High-Sensitive Fiber-Optic Gas Pressure Sensor Consisting of Cascaded Polymer–Air Cavities Based on Vernier Effect

A cascaded ultraviolet (UV) adhesive-based fiber-optic Fabry-Perot (FP) sensor utilizing the Vernier effect is proposed and experimentally validated. The sensor consists of two cascaded FP cavities, formed by fusing a section of single-mode fiber (SMF) to the interior of a short capillary glass tube (HST). A polymer cavity is created inside the capillary glass tube by initially introducing UV adhesive, followed by the formation of a series of polymer air cavities by filling the end faces of the capillary glass tube with a UV adhesive film. The sensor, benefiting from the Vernier effect, achieves a sensitivity on the order of −2.53 nm/kPa, exhibiting minimal temperature crosstalk. The pressure sensor demonstrates high sensitivity, cost-effectiveness, low resolution, and excellent repeatability, rendering it a promising candidate for applications in medical and biological sensing.