

The peculiarities of electrode processes considered next have no analogs among the so-called noncomplex systems. In their case, the same species (M" solvate-complexes) participate in both diffusion mass transport and the charge transfer step. On the contrary, in the solutions containing complexes, mass transport is determined by the flows of all particles including M", whereas the electrode potential depends only on some components within the system electrically active complexes (EACs) and products of their reduction (ligands). 

If external potentials are applied to a system of several interconnected channels, the respective field strength in each channel will be determined by Kirchhoff s laws in analogy to an electrical network of resistors [28]. Ideally, electrokinetically driven mass transport in each of the channels will take place according to magnitude and direction of these fields. This allows for complex fluid manipulation operations in the femtoliter to nanoliter range without the need of any active control elements, such as external pumps or valves. This is of particular relevance due to the demanding limitations with respect to void volumes in the system (see Sect. 2). 

Rather controversial hterature data concerning the composition of possible EAC most likely encouraged Dudek and Fedkiw [10] to analyze the model according to which any complex may be electrically active. Reduction of each of them is described by a separate kinetic equation with individual kinetic parameters, and partial currents are summed. Regularities of mass transport are considered taking into account the fact that the components of the system participate in chemical interactions, and using the principles, which are presented in Chapter 3. 

---