Functional Nanostructures

One of the major achievements of nanotachnology is the controlled synthesis of various nanostructures – nanoparticles, nanotubes and nanofilaments. These structures have new functionalities, either by themselves or by their incorporation in composites. Our team has elaborated an expertise in the synthesis of a multitude of nanostructures, working on their physical characterization and on their application in devices.

Since the appearence of the nanofilaments ressembles asbestos, there is a vivid interest in learning the health hazards related to their manipulation. We address these issues in collaboration with biologist/biochemist experts.

1. Synthesis of Carbon Nanotubes

Although carbon nanotubes (CNTs) were discovered in 1991 by S. Iijima, the details of their synthesis is still not understood. One of our goals is to find the major parameters of the growth and to tune them in such a way to synthesize large quantity and high quality CNTs for applications. We succeeded in the fabrication of large area aligned CNT carpets, which are very useful starting structures for advanced composite materials.

2. Synthesis of Inorganic Nanostructures

The main emphasis is on the synthesis of nanowires which have a high potential for applications. In the first place are TiO2, in doped anf pristine forms, ZnO and KNbO3. For the latter one we managed to grow a carpet of oriented nanowires.

3. Nanomechanics

The “Swiss Cheese Method” elaborated in the late nineties is our major technique for measuring the elastic response of individual nanofilaments, like carbon nanotubes, nanotube bundles and nanowires. It has also been successfully applied to measure the Young and shear moduli of biopolymers, as well.

4. Toxicity study of nanostructures

The health hazard related to the large scale synthesis and manipulation of nanostructures is an important issue in the scientific community and in the public opinion. We address it by tesing the uptake of well-controled and dispersed nanofilaments of various cell cultures and the cell proliferation using a large number of assays. The study is performed in close collaboration with Prof. Beat Schwaller (Department of Histology, UniFribourg).

5. Applications and Devices

One of the most popular nanostructures for application is TiO2. We master its synthesis in nanowire form at large scales. Its self-supporting membrane is suitable for various applications, ranging from photo-voltaics to humidity sensors.