Nanoparticles, Microfluidics, and Light:

Control over Photochromic Systems

Dr. Nelson Bell

Center for Integrated Nanotechnology

Sandia National Laboratories

  The manipulation of physical interactions between structural moieties on the molecular scale is a fundamental hurdle in the realization and operation of nanostructured materials and high surface area microsystem architectures. These include such nano-interaction-based phenomena as self-assembly, fluid flow, and interfacial tribology. One avenue for directed control utilizes photosensitive molecular structures to tune such interactions reversibly. This material strategy provides optical actuation of nano-interactions impacting behavior on both the nano- and macroscales and with potential to impact directed nanostructure formation, microfluidic rheology, and tribological control.
  In this colloquium, our work in development of monolayers and colloidal systems with photochromic derivatives will be described to show capabilities to control fluidic movement and the photo-aggregation and/or deposition of colloidal particles. Optical effects are characterized and related to the reversible control of the surface phenomena. Control over the optical properties of inorganic systems is under investigation in the sol-gel synthesis of doped Zinc Oxide nanoparticles. Control over particle size, dispersion and the adsorption edge of this system are of interest in the formation of next-generation solar cell devices. Novel tools that allow for understanding of the synthesis and control of nanoparticle properties are highly desirable. To further investigate nanoparticle systems, a Microfluidics Synthesis Discovery Platform™ developed by the Center for Integrated Nanotechnologies (CINT) is described. The objective of this microscale module for nanoscience research is to enable a wide variety of microfluidics experiments by the CINT user community for synthesizing nanoparticles with good control and repeatable results.