Dynamic Water-Wave Tweezers

TL;DR

This paper introduces dynamic water-wave tweezers that use interference patterns of water waves to trap and controllably transport floating particles along arbitrary paths, enabling noncontact manipulation in fluid environments.

Contribution

It presents a novel method of controlling particle movement on water surfaces using frequency detunings in wave interference patterns, expanding capabilities for fluidic object manipulation.

Findings

Robust trapping of particles at intensity maxima or vortices.

Controlled 2D particle motion via small frequency detunings.

Effective over a broad range of particle sizes and wave frequencies.

Abstract

Following a recent demonstration of stable trapping of floating particles by stationary (monochromatic) structured water waves [Nature 638, 394 (2025)], we report dynamic water-wave tweezers that enable controllable transport of trapped particles along arbitrary trajectories on the water surface. We employ a triangular lattice formed by the interference of three plane waves, which can trap particles, depending on parameters, either at intensity maxima or at intensity zeros (vortices). By introducing small frequency detunings between the interfering waves, we control 2D motion of the lattice and trapped particles. This approach is robust and effective over a relatively broad range of particle sizes and wave frequencies, offering remarkable new possibilities for noncontact manipulation of floating (e.g., biological and soft-matter) objects in fluidic environments.