Structure-Resistance Relationship of 3D Printed Electrically Conductive Woodpile-Structured Metamaterials

This work proposes metamaterial with a woodpile arrangement constructed of its electrically conductive constituent material. Electromechanical response of woodpile structured metamaterials, when compressed, was experimentally studied. Specifically, when they are compressed in the stacking direction, with struts symmetrically staggered in alternating layers. Additive manufacturing has enabled the fabrication of metamaterials with tunable electromechanical properties. Herein, the structure-resistance relationship was established as a function of microstructural parameters described by the geometry of the repetitive elements of the structure, such as characteristic diameter, length, or thickness. The relationship also can be expressed in the form of relative density. We found that conductive metamaterials with staggered-woodpile architecture could effectively manipulate the electrical properties when compressed due to their local bending motions and contact between members. Such metamaterials could have high sensitivity as well as high stiffness – low sensitivity by controlling the spacing and diameter of struts. The findings from this study suggest that structured woodpile metamaterials are promising as strain sensors when mechanically implied or human-induced forces are present. When loaded at ∼3 % compressive strain, the materials appeared to have a typical transition phase from high to low resistance.