Following the reported above results, the oxidation and reduction of the redox probe was performed directly in the microfluidic channel using the integrated electrodes and a chronoamperometric configuration of the EC setup. The potential applied to the WE was switched between -0.3 V and +0.7 V every 100 s. The value +0.7 V is well above the oxidation potential of Fe(CN)6 4-which initializes the oxidation of the redox probe, i.e., conversion of Fe(CN)6 4-to Fe(CN)6 3-. The impact of changes in the applied potential to electrical (Fig. ) and optical properties (Fig. ) can be seen at different flow rates. Decrease of E is followed in by current and wavelength in EC and optical setup, respectively. While the current between the stages differs by over 15 µA, the wavelength shifts by about 0.7 nm what is significantly lower than when oxidized and reduced forms of the probe were supplied through the flow injection loop (Fig. ). This is in relatively good agreement with the simulations that show that for a flow rate of 10 µl/min the concentration of oxidized form of the redox probe reaches about 45% of the concentration of the reduced form in the incoming liquid (Fig. ). The reason is that in the EC experiments the oxidized form is created only at the bottom of the channel (Fig. ), while in the flow injection the channel is filled homogeneously with the injected sample. This difference also means that in the EC setup, the response is quite sensitive to the detailed flow of the liquid around the fiber. This can explain why the experimental data correspond less well to the simulation in case of EC actuation as compared to the flow injection. When different flowrates are applied, a clear difference is seen in the current response, but the optical response is quite similar in both cases. In contrast to the simulations, the response at low flowrate is even smaller than for the higher flow. At very low flow rates effects not considered in the simulations, such as convection due to temperature differences in the system, will be more pronounced than when the forced convective flow is higher. This might explain the discrepancy between the simulated and experimental data.