Observation of Light-Driven Levitation Near Epsilon-Near-Zero Surfaces

TL;DR

This study demonstrates that epsilon-near-zero (ENZ) metamaterials can induce stable, light-driven levitation of dielectric particles, revealing a wavelength-dependent repulsive force that enables contactless manipulation in microfluidic systems.

Contribution

It provides the first experimental evidence of light-induced repulsive forces near ENZ surfaces, enabling stable particle levitation and advancing optical manipulation techniques.

Findings

Wavelength-dependent repulsive force observed near ENZ surfaces

Repulsion peaks near the ENZ frequency

ENZ surfaces enable stable optical levitation of particles

Abstract

Optical manipulation of micro- and nanoparticles near surfaces is fundamental for applications in sensing and microfluidics, yet controlling particle-surface interactions remains challenging. Here we experimentally investigate light-induced forces on dielectric particles near epsilon-near-zero (ENZ) metamaterial surfaces using photonic force microscopy. By illuminating trapped particles with tunable visible light, we observe a wavelength-dependent repulsive force unique to ENZ surfaces, contrasting with the attractive forces near dielectric or metallic substrates. This repulsion peaks near the ENZ frequency and may be attributed to combined optical ENZ effects and thermophoretic forces. Our findings demonstrate that ENZ metamaterials can induce stable levitation of particles via light-driven forces, offering a novel mechanism for contactless manipulation in microfluidic environments. This work advances understanding of light-matter interactions at ENZ interfaces and suggests potential for ENZ-based optical control of micro- and nanoscale objects, with potential applications in micro- and nanofluidic environments.