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.