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Programmed 4D printing shape‐memory polymers (SMPs) have been endorsed as an emerging paradigm for developing adaptive dynamic components with sophisticated architectures and biomimetic adaptation capacities. However, the species of SMPs systems are still rare while most of them are produced from expensive monomers which have restricted their mass production. Moreover, most SMPs show poor elongation at break and strain which cannot support a higher degree of bending during shape memory deformation. Herein, a kind of new epoxy vinyl ester resin ink is developed and improves the 4D printing process of shape memory epoxy‐based polymer. By adjusting the printing conditions to match the ink property, a series of precisely designed printing structures are successfully produced. The printed SMP system shows a favorable strain rate under heat‐treated conditions above its glass transition temperature (Tg) which leads to fine shape memory performance. Furthermore, the printed components obtained through micro to macro multi‐scale 4D printing structure design confirm its application potential as dynamic adaptive devices in aerospace and safety engineering. [ABSTRACT FROM AUTHOR]

This work proposes a facile and economical hybrid additive manufacturing (HAM)technology combining fused deposition modeling (FDM) 3D printing and laser‐activated selective electroless plating (ELP) for fabricating full functional end‐use 3D customized electronics. A functional acrylonitrile butadiene styrene (ABS) filament doped with dicopper hydroxide phosphate (Cu2(OH)PO4) catalysts is developed for FDM 3D printing. The 3D printed structure is selectively laser‐activated to generate CuI plating seeds on the ABS surface and then electrolessly plated. The poor surface finish, especially the layer lines, is an intrinsic defect of extrusion 3D printing, which not only affected the fabrication quality of the 3D substrates but also the electrical performance of the attached circuitry. Herein, a chemical polishing process based on acetone vapor is explored and characterized to significantly improve the surface quality and thereby the electrical performance of the attached copper layer. In this way, highly conductive metallic circuitry can be freeformly deposited and patterned on the 3D structure which is extremely attractive for customized 3D electronics. To show the application potential of this technology, a 3D conformal 555 timer astable oscillator circuit board and a hot‐wire flowmeter are developed as demonstrators. [ABSTRACT FROM AUTHOR]

Electronic skins (e‐skins) are a promising design paradigm for health care systems and human–machine interactions. Piezoresistive sensors made with simple structures, high sensitivity, mass production methods, light weight, and comfort for long‐term wearing and physiological signal monitoring remain a challenge and are urgently desirable. Here, a breathable and lightweight all‐nanofiber piezoresistive (ANFP) sensor is presented, which is composed of three layers of electrospun nanofibers (NFs). A specific interpenetrating network of conductive polyvinylpyrrolidone NFs coated by polypyrrole (PVP@PPy) and insulating polyacrylonitrile NFs is constructed by controlling the vapor growth position of PPy to enhance the sensitivity. The ANFP sensor can achieve the real‐time monitoring of multiple parts of physiological signals, and a wireless detection system is designed for the online monitoring of human pulses. The NF network endows excellent breathability and heat dissipation to the ANFP sensors during practical application, which ensures comfort and device stability during long‐term wearing. Finally, a pressure sensing array with 5 × 5 pixels is fabricated to demonstrate the potential applications in spatial pressure detection. This work provides a viable strategy to improve the wearability of e‐skins, which can promote health care and human–machine interaction applications. [ABSTRACT FROM AUTHOR]