The Analysis of Potentiometric Flexible Arrayed Urea Biosensor Modified by Graphene Oxide and ɣ-Fe₂O₃ Nanoparticles

In this work, we used radio frequency (RF) system and screen printing technology to fabricate urea biosensor based on urease-maghemite nanoparticles (ɣ-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 ɣ-Fe₂O₃ NPs. The sensing membrane was modified by adding different contents of ɣ-Fe₂O₃ NPs. The concentration of ɣ-Fe₂O₃ NPs was 1 mg/mL. When the volume ratio of urease/ɣ-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 μ M, respectively. The effect of temperature on the urea biosensor was investigated from 25 °C to 65 °C. The stability of urea biosensors was 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-ɣ-Fe₂O₃ NPs/GO/NiO sensing membrane has better average sensitivity.