Dalian Institute of Technology developed a high sensitivity temperature coefficient adjustable fiber optic strain sensor

Recently, Professor Huang Hui from Dalian University of Technology developed a kind of "high sensitivity optical fiber strain sensor with adjustable temperature coefficient". Compared with the existing mainstream fiber grating strain sensor, the sensitivity is improved by more than 100 times, especially the thermal expansion of various measured objects can be compensated, and the measurement error caused by the change of ambient temperature can be eliminated. The result was published in the journal Science Bulletin titled "A High Sensitivity Optical Fiber Strain Sensor with Adjustable Temperature Coefficient - for Temperature Compensation Testing."

The sensor is considered to be another major industry after the integrated circuit chip. Compared with electrical sensors, optical fiber sensors for flammable, as well as electromagnetic interference and other harsh environments. However, due to the thermal expansion and contraction nature of materials, fiber optic sensors are sensitive to temperature (such as fiber gratings can also be used to detect temperature changes), temperature interference; the same time, the measured object's own thermal expansion will bring measurement error, and for different Material measured objects (such as concrete, steel, aluminum, etc.), the thermal expansion coefficient varies greatly, which makes the temperature interference more complex. Therefore, it is a long-term problem for the industry to solve the problem of how to eliminate the influence of environmental temperature changes when external force and temperature change together (both of them can generate strain) and thus to accurately measure the strain and stress caused by external forces.

Huang Hui team invented the optical fiber strain sensor, the strain film, fiber collimator, and the transmission rod. Among them, the transmission lever adopts a knob structure composed of two kinds of nuts and screws with different thermal expansion coefficients, so that the thermal expansion coefficient of the transmission rod can be accurately adjusted in a wide range, thereby counteracting the thermal expansion effect of various measured objects. In addition, by using a fiber collimator to receive the light reflected by the strain film, the detection sensitivity is greatly improved. The developed optical fiber sensor has a detection range of 1.1 × 103 με, a detection limit of 5.7 × 10 3 με, a maximum operating frequency of 1.18 KHz and a temperature coefficient adjustment range of 0.15 to +0.19 dB / ° C.