Real case: A robust hydrogel strain sensor lifts up 80 kg of a boy volunteer

Conductive hydrogel represents an important development direction in modern/future electronic industry. However, successfully achieving high performance hydrogels which are capable of performing a real-world task still remain extremely challenging because most conventional approaches of constructing hydrogels are difficult to make hydrogels achieve the integration of multiple performances like robust mechanical properties, excellent conductivity and stable electrochemical performance. Here, we develop a simple and universal two-layer hydrogen bond networks (TLHBNs) strategy by which seven types of PVA based hydrogels with simultaneously robust mechanical properties (stress, strain, toughness, elasticity, fatigue resistance, notch insensitivity, anti-damage), excellent conductivity (7.2− 12.2 S m −1 , 11.7− 19.8 S m −1 , 10.5− 21.6 S m −1 ), reversible/stable network structure and constantly sensitive signal output capability are achieved via sophisticatedly layer-by-layer introducing TLHBNs to PVA hydrogel. Benefiting from the extraordinary performances, one hydrogel is so strong that it can load as heavy as 80 kg of a boy volunteer. Meanwhile, the hydrogels, assembled into flexible sensors, satisfactorily fulfills practical tasks (human joint motions and bionic skin) upon handling real-world application. This strategy, enabling extraordinary performances while using a generic and facile designing concept, opens up a new insight into the design of high-performance PVA hydrogel and beyond.