High Performance Plasmonic Nano-Biosensor Based on Tunable Ultra-Narrowband Perfect Absorber Utilizing Liquid Crystal

In this paper, a refractive index plasmonic nano-sensor based on a tunable perfect absorber has been proposed in the near-infrared region. The proposed sensor consists of a truncated cone resonator with more than 99% absorption and ultra-narrow bandwidth. Liquid crystal has been used in the designed nano-structure to tune the structure by variation of the incident angle and applying the external bias field to obtain the near perfect and ultra-narrow absorption peak. The proposed nano-sensor has a high sensitivity of 1363.63 nm/RIU and a high figure of merit of 1136.36 RIU−1 at the telecommunication wavelength of 1550 nm. Furthermore, after obtaining appropriate conditions for the liquid crystal layer, we have suggested a new resonator to boost the interaction of surface plasmons and the test medium. Therefore, the sensitivity and figure of merit are increased to the values of 1509 nm/RIU and 1257.5 RIU−1, respectively. This excellent performance of the sensor has huge potential for precision applications such as biomedical science and biosensor. Hence, the capability of the proposed nano-sensor in the field of histopathology for cancerous tissue diagnosis and detection of toxic and flammable gases to prevent endangering human health has been studied. In this case, the high sensitivity of 1368.06 nm/RIU and high figure of merit of 1179.36 RIU−1 have been obtained.