Catalytic Nanomotors and Micropump Systems Utilizing Alternate Fuels

Restricted (Penn State Only)
Author:
Wong, Flory
Graduate Program:
Chemistry
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
July 12, 2016
Committee Members:
  • Ayusman Sen, Dissertation Advisor
  • Ayusman Sen, Committee Chair
  • Thomas E Mallouk, Committee Member
  • Raymond Edward Schaak, Committee Member
  • Darrell Velegol, Outside Member
Keywords:
  • nanomotors
  • micropumps
  • electrophoretic
  • electrokinetic
  • active colloids
  • self-electrophoresis
  • density-driven flows
  • self-powered
Abstract:
Colloidal assemblies of self-powered active particles have become a focus area of research. Ranging from microscopic particle suspensions to nanoscale molecules, these systems transduce chemical energy into mechanical motion across multiple length scales following a variety of mechanisms. Understanding the energy transduction processes and the subsequent nature of particle dynamics offers unprecedented opportunities to explore the physics of small-scale colloidal systems and to harness their behavior in many useful applications. However, over a decade after the initial discovery of autonomous bimetallic nanorods, we continue to struggle to bring such systems into real-world applications. Part of the setback has been the in-depth research into hydrogen peroxide fuel. While the studies have built up the fundamental knowledge necessary for the advancement of the field, we have yet to do the same for other systems that employ alternate fuels. This dissertation aims to fill that void by developing nano- and micromotor and pump systems that does not rely on traditional hydrogen peroxide fuel, uses novel material by taking inspiration in other areas of research, and complete in-depth studies to provide a clear understanding of such systems. Chapter 1 provides a general overview of the research into chemically powered nano- and micromotors and pumps, the motivation behind my interest, and concise descriptions of the individual research projects discussed in this dissertation. Chapter 2 and 3 discusses a highly efficient silver-based nanomotor and micropump system that operates in iodine media. It is a significant step in the development of a new type of system as it is extremely efficient in fuel conversion as well as being a light-modulated system. Chapter 4 utilizes an established biopolymer to fabricate an acid-sensitive micropump and a proof-of-concept micromotor. This work provides the fundamentals that can be applied to converting other types of polymer into active colloidal systems. Chapter 5 puts forth a novel biodegradable dual-mechanism micropump made of zinc and iron. The pump is controlled by both electrokinetics and density driven flows. This new system is undaunted by high electrolyte environments and is not limited to one type of chemical fuel, as it is capable of fluid pumping in acid, salt, and buffered solutions. This dissertation concludes with a brief perspective on the future advancement in nano- and micromachine development.