Patent ID: 7060487

Claim:
An enhanced sensitivity optical biosensor, comprising: a fiber-optic coupler having a refractive index incorporating at least two optical fibers, each fiber having an input and an output; a source of light having a nominal wavelength coupled to at least one of the inputs; the coupler including a necked-down section around which an evanescent field is generated when the light passes through; a biomolecule enveloped by the evanescent field, the biomolecule exhibiting a direct or indirect affinity to a binding partner, such that attachment of the binding partner causes a change in the refractive index of the coupler which, in turn, causes a change in the ratio of the light at the fiber outputs; apparatus separate from the source of light for adjusting the nominal wavelength of the light source so that a given change in the refractive index of the coupler causes a greater change in the ratio of light present at the fiber outputs; and instrumentation for receiving die light from the fiber outputs and for determining a characteristic of the binding partner in accordance with the change in the ratio of the light at the fiber outputs.