Selective coaxial ink 3D printing for single-pass fabrication of smart elastomeric foam with embedded stretchable sensor

Cellular materials are playing a critical role in a vast number of smart applications. Latest advances in additive manufacturing have catalyzed the structural metaproperties of the cellular materials. However, a major challenge remains for straightforward and rapid fabrication of smart cellular foams with embedded sensors while minimizing negative impacts on their mechanical performances. In this work, a selective coaxial ink 3D printing method is disclosed for manufacturing a smart elastomer cellular foam at a single pass, with its capability of precisely assigning a core–shell fiber segment as a strain sensor inside the cellular structure. Mechanical test results on these core–shell fiber segments point out that higher sensitivity can be obtained upon tension rather than compression. Therefore, in consideration of the effects of cellular structure i.e. face centered tetragonal (FCT) and simple cubic (SC), it is revealed that the FCT structure outperforms with a much higher strain sensitivity. By assigning different number of cellular layers and tuning the line spacing inside the cellular structure, the mechanical effects with embedding the sensor in the smart foam are assessed and increasing the line spacing might increase the sensitivity but will degrade the repeatability. In final, the stretching performance of the smart foam is studied, and its application is demonstrated.