Sharp convex gold grooves for fluorescence enhancement in micro/nano fluidic biosensing

The enhancement of biosensing sensitivity based on a quantum dot (QD) is limited by the long distance between the QD and the substrate in in vitro detection, which prevents the development of biosensors. Here an individual sharp convex gold groove is proposed to enhance remote fluorescence by exciting and collecting fluorescence efficiently. The structure shows a higher emission power than other wider gold groove structures when the QD is individually placed at five random positions inside the groove. Compared with bare glass, the total power enhancement factor of our structure is up to 17.0 times, 6.6 times and 6.4 times when the QD is 3.5 μm, 7.6 μm and 9.0 μm away from the bottom of the groove, respectively, due to the scattered emission of the QD and guided resonance modes inside the groove. In addition, the structure is easy to fabricate. The individual sharp convex gold groove is expected to be used as one unit of multi-channels in micro/nano fluidic biosensing. The sample volume could be very small or large according to real applications due to the particular geometric features of our structure.