Trapping plasmonic nanoparticles with MHz electric fields

Dielectrophoresis drives the motion of nanoparticles through the interaction of their induced dipoles with a non-uniform electric field. We experimentally observe rf dielectrophoresis on 100 nm diameter gold nanoparticles in a solution and show that for MHz frequencies, the nanoparticles can reversibly aggregate at electrode gaps. A frequency resonance is observed at which reversible trapping of gold nanoparticle clouds occurs in the gap center, producing almost a 1000-fold increase in density. Through accounting for gold cores surrounded by a conducting double layer ion shell, a simple model accounts for this reversibility. This suggests that substantial control over nanoparticle separation is possible, enabling the formation of equilibrium nanoarchitectures in specific locations. (C) 2022 Author(s).

Automated summary

Dielectrophoresis is found to drive the motion of nanoparticles through the interaction of their induced dipoles with a non-uniform electric field. The reversible aggregation of 100 nm diameter gold nanoparticles in electrode gaps is experimentally observed under MHz frequencies. A frequency resonance is observed, resulting in a significant increase in the density of gold nanoparticle clouds. A simple model is proposed to explain this reversibility, suggesting the possibility of substantial control over nanoparticle separation.