The goal of this study was to reduce the drift effect of RuO2 urea biosensors. A new calibration circuit (NCC) based on the voltage regulation technique with the advantage of having a simple structure was presented. To keep its simplicity, the proposed NCC was composed of a non-inverting amplifier and a voltage calibrating circuit. A ruthenium oxide (RuO2) urea biosensor was fabricated to test the calibrating characteristics of the drift rate of the proposed NCC. The experiment performed in this study was divided into two main stages. For the first stage, a sound RuO2 urea biosensor testing environment was set-up. The RuO2 urea sensing film was immersed in the urea solution for 12 h and the response voltage was measured using the voltage-time (V-T) measurement system and the proposed NCC. The results of the first stage showed that the RuO2 urea biosensor has an average sensitivity of 1.860 mV/(mg/dL) and has a linearity of 0.999 which means that the RuO2 urea biosensor had been well fabricated. The second stage of the experiment verified the proposed NCC's functions, and the results indicated that the proposed NCC reduced the drift rate of RuO2 urea biosensor to 0.02 mV/hr (98.77% reduction).
Keywords: calibration circuit; drift effect; ruthenium oxide (RuO2); urea biosensor.