Some aspects of improving surface plasmon resonance response in immunosensing applications are considered. Both from calculations and experiments, it was found that maximum sensitivity is obtained for a silver layer about 55 nm thick in direct contact with the species to be quantified. Application of an intermediate layer with high permittivity can be useful in suppressing background responses. Experimentally, a protein surface-coverage fraction of ca. 0.1 could be measured, corresponding to ca. lo-" mol 1-l antibody.

A surface plasmon based chemooptical sensor has been optimized by the use of computer simulation programs. Calculated and experimentally measured performances are in good agreement, showing the value of the simulation tool.

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Abstract.Two novel types of planar waveguide sensors for the chemical domain are introduced. Both are realized by thin film technologies. They consist of multilayered structures coated by a very thin organic overlayer that is able to absorb the species to be measured out of the environment. This absorbtion results in a change in its dielectric function. In the first sensor to be demonstrated this change is measured using a surface plasmon mode as a probe. In the second one the radiationless energy transfer from luminescent centres incorporated in one of the layers to the overlayer serves as a probe.

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