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Wearable sensors have garnered considerable attention due to their flexibility and lightweight characteristics in the realm of healthcare applications. However, developing robust wearable sensors with facile fabrication and good conformity remains a challenge. In this study, a conductive graphene nanoplate‐carbon nanotube (GC) ink is synthesized for multi jet fusion (MJF) printing. The layer‐by‐layer fabrication process of MJF not only improves the mechanical and flame‐retardant properties of the printed GC sensor but also bolsters its robustness and sensitivity. The direction of sensor bending significantly impacts the relative resistance changes, allowing for precise investigations of joint motions in the human body, such as those of the fingers, wrists, elbows, necks, and knees. Furthermore, the data of resistance changes collected by the GC sensor are utilized to train a support vector machine with a 95.83% accuracy rate for predicting human motions. Due to its stable humidity sensitivity, the sensor also demonstrates excellent performance in monitoring human breath and predicting breath modes (normal, fast, and deep breath), thereby expanding its potential applications in healthcare. This work opens up new avenues for using MJF‐printed wearable sensors for a variety of healthcare applications. [ABSTRACT FROM AUTHOR]

The dispersibility of fillers determines their effect on the mechanical properties and anisotropy of the 3D‐printed polymeric composites. Nanoscale fillers have the tendency to aggregate, resulting in the deterioration of part performance. An in situ filler addition method using the newly developed dual‐functional toughness agents (TAs) is proposed in this work for the homogeneous dispersion of carbon nanotubes (CNTs) in elastomer composites printed via multi jet fusion. The CNTs added in the TAs serve as an infrared absorbing colorant for selective powder fusion, as well as the strengthening and toughening fillers. The printability of the TA is theoretically deduced based on the measured physical properties, which are subsequently verified experimentally. The printing parameters and agent formulation are optimized to maximize the mechanical performance of the printed parts. The printed elastomer parts show significant improvement in strength and toughness for all printing orientations and alleviation of the mechanical anisotropy originating from the layer‐wise fabrication manner. This in situ filler addition method using tailorable TAs is applicable for fabricating parts with site‐specific mechanical properties and is promising in assisting the scalable manufacturing of 3D‐printed elastomers. [ABSTRACT FROM AUTHOR]

Fabric‐based materials have demonstrated promise for high‐performance wearable applications but are currently restricted by their deficient mechanical properties. Here, this work leverages the design freedom offered by additive manufacturing and a novel interlocking pattern to for the first time fabricate a dual‐faced chain mail structure consisting of 3D re‐entrant unit cells. The flexible structured fabric demonstrates high specific energy absorption and specific strength of up to 1530 J kg−1 and 5900 Nm kg−1, respectively, together with an excellent recovery ratio of ≈80%, thereby overcoming the strength–recoverability trade‐off. The designed dual‐faced structured fabric compares favorably against a wide range of materials proposed for wearable applications, attributed to the synergetic strengthening of the energy‐absorbing re‐entrant unit cells and their unique topological interlocking. This work advocates the combined design of energy‐absorbing unit cells and their interlocking to extend the application prospects of fabric‐based materials to shape‐adaptive protection. [ABSTRACT FROM AUTHOR]