Signal-Enhanced Fiber-Optic LSPR Sensor With Hybrid Nanointerface for Ultrasensitive Detection of Putrescine in Low Concentrations

The development of signal enhancement techniques in fiber optic sensors has facilitated accurate measurements of low concentration samples. In this paper, a fiber optic sensor based on local surface plasmon resonance (LSPR), which combines offset splicing and S-taper techniques with low-dimensional materials, is proposed for putrescine (PUT) detection. The multimode fiber-single-mode fiber-multimode fiber sliding structure is fabricated by lateral offset technique. In addition, S-taper is fabricated on the misaligned MMF, which can produce more light energy leakage. Gold nanoparticles, cerium oxide nanorods, and multi-wall carbon nanotubes are attached to the fiber probe to improve the sensitivity of the fiber optic sensor and achieve fast sample detection. PUT is detected by specific recognition of the diamine oxidase. Based on the above two methods, the optical fiber probe is applied to the detection of PUT. The sensitivity of 795.33 pm/μM and the detection limit of 0.8223 μM are achieved over the detection range of 0-100 μM. The experimental results show that the signal-enhanced fiber optic sensor has great potential for fast, accurate, and label-free PUT.