Origami Tribo-Metamaterials with Mechanoelectrical Multistability.

The emerging mechanical functional metamaterials reported with promising mechanoelectrical characteristics bring increasing attention to structurally functional materials. It is essential to deploy mechanical metamaterials in energy materials for effective triggering and controllable mechanoelectrical response. This study reports origami tribo-metamaterials (OTMs) that design triboelectric materials in the origami-enabled, tubular metamaterials. The octagonal, hexagonal, and conical origami units are deployed as the metamaterial substrates to trigger the triboelectric pairs for mechanoelectrical multistability. For the octagonal OTM configuration with the triboelectric pair of fluorinated ethylene propylene-paper, the peak open-circuit voltage, short-circuit current, and transferred charge are obtained as 206.4 V, 4.66 μA, and 0.38 μC, respectively, and the maximum instantaneous output power density is 0.96 μW/cm with the load resistance of 20 MΩ. The OTM takes advantage of the origami metamaterials to obtain the multistable force-displacement response as effective stimuli for the triboelectric materials, which leads to tunable mechanoelectrical performance for speed and weight sensing and energy harvesting. The proposed OTM not only offers a strategy to structurally design energy materials to achieve desirable mechanoelectrical response, but also provides a guideline for the applications of mechanical functional metamaterials in practice.