ﻻ يوجد ملخص باللغة العربية
Additive manufacturing strives to combine any combination of materials into three dimensional functional structures and devices, ultimately opening up the possibility of 3D printed machines. It remains difficult to actuate such devices, thus limiting the scope of 3D printed machines to passive devices or necessitating the incorporation of external actuators that are manufactured differently. Here we explore 3D printed hybrid thermoplast/conducter bilayers, that can be actuated by differential heating caused by externally controllable currents flowing through their conducting faces. We uncover the functionality of such actuators and show that they allow to 3D print, in one pass, simple flexible robotic structures that propel forward under step-wise applied voltages. Moreover, exploiting the thermoplasticity of the non-conducting plastic parts at elevated temperatures, we show how strong driving leads to irreversible deformations - a form of 4D printing - which also enlarges the range of linear response of the actuators. Finally, we show how to leverage such thermoplastic relaxations to accumulate plastic deformations and obtain very large deformations by alternatively driving both layers of a bilayer; we call this ratcheting. Our strategy is scalable and widely applicable, and opens up a new approach to reversible actuation and irreversible 4D printing of arbitrary structures and machines.
Optical metasurfaces have been heralded as the platform to integrate multiple functionalities in a compact form-factor, potentially replacing bulky components. A central stepping stone towards realizing this promise is the demonstration of multifunct
Ultrashort photoemitted electron bunches can provide high electron currents within sub-picosecond timeframes, enabling time-resolved investigations of ultrafast physical processes with nanoscale resolution. Non-resonant conductive nanotips are typica
Numerical simulations of assemblies of grains under cyclic loading exhibit ``granular ratcheting: a small net deformation occurs with each cycle, leading to a linear accumulation of deformation with cycle number. We show that this is due to a curious
To enable robust rheological measurements of the properties of yield stress fluids, we introduce a class of modified vane fixtures with fractal-like cross-sectional structures. A greater number of outer contact edges leads to increased kinematic homo
We demonstrate and characterize a source of Li atoms made from direct metal laser sintered titanium. The sources outgassing rate is measured to be $5 ,(2)cdot 10^{-7}$,$rm{Pa}~ rm{L}~ rm{s}^{-1}$ at a temperature $T=330,^circ$C, which optimizes the n