Fiber optic pressure sensors have been widely used in recent decades. Most of the fiber optic pressure sensors use fiber gratings and Fabry-Perot cavity. However, they have the drawbacks of in achieving distributed sensing. In this paper, a lossless fiber pressure sensor based on a structure composed of two ratios of the polydimethylsiloxane (PDMS) and single-mode fiber is proposed. The PDMS has often been used as a flexible structural material. When the pressure is acting radially on the PDMS, the internal fiber is driven to produce an axial strain of a larger range, and the optical frequency domain reflectometer (OFDR) is used to demodulate the fiber strain. The experimental results prove that the designed sensor has a repeatable response with a sensitivity of 17.519 με/N within the range of 20 N (2548 kPa). The minimum pressure resolution and spatial resolution of the sensor can reach values of 0.5 N and 0.5 cm, respectively. Compared to a single ratio PDMS sensor, which has a non-linear response to the pressure, the range is increased by about 1.4 times. Based on the obtained results, the proposed sensor has application prospects in pressure sensors.

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