Patent ID: 7652767

Claim:
An optical sensor, comprising: an optical emitter mounted on a substrate; an optical detector mounted on said substrate adjacent to said optical emitter; and a reactive surface located opposite said substrate, optical emitter and optical detector, wherein an area of said reactive surface is exposed to a fluid and an optical property of said reactive surface changes upon exposure to a target material, wherein said optical emitter emits light onto said reactive surface, and said optical detector receives reflected light from said reactive surface and is operable to detect the change in said optical property when said reactive surface is exposed to said target material, the change in optical property being independent of an angle of incidence of said emitted light onto said reactive surface and including at least one of a change in index of refraction, a change in optical absorption, a change in polarization of the reflected light, a change in fluorescence, and a changed optical property resulting from a change in geometry of said reactive surface, and wherein said optical detector comprises a first and a second optical detector, said first optical detector located on said substrate to receive reflected light from a first area of said reactive surface and said second optical detector located on said substrate to receive reflected light from a second area of said reactive surface that is different than said first area.