Detection of ${\rm SiO}_{2}$ Thin Layer by Using a Metallic Mesh Sensor

The effectiveness of metallic mesh sensors to quantitatively measure thickness was evaluated by transmission spectra of sub- μm-thick SiO₂ layers deposited on a 6-μm-thick metallic mesh. Initially, we simulated the transmission spectra and the localized electric field distribution of different-sized periodic structures using the finite difference time domain method. Both the wavelength of the resonance peak and the decay distance of the localized electric field changed linearly with the size of the geometric parameters of the metallic meshes. These electro-magnetic properties enabled smaller-sized periodic structures to acquire exponentially higher sensitivity for the thin dielectric layer. The experiment resulted in distinct and systematic frequency shifts over 100-nm-thick SiO₂ (101 GHz of shift and 61% of CV). Potential of the metallic meshes as label-free and frequency-flexible biosensors was performed, which have high sensitivity for thin target using small size of periodic structures.