Contact-Based Assembly of Nano-scale Structures: Synthesis of Mechanics and Tools of Nanomanipulation
thesisposted on 2013-06-28, 00:00 authored by Christopher A. Pelzmann
Construction of new useful nanoscopic structures and mechanisms—such as nano-electromechanical systems (NEMS)—requires advanced nano-fabrication tools and techniques. Emerging NEMS devices potentially involve complex, asymmetric, three-dimensional arrangements of nano-scale elements, which are beyond the capabilities of currently available "top-down" and "bottom-up" manufacturing methods. Mechanical assembly of nano-scale objects via "contact-based" manipulation has the potential to fill the void between these currently available methods and as such may prove fundamental in the advancement of nanomanufacturing. Fabrication of advanced nanoscopic structures and mechanism by means of mechanical manipulation is currently limited due to an insufficient understanding of nano-scale multibody systems. This includes uncertainty regarding the response of individual nano-scale bodies and multi-link chains to externally applied forces. Expanding the understanding of these behaviors may enable the design and operation of advanced nanomanipulation tools as well as the assemblies they produce. Toward these ends, this work investigates the kinematics and mechanics of nanoscopic multibody systems. This is accomplished in three parts: through the construction of a novel optical based nanomanipulation system; the experimental study of multi-walled carbon nanotubes (MWCNTs), pairs of tubes in contact, and multi-pair chains; and the integration of the observed mechanical behavior into a multibody system model. Here, the nanomanipulation system demonstrates the ability to use optical visualization in the positioning of free-standing structures with a minimum dimension as low as 100 nm under ambient conditions. This system is used to examine both the structural properties of multi-walled carbon nanotubes (MWCNTs) and the mechanics of the 'joint' formed between pairs when assembled into chains. Specific attention is given to this nano-scale joint regarding its formation due to natural adhesion, its kinematic and mechanic characteristics, and the alteration of these characteristics through the use of localized heat treatment. Finally, the observations are used to propose a joint model capturing both the elastic and inelastic behavior of the adhesive contact for use in dynamic multibody formulations. Through these contributes, this work offers tools and mechanical theory for use in advancing the field of contact nanomanipulation.