3D trapping and dynamic axial manipulation with frequency-tuned spiraling acoustical tweezers

TL;DR

This paper demonstrates that holographic acoustical tweezers based on spiraling transducers can achieve 3D trapping and axial manipulation of microparticles and cells by frequency tuning, expanding capabilities beyond traditional 2D manipulation.

Contribution

It introduces a method for 3D trapping and axial displacement of particles using frequency-tuned spiraling acoustical tweezers, a significant advancement over previous 2D-only techniques.

Findings

3D radiation trapping of particles achieved with spiraling tweezers.

Particles can be displaced axially by tuning the driving frequency.

The method enables 3D manipulation with a single-beam acoustical tweezers.

Abstract

Holographic acoustical tweezers (HAT) based on Archimedes-Fermat spiraling InterDigitated Transducers (S-IDTs) are a versatile tool for the selective manipulation of microparticles [Baudoin et. al., Sci. Adv., 5: eaav1967 (2019)] and cells [Baudoin et. al., Nat. Commu., 11, 4244 (2020)] in a standard microfluidic environment. These binary active holograms produce some focused helical wave, with the ability to trap particles at the vortex core. Yet, all the studies conducted with S-IDTs have so far been restricted to 2D manipulation only. Here we show (i) that 3D radiation trap for microparticles and cells can be obtained with spiraling tweezers with sufficiently large aperture and (ii) that the particles can be displaced axially by simply tuning the driving frequency, without any motion of the transducer. This work opens perspectives for 3D cells and microparticles manipulation with single-beam acoustical tweezers.