Robust Design of Bimetallic ZnO Nanofilm SPR Sensor using Taguchi Method

Taguchi’s L9 static design was employed to determine the robust design of a zinc oxide (ZnO) nanofilm surface plasmon resonance (SPR) bimetallic sensor. The control factors such as incident wavelength and different thicknesses of silver, gold and ZnO layers were selected. Noise factors include thickness of the chromium layer and the diameter of the biomolecules (i.e. urea) which were simulated using Finite-Difference-Time-Domain (FDTD). Results obtained show that the thickness of the gold layer has a 41.32% dominant factor effect on the minimum reflectance of light
$(\mathbf{R}_{\mathbf{min}})$
, whereas the incident wavelength has a 73.15% dominant factor effect on the full-width-at-half-maximum (FWHM) of the SPR signal. The confirmation tests carried out show that the values of
$\mathbf{R}_{\mathbf{min}}$
and FWHM were optimized using Taguchi's orthogonal array method leading to a robust design of the SPR sensor.