ENHANCED NEAR-FIELD RADIATION TRANSPORT AND NANO-ENTITY DETECTION IN AQUEOUS SOLUTION WITH A SI3N4-BASED INTEGRATED WGM/SPR MICROSENSOR

In this emerging proof-of-concept simulation study, we demonstrated the enhancement of near-field radiation transport in a whispering-gallery mode (WGM) ring resonator via integration with surface plasmon resonance (SPR). The integrated sensor is made of a Si₃N₄ micro-ring with the internal core coated with a thin metal film of silver or gold. It is used for nano-entity detection in an aqueous solution environment. The radiation enhancement F-factor is adopted to quantify the performance of the integrated sensor. It was found that the sensitivity of the integrated sensor was enhanced about 2 to 4.8 times compared to a pure Si₃N₄ WGM ring sensor without SPR. The integrated WGM/SPR microsensor may be combined with the reverse transcription-polymerase chain reaction technology to extend the limit of detection. The Q-factor of the proposed Si₃N₄-based integrated sensor is one to two orders of magnitude higher than that of a similar silica-based integrated sensor; thus, the new sensor may effectively detect nano-entities in aqueous solutions and has outstanding advantages in terms of small size, rapid detection with fewer samples, and high accuracy.