Abstract
Methods of modern chemistry are a powerful tool in generating functional materials suitable as chemically sensitive layers to be combined with a variety of transducer principles. Molecular pits in polymers are formed by molecular imprinting, by suitable double-imprinting e.g. PAHs can be detected down to the sub-μg/l level. The resulting selectivity patterns depend both on the polymerization temperature and the template/mononomer composition. Organic contaminants in water can be either directly assessed in liquid phase or separated from the matrix by a porous Teflon membrane. Thus the detection limits can be reduced to the ppm-level due to the a much lower noise level in gaseous phase. Even complex processes such as engine oil degradation can be followed by suitably imprinted polymers. Pits on the nm- to μm scale are reached by surface templating polymers with microorganisms. The resulting layers show reversible, antibody-like interactions and thus are optimal sensor layers. The successful on-line detection of tobacco mosaic viruses (TMV) can be achieved by these surface imprinted layers.
Highlights
One of the time-consuming key aspects in the development of chemical sensors [1] is the design of suitable sensitive layer materials
In this paper we present some recent results obtained by different imprinting techniques that are improved e.g. by using more than one template, by separating the analytes from the matrix, by following complex processes or by applying biogeneous templates
Applying an array of devices [6] with up to six channels or more showing different selectivities followed by multivariate data analysis leads to reliable sensor results. We demonstrated this principle by mounting a quartz crystal microbalances (QCM) containing six electrode pairs in the headspace of a small composter and monitoring the concentrations of four predefined key-analytes, namely small aliphatic alcohols, ethyl acetate, limonene and humidity
Summary
One of the time-consuming key aspects in the development of chemical sensors [1] is the design of suitable sensitive layer materials. This can be overcome by using (molecular) imprinting methods [3], where the analyte-to-be is used as a template during layer polymerisation and leaves behind adapted cavities in the highly cross linked material.
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