A soft electronic skin simulating the multi-scale human touch for the detection of fruit freshness

Abstract

Realizing biomimicry for human tactile perception is a meaningful challenge. In this work, a soft matter system with multi-scale energy dissipation structure is designed to realize flexible sensing and detection by biomimetic human touch. At the molecular scale, the supramolecular interactions are introduced into the hydrogel system, including the hydrophobic interaction and the ion attraction between macromolecular segments. At the micron scale, a system of “button” permeable macromolecules is constructed to absorb external forces and store energy through the sliding of macromolecules inside the “button”. By adjusting the molecular scale and micron scale structure, the obtained hydrogels demonstrate excellent mechanical properties, electrical conductivity and response sensitivity. This novel hydrogel withstands 200 compression cycles without creep deformation and outputs a stable response signal in terms of compression cycles with the signal volatility of around 1 %. Based on its good durability, this hydrogel, which simulates human multi-scale tactility, has outstanding application potential in detecting fruit damage that is difficult to observe. Notably, the construction of this multi-scale energy dissipation structure is universal for increasing the mechanical property of ACG hydrogels. The high-strength hydrogels adjusted by this strategy is significantly toughened, and the mechanical properties increased by 38 %. This work is of guiding significance for the preparation of high-performance hydrogels.