| There is considerable interest in devising nanofabrication strategies that
rely on the molecular self-assembly of complex fluids and materials. Our
efforts over the past several years have been focused on conceiving
strategies to drive and direct that self assembly, largely by developing
multiscale modeling models and methods capable of predicting the structure
and properties of complex fluids and materials under external fields,
including confinement, electric fields, or flow fields. These models and
methods can vary considerably in nature and level of resolution, depending
on the system and issues of interest. In this presentation I will discuss
three modeling approaches, along with their usefulness and limitations, in
the context of three distinct nanofabrication platforms. The first is
concerned with the elongation and presentation of long DNA molecules in
nanofluidic channels. A coarse grain model, that includes fluctuating
hydrodynamic interactions, has been used to design a gene mapping device and
to interpret experimental data pertaining to the structure and dynamics of
confined chromosome-length DNA. The validity of our results is established
by comparison to experiments, to results of detailed molecular dynamics
simulations, and to results from coarse grain Lattice-Boltzmann simulations.
The second application is concerned with the study of liquid-crystal based
biosensors. A multiscale model has been used to design liquid-crystal based
devices in which nanoscale particles self assemble into highly regular
structures, including chains, upon exposure to applied fields. As discussed
in this presentation, the model can be used to explain the defects and
transmission images that arise in laboratory experiments. The model is
validated by comparison to results from experiments and atomistic
simulations. The third application is concerned with the formation of
ordered, defect-free block copolymer structures on nanopatterned substrates.
A new mesoscopic formalism has been developed to describe the structure and
dynamics of block copolymer blends and composites, and we use it to explain
the effects of surfaces and different types of confining walls on the free
energy (and the concomitant stability) of a variety of morphologies of
interest for lithographic fabrication. The results of these calculations are
consistent with experimental observations, and also with those of detailed
many-body simulations. |