3D-printed customizable TPU/ANF/CNT interpenetrating-network composites with synergistic energy absorption and real-time pressure sensing for smart protective applications

The development of lightweight, customizable materials with high energy absorption capacity is increasingly critical across engineering domains, driven by growing demands for impact protection in dynamic environments. In this study, we present lightweight interpenetrating-network composites comprising aramid nanofiber (ANF)/carbon nanotube (CNT) aerogel-filled thermoplastic polyurethane (TPU) gyroid-structured foams, fabricated via 3D printing and infiltration. The 3D-printed customizable TPU foam, featuring both macroscale porosity and microscale cellular architecture, offers excellent wearer comfort, elasticity (95.7% deformation recovery after 3000 compression cycles), and energy absorption. Concurrently, the ANF/CNT aerogel significantly enhances energy dissipation performance while enabling real-time pressure sensing across a wide range (0–0.9 MPa) with high sensitivity (gauge factor = 4.77). This integrated design achieves a synergistic balance between protection and sensing functionality. Moreover, by tuning the mechanical properties through different TPU materials and aerogel filling densities, the system allows for customization to meet specific application requirements. Prototype demonstration and validation in protective equipment applications, including impact-adaptive sports pads and smart helmets, demonstrated real-time pressure mapping capabilities. This multifunctional composite, combining scalable fabrication, exceptional impact mitigation, energy dissipation, and embedded sensing intelligence, presents a new paradigm for next-generation smart protective materials.