Polarization-Dependent Plasmonic Nano-Tweezer as a Platform for On-Chip Trapping and Manipulation of Virus-Like Particles

Plasmonics advanced materials with the capability of environmental variation detection extend the application of visible light, satisfying the demands of less footprint, easy-to-use, and high tunability for visible-sensitive materials. In this area, localized surface plasmon can significantly enhance the electric field smaller than the radiation wavelength providing a strong gradient force required in optical tweezing systems. Owing to this beneficial advantage over the conventional optical tweezers, the plasmonic tweezers have matured to a stage where today become increasingly attractive for trapping and manipulation of nanoparticles. In this work, we are proposing a tunable plasmonic nano-tweezer that operates according to the polarization of excitation laser light. The proposed novel structure encompasses a gold nano-ring and a gold nano-disk in which by changing the beam polarization, the hot spots position also changes, and the nanoparticles can be relocated around the circumference of a circle trapped at a certain point. According to 3D finite-difference-time-domain simulations, the proposed nano-tweezing system can potentially exert a trapping force of 164 pNW⁻¹ on a 20 nm HIV-1 virus-like particle.