Bioinspired electronic tongue with frequency-encoded signal processing for intelligent pH monitoring in wastewater management

The development of intelligent pH monitoring systems is essential for enhancing industrial wastewater management and environmental protection. Herein, we report a bioinspired electronic tongue that incorporates an iridium oxide–graphene oxide hybrid architecture, integrating electrochemical sensing, frequency-encoded signal processing inspired by neuronal spiking dynamics, and automated feedback control. The system exhibits outstanding pH sensitivity (175 Hz/pH within the 3–9 range) via Nernstian potentiometric transduction. The iridium oxide sensor delivers a stable response (−66.48 mV/pH), while the graphene oxide transistor-based artificial neuron enables frequency-encoded spiking output (275–1350 Hz). Key innovations comprise (i) a dual-gate structure for field-amplified signal conversion, (ii) biomimetic excitatory/inhibitory spiking dynamics (Vth shift: 57.14 mV/pH), and (iii) a logic-gated alarm module with programmable thresholds (X = 0.15 V, Y = 0.24 V) for automated control in wastewater treatment. The integrated platform achieves real-time pH monitoring with less than 4% signal drift and millisecond-scale response time, demonstrating enhanced long-term stability compared to a commercial glass-electrode pH meter under identical testing conditions. This work establishes a scalable framework for intelligent chemical sensing that merges solid-state reliability with bioinspired signal processing principles, offering promising potential for industrial and environmental monitoring applications.