Optical Tweezers with AC Dielectric Levitation: A Powerful Approach to Microparticle Manipulation

TL;DR

This paper introduces a novel method combining AC dielectric levitation with optical tweezers to manipulate larger particles and cells with reduced damage, overcoming traditional optical force limitations.

Contribution

The study presents a multiphysics approach integrating dielectrophoretic and optical forces, enabling effective manipulation of micro- and nano-scale objects beyond previous optical tweezers capabilities.

Findings

AC dielectric levitation enables manipulation of larger particles.

The method reduces bio-damage to cells during manipulation.

Finite element simulation elucidates levitation mechanism.

Abstract

Optical tweezers, with their high precision, dynamic control, and non-invasiveness, are increasingly important in scientific research and applications at the micro and nano scales. However, manipulation by optical tweezers is challenged by adsorption forces, including van der Waals forces, capillary forces, and electrostatic forces, which are present between micro- and nano-objects. Due to the inherent limitations of optical forces imposed by laser power, these adsorption forces are difficult to overcome. Inspired by maglev trains, we propose a multiphysics coupling method that combines dielectrophoretic and optical gradient forces to achieve broad applicability and low-damage micro-nanoscale particle manipulation. We developed a device that introduces electric fields to detach objects from hard substrates using alternating current (AC) dielectric levitation before manipulation with optical tweezers. We utilized micron-sized polystyrene (PS) microspheres as objects and elucidated the levitation mechanism through finite element simulation. For larger particles, such as a 100 {\mu}m PS microparticle and a 200 {\mu}m micro-gear, AC dielectric levitation enabled manipulation by optical tweezers. Also, the better viability of three kinds of cells displayed the low bio-damage of the proposed method. Given its broad applicability and biocompatibility, AC dielectric levitation technology significantly expands the capabilities of optical tweezers, allowing for the manipulation of larger particles and cells. This advancement addresses the limitations of optical tweezers in handling large-scale particles and enhances their versatility in various applications.