Polymer Dry-Lift Off Patterning of Cells and Proteins
B. Ilic, H. G. Craighead
School of Applied and Engineering Physics
Cornell University, Ithaca, NY
Precise placement of biochemicals on device structures and controlling of the cell culture environment are important for tissue engineering, sensors and fundamental studies of cell behavior. We present a novel dry lift-off method  that allows precise patterning of chemically sensitive biological materials on a variety of surfaces with lateral dimensions of 100nm. Our dry lift-off technique uses a conformal Parylene layer, which is a pinhole-free and biocompatible vapor phase deposited inert polymer. This layer is photolithographically patterned using standard ultraviolet sensitive photoresists, and dry etching in a reactive ion etch chamber using oxygen plasma (Fig. 1a-1b). The patterned Parylene layer acts as a template to physically pattern subsequently deposited chemically sensitive biomolecular materials (Fig. 1c). Without chemically treating the surface to enhance adhesion, the poor characteristics of the Parylene bond to the underlying substrate allows Parylene to be mechanically peeled from the substrate, resulting in a geometrically confined negative tone of immobilized biological material (Fig. 1d). To demonstrate the power of the polymer peeling lithography, we fabricated a variety of topologies, such as isolated dots, spirals, and parallel lines, of different biochemicals on silicon substrates using both projection and electron beam lithography. As examples, we have patterned antibodies, poly-L-lysine, and aminopropyltriethoxysilane self assembled monolayers which were respectively used to pattern Escherichia coli serotype O157:H7 bacteria cells (Fig. 2a), cultured rat basophilic cells (Fig. 2b), and 20nm diameter aldehyde-sulfate flourescent polystyrene beads (Fig. 2c). Additionally, we have patterned protein A, laminen, fibernectin, carbon nanotubes, and a multi-layer structures of protein A Igg AntiIgg shown in figure 2d. We demonstrate prototype patterns over areas in excess of 3cm2. Scanning electron and atomic force microscopy were used to investigate the topography and morphology of the patterned surfaces.
1. B. Ilic and H. G. Craighead, "Topographical Patterning of Chemically Sensitive
Biological Materials Using a Polymer-Based Dry Lift Off", Biomedical Microdevices, 2, 317-322 (2000).