An optical waveguide SPR sensor is adapted for differential measurement.
The optical waveguide SPR sensor includes a base, a bottom layer, and at
least one set of optical waveguide layers. The set of the optical
waveguide layers includes a measuring optical waveguide channel and a
reference optical waveguide channel. The measuring optical waveguide
channel includes an SPR sensing film layer. The measuring optical
waveguide channel and the reference optical waveguide channel are
independently configured and substantially parallel one to another. The
bottom layer has a refractive index higher than a refractive index of the
optical waveguide layer.