Optofluidic transport and particle trapping using an all-dielectric quasi-BIC metasurface

TL;DR

This paper introduces an all-dielectric quasi-BIC metasurface that enables nanoscale control of fluid and particle manipulation using light, avoiding thermal issues associated with plasmonics, with potential for biosensing.

Contribution

It presents a novel optofluidic system leveraging quasi-BIC driven dielectric metasurfaces for efficient particle trapping and fluid control at the nanoscale.

Findings

Particles down to 200 nm can be rapidly aggregated and transported.

Flow velocity can be increased up to 3 times at resonance.

Particle dynamics depend on laser wavelength and power.

Abstract

Manipulating fluids by light at the nanoscale has been a long-sought-after goal for lab-on-a-chip applications. Plasmonic heating has been demonstrated to control microfluidic dynamics due to the enhanced and confined light absorption from the intrinsic losses of metals. Dielectrics, counterpart of metals, is used to avoid undesired thermal effects due to its negligible light absorption. Here, we report an innovative optofluidic system that leverages a quasi-BIC driven all-dielectric metasurface to achieve nanoscale control of temperature and fluid motion. Our experiments show that suspended particles down to 200 nanometers can be rapidly aggregated to the center of the illuminated metasurface with a velocity of tens of micrometers per second, and up to millimeter-scale particle transport is demonstrated. The strong electromagnetic field enhancement of the quasi-BIC resonance can facilitate increasing the flow velocity up to 3-times compared with the off-resonant situation. We also experimentally investigate the dynamics of particle aggregation with respect to laser wavelength and power. A physical model is presented to elucidate the phenomena and surfactants are added to the particle colloid to validate the model. Our study demonstrates the application of the recently emerged all-dielectric thermonanophotonics in dealing with functional liquids and opens new frontiers in harnessing non-plasmonic nanophotonics to manipulate microfluidic dynamics. Moreover, the synergistic effects of optofluidics and high-Q all-dielectric nanostructures can hold enormous potential in high-sensitivity biosensing applications.