Determination of heterogeneous electron transfer rate constants at interdigitated nanoband electrodes fabricated by an optical mix-and-match process

Abstract

Interdigitated microband electrodes are important electroanalytical tools, and have been used in the construction of advanced sensing and biosensing devices for a long time. Nanoband-based systems, on the other hand, are more difficult to come by, as their fabrication involves the use of costly and scarce e-beam lithography resources. In this work we present the fabrication of interdigitated nanobands down to 400 nm using optical techniques exclusively. The process combines a step-and-repeat process to define Cr-Au nano- and microbands, and a standard lithography to pattern the active areas and contacts through an SU-8 passivation layer. This work presents the physical and electrochemical characterization of these devices, and our results also show that generator-collector experiments at these nanometric devices can be used in conventional electroanalytical applications, but also to measure electrode kinetics. While electrode kinetics does not affect collection efficiency to a great extent, the fast mass transport rates achieved at these devices makes the voltammetric current critically dependent on electron transfer rates.