Fully Integrated Deep-Ocean Flexible Temperature–Depth Sensor with Neural Network Compensation

Earth’s deep ocean shapes global heat transport, carbon cycling and abyssal circulation, yet large regions remain undersampled. While conventional instruments provide precise single point measurements, their rigidity and weight limit deployment on emerging platforms that could extend observational reach. Here, we introduce the fully integrated, flexible temperature–depth sensor deployable on curved and mobile surfaces for deep-sea measurements. The compact, lightweight, stress-adaptive low-power electronics (average quiescent current: 24.63 µA) unit operates as a co-designed cyber–physical platform, where the porous laser-induced graphene–polydimethylsiloxane composite sensing element achieves a broad measurement range over 0–10 MPa hydrostatic pressure, while temperature–pressure compensation through a dual-hidden-layer neural network combined with polynomial fitting yields a depth error of ≤±0.91% full scale and temperature accuracy of ≤±0.29 °C. Deep-sea trials to 4812.2 m show structural integrity under ~50 MPa hydrostatic pressure, demonstrating durability in extreme environments and enabling sensing on platforms inaccessible to conventional instruments. Marine pressure monitoring helps reveal ocean dynamics and assess human impacts. This work reports a self-contained low-power flexible marine temperature depth (FMTD) sensor featuring wide range, high precision and restrained temperature drift.