Patent ID: 8027040

Claim:
A method for determining the concentration of an analyte using a substrate comprising a conductive region and a recognition layer, the conductive region having a first surface operatively coupled with the recognition layer, the conductive region comprising at least one metal particle or structure having a near field and a semiconductor disposed in the near field of the at least one metal particle or structure, the semiconductor being part of a photodetector, the method comprising: contacting the substrate with the analyte to bind at least a portion of the analyte with the recognition layer; directing radiation to the conductive region and the recognition layer, the combination of the at least one metal particle or structure, the semiconductor and the analyte exhibiting plasmon effects when the radiation is directed to the conductive region and the recognition layer; electrically transducing the response of the said plasmonic excitation of the combination of the metal particle or structure, analyte and semiconductor, through light absorption in the semiconductor and subsequent change of the conductivity of said semiconductor, at least a part of a spectrum being related to said plasmon effect being absorbed in the semiconductor through scattering into the semiconductor and subsequent absorption or through evanescent coupling to the semiconductor; and determining the concentration of the analyte from at least part of the spectrum of said light absorption.