pH sensor based on tilted fiber Bragg grating surface plasmon resonance with a polyaniline reaction deposition film layer.

In this paper, we propose a surface plasmon resonance (SPR) fiber-optic pH sensor combined with a tilted fiber Bragg grating (TFBG) by continuously coating gold and polyaniline (PANI) onto the surface of a TFBG. The micron-scale thickness polyaniline film provides the sensor with good sensitivity, and it achieves accurate measurement of pH values ranging from 2 to 12 by utilizing the pH-responsive mechanism of PANI and the surface plasmon resonance characteristics. Experimental results show that within the 2-12 pH range, the sensitivity of the TFBG surface plasmon resonance pH sensor based on PANI coating is 0.50335 nm/pH, and results demonstrate, a linear correlation coefficient between wavelength and pH value reaching 0.96614. This indicates significant potential for future engineering applications in real-world pH measurement using this sensor.

Realization of an ultra-high pressure dynamic calibrate system by drop hammer based on fiber Bragg grating strain sensor.

In this letter, we propose a novel technique for dynamic ultra-high pressure calibration that measured pressure by FBG based strain sensor. Generally, the traditional method of dynamic ultra-high pressure calibration by standard sensor is costly and it is difficult to improve the accuracy. Therefore, we prefer FBG strain sensor to replace the standard sensor to calibrate the ultra-high pressure. In this proposal, the calibration process is that the central wavelength of the FBG attached to the elastic element changes rapidly with the strain of the elastic element during the drop hammer impact, synchronously. This allows the calibration accuracy to be easily increased to 0.02% and the cost to be reduced by 1/100 compared to traditional calibration techniques. The experiment results show that coefficient of linear correlation between the strain waveform and the pressure signal reaches 0.999. The strain calibration based on FBG is of great significance to the measurement and calibration of dynamic ultra-high pressure sensors.