A Dual-Band Reconfigurable Spoof Localized Surface Plasmon Sensor Based on Fano Resonance for Dielectric Sensing

Abstract

Spoof localized surface plasmons (SLSP) possess significant advantages in sensitivity to dielectric environments and have been widely used in sensing applications. In this work, a dual-band, reconfigurable SLSP sensor based on Fano resonance is proposed to achieve rapid and noninvasive detection of dielectric materials. The sensor functions in two operating bands, 0.995 and 2.147 GHz, which are controlled by the on and off states of the PIN diode. Furthermore, an equivalent circuit (EC) model is introduced to elucidate the reconfigurable mechanism of the sensor, and the model’s accuracy is validated by numerical simulations. In the sensing experiments, the proposed SLSP sensor exhibits stable Fano resonant characteristics and reliable reconfigurable performance under practical fabrication conditions. In particular, the sensor demonstrates competitive performance in solution concentration detection, with an average frequency sensitivity of 45.9 MHz/RIU for ethanol sensing and an average amplitude sensitivity of 435.41 dB/RIU for sucrose sensing, both obtained in the off state over the investigated concentration range. For the purpose of determining the detection limit of the SLSP sensor, several substrates with different dielectric constants were examined, and the results indicate that its minimum resolution is below 0.1. Compared to the existing work, the proposed sensor demonstrates competitive sensing performance together with electrical reconfigurability, providing a promising approach for low-cost, rapid, and noninvasive detection of dielectric materials.