Multiple Mechanical Sensing Based on Cascaded S-Tapered Multimode Fiber and Grapefruit Hole Fiber Structure

This article presents a new composite structure for highly sensitive measurement of mechanical properties, consisting of an S-shaped tapered multimode fiber (STM) and a grapefruit core six-air-hole fiber. The structure utilizes the integrated Michelson interference Vernier effect based on the multibeam superposition principle [VMI-STM-grapefruit-core six-hole fiber (SCF)]. The structure’s superior performance in tensile strain sensing is demonstrated through control group experiments, and a coating process utilizing thermal insulation silicone is implemented to increase tensile strain sensitivity and reduce temperature-induced crosstalk. The strain sensitivity can reach up to 12.8 pm/
$\mu \varepsilon $
, exhibiting a high stability level. Additionally, a vector curvature sensing test is conducted, and a novel resolution method is proposed to precisely measure the absolute position of the bending sensor in the plane. The structure’s small size, lightweight, and rapid response make it advantageous for medical devices and intelligent, flexible wearable sensing technologies. The research and practical utilization of such sensors are expected to drive advancements in relevant fields and foster the development of intelligent manufacturing.