Polydimethylsiloxane (PDMS) has been one of the most actively developed polymers for microfluidics, which irreversibly seals on silicon-based surfaces (e.g., glass) after it is exposed to air plasma. The problem lies in its use in the fabrication of microfluidic electrochemical cells. The metal electrodes (e.g. gold) are inert to the plasma, which causes leakage in the PDMS-gold interface of the cell, affecting the data obtained in electrochemical detection experiments. In recent years, advances have been made in sealing methods of PDMS-glass and PDMS-gold interfaces, using a peptide bond by the reaction of a carboxylic acid and an amine, for the fabrication of microfluidic devices. In this work we have studied the effect of the variation of the width of gold electrodes in the sealing of the PDMS-gold interfaces of the electrochemical cells. It was observed that, using the plasma method, at a width of 3 μm, the system supported leakage pressures of 105 kPa, decreasing to 19 kPa at a width of 700 μm. The influence of the width of the electrode on the leakage pressure can be due to the fact that around the electrode there is a stronger bonding force and, the smaller the width of the electrode, the greater the pressure needed to deform the PDMS. Leakage pressure measurements on chips sealed with the carboxyl-amine method are planned. It is expected that the carboxyl-amine method will support higher pressures than the plasma method at large electrode widths due to the higher adhesion forces between the PDMS-gold interfaces in this method. At small widths, the plasma method is expected to be superior.