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The use of force spectroscopy to study the adhesion of living fibroblasts to their culture substrate was investigated. Both primary fibroblasts (PEMF) and a continuous cell line (3T3) were studied on quartz surfaces. Using a fibronectin- coated AFM cantilever, it was possible to detach a large proportion of the 3T3 cells from the quartz surfaces. Their adhesion to the quartz surface and the effects of topography on this adhesion could be quantified. Three parameters characteristic of the adhesion were measured: the maximum force of detachment, the work of adhesion, and the distance of detachment. Few PEMF cells were detached under the same experimental conditions. The potential and limitations of this method in measuring cell/surface interactions for adherent cells are discussed.
Complementary methods have been developed for surface nanostructuring using molecular self-assembly, reactive ion etching and replication techniques. First, controlled surface nanostructures with tunable lateral dimensions from tens of nanometer to tens of micrometers have been produced by polymer self-assembly, over large area and at low cost. The resulting nanostructures could find applications as antireflective layer or as security features for traceability and anti-counterfeiting applications.
In this work, nanosphere lithography was integrated with standard microfabrication for the wafer-scale fabrication of silicon nitride (SiN) membranes with arrays of submicrometer holes. A monolayer of polystyrene (PS) beads with a mean diameter of 428 or 535 nm was spin coated onto the front side of a (100)-silicon wafer double-side coated with 100 nm of low-stress SiN. The size of the deposited PS beads was reduced by oxygen plasma reactive ion etching. This allowed to tune the hole size in the released SiN membrane while maintaining the hole array periodicity. Using the size-reduced PS beads as a lift-off template in a standard nanosphere lithography lift-off procedure, a 20 nm thick chromium hole etch mask was realized. This hole mask was patterned by UV photolithography, thus allowing for the local dry-etching of holes into the SiN...
In this work, nanosphere lithography was integrated with standard microfabrication for the wafer-scale fabrication of silicon nitride (SiN) membranes with arrays of submicrometer holes. A monolayer of polystyrene (PS) beads with a mean diameter of 428 or 535 nm was spin coated onto the front side of a (100)-silicon wafer double-side coated with 100 nm of low-stress SiN. The size of the deposited PS beads was reduced by oxygen plasma reactive ion etching. This allowed to tune the hole size in the released SiN membrane while maintaining the hole array periodicity. Using the size-reduced PS beads as a lift-off template in a standard nanosphere lithography lift-off procedure, a 20 nm thick chromium hole etch mask was realized. This hole mask was patterned by UV photolithography, thus allowing for the local dry-etching of holes into the SiN...
We present the fabrication of thin membranes with dense arrays of nanometer and submicrometer pore arrays by the integration of standard micromachining with three pore patterning techniques: electron beam lithography (EBL), nanosphere lithography (NSL) and aluminum anodization. Using a serial top-down EBL technique we exploit a fine size, positioning and flexibility of this tool. NSL and aluminum anodization, as self-organized bottom-up processes, guaranties cost efficiency and throughput. In our work, we have fabricated silicon nitride (SiN) and alumina (Al2O3) membranes with a thickness down to 100 nm, side length ranging from 200 μm up to 2.4 mm and pore size ranging from 20 nm to 500 nm.
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