RIfS is used especially as a detection method in chemo- and biosensors.
Chemosensors are particularly suitable for measurements under difficult conditions and in the gaseous phase. As sensitive layers, mostly non-selective measuring polymers are used which sort the analytes according to size (the so-called molecular sieve effect when using microporous polymers) or according to polarity (e.g. functionalized polydimethylsiloxanes). When performing non-selective measurements, a sum signal from several analytes is measured which means that multivariate data analyses such as neural networks have to be used for quantification. However, it is also possible to use selectively measuring polymers, so-called molecular imprinted polymers (MIPs) which provide artificial recognition elements.
When using biosensors, polymers such as polyethylene glycols or dextrans are applied onto the layer system, and on these recognition elements for biomolecules are immobilized. Basically, any molecule can be used as recognition element (proteins such as antibodies, DNA/RNA such as aptamers, small organic molecules such as estrone, but also lipids such as phospholipid membranes).
RIfS, like SPR is a label-free technique, which allows the time-resolved observation of interaction among the binding partners without the use of fluorescence or radioactive labels.