C8.1 - Chemical Sensors in Environmental Chemistry - Monitoring Air and liquid Phase

SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Proceedings SENSOR 2011
C8 - Bio-Chemo Sensors
F. Dickert, B. Najafi, S. Yagub, M. Ghulam, S. Aigner, P. Lieberzeit - University of Vienna (Austria), I. Heeren - Robert Bosch GmbH, Stuttgart (Germany)
502 - 505


On site monitoring and controlling demands, chemical sensors capable of continuous data acquisition. For this purpose, robust materials based on sol/gel processes and organic polymers as recognition layers were combined with universally applicable mass sensitive devices and interdigital transducers. The problems can be solved by patterning
polymers with the analytes to be investigated, or to convert natural antibodies by a double casting process to plastic replicae of the natural analogues. Response times due to enhanced diffusion are optimised by generating nano-particles in the range of 100 - 300 nm by precipitating the prepolymers in suitable solvents. Gas phase monitoring was performed with QCMs (Quartz-Crystal-Microbalance) and SAWs (Surface-Acoustic-Wave), interdigital transducers are also suitable. All types of VOCs (volatileorganic- compounds) are accessible down to the sub-ppm range. These strategies are also transferred to condensed phase, both in water and organic solvents.
Work place monitoring was performed by detecting perchloro ethylene in the sub-ppm range as dry-cleaning. Complex mixtures generated e.g. by composters are evaluated by QCM-arrays using pattern recognition. Selective sensors for distinct vapours e.g. thiols can be optimised applying nanoparticles, sulfides of Cu, Ag and Mo. A large variety of pollutants as PAHs, pesticides a.s.o. are detected by these sensors. As an example the selectivity of QCMs coated with patterned polymers are highlighted. The pesticide atrazine can be analysed without any cross-sensitivity to the structural similar propoxur.
We focus us on characterizing the composition of fuel to detect main components and ingredients. According to environmental improvements bioalcohol is added to fuel. We have developed sensors which allow a continuous detecting this ingredient. In principle, this can be done by capacitive measurements, cross-selectivity to other ingredients cannot be guaranteed in this case. Thus, sensitive layers were applied, again. Low cost resistive measurements give appreciable changes in adding bioalcohol to fuel. Lowering of resistance is due to separationof ion pairs M+Xtion. The range of effects observed can be varied by in mobile ions by solvausing anionic net works based on less acidic functional groups -COOH or strong acids -SO3H. Thus, the coating can easily be adapted to the electronics.