Photonic crystal fiber (PCF) is the crucial component of optical fiber. Today, PCF has sparked widespread interest because of its potential in sensor systems, photonic devices, and communication. However, the features of technologies are updating day by day, and to keep up with the latest features, optical fiber sensors are a key issue for the Internet of Things (IoT) technologies. The primary goal of the offered project is to design an optical sensor for IoT-compatible devices with maximum sensitivity and minimum loss. Therefore, this project presents a unique circular-shape PCF sensor based on surface plasmon resonance (SPR) for evaluating analyte refractive index (RI). With the utilization of the finite element approach, sensing capabilities of the proposed structure have been examined via numerical simulations incorporating an iterative optimization. However, in this configuration, several capillaries are collected and conducted to yield a circular-shape silica structure, then coating the flattened layer with a gold (Au) material. The gold material obtains the SPR pulse in the PCF’s broadcast spectrum. In this structure, the operating wavelength range of 0.94 − 0.62 µm yields efficient results. All the parameters are numerically simulated for the analyte, with RI = 1.34–1.37. After the simulation and formal analysis, the offered sensor gives the highest wavelength sensitivity response of 18403.59 nm/RIU and a minimum loss peak of 193.87 dB/cm. We believe the structural design can also be an appropriate candidate for biological and organic detection, as well as other IoT-based applications.