▎ 摘　　要

In this work, we used radio frequency (RF) system and screen printing technology to fabricate urea biosensor based on urease-maghemite nanoparticles (gamma-Fe2O3 NPs)/graphene oxide (GO)/nickel oxide (NiO) sensing membrane on silver conductive wire printed polyethylene terephthalate ( PET) substrate. The V- T measurement system was used to investigate the sensing characteristics of urea biosensors based on GO/NiO sensing membrane modified by gamma-Fe2O3 NPs. The sensing membrane wasmodified by adding different contents of gamma-Fe2O3 NPs. The concentration of gamma-Fe2O3 NPswas1mg/mL. When the volume ratio of urease/gamma -Fe2O3 NPs was 1/1, it had the best sensitivity. The average sensitivity, the linearity, and the limit of detection of (LOD) of the best urea biosensor in this work were 52.36 mV/decade +/- 0.22 mV/ decade, 0.996, and 7.91 mu M, respectively. The effect of temperature on the urea biosensorwas investigated from25 degrees C to 65 degrees C. The stability of urea biosensorswas evaluated by the effect of hysteresis and long-term storage stability. After 29 days, the average sensitivity remained 80.62% of the initial value. Compared with other urea biosensors, our urea biosensor based on urease-gamma -Fe2O3 NPs/GO/NiO sensing membrane has better average sensitivity.