Nanoscale Manipulation, Probing, and Assembly Using Microfluidic Flow Control

Abstract

Nanoparticles have unique properties that can be beneficial in fields ranging from quantum information to biological sensing. To take advantage of some of some of these benefits, techniques are required that can select single particles and place them at desired locations with nanoscale precision. This capability allows for bottom-up assembly of nanoparticle systems and facilitates development of improved tools for probing nanoscale physics. Current manipulation approaches are inadequate for positioning nanoparticles such as single quantum dots. Quantum dots can act as single photon sources, and are useful for applications in nanophotonics and quantum optics. In this thesis, I present a technique for manipulation of single quantum dots and other nano-objects. Using this technique, I demonstrate nanoparticle manipulation, assembly, and probing with nanoscale precision.

The nanomanipulation approach I introduce employs electroosmotic flow to position colloidal nanoparticles suspended in an aqueous system. Single quantum dot manipulation is demonstrated with a precision better than 50 nm for holding times of up to one hour. This technique is useful for studying the behavior of single quantum dots and their interactions with the environment in real time. A fluid chemistry was developed for the deterministic immobilization of nanoparticles along a two-dimensional surface with 130 nm precision. In addition, a technique for assembling systems of silver nanowires is demonstrated. A method for imaging the local density of optical states of silver nanowires is presented using single quantum dots as probes, achieving an imaging accuracy of 12 nm. Spontaneous emission control is accomplished simultaneously by placing the quantum dot at various locations along the wire. Together, these experiments illustrate the versatility of microfluidics for the advancement of nanoscience research and engineering.