An all-solid-state electrochemical system incorporating a potentiometric sensor and hydrogel electrolyte for...

Fish freshness is a critical factor in food safety. Electrochemical sensors offer advantages in portability, sensitivity, and accuracy for on-site analysis. This study develops an all-solid-state electrochemical system that integrates a potentiometric pH sensor with a hydrogel electrolyte for rapid fish freshness evaluation. The pH sensor employs phytic acid-doped polyaniline as sensing material, which exhibits a super-Nernstian response of -75.28 mV/pH and reaches equilibrium within 10 s. The solid electrolyte is a glycerol-containing hydrogel with anti-freezing and water-retention capabilities, enabling reliable operation from -18 °C to 25 °C. The sensor for fish freshness evaluation works by detecting the pH increase in the hydrogel electrolyte, caused by the diffusion and dissociation of total volatile basic nitrogen (TVB-N), an indicator of fish spoilage. The system completes a freshness test within 5 min and shows good correlation with the standard TVB-N method, providing a portable and rapid approach for on-site fish quality monitoring.