Sensitivity enhancement of an intensity-based photonic crystal biosensor using a laser excitation source

Photonic Crystal Slabs (PCSs) are nanostructured, dielectric waveguides that feature resonances with small bandwidths and very high reflectivity in the visible spectrum. As refractive index-sensitive transducers, PCSs have been studied for biosensing applications in the past decades [1]. Incident light can couple to and from quasi-guided modes at resonance wavelengths. Due to the evanescent field of the guided mode, the resonance wavelength is sensitive to changes of refractive index in the surrounding media. Intensity-based refractive index sensing offers the opportunity for miniaturized and inexpensive readout systems for point-of-care applications. A system of the size of a microtiter plate for the readout of label-free cellular essays has recently been published and shows the high potential of this approach [2].