Embedding mechanical logic into soft robotics, microelectromechanical systems (MEMS), and robotic materials can greatly improve their functional capacity. However, such logical functions are usually pre-programmed and can hardly be altered during in-life service, limiting their applications under varying working conditions. Here, we propose a reprogrammable mechanological metamaterial (ReMM). Logical computing is achieved by imposing sequential excitations. The system can be initialized and reprogrammed via selectively imposing and releasing the excitations. Realization of universal combinatorial logic and sequential logic (memory) is demonstrated experimentally and numerically. The fabrication scalability of the system is also discussed. We expect the ReMM can serve as a platform for constructing reusable and multifunctional mechanical systems with strong computation and information processing capability.

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Transformations in shape are critical to actuation in engineered metamaterials. Existing engineering metamaterials are typically limited to a small number of shape transformations that must be built-in during material synthesis. Here, inspired by the multistability and programmability of kirigami-based self-folding elements, a robust framework is introduced for the construction of sequentially programmable and reprogrammable mechanical metamaterials. The materials can be locked into multiple stable deployed configurations and then, using tunable bistability enabled by temperature-responsive constituent materials, return to their original reference configurations or undergo mode bifurcation. The framework provides a platform to design metamaterials with multiple deployable and reversible configurations in response to external stimuli.

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Theoretical analysis and calculation show that applying a magnetic field in a microwave plasma thruster operating at 2.45GHz can improve the thruster performance, whereby an electron cyclotron resonant layer at thruster startup state contributes to the increase of microwave energy dissipated in plasma, and a strong magnetic field up to 0.5T can increase the peak temperature of inside plasma when the thruster operates in steady state. Experimental measurements of the thruster with applied field and operating on argon gas show high coupling efficiency. Plasma plume diagnostics deduce a high degree of gas ionization in the thruster cavity. This shows the feasibility of operating a microwave plasma thruster with an applied magnetic field.