Our research focuses on measuring and manipulating colloidal and macromolecular interactions, dynamics, and structures on macroscopic substrates. This has broad relevance to traditional complex fluid applications (coatings, ceramics, foods) and emerging nanotechnologies related to fabrication of devices (sensors, diagnostics, microfluidics) and materials (photonic, biomimetic). The objective is to develop experimental and analytical tools to rationally manipulate material properties and process characteristics with explicit consideration of thermodynamic and kinetic factors inherent to the colloidal domain. In our group, colloidal interactions are measured with exquisite sensitivity by monitoring equilibrium and non-equilibrium structures using optical microscopy and scattering methods. To interpret and predict the control parameters in interfacial colloidal systems, we have employed analytical and simulation techniques to rigorously model many-body, low Reynolds number hydrodynamics and particle interactions on the order of kT.
Within this broad framework, we have several immediate areas of interest. We are developing novel combinations of total internal reflection, video, and confocal microscopy techniques to allow direct, real space measurement of three dimensional colloidal trajectories in interfacial ensembles. These methods are being used to investigate colloidal photonic crystal assembly on templated substrates, the use of colloids as novel probes of biomolecular microarrays, measurements of metal nanoparticle-surface interactions, and "imaging" of potential energy landscapes on heterogeneous surfaces. Our initial work has focused on a stepwise escalation of experimental and analytical complexity from single-particle/wall problems to multi-particle/wall problems, which provides a foundation for understanding increasingly complex interfacial colloidal and macromolecular systems.
Stokesian dynamic simulations of interfacial and confined colloidal systems.
Multi-body & multi-dimensional interfacial colloidal forces and hydrodynamics.
Patterned potential and free energy landscapes interrogated using diffusing colloidal probes.
Colloidal self assembly on chemically and physically patterned substrates.
Colloidal directed assembly using external applied fields.
Phase behavior tuned via temperature & specific ion dependent polymeric forces.
Equilibrium & non-equilibrium colloidal structure characterization and manipulation.
Protein-protein & protein-synthetic macromolecule interactions using nanoparticle probes.
