Liquid transfer of graphene to the cylindrical gold nanostructures for sensitivity enhancements of SPR glucose sensor

It remains a great challenge to construct nanostructures and modify two-dimensional (2D) nanomaterials on the cylindrical surface of a micro-scale biosensor to enhance its performance. In the paper, a novel fiber surface plasmon resonance (SPR) biosensor was proposed to enhance the sensitivity of glucose monitoring by forming nanostructures and coating graphene on the gold film. Ultrasonic cavitation was used for the first time to form nanostructures on the cylindrical gold film surface, thus inducing local surface plasmon resonance (LSPR). To enhance the adsorption of glucose molecules, a liquid transfer method was innovatively proposed to cover the surface of the cylindrical roughened gold film of the biosensor with multilayer chemical vapor deposition (CVD) graphene. According to the experimental results, the SPR sensor treated with ultrasonic cavitation for 15 min and modified with two-layer graphene achieved top sensitivity, exhibiting about 3.57 times enhancement compared to the untreated one. This result verifies the sensitivity enhancement effect of both methods, ultrasonic cavitation to construct nanostructures and the liquid transfer of graphene, which may also be applied to construct nanostructures and modify 2D nanomaterials on arbitrary shapes of micro-scale biosensors.