FULLERENE LIQUID CRYSTAL MIXTURES AS QMB-COATING AND SAW-COATING - DETECTION OF DIESEL-VAPOR AND SOLVENT-VAPOR/

The detection of diesel fuel and different solvent vapours in air is d escribed. Due to the very low vapour pressure of diesel fuel, highly m ass sensitive quartz microbalance (QMB) and surface acoustic wave (SAW ) sensors are used. Micro porous coatings are presented consisting of liquid crystals and buckminster fullerenes. Thereby the globular compo und disturbs the structure of the rod-like component and cavities and channels are created. With these mixtures it is possible to attain a r esolution of 0.5% of the vapour pressure of diesel in air with the QMB ; an even fivefold increase of sensitivity can be obtained with highly sensitive SAW devices operating at 433 MHz. In the latter case alkyls ilane monolayers are used to promote adhesion, which themselves show a similar sensitivity as the QMB, but with an instantaneous response.