Integration of freestanding polyelectrolyte multilayer membranes in larger scale structures

Ultrathin, semi-permeable membranes are not only essential in natural systems (membranes of cells or organelles) but they are also important for applications (separation, filtering) in miniaturized devices. Membranes, integrated as diffusion barriers or filters in micron scale devices need to fulfill equivalent requirements as the natural systems, in particular mechanical stability and functionality (e.g. permeability), while being only tens of nm in thickness to allow fast diffusion times. Promising candidates for such membranes are polyelectrolyte multilayers, which were found to be mechanically stable, and variable in functionality. In this thesis two concepts to integrate such membranes in larger scale structures were developed. The first is based on the directed adhesion of polyelectrolyte hollow microcapsules. As a result, arrays of capsules were created. These can be useful for combinatorial chemistry or sensing. This concept was expanded to couple encapsulated living cells to the surface. The second concept is the transfer of flat freestanding multilayer membranes to structured surfaces. We have developed a method that allows us to couple mm2 areas of defect free film with thicknesses down to 50 nm to structured surfaces and to avoid crumpling of the membrane. We could again use this technique to produce arrays of micron size. The freestanding membrane is a diffusion barrier for high molecular weight molecules, while small molecules can pass through the membrane and thus allows us to sense solution properties. We have shown also that osmotic pressures lead to membrane deflection. That could be described quantitatively.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Universität Potsdam

Year

2006

Author dc:creator

• Nolte, Marc

Contributors dc:contributor

• Möhwald, Helmuth

• Freistehende Membranen
• Kraftsensoren
• polyelectrolyte membranes
• force sensors
• diffusion barrier

Repository record source_url

https://publishup.uni-potsdam.de/frontdoor/index/index/docId/654

OAI identifier oai:identifier

oai:kobv.de-opus4-uni-potsdam:654