A novel nonplanar multi-chamber flexible array dissolved oxygen sensor for aquaculture robotic fish

Dissolved oxygen is crucial in aquaculture, as it directly affects the health and survival of aquatic organisms. With increasing demand for detailed environmental data to enable three-dimensional monitoring, the use of lightweight, compact sensors in underwater mobile devices has become essential. In this study, a flexible dissolved oxygen sensor was developed, and the sensor features a compact, two-electrode array, encapsulated in PDMS to provide flexibility and secure attachment. A multi-electrolytic cell array structure amplifies the current signal from the sensing electrodes. Efficient encapsulation of the electrodes and electrolyte prevents displacement by water flow, ensuring stable and reliable detection performance. The results demonstrate the sensor's stability, with a detection error of less than 0.2 compared to commercial sensors. The mean absolute error across four different aqueous environments was 0.083. Moreover, the sensor maintained excellent performance over a 14-day testing period. We also successfully integrated the sensor into a bionic robotic fish, enabling threedimensional detection of dissolved oxygen in the environment. This research advances the development of compact, high-performance underwater sensors, particularly for applications in aquaculture.