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Purpose While additive manufacturing via melt-extrusion of plastics has been around for more than several decades, its application to complex geometries has been hampered by the discretization of parts into planar layers. This requires wasted support material and introduces anisotropic weaknesses due to poor layer-to-layer adhesion. Curved-layer manufacturing has been gaining attention recently, with increasing potential to fabricate complex, low-weight structures, such as mechanical metamaterials. This paper aims to study the fabrication and mechanical characterization of non-planar lattice structures under cyclic loading. Design/methodology/approach A mathematical approach to parametrize lattices onto Bèzier surfaces is validated and applied here to fabricate non-planar lattice samples via curved-layer fused deposition modeling. The lattice chirality, amplitude and unit cell size were varied, and the properties of the samples under cyclic-loading were studied experimentally. Findings Overall, lattices with higher auxeticity showed less energy dissipation, attributed to their bending-deformation mechanism. Additionally, bistability was eliminated with increasing auxeticity, reinforcing the conclusion of bending-dominated behavior. The analysis presented here demonstrates that mechanical metamaterial lattices such as auxetics can be explored experimentally for complex geometries where traditional methods of comparing simple geometry to end-use designs are not applicable. Research limitations/implications The mechanics of non-planar lattice structures fabricated using curved-layer additive manufacturing have not been studied thoroughly. Furthermore, traditional approaches do not apply due to parameterization deformations, requiring novel approaches to their study. Here the properties of such structures under cyclic-loading are studied experimentally for the first time. Applications for this type of structures can be found in areas like biomedical scaffolds and stents, sandwich-panel packaging, aerospace structures and architecture of lattice domes. Originality/value This work presents an experimental approach to study the mechanical properties of non-planar lattice structures via quasi-static cyclic loading, comparing variations across several lattice patterns including auxetic sinusoids, disrupted sinusoids and their equivalent-density quadratic patterns.

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The fields of soft robotics and soft electronics have introduced novel technologies for tracking dynamic pose of the human body. These new flexible sensors use material softness and elasticity to allow for high conformability, low risk of injury or discomfort, and ease of integration into other flexible materials such as clothing. Here, we present a glove embedded with soft capacitive strain sensors for measuring finger bending and fingertip pressure, while leveraging low-cost components. Previous capacitive sensing approaches have shown limitations in dimensional scalability of the sensor geometry and system-level scalability of sensors, wiring, and networking methods. We overcome these previous limitations by using sensors with novel geometry and leverage I2C communication protocol to reduce the quantity of interfacing wires to four, even for sensor counts on the order of 103. We show that the sensory glove is able to capture the salient features of hand proprioception by sensing the presence and continuous intensity of touch and finger curvature. Finally, we demonstrate the application of this glove towards the recognition of the letters comprising the American Manual Alphabet, which is used to augment the American Sign Language, and utilize the glove to perform a teleoperation task.