Multiple Features-Based Improved Nanohole Array Plasmonic Biosensor

Abstract

In recent years, gold nanohole array-based biosensors have gained tremendous attention due to their high sensitivity, label-free biosensing, and real-time simultaneous multiple analyte detection capabilities. However, nanohole array-based biosensors using conventional sensing methods lack the resolution of traditional surface plasmon resonance (SPR) sensors. In this work, we present numerical methods utilizing multiple peaks of these biosensors’ transmission spectra to achieve higher sensitivity and lower detection limits. Using finite-difference time-domain (FDTD) simulations, we compared the sensing performance of the proposed numerical methods to traditional peak-shift and spectral integration methods. We added noise to the transmission spectra to simulate a realistic system and determined the change in the performance. We also optimized the geometrical parameters of the gold nanohole array for optimal sensing performance. Finally, we applied the proposed method to two critical real-life biosensing applications and reported the sensitivity and limit of detection (LOD). The proposed numerical methods show much higher sensitivity and lower detection limits than the traditional techniques. The observed detection limits are as low as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim {2} \times {10}^{-{6}}$ </tex-math></inline-formula> refractive index unit changes near the surface. The proposed methods can be utilized for any sensing systems that employ transmission spectra and will outperform traditional methods if there are multiple peaks present in the transmission spectra.