Wearable and implantable devices require conductive, stretchable and biocompatible materials. However, obtaining composites that simultaneously fulfil these requirements is challenging due to a trade-off between conductivity and stretchability. Here, we report on Ag–Au nanocomposites composed of ultralong gold-coated silver nanowires in an elastomeric block-copolymer matrix. Owing to the high aspect ratio and percolation network of the Ag–Au nanowires, the nanocomposites exhibit an optimized conductivity of 41,850 S cm⁻¹ (maximum of 72,600 S cm⁻¹). Phase separation in the Ag–Au nanocomposite during the solvent-drying process generates a microstructure that yields an optimized stretchability of 266% (maximum of 840%). The thick gold sheath deposited on the silver nanowire surface prevents oxidation and silver ion leaching, making the composite biocompatible and highly conductive. Using the nanocomposite, we successfully fabricate wearable and implantable soft bioelectronic devices that can be conformally integrated with human skin and swine heart for continuous electrophysiological recording, and electrical and thermal stimulation.

可穿戴和可植入设备需要导电，可拉伸和生物相容的材料。然而，由于在导电性和可拉伸性之间进行折衷，因此获得同时满足这些要求的复合材料具有挑战性。在这里，我们报道了在弹性体嵌段共聚物基质中由超长金涂层银纳米线组成的Ag-Au纳米复合材料。由于Ag-Au纳米线的高纵横比和渗滤网络，纳米复合材料的最佳电导率为41,850 S cm ^-1（最大为72,600 S cm ^-1）。在溶剂干燥过程中，Ag-Au纳米复合材料的相分离产生了一种微观结构，该微观结构产生了266％的最佳拉伸性（最大840％）。沉积在银纳米线表面的厚金护套可防止氧化和银离子浸出，从而使复合材料具有生物相容性和高导电性。使用纳米复合材料，我们成功地制造了可穿戴和可植入的软生物电子设备，这些设备可以与人体皮肤和猪心脏保形地集成在一起，以进行连续的电生理记录以及电刺激和热刺激。