Surface plasmons are coherent electron oscillations that occur at the interface between two materials. A wave with varying electron density propagates along the interface.
The oscillations in the charge density at the interface are addressed as surface plasmon polariton waves. Such oscillations were first described in 1957 (1). This type of wave can be excited by the irradiation with light or by electron bombardment.
The application of surface plasmons for sensing technology has been pointed out in 1982 (2, 3). A sensor for the analysis of the anaesthetic gas halothane was constructed. Variations in the optical properties of an organic film due to gas exposure in the ppm range have been demonstrated.
In other sensor applications, surface plasmon resonance (SPR) signals originating from antigen antibody interactions can be used for the detection of these compounds. Doping the polymeric latex particles used for sensing with a colorant may enhance the change of SPR signals by a factor of more than 100. This type of amplification based on the dye-doped particles is widely applicable for the analysis of antibody antigen interactions and DNA interactions at low concentrations (4). The first sensors developed using the principle of surface plasmons were comparatively large. A prism is needed. There are two methods to construct smaller devices:
SPR can be described qualitatively ...