Nowadays, one of the biggest issues addressed to electronic sensor fabrication is the build-up of efficient electrodes as an alternative way to the expensive, complex and multistage processes required by traditional techniques. Printed electronics arises as an interesting alternative to fulfill this task due to the simplicity and speed to stamp electrodes on various surfaces. Within this context, the Fused Deposition Modeling 3D printing is an emerging, cost-effective and alternative technology to fabricate complex structures that potentiates several fields with more creative ideas and new materials for a rapid prototyping of devices. We show here the fabrication of interdigitated electrodes using a standard home-made CoreXY 3D printer using transparent and graphene-based PLA filaments. Macro 3D printed electrodes were easily assembled within 6 min with outstanding reproducibility. The electrodes were also functionalized with different nanostructured thin films via dip-coating Layer-by-Layer technique to develop a 3D printed e-tongue setup. As a proof of concept, the printed e-tongue was applied to soil analysis. A control soil sample was enriched with several macro-nutrients to the plants (N, P, K, S, Mg, and Ca) and the discrimination was done by electrical impedance spectroscopy of water solution of the soil samples. The data was analyzed by Principal Component Analysis and the 3D printed sensor distinguished clearly all enriched samples despite the complexity of the soil chemical composition. The 3D printed e-tongue successfully used in soil analysis encourages further investments in developing new sensory tools for precision agriculture and other fields exploiting the simplicity and flexibility offered by the 3D printing techniques.

Most materials exhibit positive Poisson's ratio (PR) values, but special structures can also present negative and, even rarer, zero (or close to zero) PR. Null PR structures have received much attention due to their unusual properties and potential applications in different fields, such as aeronautics and bioengineering. Herein, a new and simple near‐zero PR 2D topological model is presented based on a structural block composed of two smooth and rigid bars connected by a soft membrane or spring. It is not based on reentrant or honeycomb‐like configurations, which have been the basis of many null or quasinull PR models. The topological model is 3D printed, and the experimentally obtained PR is −0.003 ± 0.001 which is one of the closest to zero values ever reported. The possibility to extend this model to 3D systems with compression in any direction is discussed. The advantages and disadvantages of these models are also addressed.

Triply Periodic Minimal Surfaces (TPMS) possess locally minimized surface area under the constraint of periodic boundary conditions. Different families of surfaces were obtained with different topologies satisfying such conditions. Examples of such families include Primitive (P), Gyroid (G) and Diamond (D) surfaces. From a purely mathematical subject, TPMS have been recently found in materials science as optimal geometries for structural applications. Proposed by Mackay and Terrones in 1991, schwarzites are 3D crystalline porous carbon nanocrystals exhibiting the shape of TPMS. Although their complex topology poses serious limitations on their synthesis with conventional nanoscale fabrication methods, such as Chemical Vapour Deposition (CVD), TPMS can be fabricated by Additive Manufacturing (AM) techniques, such as 3D Printing. In this work, we used an optimized atomic model of a schwarzite structure from the D family (D8bal) to generate a surface mesh that was subsequently used for . This D schwarzite was 3D-printed with thermoplastic PolyLactic Acid (PLA) polymer filaments. Mechanical properties under uniaxial compression were investigated for both the atomic model and the 3D-printed one. Fully atomistic Molecular Dynamics (MD) simulations were also carried out to investigate the uniaxial compression behavior of the D8bal atomic model. Mechanical testings were performed on the 3D-printed schwarzite where the deformation mechanisms were found to be similar to those observed in MD simulations. These results are suggestive of a scale-independent mechanical behavior that is dominated by structural topology.

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Additive manufacturing allows to produce parts with complex geometries is an essential tool in materials science. Schwarzites is a class of carbon allotropes with interesting mechanical properties. However, most of the schwarzite studies are theoretical until now because the synthesis of large schwarzite fragments remains elusive. In this work, we have carried out molecular dynamics simulations, and extensive experimental tests of 3D printed schwarzites to study their mechanical behavior. Our results show that this behavior does not strongly depend on printed used material, model size, or the number of structural unit cells. We also observed a strong correlation between the stress‐strain curves of 3D printed and the ones obtained from fully atomistic molecular dynamics simulations. Both results show the same trends for almost all investigated schwarzites, suggesting that topological features and scale‐size invariant dominate some deformation mechanisms. Our results further validate the use of atomic models of materials with complex geometries that are impractical or very difficult to synthesize, translated into macro models that can be 3D printed, and offer an innovative engineered approach to produce new materials with tunable mechanical behavior.