Proposed triaxial atomic force microscope contact-free tweezers for nanoassembly

Abstract

We propose a triaxial atomic force microscope contact-free tweezer (TACT) for thecontrolled assembly of nanoparticles suspended in a liquid. The TACT overcomes fourmajor challenges faced in nanoassembly, as follows. (1) The TACT can hold and position asingle nanoparticle with spatial accuracy smaller than the nanoparticle size (∼5 nm). (2) The nanoparticle is held away from the surface of the TACT by negativedielectrophoresis to prevent van der Waals forces from making it stick to the TACT. (3) TheTACT holds nanoparticles in a trap that is size-matched to the particle and surrounded bya repulsive region so that it will only trap a single particle at a time. (4) The trap canhold a semiconductor nanoparticle in water with a trapping energy greater thanthe thermal energy. For example, a 5 nm radius silicon nanoparticle is held with10 kBT at room temperature. We propose methods for using the TACT as a nanoscalepick-and-place tool to assemble semiconductor quantum dots, biological molecules,semiconductor nanowires, and carbon nanotubes.