Electric-field mask electrospinning enabled elastomer mats with a biomimic pore micro-structure for permeable and...

Comfortable ultrathin film electronics capable of continuous and long-term monitoring of physiological signals are in great demand for intelligent healthcare and body motion tracking. Conventional film sensors suffer from a trade-off between thickness and mechanical properties. Thus, it remains challenging to achieve a combination of superior breathability, ultralow thickness, excellent mechanical robustness, and reproducible electromechanical response in free-standing ultrathin film strain sensors. Herein, an electric-field mask electrospinning strategy is proposed to fabricate 6-8 micron-thick thermoplastic polyurethane fiber mat sensors with hierarchical pores and programmable surface topography inspired by the Cyperus rotundus leaf epidermis. These mats with hierarchical pores exhibit robust mechanical properties and a water vapor transmission rate (WVTR) of 2103 ± 98 g m^-2 day^-1. Besides, ultrathin and permeable film strain sensors were fabricated utilizing polydopamine as an interfacial layer to tightly link TPU nanofibers and silver nanoparticles. The hierarchical pores in TPU mats evacuate local stress distribution to guide microcrack propagation at pore edges while retaining conductive pathways in the skeletons, thereby ensuring tunable sensitivity over a broad strain range. Such film strain sensors enable precise recognition of muscle movements, high-fidelity and sweat-resistant electrocardiogram monitoring, offering a reliable and scalable strategy for developing ultrathin, permeable, and mechanically robust film electronic skins.