Plug-in label-free optical fiber DNA hybridization sensor based on C-type fiber Vernier effect

A reflective Fabry-Perot interference (FPI) label-free biosensor based on Vernier effect is designed and implemented for in situ real-time DNA hybridization detection. The sensor is made by splicing single-mode fiber (SMF), a segment of C-type fiber and SMF. The Vernier effect occurs between the solid cavity FPI and the air cavity FPI. In our experiment, a high sensitivity of 10791.12 nm/RIU is obtained in the refractive index (RI) range of 1.3311–1.3450. On this basis, we immobilized probe DNA (pDNA) on the surface of SMF to detect the complementary DNA (cDNA), demonstrating use for label-free sensing of DNA hybridization. The experimental results show that the sensor can detect 1 µM cDNA with high specificity. The paper demonstrates the first research of optical fiber DNA biosensor based on the open microcavity FPI Vernier effect. In addition, the sensor has the advantages of high sensitivity, strong stability, simple structure and simple fabrication. It can also be applied to other biomolecule detection based on probe-target biological binding events, which has great application potential in medical diagnostics, food science, genetic engineering and other biological fields.