Electronic skins, as the integration of multiple distinct sensors, have aroused broad interests owing to their great potential in sensing applications. However, problems including the interference between sensing components and the difficulty in synchronous monitoring are practically encountered when they are applied to mixed signals. In this work, efforts are devoted to trouble‐free technical strategies for laminating three sensors with different sensing abilities into a skin‐like electronic device. The use of ionic liquid, combined with particular circuit topologies, ensures the reliable stability against mechanical disturbance during the real‐time sensing tests. The intrinsic layered structure and three independent sensing functions of natural skins are successfully presented by this particular device in which three sensors with the ease of preparation are spatially integrated. The changes of temperature, pressure, and infrared light can be recorded simultaneously yet without mutual signal interference. The perfect integration of multiple functional sensors into a single skin‐like device without any signal interference makes an important progress for pursuing the goal of future electronic skins that can practically be used as skin.
For the purpose of stretchable electronics, broad interests have been paid to elastic conductors by which high tensile strain over 100% can be readily achieved. Here, a scalable-processing, dyeing-like strategy for highly stretchable polypyrrole elastomer (1450% in strain) is conceived without particular topological design. This approach effectively improves the mechanical properties of the classic insoluble polypyrrole by confined polymerization within an elastic polymer network. In terms of the easy processing, it is technically possible to prepare stretchable electronics with arbitrary shape and size for wearable electronics with low cost. The mechanism of interpenetrated networks coexisting with microphase separation is comprehensively illustrated at molecular scale. The as-fabricated polypyrrole elastomers are utilized as temperature or strain sensors for automatic fishing and region-distinct dual signal sensing. Further integration of multiple sensors offers immediate alarm for old people falling at home, which thereby proves its promising potential in practical applications.
Despite great progresses
in bioprinting materials and technologies,
immense challenges still remain when printing tubular tissues or organs
with satisfying mechanical and chemical properties, such as blood
vessel, colon, and trachea. Herein, a promising extrusion system based
on an interfacial diffusion printing (IDP) technique for one-step
printing of tubular tissue grafts is proposed. Specifically, this
technique offers great convenience to prepare hollow hydrogel fibers
with excellent mechanical properties and satisfactory biocompatibility.
The tubular diameter can be readily adjusted within 6 mm, which renders
the possibility of these hydrogel tubes to serve as small-diameter
vascular grafts. In the model of animal trials, the hydrogel grafts
with the capability of enduring arterial pressure are mechanically
stable in rabbit carotid artery replacement. Because of its intrinsic
simplicity and generality, the IDP technique is considered to be one
of the reliable choices for more complicated bioengineering.
Hydroxyapatite (HA), the main inorganic component of bone tissue, is mineralized with collagen fibril scaffolds during bone formation. Inspired by the process, a self-assembled porous network architecture was designed and synthesized by using the 2-ureido-4[1H]-pyrimidone (UPy) modified glycerol molecule UPy-Gly, which was further utilized as a template for biomimetic mineralization. When incubated in simulated body fluid (SBF), the HA nucleus first formed in the holes of the template by the induction of hydroxyls on the surface, grew along the nanofibers, and fused with the template to fabricate hydroxyapatite composites (UPy-Gly/HA). Transmission electron microscopic observation demonstrates that the mineral clusters are accumulated by lamella-like nano hydroxyapatite and the elasticity modulus measured by atomic force microscopy is about 5.5 GPa, which is quite close to the natural cancellous bone tissue of human both in structure and in mechanical properties. The Cell Counting Kit 8 (CCK-8) assay of UPy-Gly and UPy-Gly/HA shows noncytotoxicity to mouse fibroblast L-929 cells. This bioinspired composite will be a promising material for potential use in bone tissue implantation and regeneration engineering.
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