The 3×3 mm working areas of two ITO microchips were aligned to overlap and then fixed using a double-sided tape to form a sealed microchannel. Electrochemical characterization of the dual ITO microchip was carried out using cyclic voltammetry (CV) and chronoamperometry. Briefly, the microchannel was first filled with 200 μM DA and 0.1 mM FcCH2OH, respectively . Then the generator electrode was scanned from 0 V to +0.35 V (vs. Ag/AgCl) at a scanning rate of 0.05 V/s, while the collector electrode was fixed at 0 V (vs. Ag/AgCl) in a dual mode measurement where redox cycling was induced. The applicability of the dual ITO microchip was demonstrated with DA solutions at different concentrations (0, 0.01, 0.05, 0.1, 0.5, 1, 10, 50, 100 µM). Basically, the generator and collector electrodes were set at +0.35 V and 0 V (vs. Ag/AgCl) for 50 s and the oxidation and reduction currents at 50 s were used to obtain a calibration curve. The limit of detection (LOD) was calculated based on three replicates using the following equation: LOD = 3.3 × (standard deviation of the calibration curve/slope of the calibration curve) . All electrochemical experiments were performed using a multipotentiostat.