The development of robust and flexible pH sensors is critical for accurate in-situ monitoring of marine environments, particularly for applications such as ocean acidification research and underwater vehicle-based sensing. In this study, we present a highly stable and flexible pH sensor based on iridium oxide (IrOx) electrodes with potential for reliable operation in complex marine settings, based on its performance in laboratory-simulated conditions and long-term stability in real seawater. The sensor exhibits a near-Nernstian response with an average sensitivity of −65.07 mV/pH in aqueous solutions (pH 3–10), demonstrating excellent stability after 4000 bending cycles with minimal hysteresis. A rapid response time of 9.29 s and negligible potential drift (±5 mV over 5 min) highlight its precision and repeatability. While cation interference, particularly from Mg²⁺, induces slight potential shifts (4–5 mV), the sensor maintains its Nernstian behavior across all tested interferents including Na⁺, K⁺, Ca²⁺, and Mg²⁺. High-resolution measurements within the marine-relevant pH range (7.9–8.4) confirm excellent sensor performance with sensitivities exceeding −64.5 mV/pH. This targeted validation, combined with the sensor’s exceptional mechanical flexibility, underscores its suitability for real-time pH monitoring in dynamic marine systems. These findings demonstrate the sensor’s potential for advancing marine chemistry research and environmental monitoring applications.
Sun Y., Chen B., He P., Xu Z., Dong Y., Liu S., 2026. Mechanically flexible pH sensor demonstrating high sensitivity in seawater and long-term operational stability for ocean environmental applications. Colloids and Surfaces A: Physicochemical and Engineering Aspects 749(Part 2): 141238. doi: 10.1016/j.colsurfa.2026.141238. Article (subscription required).
