Field Directed Assembly for Nanomanufacturing and Nanoscale Device Integration

Benjamin Yellen

Mechanical Engineering and Materials Science Department

Duke University

Abstract

Over the last few decades, a new nanomanufacturing paradigm based on “bottom up” self-assembly strategies has emerged as a viable method for integrating nanoscale optical, electronic, and biological components into useful microsystem architectures. The main advantage of self-assembly techniques is that the device components can be fabricated separately and then placed into desired geometric arrangements, as opposed to the current paradigm based on monolithic integration strategies.  Not only does this self assembly technique enable the integration of a broader class of materials into useful systems than do monolithic strategies, it can also significantly reduce the costs due to the self-guiding placement of materials onto various 2-D and 3-D substrates.  However, the inherently stochastic characteristics of self-assembly present a significant engineering challenge in how to deal the variability of the starting material, as well as the variability in the assembly process itself.  Thus, there remains an urgent need to develop techniques for sorting colloidal particles, such as nanotubes/nanowires, biological components, and other active materials, and for uniformly placing them into precise patterns.

 

In the course of this talk, I will present my recent and future work on magnetically guided self-assembly systems, and I will point out critical differences between molecular and mesoscale self-assembly mechanisms. I will show why magnetic forces, which are considered too weak for molecules, are capable of overcoming hydrodynamic forces and the effects of Brownian motion on mesoscale objects. I will also demonstrate how novel self-assembly mechanisms can be designed to take advantage of the long-range nature of attractive and repulsive magnetic forces. Throughout this talk, I will introduce potential applications for these techniques in cell printing, microarrays, and biomedical implants, as well as for other lab-on-a-chip applications.  Finally, I will outline my future work and goals to apply the techniques I have previously developed to new fields in electrochemical energy production and nano-patterning.