Electrochemical optimization of platinum and gold nanogap interdigitated electrode arrays

Title : Electrochemical optimization of platinum and gold nanogap interdigitated electrode arrays

Abstract:

In this work we compare the electrochemical behavior of the fabricated platinum and gold nanogap interdigitated electrode arrays (nIDAs) for Lab-on-a-Chip (LoC) applications. Chronoamperometric measurements were carried out to achieve a signal amplification compared to a single electrode configuration. In chronoamperometric measurements a significant amplification can be achieved by interdigitated electrode arrays in combination with a reversible redox process. The attainable signal amplification depends on the electrode distance, the smaller the electrode gap the higher the amplification. Therefore, a gap size in the nanometer range is desired for the fabricated electrode array. Conventional microfabrication techniques were used for the fabrication of the sensor chip with adjustable nanogaps.

Two redox couples, ferrocenemethanol (FcMeOH) and p-aminophenol (pAP), were selected for the electrochemical experiments. The redox potentials of both tested substances were determined by cyclic voltammetry. The scan ranges from 0.0 V to +0.3 V for FcMeOH and from -0.3 to +0.4 V for pAP (vs. Ag/AgCl as reference electrode) were determined as optimum. Suitable cleaning procedures were developed and optimized to suit the different requirements for Pt and Au chips. Cleaning of Pt nIDAs (regardless of the redox couples to be used) includes an initial treatment in O2 plasma and an electrochemical cleaning. For the Au chips, O2 plasma cleaning alone is sufficient. No influence of the electrochemical cleaning in 0.1 M PBS (phosphate buffered saline) on the signal amplification achievable by the Au chips was observed. With the presented process a maximum amplification of 160 for Pt and 130 for Au can be achieved. This is the highest published amplification in bulk solution for the measurements with IDAs.

The results show that not only high signal amplification but also high current efficiency above 99 % has been reached for both Au and Pt nIDAS with both tested solutions FcMeOH and pAP. High signal amplification and current efficiency make the fabricated nIDA an exellent candidate for further ELISA experiments.

Biography:

Volha Matylitskaya, studied chemistry at P.M. Mascherov University in Vitebsk (Belarus). She received her PhD degree from J.W. Goethe University of Frankfurt/Main (Germany) in 2009. The subject of her dissertation was the study the possibility of niobium oxynitride formation by Rapid Thermal Processing. During her PhD Dr. Matylitskaya dealt with the solid state chemistry as well as with the methods of the solid state analysis. Ms. Matylitskaya currently works at the Research Center for Microtechnology at the University of Applied Sciences Vorarlberg (Austria). The current focus of her research is the electrochemical characterization of the fabricated interdigital electrode arrays and investigation of their potential for lab-on-a-chip applications.