Bioinspired structural coupling of superhydrophobicity and sensing for ternary interactions

Developing amphibious human–machine interfaces (HMIs) with high information density is pivotal for the next generation of soft robotics and Internet of Things. However, current resistive sensors face a fundamental tradeoff wherein the extrinsic encapsulation required for waterproofing inevitably restricts the microstructures essential for high-sensitivity contact sensing, thereby suppressing the directional discriminability required for advanced logic. Herein, we report a monolithic superhydrophobic sensor that resolves this conflict through a facile mechanical microengraving and solvent-assisted swelling strategy. This system is inspired by the structural monism of the semiaquatic fishing spider. Distinct from conventional coating methods that introduce parasitic insulating layers, our approach embeds conductive carbon black nanoparticles directly into the polymer matrix. This creates an “interface-free” architecture that sustains a robust air plastron for intrinsic superhydrophobicity (contact angle of >153°) while preserving direct electromechanical contact. Consequently, the sensor exhibits exceptional environmental immunity against corrosive fluids (acid, alkali, and saline solutions) and achieves high-fidelity bidirectional mechanotransduction, capable of decoupling the bidirectional bending with a rapid response (rise and recovery times of 240 and 200 ms, respectively). Leveraging these unique properties, we demonstrate a ternary-logic interaction system that exponentially expands the command capacity of wearable HMI devices. Moreover, a “water ghost” robotic skin that can acquire actionable spatial information through directional collision perception in underwater environments is demonstrated. This work establishes a generic design paradigm for engineering environment-adaptive, intelligent skins that function reliably across the terrestrial-aquatic boundary.