Switchable two-state plasmonic tweezers for dynamic manipulation of nano-objects

TL;DR

This paper introduces a switchable plasmonic platform capable of dynamically trapping nano-objects in two distinct states, controlled by laser focus position, with potential applications in nanofluidics and dynamic trapping studies.

Contribution

The work presents a novel plasmonic trapping system with switchable states activated by laser focus, enabling dynamic control of nano-object trapping.

Findings

Able to trap 100 nm particles in two states

Switching controlled by laser focus position

Static state can trap particles as small as 40 nm

Abstract

In this work we present a plasmonic platform capable of trapping nano-objects as small as 100 nm in two different spatial configurations. The switch between the two trapping states, localized on the tip and on the outer wall of a vertical gold nanochannel, can be activated by a variation in the focusing position of the excitation laser along the main axis of the nanotube. We show that the trapping mechanism is facilitated by both an electromagnetic and thermal action. The inner and outer trapping states are respectively characterized by a static and a dynamic behavior and their stiffness was measured by analyzing the position of the trapped specimens as a function of time. In addition, it was demonstrated that the stiffness of the static state is high enough to trap of particles as small as 40nm. These results show a simple, controllable way to generate a switchable two-state trapping regime, which could find applications as a model for the study of dynamic trapping or as mechanism for the development of nanofluidic devices.