The proposed research project focuses on the characterization of microfabricated membranes with attention to material/structural optimization and the functionality of the membranes as biological filters. The technologies of surface and bulk micromachining are used to create membranes with a multitude of pore configurations and arrangements, capable of high densities and uniform pore sizes. By using a combination of photolithography and deposition/selective removal of sacrificial layers, well- controlled pore sizes (less than a 5% variation) in the tens of nanometers on silicon substrates are achieved. Several issues related to processing and material selection will be examined to render the membranes more compatible with bioseparation applications. By investigating different perm-selectivity criteria such as structural materials, geometry, and surface chemistries, it is expected that the physical foundations of fabricating membranes for bioseparation will be better understood. Aim 1 is "Filter design and functionality" and includes: a) Investigating defects inherent in the current process, b) Improving flow rates by alterations in structural layer thicknesses and hole density; and c) Evaluating the mechanical properties of the membrane using different top structural layer materials. Aim 2 ("Interactions with Biological Systems") will] consist of: a)Examining biocompatibility and thrombogenicity for membranes of different microfabricated structural materials; b) Implementing Anti-fouling and surface modification strategies for microfabricated membranes using solution and vapor phase deposition techniques; and c) Investigating the diffusion and exclusion of biological proteins and molecules through microfabricated filters. Finally, Aim 3, "Integrated Filtration Systems" includes a) integrating charge-based separation capabilities to microfabricated membranes to create "functional" interfaces and b) Characterizing Integrated Filters via Bead and Protein Separation Studies.
Through this project, it is hoped that the use microfabrication technology will be explored to not only create controlled interfaces, but also understand fundamental processing advances which will facilitate integration of microfabrication technology with biology. It represents an important step in the merging of disciplines to answer critical questions at the interface of biology and engineering, and paves the way for the development of membranes uniquely suited for biomedical applications in viral filtration and immunoisolation. ***
