Photocurable 3D printing gels with dual networks for high-sensitivity wearable sensors

Conductive hydrogels have attracted significant wide attention in flexible electronics as wearable devices. However, most conductive hydrogels are currently fabricated by casting. Here, a photocurable 3D printing composite mainly composed of acrylamide and acrylic acid is designed to realize the rapid construction of hydrogel wearable sensing devices with complex structures. Meanwhile, the introduction of iron ions makes it form a coordination bond with the carboxyl group of poly (acrylamide-co-acrylic acid) (P(AAm-co-AAc)). The physical entanglement provided by the Fe3+ coordination bond works synergistically with the covalent bond, enabling the hydrogel with excellent mechanical properties to achieve an elongation at a break of 802%. The as-printed hydrogel added with lithium chloride has exceptional resistance signal detection ability, which can accurately and stably detect human motion. In addition, the anti-water loss and anti-freezing properties provided by glycerol make the hydrogel to be suitable for more severe environments. In summary, this work introduced a strategy for rapidly preparing flexible hydrogel sensors by photocurable 3D printing, which provides a new realization approach for the personalized customization of flexible wearable devices.