ABSTRACT
Surface plasmons(SP) are charge density waves which involve the oscillation of surface electron density at the metal interface. The use of SP as a method of signal transduction for biosensor development has been shown to be feasible with a Kretschman or a grating configuration. However, neither of these configurations lend themselves to miniaturization for in vivo sensing. An alternative approach has been employed here based on the observation that the visible absorption spectrum of small metallic particles is dominated by the SP resonance of the valence electrons. The resonance conditions depend on the size and shape of the metal particle and the local environment in which the particles are embedded. Preliminary experiments indicate that the absorption spectra of thin silver island films are sensitive to deposition and annealing conditions due to changes in the size and shape of the deposited islands. The effects of immersing these deposited films into different solvents and solutions indicates that a significant perturbation of the absorption curves occurs, inferring a perturbation of the surface plasmon resonance conditions. If this local environment is functionalized to provide a degree of chemical selectivity, then subsequent binding of an analyte should result in a change in the optical absorption spectrum which could provide the basis of transduction scheme for a biosensor.
