Innovative optical pH sensors for the aquaculture sector: Comprehensive characterization of a cost-effective solution

Optical fiber sensors show potential for monitoring multiple parameters essential to the growth and health of fish, particularly the pH value of the aquaculture medium. Two types of optical fiber sensors, using tapered silica single mode fibers with a Bragg grating inscribed and D-shaped plastic optical fibers (home-made and reused) were produced. A pH-sensitive layer made of polyaniline (PANI) was deposited on the optical fibers' surface. The sensors demonstrated reproducibility and repeatability with a sensitivity of −0.22 ± 0.02 dB/pH, −472 ± 9 Counts/pH, and −(26 ± 2) × 102 Counts/pH for tapers, D-shape home-made, and reused, respectively, but only for increasing pH. Stabilization time tests indicated that a minimum of 60 s is required for a stable response, with no significant cross-sensitivities regarding temperature and ionic strength.