Fabrication of Electrochemically Deposited Microelectrodes for Microfluidic MEMS Applications

In this paper the electrochemical deposition of three metals, namely gold, palladium, and platinum over gold microelectrode seeded by titanium thin layer in microfluidic channel has been investigated. Modified microelectrodes were characterized with cyclic voltammetry, scanning electron microscope (SEM), and surface profilometry. Cyclic voltammograms data of all modified electrodes, namely aurized, palladized, and platinized microelectrodes exhibited their characteristic oxygen deposition peak (aurized) and hydrogen adsorption peaks (platinized and palladized). The real surface area, or roughness factor, and height of each microelectrode were measured after every single deposition patch. Obtained results revealed that aurized and palladized microelectrodes reached their maximum value of surface area after approximately 10 minutes of electrochemical deposition, whereas platinized microelectrodes exhibited gradual increase in surface area even after long time of electrochemical deposition. Using aurized microelectrodes for chronoamperometric analysis of dopamine exhibited similar behavior. Furthermore, SEM and surface profilometry results revealed that the process of electrochemical deposition of microelectrode in microfluidic channels is influenced by the edge effect, where the deposition process proceeds mainly at the kinks along the step (~ 21 nm high) of the microelectrodes.