Investigation of the Electrode Polarization Effect for Biosensor Applications

My research focuses on electrokinetic transport. Particularly, in this dissertation, we focus on fabrication and testing of micro electrodes with nanostructured surfaces to minimize the electrode polarization (EP) effects for biosensor applications. In the first study, electrochemical deposition of gold nanoparticles on to planar gold electrodes was used to generate rough surfaces. Dendritic nanostructures that reduced EP up to two orders of magnitude was obtained by optimizing the deposition conditions. These structures also enhanced dielectrophoresis (DEP) response of our bio-chips, making them usable in physiological buffers. In further studies we discovered a universal scaling of EP in the frequency domain, which reduced hundreds of dimensional impedance vs frequency experimental data to a single nondimensional equation. This finding is crucial, since one can now determine EP effects for any electrode size and buffer conductivity before electrode fabrication and experimentation. We also showed that the universal scaling applies to the dendritic nanostructured electrodes, which behaves like planar electrodes in much lower conductivity solutions with larger electric double layer thickness