An optofluidic antenna for enhancing the photon collection rate from analytes in solution

In this work, we developed a planar dielectric antenna for analytes diffusing in aqueous solution. The so-called optofluidic antenna can collect more than 86% of all photons from a randomly oriented dipole-like emitter. The antenna involves a sub-micrometer water channel capped with air where the analytes are interrogated. The small dimension of the water channel in combination with the water/air interface confines the motion of the analytes, resulting in a slowing down of the translational diffusion. We characterize the photonic properties of the optofluidic antenna by investigating different dye molecules using fluorescence correlation spectroscopy. Moreover, we demonstrate the performance of our antenna by studying the dynamical behavior of the Holliday junction (HJ) at the single-molecule level using multiparameter fluorescence detection, which allows us to identify the HJ’s different FRET states in real-time.