Complex 3D functional architectures are of widespread interest due to their potential applications in biomedical devices, [1][2][3][4][5] metamaterials, [6][7][8][9][10] energy storage and conversion platforms, [11][12][13][14][15][16] and electronics systems. [17][18][19][20][21][22][23] Although existing fabrication techniques such as 3D printing, [4,14,[24][25][26][27][28][29][30][31][32] templated growth, [33][34][35][36] and controlled folding [2,[37][38][39][40][41][42][43] can serve as powerful routes to diverse classes of 3D structures that address requirements in a number of interesting technologies, each has some set of limitations in materials compatibility, accessible feature sizes, and compatibility with well-developed 2D processing techniques used in the semiconductor and photonics industries. [44][45][46] Despite significant efforts in research and development, there remains a need for methods that provide access to complex 3D mesostructures that incorporate high-performance materials.Capabilities for controlled formation of sophisticated 3D micro/nanostructures in advanced materials have foundational implications across a broad range of fields. Recently developed methods use stress release in prestrained elastomeric substrates as a driving force for assembling 3D structures and functional microdevices from 2D precursors. A limitation of this approach is that releasing these structures from their substrate returns them to their original 2D layouts due to the elastic recovery of the constituent materials. Here, a concept in which shape memory polymers serve as a means to achieve freestanding 3D architectures from the same basic approach is introduced, with demonstrated ability to realize lateral dimensions, characteristic feature sizes, and thicknesses as small as ≈500, 10, and 5 µm simultaneously, and the potential to scale to much larger or smaller dimensions. Wireless electronic devices illustrate the capacity to integrate other materials and functional components into these 3D frameworks. Quantitative mechanics modeling and experimental measurements illustrate not only shape fixation but also capabilities that allow for structure recovery and shape programmability, as a form of 4D structural control. These ideas provide opportunities in fields ranging from micro-electromechanical systems and microrobotics, to smart intravascular stents, tissue scaffolds, and many others. www.advmat.de www.advancedsciencenews.com A collection of recent publications reports schemes that exploit compressive buckling as a means for assembly of complex 3D functional devices in a diversity of configurations and with a broad range of material compositions, including critical dimensions that span nanometer to centimeter length scales. [47][48][49][50][51] Here, relaxation of a prestrained elastomer substrate, as an assembly platform, imposes stresses on a 2D precursor structure to transform its geometry into a desired 3D shape. With a few exceptions, [52,53] deformations of the micro/ nanomaterials in the precursor rema...

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Robots with submillimeter dimensions are of interest for applications that range from tools for minimally invasive surgical procedures in clinical medicine to vehicles for manipulating cells/tissues in biology research. The limited classes of structures and materials that can be used in such robots, however, create challenges in achieving desired performance parameters and modes of operation. Here, we introduce approaches in manufacturing and actuation that address these constraints to enable untethered, terrestrial robots with complex, three-dimensional (3D) geometries and heterogeneous material construction. The manufacturing procedure exploits controlled mechanical buckling to create 3D multimaterial structures in layouts that range from arrays of filaments and origami constructs to biomimetic configurations and others. A balance of forces associated with a one-way shape memory alloy and the elastic resilience of an encapsulating shell provides the basis for reversible deformations of these structures. Modes of locomotion and manipulation span from bending, twisting, and expansion upon global heating to linear/curvilinear crawling, walking, turning, and jumping upon laser-induced local thermal actuation. Photonic structures such as retroreflectors and colorimetric sensing materials support simple forms of wireless monitoring and localization. These collective advances in materials, manufacturing, actuation, and sensing add to a growing body of capabilities in this emerging field of technology.

Separator modification has recently blossomed as an effective strategy to enable dendrite‐free Zn metal anodes. Nonetheless, the explored avenues are not conducive to mass production by far, and little attention is paid to the essence of separator regulation. Herein, a scalable Ti3C2Tx MXene‐decorated Janus separator is designed by spray‐printing MXene nanosheets over one side of commercial glass fibre (GF). The thus‐derived MXene‐GF separator affords abundant surface polar groups, good electrolyte wettability, and high ionic conductivity, which is beneficial to homogenizing local current distribution and promoting Zn nucleation kinetics. It is noted that MXene‐GF displays adjustable dielectric constants with an optimized value of 53.5, offering a directional electrical field to expedite Zn‐ion flux and repel anions. Accordingly, dendrite‐free Zn anode equipped within symmetric cells can be achieved with MXene‐GF, enabling a stable cycling for 1180 h at 1 mA cm−2 and 1200 h at 5 mA cm−2. More impressively, the assembled aqueous Zn‐ion battery full cell with Janus MXene‐GF separator realizes a favorable capacity retention ratio (77.9%) upon cycling for 1000 cycles at 5.0 A g−1. This strategy with scalability and effectiveness offers a new insight into high‐performance metal anodes.

The burgeoning Li‐ion battery is regarded as a powerful energy storage system by virtue of its high energy density. However, inescapable issues concerning safety and cost aspects retard its prospect in certain application scenarios. Accordingly, strenuous efforts have been devoted to the development of the emerging aqueous Zn‐ion battery (AZIB) as an alternative to inflammable organic batteries. In particular, the instability from the anode side severely impedes the commercialization of AZIB. Constructing an artificial interphase layer (AIL) has been widely employed as an effective strategy to stabilize the Zn anode. This review specializes in the state‐of‐the‐art of AIL design for Zn anode protection, encompassing the preparation methods, mechanism investigations, and device performances based on the classification of functional materials. To begin with, the origins of Zn instability are interpreted from the perspective of electrical field, mass transfer, and nucleation process, followed by a comprehensive summary with respect to functions of AIL and its designing criteria. In the end, current challenges and future outlooks based upon theoretical and experimental considerations are included.