Highly stretchable, sensitive and healable epidermal electronics enabled by dynamic hard domains and multidimensional conductive fillers for human motion and biopotential sensing

Abstract

Integration of self-healing ability and biomimetic structures into epidermal electronics is of great interest. Herein, mimicking the merits of human skin, dynamic hard domains and multidimensional conductive fillers were introduced into epidermal electronics. Firstly, aromatic disulfide bonds and H-bonds as dynamic hard domains from bis-(4-aminophenyl) disulfide and tetraethylene glycol were incorporated into polyurethane-urea (PU), and provided desired mechanical properties and self-healing capability. To enhance the strength and toughness, ZIF-67 nanoparticles with micro-pores and uncoordinated imidazole groups were introduced into PU matrix, producing excellent filler-matrix interfaces owing to the formation of high-density H-bonds and mechanical insertion. The optimized PU/ZIF-6710% composite exhibited high performance with a tensile strength of 4.15 MPa, an elongation at break of 1342.31 %, a toughness of 40.73 MJ m−3, a fracture energy of 157.75 kJ m−2, and healing efficiency of 93.25 %. Benefiting from the supramolecular PU with dynamic hard domains and multidimensional conductive fillers, the as-prepared multifunctional films exhibited excellent self-healing ability and sensing performance with a wide detection range (609 %), high sensitivity (3416.71), fast response time (65 ms), low detection limit (0.026 %), and excellent robustness (∼1000 cycles at 50 % strain). Different human motions and high-quality electrophysiological signals were successfully detected by the original and healable epidermal electrodes.