Advances in Soft Matter Nanofabrication
Doctoral thesis, 2015
The focus of this thesis is placed on the fabrication of engineered nanodevices for the manipulation of soft matter thin films. By combining top-down micro- and nanofabrication approaches with bottom-up self-assembly strategies, new research platforms were developed, tested and characterized.
A large part of the studies described herein were performed on electron beam-sculpted Teflon AF surfaces, which served as substrate for molecular lipid films and biological cells. The effects of e-beam exposure of Teflon AF deposits, including changes in hydrophobicity, topography, surface potential and roughness, have been investigated in detail. Lipophilic nanolanes of 50 nm width were created in this manner. The studies show, for example, how spreading of a phospholipid monolayer film originating from a single giant multilamellar vesicle source can be confined and guided by e-beam-exposed frames on the polymer surface. The studies also reveal the preferential adhesion of biological cells on these e-beam-treated Teflon AF surfaces, where the shape of the patterned areas strongly affects cell adhesion.
By applying perfluorinated solvent as developer to complete the ebeam-lithography procedure, Teflon AF was introduced as non-amplified negative e-beam resist. Nanostructures with feature sizes as small as 30 nm in width and 40 nm in pitch were fabricated. This new resist was characterized by determining its contrast, sensitivity, and film thickness. The accommodation of single DNA origami scaffolds on developed Teflon AF nanopillars has been investigated as an exemplary application, and about 80% coverage of the available pillar surface was achieved.
Moreover, a novel, contact-free technology was developed to generate surface-supported networks of lipid nanotubes and flat giant unilamellar vesicles on a micro-patterned SU-8 substrate. The nanotubes were formed by thermomigration of a phospholipid double bilayer, where the migration of lipid material on the patterned surface was initiated and controlled by a temperature gradient created with an IR laser.
In the work presented here, a number of specific problems have been tackled in an interdisciplinary approach, making use of micro- and nanotechnologies, new materials and biomimetic principles that can open up new experimental opportunities to address further fundamental research questions.
negative e-beam resist
electron beam lithography