Additive Manufactured Programmable Scaffold Sensor Based on Triply Periodic Minimal Surfaces for Broad-Spectrum Pressure Detection

Achieving both high sensitivity and a wide detection range in flexible pressure sensors poses a challenge due to their inherent trade-off. Although porous structures offer promising solutions, conventional methods (templating, foaming, and freeze-drying) fail to precisely control cavity dimensions, spatial arrangement, and 3D morphology, which are crucial for sensing performance. Here, we propose a scalable fabrication strategy that integrates triply periodic minimal surface (TPMS) geometries─precisely engineered via FDM 3D printing─with ultrasonic impregnation of carbon black (CB) into TPU scaffolds. The TPMS framework, featuring an optimized curvature and uniform pore distribution, ensures exceptional durability (2.2 MPa at 70% strain) and stress homogenization, outperforming traditional honeycomb and lattice structures. Ultrasonication-driven zero-dimensional nanofiller embedding creates interpenetrating conductive networks, enabling ultrawide pressure detection (0.1-2.2 MPa) with tunable, stage-dependent sensitivities (gauge factors of 8.41, -0.43, and 1.71). Finite element simulations elucidate the mechanisms underlying stress mitigation and stage-dependent gauge factors, while experimental validation highlights a rapid response (100 ms), exceptional durability (1000 cycles), and precise real-time monitoring of plantar pressure, gestures, and gait anomalies. This work overcomes the sensitivity-range trade-off and provides a scalable and versatile platform for next-generation flexible sensors, with applications in personalized health diagnostics, smart rehabilitation, and advanced human-machine interfaces.