Rapid Fabrication of a Nano Interdigitated Array Electrode and its Amperometric Characterization as an Electrochemical Sensor

Nano interdigitated array (IDA) electrodes (electrode finger width = 100 nm; finger spacing = 200 nm; surface area = 0.2 mm²) have been fabricated and characterized amperometrically for the electrochemical detection of the concentrations of reversible redox species. Using p-aminophenol as the redox species, a detection limit of 10 pM of the species concentration has been achieved. This detection limit is three orders of magnitude lower than the micro IDA counterpart that has been reported to date, proving the enhanced redox cycling at the nano IDA electrodes. Using a higher electron dose, the proximity effect of the electron beam in the e-beam lithography process has been utilized to reduce the duration of the nano IDA pattern transfer step to less than 30 minutes. This makes it possible to fabricate the entire sensor within a day, including the electrode metal evaporation, metal lift-off and electroplating of reference electrode.