Micro-nano optical fiber liquid hydrogen ion concentration sensor based on polyaniline film

Abstract

The detection of hydrogen ion concentration in liquids has important applications in life and production. The paper proposes and implements an all-fiber interferometric sensor structure for hydrogen ion concentration in liquid with polyaniline membrane, and experimental studies on its hydrogen ion concentration detection characteristics are carried out. In the range of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> ~10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> mo1/L variation of the hydrogen ion concentration, as the ion concentration increases, the sensor interference wavelength drifts to the short-wave direction, and the sensor sensitivity is -15.74nm/mol/L. The experimental results show that the binding of hydrogen ions to the polyaniline main chain leads to a decrease in the refractive index of the membrane as the hydrogen ion concentration increases, which not only verifies the optical property change of the polyaniline membrane after the reaction to hydrogen ions, but also provides a new method for the detection of liquid hydrogen ion concentration. The fiber optic sensor also offers the advantages of good solid film strength, ease of fabrication and low cost.