Inorganic frameworks obtained by the sol-gel route can be templated by a molecular
imprinting (MIP) approach to generate functional cavities. Such MIP ceramics show highly
appreaciable properties for chemical sensor applications, because they are inherently chemically
and thermally robust. In combination with mass-sensitive devices (e.g. quartz crystal micro balance
– QCM, surface transverse wave oscillator - STW), they yield highly selective and sensitive
chemical sensors. Gas phase measurements with volatile organic compounds (VOCs) e.g. lead to
sensitivities below 1 ppm. Sensitivity can be tuned by the sol-gel-precursor: when hydrolysing more
bulky alkoxides, this leads to enhanced sensitivity by increasing porosity as a consequence of
slower solvent evaporation. By adding products of oxidative oil degradation to the sol-gel mixture,
we succeeded in generating sensors for degradation processes in these complex matrices. This
allows parallelly monitoring both the chemical state of oil and changes in viscosity. Sensitivity is
enhanced according to the Sauerbrey equation by going from 10 MHz QCM transducers to higher
frequencies either by etching the quartz substrates and so reducing the resonator thickness or by
applying STWs.
Tunable Electrical Properties of Aligned Single-Walled Carbon Nanotube Network-based Devices: Metallization and Chemical Sensor Applications
