Characterization of Nanopore Processes by Optical Waveguiding in Nanoporous Thin Films
McDonnell Douglas Engineering Auditorium
Featuring K. H. Aaron Lau, Ph.D., Postdoctoral Fellow, Biomedical Engineering, Northwestern University
Abstract: Nanoporous thin films have been widely used as templates for fabricating multifarious material nanostructures and nanoarchitectures. They may also act as optical slab waveguides if the characteristic dimension of the pores is much smaller than the wavelength of the light being guided and scattering losses are small. Waveguide mode excitation is highly sensitive to the dimensions and optical properties of the waveguide material. The optical response, morphologies and volume fractionsof both the pore material and the solid matrix contribute to an effective refractive index of a nanoporous thin film. Therefore, material deposition and assembly processes within the nanopores may be sensitively monitored by characterization of the nanoporous waveguide mode excitation conditions. If suitable ligands are immobilized on the pore surfaces, the nanoporous thin film waveguide may also act as a highly sensitive biosensor, since waveguiding within the nanoporous structure effectively integrates the optical response over the vast internal surfaces. Through several examples, including biosensing, surface-initiated polymerization and polyelectrolyte layer-by-layer deposition within nanopores, this seminar will discuss the fundamentals of nanoporous waveguide sensing and highlight the sensitivity and versatility of the technique. Biosketch: Dr. Lau earned his Sc.B. and Sc.M. in Materials Engineering, both from Brown University (2000, 2002). He earned his Ph.D. in Chemistry from the Johannes Gutenberg University Mainz, Germany, for his research at the Max Planck Institute for Polymer Research in Mainz (2008). His Ph.D. research focused on nanostructured thin films and their applications in waveguide sensing and the generation of (bio)macromolecular structures. Prior to his Ph.D., he also conducted research at the Danish Technological Institute in Copenhagen and at the Institute of Materials Research and Engineering in Singapore. Currently, Dr. Lau is a postdoctoral fellow at Northwestern University where he is researching biomimetic polymers for biointerfacial applications.