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

In this work, we used radio frequency (RF) system and screen printing technology to fabricate urea biosensor based on urease-maghemite nanoparticles ( \gamma -Fe 2 O 3 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 -Fe 2 O 3 NPs. The sensing membrane was modified by adding different contents of \gamma -Fe 2 O 3 NPs. The concentration of \gamma -Fe 2 O 3 NPs was 1 mg/mL. When the volume ratio of urease/ \gamma -Fe 2 O 3 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 }\text{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- \gamma -Fe 2 O 3 NPs/GO/NiO sensing membrane has better average sensitivity.