Density-Based Chemical Analysis and Three Dimensional Self-Assembly Using Magnetic Levitation.

摘要

Magnetic levitation (MagLev) is a method for suspending objects against gravity using magnetic fields and field gradients. A useful feature of MagLev is its ability to relate the position at which at object levitates with the density of that object. The goal of this dissertation is to develop MagLev into a simple, low-cost, and versatile tool for analysis and three dimensional self-assembly. Chapter 1 provides an overview of MagLev and of its characteristics as a technique for enabling density-based analysis, separations, and self-assembly.;Chapters 2 and 3 describe MagLev as a technique for three dimensional (3D) self-assembly. Chapter 2 focuses on the self-assembly of mm- to cm-scale diamagnetic objects---each programmed by shape and distribution of density---into three-dimensional assemblies. This chapter demonstrates the ability of MagLev to position and align optically functional components, and to generate multilayered, interlocking structures. Chapter 3 details 3D self-assembly of a large number of objects, and the effects of soft templates (produced by the magnetic field), and rigid templates (both levitating objects and the walls of the container), on the packing and shaping of magnetically levitating clusters of both spherical and non-spherical objects.;Three manuscripts in the Appendix present additional examples of MagLev in chemical analysis. Appendix 1 examines the fundamental aspects of MagLev as an analytical system for measuring densities of solids and liquids. Appendix 2 describes MagLev as a method for monitoring solid-supported reactions and for distinguishing differences in chemical composition of polymers. Appendix 3 surveys applications of MagLev as a sensor for characterizing samples of food and water based on measurements of density.