Plasmonic nanohole array for biosensor applications

We explore the optical biosensing platform in plasmonic nanoholes array. The periodic nanohole structure of the biosensor and the gold coating of the sensor surface produce extraordinary light transmission (EOT) resonances of which the resonance peak shifts proportionately to the change of environment refractive index (RI). Detailed simulations studies were carried out to establish the resonance spectrum and sensitivity in relationship with the nanohole array pitch, diameter and gold thickness for hexagonal lattice arrangement. The plasmonic sensors were fabricated by top down approach utilizing mask-based deep ultraviolet (DUV) lithography. The plasmonic nanohole sensor was tested with a direct coupling method of incident light which allows robust and sensitive sensing platform with minimal alignment requirements. The measured bulk refractive index sensitivity is 409.4 nm/RIU and the surface mass sensitivity is 1.802 nm/ng mm^-2. The sensor structures have shown promising designs and performance for achieving compact and low-cost sensor for biosensing applications.