Fabrication of thin film Ag/AgCl reference electrode by electron beam evaporation method for potential measurements

In this study, the novel approach for fabricating thin film Ag/AgCl electrodes was proposed using Electron beam evaporation method for potential measurements as reference electrodes. A silver (Ag) and silver-silver chloride (Ag/AgCl) thin films with a thickness of 300 nm were evaporated on the silicon substrate which had been initially oxidized to create the insulating silicon dioxide (SiO 2 ) layer. The dimension of the electrodes was about 0.5 x 2.0 mm. The characterization of AgCl layers was performed with Field Emission Scanning Electron Microscopy – FeSEM, X-Ray Diffraction and Energy Dispersive X-Ray spectroscopy (EDS), Raman spectroscopy, optical microscopy. The Open Circuit Potential (OCP) measurements in buffer solution pH 7 were investigated between the fabricated Ag/AgCl electrodes and a commercial Ag/AgCl electrode as the reference electrode. The measured OCP values had insignificant disparity. The good reproducibility and potential stability with the average potential value and deviation were within 334.0 mV ± 4.07 mV. In addition, a pH sensing test was also performed by using a laboratory-made potentiometer, which showed a sensitivity of 48.01 mV/pH, with the correlation coefficient being greater than 0.99. The results showed that the fabricated thin film Ag/AgCl electrodes which could be obtained by a simple and fast process, had high purity and could be used as reference electrodes for potential measurements.