On-demand rapid transport and stable trapping of nanoparticles of nanoparticles by a hybrid electrothermoplasmonic nanotweezer (Conference Presentation)

Abstract

In plasmon nano-optical tweezers, plasmonic nanoantennas are illuminated to generate highly localized and enhanced electromagnetic field in the vicinity of the nanoantenna. The highly localized and enhanced electromagnetic field creates much stronger optical gradient forces and tighter potential wells for confining particles than in conventional optical tweezers, thus providing a means to trap nanoscale objects and molecules. This approach have been successfully applied for trapping small particles such as protein molecules. However a long standing problem in this field is how to rapidly load the potential well without relying on Brownian diffusion. Conventional design rely on Brownian diffusion to load the trap, which is very slow and could take several minutes to hours depending on the concentration of the nanoscale objects. Furthermore since the plasmonic trapping sites are pre-patterned on a substrate, current plasmonic nanotweezers suffer from the problem of lack of dynamic control over the particles in the trap. Recently we have addressed these challenges by introducing a novel design paradigm known as the Hybrid Electrothermoplasmonic Nanotweezer (HENT)1, where the intrinsic photo-induced heating of the plasmonic nanoantenna is combined with an applied AC electric field to induce a large scale microfluidic flow on-demand. The microfluidic flow enables rapid delivery of suspended nanoparticles to an illuminated plasmonic nanoantenna where they are trapped within a few seconds. In this talk I will discuss the working principle of HENT, as well as HENT-based nanotweezers utilizing alternative plasmonic materials.