Exfoliated Flexible Photonic Crystal Slabs for Refractive Index and Biomolecular Sensing

Using the optical transduction properties of 1-D photonic crystal slabs (PCSs) is a promising approach for label-free biosensing in the field of flexible and wearable biosensing. In this work, we demonstrate the fabrication of flexible PCSs (f-PCSs) via an exfoliation method from rigid PCSs. We investigate the processing effect on the optical properties and show that the optical resonances are maintained, but affected. The quality factor changes from 50 to 31 for the transverse electric (TE) mode and from 187 to 136 for the transverse magnetic (TM) mode after the process. We demonstrate the use of f-PCS for refractive index sensing and achieve a limit of detection (LOD) of 3.6E⁻⁴ refractive index units (RIUs). Furthermore, we introduce vapor-phase functionalization of the f-PCS and show the first results of biosensing of antibodies from diluted feline serum.