Electrochemical Detection of the Neurotransmitter Dopamine by Nanoimprinted Interdigitated Electrodes and a CMOS Circuit With Enhanced Collection Efficiency

The interdigitated microelectrodes presented in this work desire to achieve a high collection efficiency for electrochemical dopamine detection by reducing the separation between electrodes. Sub-μm microelectrodes can be batch fabricated through nanoimprint lithography without relying on the expensive electron-beam lithography repeatedly. The applied reduction and oxidation potentials were determined by cyclic voltammetry at -0.2 V and 0.6 V, respectively. The measured current values agreed well with the analytic values. Measured sensitivities were 2.89 and 1.73 nA/μM for electrodes with gaps of 300 and 600 nm, respectively, and the average collection efficiency values were 97.9% and 95.4%. Signal transduction was also demonstrated by using a CMOS (complementary metal-oxide semiconductor) sensing circuit. The detectable resolution was about 0.1 μM. Nafion-coated electrodes were shown to provide a high selectivity of 41:1 with respect to ascorbic acid.