Exceptional Resilience of Small-Scale Au₃₀Cu₂₅Zn₄₅ under Cyclic Stress-Induced Phase Transformation

Shape memory alloys that produce and recover from large deformation driven by martensitic transformation are widely exploited in biomedical devices and microactuators. Generally their actuation work degrades significantly within first a few cycles and is reduced at smaller dimensions. Further, alloys exhibiting unprecedented reversibility have relatively small superelastic strain, 0.7%. These raise the questions of whether high reversibility is necessarily accompanied by small work and strain and whether high work and strain is necessarily diminished at small scale. Here we conclusively demonstrate that these are not true by showing that Au₃₀Cu₂₅Zn₄₅ pillars exhibit 12 MJ m^–3 work and 3.5% superelastic strain even after 100 000 phase transformation cycles. Our findings confirm that the lattice compatibility dominates the mechanical behavior of phase-changing materials at nano to micron scales and points a way for smart microactuators design having the mutual benefits of high actuation work and long lifetime

Triboelectric nanogenerators enabled internet of things: A survey

As pioneering information technology, the Internet of Things (IoT) targets at building an infrastructure of embedded devices and networks of connected objects, to offer omnipresent ecosystem and interaction across billions of smart devices, sensors, and actuators. The deployment of IoT calls for decentralized power supplies, self-powered sensors, and wireless transmission technologies, which have brought both opportunities and challenges to the existing solutions, especially when the network scales up. The Triboelectric Nanogenerators (TENGs), recently developed for mechanical energy harvesting and mechanical-to-electrical signal conversion, have the natural properties of energy and information, which have demonstrated high potentials in various applications of IoT. This context provides a comprehensive review of TENG enabled IoT and discusses the most popular and significant divisions. Firstly, the basic principle of TENG is re-examined in this article. Subsequently, a comprehensive and detailed review is given to the concept of IoT, followed by the scientific development of the TENG enabled IoT. Finally, the future of this evolving area is addressed.</p