Characterization of micromachined silicon membranes for immunoisolation and bioseparation applications

The application of microfabrication technology to create precise separation and isolation membranes for biomedical applications is described. By utili zing fabrication techniques commonly employed in the microelectronics indus try (MEMS), membranes can be fabricated with well-controlled and uniform po re sizes, allowing the optimization of membrane parameters for biomedical a pplications in cell immunoisolation and viral filtration. Using bulk and su rface micromachining to create diffusion membranes, pore sizes down to 18 n m have been attained through deposition and subsequent etching of sacrifici al layers on silicon. Membranes were shown to be sufficiently permeable to small biomolecules such as oxygen, glucose, and insulin, while excluding th e passage of larger proteins such as immunoglobulin G (IgG). The semipermea bility of microfabricated membranes, their biocompatibility, ease in steril ization, along with their thermal and chemical stability, may provide a sig nificant advantages for biomedical applications. Microfabrication technolog y may also be applied to other materials of interest for the development of highly controlled membranes. (C) 1999 Elsevier Science B.V. All rights res erved.