Screen Printed Thick Film Reference Electrodes for Electrochemical Sensing

This paper presents printed thick film Ag vertical bar AgCl vertical bar KCl reference electrodes (RE) for electrochemical sensors. The screen-printed REs with 10-mu m thick glass-KCl salt matrix layer exhibit a stable potential of 5 mV. Cyclic voltammetric analysis shows that the anodic and cathodic peak current of the RE increases with the scan rate in the range of 25-150 mVs(-1). The analytical performance of the REs shows a stable open circuit potential for the NaCl concentrations in the range of 30-100 mM. Testing the presented REs for electrochemical pH sensor application (with RuO2-based sensitive electrode) the sensitivity of 55 mV/pH was noted in the pH range of 4.5-9. Evaluating the effect of temperature on the performance of REs, a potential variation of -3.8 mV/degrees C was observed. Finally, a LabVIEW interface was developed to store, analyze, and calculate the sensitivity of the sensor under different temperature conditions. The LabVIEW interface can also be used to calculate the pH-value/temperature of unknown solutions under known temperature/pH conditions.