Biological sensors.

摘要

A biological sensor which utilises the phenomenon of surface plasmon resonance to detect the refractive index change which occurs when two components - for example antibody and corresponding antigen - react with one another. Surface plasmon resonance takes place at the sloping exit surface of an optical waveguide such as a fibre optic 23. The input end of fibre optic 12 is connected to a light source 12. A layer 25 of metal is applied to the sloping exit surface so as to cause total internal reflection of the light proceeding down the fibre optic. Reflected light is detected by a detector 13. A sensitive, for example antibody, layer 26 is applied to the metal layer. Sample (not shown) reacts with layer 26 in such a way that the refractive index changes. Provided conditions are correct, this variation in refractive index can be monitored in detector 13 by virtue of the surface plasmon resonance which occurs in the area of total internal reflection.