Deep-probe biosensing using peak-type metal-clad waveguides

A typical optical waveguide sensor is based upon monitoring the resonance angle at which light is coupled into the waveguide. Hence, the in-coupled light intensity versus illumination angle gives rise to a peak-type sensorgram. As opposed to this, the metal-clad waveguide is used in reflection mode, just as the well-known surface-plasmon resonance biosensor. Thus, metal-clad waveguide sensors facilitates two different operation modes depending on the metal used, dip-type and peak-type operation which are optimal for different sensing purposes such as refractive index measurements, detection of micron-scale objects or to measure thin adlayers on the sensor surface