  In addition to optical tweezers, magnetic tweezers and dielectrophoresis
technique, trapping and manipulating micro or nano particles with electrostatic
tweezers attracted attention in recent years. Here we present a simulation
study on the contributions of electrostatic energy, change of entropy, as well
as van der Waals interaction in the trapping performance of a 10 nm sized,
pentagon shaped nano trap for a charged nanoparticle in saline. The results
show that the system has a moderate trapping well of moderate depth; van der
Waals interaction enhances the trapping capability, and the entropy term
induced in distribution contributes significantly in the trapping capability.
This work provides some valuable clues to the development of practical
submicron devices of electrostatic tweezers working in a solution with ions.
