Bioinspired Dual-Scale Crack Manipulation Enabling 325%-Stretchable Metal Film Conductors for AI-Empowered Electronic Skins

The advancement of electronic skins toward commercialization calls for cost-effective and robust flexible conductors, among which metal films are attractive candidates but suffer from poor stretchability. Conventionally, cracks formed in strained metal films are universally considered detrimental and sought to be suppressed. Herein, we demonstrate that cracking is not a drawback, but rather an effective design parameter for on-demand tailoring of film properties. By exploiting the size effect in crack engineering, we propose a bioinspired, dual-scale architecture that endows metal film conductors with up to 325% stretchability. We show that through the synergy of nanoscale pore implantation and microscale substrate roughening, progressively evolved crack patterns can be programmed within metal films by modulating structural parameters. This tunable film cracking behavior yields a nearly 25-fold regulation of stretchability, representing a remarkably wide tunable range among previously deposited metal counterparts. Leveraging these advances, a stretchable metal film-based, AI-empowered electronic skin is constructed, demonstrating excellent practicality across diverse flexible sensing scenarios. Our strategy highlights the pivotal role of the size effect in precise crack manipulation, and the multi-scale regulation paradigm establishes a fresh route to performance improvement of flexible conductors.