In this paper, we present a fiber sensor using a fiber Bragg grating encapsulated in a half-polymer-filled metal cylinder for measuring liquid level variation. The operating mechanism of this novel design is based on transferring radial pressure into axial strain to induce Bragg wavelength shift. Product Function: Detection and determination of liquid level positions for various liquids with temperature differences in different environments. Principle of Fiber Bragg Grating Liquid Level Sensor: OFSCN®.