A micromachined pressure sensor based on the measurement of the pressure-dependent thermal conductivity of gaseous media (Pirani principle) is presented. The sensor consists of a freestanding microbridge with a defined distance to the substrate which acts as a heat sink. The theory to compute the necessary geometrical dimensions of the sensor element is presented. Due to a novel fabrication process, based on a sacrificial layer of ZnO, the sensor can readily be adapted to operate in different pressure ranges, even exceeding atmospheric pressure. A fully integrated bridge arrangement was used to compensate for ambient temperature changes. Experimental results for different sensor geometries are presented which correspond well with the theory. Basic design rules for micromachined Pirani pressure sensors are derived from the measurements.

Different kinds of thin-film coatings were investigated with regard to their applicability as hydrophobic coatings for MEMS. The films were deposited onto silicon and borosilicate glass substrates by spincoating of Dyneon TM PTFE and PFA, plasmapolymerization of HMDS-N and C 4 F 8 as well as liquid-phase and vapor-phase coating of SAMs from DDMS, FDTS, FOTS and Geleste Aquaphobe TM CM. The layer properties were analyzed using profilometry, FTIR, SEM and contact angle measurements. Furthermore, the adhesion of the layers to the substrates was determined in an acetone ultrasonic bath. The influence of various deposition process parameters on the properties of the films was investigated. As these layers can be used in microfluidic systems, as water-repellent layers and as anti-stiction coatings, they are suited for versatile fields of application.

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We report on the measurement of the electro-optic properties of poled polymers at λ=1.55 μm via the Teng and Man technique. Measurements of the electro-optic coefficient obtained for two different sandwich structures, using either indium tin oxide (ITO) or aluminum doped zinc oxide (ZnO:Al) semitransparent electrodes, are compared. The experimental results show that the use of ITO electrodes can lead to a largely wrong evaluation of the electro-optic coefficient r33, with respect to that obtained when using ZnO:Al electrodes, whose plasma resonance is shifted to longer wavelengths. Results on the disperse red 1/methyl-metacrylate based sidechain benchmark system are reported.