Synergistic Meta‐Perforated Substrates for Hypersensitive Crack‐Based Strain Sensors

Crack‐based strain sensors offer ultrahigh sensitivity, yet their response at infinitesimal strains remains limited. Previous efforts to enhance sensitivity and piezoresistive behavior rely on controlling crack morphology or inducing stress concentration around predefined structural features. Here, we introduce a meta‐perforated substrate that integrates both mechanisms. Engineered perforations concentrate axial strain ( ε xx ), while a re‐entrant auxetic meta‐structure enhances lateral deformation ( ε yy ), producing a synergistically reduced local Poisson's ratio ( ν ) that promotes rapid crack opening at small strains. Systematic finite element analysis (FEA) and digital image correlation (DIC) quantify how perforation size, shape, and arrangement modulate ε xx and ν through changes in effective modulus and anisotropic stress transfer. A regression‐based predictive model constructed from the FEA dataset identifies an optimal geometry ( P r = 25%, Cir = 0.79, tan θ = 0.5). The resulting meta‐perforated sensor achieves a 760‐fold increase in sensitivity and a gauge factor of 1,290 at 0.1% strain, with negligible hysteresis and durable performance over 15 000 cycles. This integrated mechanical‐design strategy establishes a general framework for programmable strain‐field engineering to enable hypersensitive, low‐strain detection in compliant sensing systems.