2D photonic crystal biosensing platform based on coupled defective ring-shaped microcavity-two waveguides for diabetes detection using human tears

This paper describes a two modes refractive index sensor based on photonic crystals (PhCs) for detecting diabetes in human tears samples. PhC-based biosensors are promising platforms to detect the analyte due to their high sensitivity and selectivity, low cost, and can be easily integrated with other electrical components. The proposed PhC biosensor consists of two waveguides coupled with one defective ring-shaped microcavity, the microcavity was created by removing seven lattice holes and shifting the inner ring-shaped hole vertically down by 0.45a, the whole microcavity system is separated from the two waveguides by three holes. The achieved sensitivity for this device comes out to be 659.83 nm RIU-1. The Q-factor, figure of merit (FOM), and limit of detection (LOD) were about 106, 106 RIU-1,and 10-7 RIU respectively. In general, our results revealed that the proposed device has appreciable potential to be used as a powerful tool to detect diabetes using tears. Furthermore, the proposed biosensor can be used as an alternative to painful pinpricks for diabetes testing. A brief comparison between the presented design and related literatures for detecting diabetes using refractive index biosensors is made to ensure effectiveness and the validity of the proposed biosensor. The high performance and simple design of the proposed biosensor make it a suitable candidate for bio-sensing applications.