Double formant PCF-SPR sensor with high sensitivity and wide detection range for detecting analytes with low refractive indexes

A double U-shaped PCF-SPR sensor is proposed for the detection of analytes with low refractive indexes (RI). The U-shaped structure facilitates the penetration of analytes. Compared with a single formant sensor, the sensor exhibits double formant characteristics. Therefore, the analytes to be measured can be identified more accurately. This study employs the finite element method (FEM) to analyze the sensor. The findings suggest that the sensor is capable of detecting analytes with low RI ranging from 1.15 to 1.33 over an ultra-wide wavelength range of 800–6400[Formula: see text]nm. The maximum wavelength sensitivities of the first and second peaks of the sensor are 54,300[Formula: see text]nm/RIU and 60,000[Formula: see text]nm/RIU, respectively. In addition, this paper introduces double peak shift sensitivity (DPSS), the highest DPSS value is 55,700[Formula: see text]nm/RIU. Owing to these distinct characteristics, the sensor has great application prospects in the field of biosensing, especially in drug detection.