detection of cancer cells using a photonic crystal biosensor ‎containing a defect layer surrounded by graphene

The optical properties of graphene have been extensively studied both theoretically and ‎experimentally for many photonic and optoelectronic applications due to its strong interaction ‎with light over a wide range of wavelengths. a biosensor based on a defective photonic crystal ‎consisting of three periods of alternating layers of sio2 and air is proposed, ‎‎(sio2/air)/graphene/nanocomposite/graphene, according to kretschmann configuration and ‎used to diagnose cancer. the defect layer is a composite layer consisting of silver nanoparticles ‎and sio2 dielectric, which is sandwiched between graphene layers. the influence of the number ‎of graphene sheets and photonic crystal layers on the performance of the proposed biosensor is ‎investigated. the results revealed that three periods are the optimum number of repetitions for ‎photonic crystal layers, and a couple of graphene monolayers is required for improved ‎performance of the suggested biosensor. the sensor’s sensitivity is defined as s=δλ/riu, with a ‎value of 7.8 nm shift in the plasmon resonance wavelength per 0.01 change in refractive index ‎unit.‎