Microfluidic channel of dual grating structures for directional fluorescence emission enhancement

One-dimensional (1D) gratings can control the intensity and direction of fluorescence emission, which are widely applied in biological detection. However, they are limited in bio-detection due to the small region for light-matter interaction. In this work, we propose a microfluidic channel with a dual-grating structure, which, as shown by numerical simulations, has excellent directional fluorescence enhancement, with an enhancement of more than 100-fold. This enhancement is due to the resonance modes of the metal groove grating (MGG) and the dielectric grating (DG), along with the F-P cavity mode between the upper and lower gratings of the hybrid structure. High E-field achieved within the grooves of the MGG and within the microfluidic channel can greatly facilitates fluorescence excitation when the fluorophores are in the channel. Additionally, this hybrid structure offers the capability of dual-layer, multi-wavelength, high sensitivity parallel detection for multiple analyte. This work opens up vast prospects for its application in the field of high-sensitivity microfluidic fluorescence biochemical detection, environmental analysis, and other luminescent devices.