Recent advances in additive manufacturing enable redesigning material morphology on nano-, micro-, and meso-scale, for achieving an enhanced functionality on the macro-scale. From non-planar and flexible electronic circuits, through biomechanically realistic surgical models, to shoe soles individualized for the user comfort, multiple scientific and technological areas undergo material-property redesign and enhancement enabled by 3D printing. Fiber-device technology is currently entering such a transformation. In this paper, we review the recent advances in adopting 3D printing for direct digital manufacturing of fiber preforms with complex cross-sectional architectures designed for the desired thermally drawn fiber-device functionality. Subsequently, taking a recursive manufacturing approach, such fibers can serve as a raw material for 3D printing, resulting in macroscopic objects with enhanced functionalities, from optoelectronic to bio-functional, imparted by the fiber-devices properties.
Flexible solar cells are one of the most significant power sources for modern on-body electronics devices. Recently, fiber-type or fabric-type photovoltaic devices have attracted increasing attentions. Compared with conventional solar cell with planar structure, solar cells with fiber or fabric structure have shown remarkable flexibility and deformability for weaving into almost any shape and assembling with any portable electronic equipment as a sustainable power supply. This review comprehensively summarizes the recent progress of wearable fiber-type and fabric-type solar cells as well as its applications in hybrid energy textiles. For solar cells of dye-sensitized type, organic type and perovskite type, the discussion involves working mechanism, structural design, material selection, preparation technology and potential applications. In addition, challenges and technical difficulties that may hinder its large-scale commercial application are also summarized and discussed. It is hoped that, this review will be of help for future researches on textile-type energy devices, to finally make it an everyday lifestyle in a near future.
Humidity sensors have become an essential need for improving daily life quality. Here, a novel humidity sensitive fiber was fabricated using the soft polydimethylsiloxane (PDMS) as the core layer and the non-swellable polyvinylidenedifluoride (PVDF) embedded with a swellable MIL-88A as the outer layer. Noticeably, the PDMS fiber was chosen as a carrier due to its smoothness, softness and good tensile properties. The isoreticular FeIII dicarboxylate MIL-88 family with swellable metal–organic frameworks (MOFs) can undergo reversible dynamic structural transformations with a response to external humidity change. The resulted fiber with swellable MOFs showed three kinds of deformation for a single solvent and also had good deformation performance for two-component miscible solution with different volume ratios. As a proof of concept, a shape-memory effect at relative humidity from 10 to 90% and the simulated salt solutions instead of relative humidity changes were used to evaluate humidity change. In addition, a deep insight into the self-shape-change mechanism among those phenomena was investigated, wherein expansion deformation of the PDMS fiber as well as the structural transformation of the MIL-88A worked in different conditions.
In search of effective and stable bifunctional electrocatalyst for electrocatalytic water splitting is still a major challenge for the highly efficient H2 production. Here, we reported a facile strategy to design high-indexed Cu3Pd13S7 nanoparticles (NPs) in situ synthesized on the three-dimensional (3D) carbon nanofibers (CNFs) by combining electrospinning and chemical vapor deposition (CVD) technology. The high-index facets with abundant active sites, the 3D architecture CNFs with high specific surface area and synergistic effect of Cu–Pd–S bonds with strong electron couplings together promote the electrocatalytic performance. The Cu3Pd13S7/CNFs shows excellent electrocatalytic activity with low overpotentials of 52 mV (10 mA cm−2) for hydrogen evolution reaction (HER) and 240 mV (10 mA cm−2) for oxygen evolution reaction (OER). The excellent protection of Cu3Pd13S7 by CNFs from aggregation and electrolyte corrosion lead to the high stability of Cu3Pd13S7/CNFs under acidic and alkaline conditions.
The new generation of electronics tends to be well-performed, facile and environmentally friendly. Here, we report a bio-assembled sensitive pressure senor based on reduced graphene oxide-bacterial cellulose/bacterial cellulose (RGO-BC/BC) bilayer films, integrated by bacteria in one step. The advantage of this integration is that there is strong nanofiber connection between the conductive RGO-BC and insulative highly compressible porous BC layer, which confers RGO-BC/BC film electrode with good robustness, tailorability, flexibility and wearability. Without extra bonding-interface or postprocessing, the RGO-BC/BC bilayer films could be directly assembled into pressure sensing devices. Ascribed from the good reversible compressibility of the BC layer and incorporated bilayer structure, the pressure sensor performs good sensitivity and excellent durability and bending stability. The facile sensitive capacitive sensor could monitor the human hand or finger motion in real time. The sensing array is able to detect the spatial distribution of pressure mounted in the flat plane as well as curved surface of human body, succeeding in the correction of human walking posture for health care. The e-skins are potential in wearable electronics, artificial intelligence, soft robots, healthcare etc.
Polypropylene (PP) membrane has been widely used in water purification and other fields owing to special pore structure, excellent mechanical properties and resistance to acids, alkalis and organic solvents. However, it is difficult for PP to introduce the hydrophilic chemical compositions for oil–water separation. Herein, superhydrophilic and underwater superoleophobic PP membranes were prepared by ALD for efficient gravity-driven oil–water separation. Owing to synergistic effect, oil contact angle of TiO2 coated PP membrane under water can reach above 150°. Hence, TiO2 coated PP membrane has great oil-repelling performance. Because of the superwetting property, TiO2 coated PP membrane can easily separate oil–water mixture and have high separation efficiency (more than 95%). The outstanding recyclability and mechanical stability of TiO2 coated PP membrane suggest the promising potential application in practical oil–water separation.