Wide-angle perfect absorber using a 3D nanorod metasurface as a plasmonic sensor for detecting cancerous cells and its tuning with a graphene layer

Abstract

We investigate a high-sensitivity plasmonic sensor that uses a hexagonal nanorod array metasurface with for identifying malignant hepatic metastases from healthy liver cells. This designed plasmonic metasurface has some advantages such as nanoscale dimensions, a high figure of merit and sensitivity to the refractive index, and insensitivity to the incident angle for 0° to 60°. With the 3D finite-difference time domain method, we study the output characteristics and the effect of geometrical parameters, materials, and incident angle on the plasmon-induced absorption resonances as well. A sensitivity of 1250 nm per refractive index unit (RIU) can be achieved when the change of the sensing medium refractive index Δn=0.2, and the maximum figure of merit achieved is about 610 RIU−1. Also, graphene metasurfaces are used to obtain tunable characteristics. Our proposed structure not only has a nanoscale footprint of 200×200×50 nm3, but also its plasmon-induced absorption resonances are not sensitive to the incident angle. This device holds great potential for the design of nanosensor devices and perfect absorbers.