Aquatic Skin Enabled by Multi‐Modality Iontronic Sensing

Abstract Perception of information is of critical importance for aquatic activities; however, the complex underwater situation faces unique technical challenges to address. Thus, an underwater environment‐incorporated sensing strategy, referred to as aquatic skin, has been introduced with multi‐modality sensing capacities of contact pressure, tactile mapping, depth, temperature, and salinity in a flexible architecture. Remarkably, this has been all achieved by a multi‐modality iontronic sensing principle in an all‐in‐one structural configuration, simplifying the sensor design, material preparation, device fabrication, and signal processing. Particularly, an inverse iontronic sensing mechanism, utilizing complementary elastomeric‐electrode and environmental‐electrode interfaces, is developed for contact pressure detection with exceptional resolution and hydraulic balance. Moreover, a hydrophobic ionic gel with adjustable surface morphologies has been developed as the functional sensing layer for all the units with long‐term stability. Consequently, the aquatic skin can achieve sub‐Pascal resolution of contact pressure detection (0.59 Pa), and sub‐millimeter spatial resolution of tactile mapping (522 pts cm −2 ) over an extended range of depths (0–40 m), while the environmental influences can be spontaneously eliminated through a self‐compensation process. The aquatic skin is applied toward several representative underwater scenes, including real‐time monitoring of vital/environmental signals, tactile recognition of creatures, and biomechanical analysis of fish swimming.