High Sensitivity Flow Velocity Sensor Based on All-Fiber Target-Type Structure

An all-fiber target-type flow velocity sensor was proposed and experimentally demonstrated based on the Michelson interferometer (MI). Commercially available single mode fiber (SMF) was used as the basic material and assisted with the arc discharge technology the sensing structure can be fabricated with high efficiency and quality. The designed sensor structure contains a peanut-shape structure that acts as a coupler/splitter, a SMF that acts as a cantilever beam, and a spherical tip that acts as a target, which all can be realized by arc discharge technology. The simulation verifies the effectiveness and high sensitivity of the peanut-shape structure for flow velocity measurement, and the key parameters were optimized. A comprehensive experiment was carried out on the flow velocity experiment. The experimental results show that the sensor has high sensitivity of -1.30 nm/(cm/s), precision of 1.4% and detection limit (DL) of 0.015 cm/s in the range of 0-11 cm/s. In addition, the temperature sensitivity is 58.5 pm/°C and the flow velocity-temperature cross-sensitivity is less than 0.05 (cm/s)/°C. Such a high-sensitivity, low cross-sensitivity and low-cost sensor, is very promising for the applications on high-precision liquid and abysmal sea flow velocity measurement.