Patent ID: 7682566

Claim:
A sensor unit comprising: a dielectric block provided with a thin film disposed on a surface thereof, wherein: said thin film comprises a sensing surface for detecting a reaction of a sample, illuminating light is applied to an interface in a form satisfying a total reflection condition, wherein said interface is disposed between said thin film and said dielectric block, and when said sample in a sample fluid contacts said sensing surface, a resonance angle for creating surface plasmon resonance is changed by said reaction of said sample, and a protection layer overlaid on an outer surface of said dielectric block, wherein said protection layer protects a first region of said dielectric block that passes said illuminating light that is incident on said interface, and a second region of said dielectric block that passes light reflected by said interface, wherein said dielectric block is constituted by a prism having a polygonal shape as viewed in a section, said surface with said thin film is directed upwards, and said protection layer is positioned on two outer surfaces of said prism, and wherein said protection layer is constituted by a peelable protection tape, and said protection tape is peeled away before assay of said reaction of said sample.