Multi-physics simulations of label-free optical-electrical forces acting on a silica nanoparticle trapped in a SANE plasmonic nanopore

Abstract

This work presents Multiphysics COMSOL simulations that help dissect the relative contributions of multiple forces of optical and electrical origin acting on a 20 nm diameter silica nanoparticle trapped by a plasmonic nanopore sensor. Specifically, the nanosensor uses the principle of self-induced back action (SIBA) to trap nanoparticle optically at the center of a double nanohole (DNH) structure integrated on top of a solid-state nanopores (ssNP). This novel SIBA actuated nanopore electrophoresis (SANE) sensor allows simultaneous recording of optical and electrical data features that are generated by the interaction of multiple underlying forces: Plasmonic optical trapping, electroosmosis, electrophoresis, viscous drag and heat conduction forces are all felt by a silica nanoparticle trapped by the sensor. This work aims to simulate these underlying forces in order to help understand how they contribute to the optical-electrical measurements generated by sensor. Furthermore, experimental measurements of 20 nm silica nanoparticles trapped the SANE sensor were compared against computational predictions to test the qualitatively trends seen in experimentally measured signal profiles during the nanoparticle’s approach to the optical trap and its translocation through the plasmonic nanopore, located immediately below the optical trap.