Leaky Waveguide Grating (LWG) Biosensor

A novel leaky waveguide grating (LWG) biosensor is reported where a continuous waveguide film of chitosan was photo patterned, resulting in a periodic modulation of the concentration of recognition elements (streptavidin in this case). This resulted in a periodic variation in the refractive index of the waveguide film, forming a phase grating at resonance angles of the LWG. Thus, a diffraction pattern was observed at resonance angles, but not at other angles. The position of resonance angles and hence diffraction pattern was a function of the refractive index of chitosan waveguide strips, forming the basis of biosensing and quantitative measurements.