Research on pH Sensor Based on Micro-Nano Fiber Modified with Calcium Alginate Hydrogel

We presented a novel pH sensor based on micro-nano fiber (MNF) modified with calcium alginate hydrogel. Two biocompatible polyelectrolytes, sodium alginate (NaAlg) and calcium chloride (CaCl2), were chemically reacted to form a calcium alginate hydrogel with three-dimensional network structure, which was coated on the surface of MNF for pH sensing. When the pH of surrounding solution changes, the sensor has a high sensitivity and linear correlation in the pH range of 2–9 due to the change in the refractive index of the hydrogel. The sensitivity of the single-layer and three-layer hydrogel-coated MNF sensor is -1.57 nm/pH, -2.50 nm/pH, respectively, which makes the sensor very promising for physiological sensing applications.