Electrochemical detection of dopamine using a simple redox cycling-based device

Here, a dual ITO microchip was fabricated for high sensitive detection of dopamine (DA) based on redox-cycling. The ITO electrodes with 3×3 mm working areas were made via photolithography and dry etching processes. The microchip was obtained by first aligning the working areas of two ITO electrodes to overlap and then fixing them in that position using a double-sided tape, which also formed a sealed microchannel between the ITO electrodes for test solution delivery. The ITO electrodes and microchips were electrochemically characterized using EIS, cyclic voltammetry and chronoamperometry. Compared to a single ITO electrode in a microchannel, the microchip had a significantly higher signal due to redox cycling. The microchip was lastly used for the detection of DA at varying concentrations. According to the results, the microchip had an LOD of 0.15 μM in a linear detection region of 0.1 to 50 μM. The microchip requires less than 1 μl of solution to complete the analysis and has great potential to be applied for immunosensing.