High-Order Localized Spoof Surface Plasmons Resonator for High Sensitivity Sensing

This paper proposes a toroidal plasmons resonator composed of a slotted circle and a ring fed by a microstrip line. Multi-modes Mie resonances are well excited by the feed of the microstrip line. A toroidal magnetic field is demonstrated and analyzed by CST simulation at 14.318 GHz. The higher-order resonance shows higher sensitivity for permittivity sensing. By reconstructing the structure, the excited octupole has a high sensitivity of 3.68 GHz/RIU and quality factors of 340.6 with a ${Q}$ -factor of 340.6. The high sensitivity, high Q-factor, and compact size make it a good choice for sensing applications.