▎ 摘　　要

From our other works, we have developed urea biosensor based on graphene oxide/nickel oxide sensing film modified either by Au nanoparticles or gamma-Fe(2)O(3 )nanoparticles. In this study, we have further developed back-end calibration circuit to reduce the drift effect and hysteresis effect of the two types of the urea biosensors. The back-end calibration circuit is composed of non-inverting amplifiers, error amplifiers, P-MOSFLT transmission transistor, feedback networks, output voltage capacitors and resistor dividers. After applying the back-end calibration circuit, the drift rate of urea biosensor modified by Au NPs is reduced from 3.06 mV/hr to 0.28 mV/hr, which is 90.85% reduction. The drift rate of urea biosensor modified by gamma-Fe2O3 NPs is reduced from 3.92 mV/hr to 0.57 mV/hr, which is 85.46% reduction. Through the back-end calibration circuit to reduce the hysteresis effect, the hysteresis voltage for the forward cycle and reverse cycle of the urea biosensor modified by Au NPs are reduced by 26% and 30%, respectively. The hysteresis voltage for the forward cycle and reverse cycle of the urea biosensor modified by gamma-Fe2O3 NPs are reduced by 23% and 28%, respectively.