dressing for its intrinsic hydrophilicity. The left biofluid continuously hydrates the wound and complicates the healing process. [7] Therefore, it is urgently needed to develop a new wound dressing to effectively remove the excessive biofluid.Bio-interface plays a significant role in the interaction between biofluid and biomaterial. [8] Surface wettability of wound dressings can generally affect the wetting behavior of biofluid around wounds. Hydrophilic materials, like most conventional dressings, easily get wetted by biofluid thus overhydrating wound. [7] In contrast, as the waterproof outer layer of dressings, hydrophobic materials prevent unexpected contacting of external fluid with the wounds, but they cannot facilitate biofluid removal. [9][10][11] Recently, several materials with asymmetric wettability have shown their unique capability to transfer water droplet, for instance, a polyester fabric with wettability gradient, [12] a polyurethane (PU)/polyvinyl acetate composite fibrous film, [13] and a one-side fluorinated cotton fabric membrane. [14] Therefore, the control of surface wettability may offer an opportunity to design wound dressings with the capability of effective biofluid management.Herein, we electrospan a hydrophobic PU nanofiber array onto a hydrophilic microfiber network, constructing a selfpumping dressing as a biofluid pump (Figure 1a). Such a selfpumping dressing can unidirectionally drain the excessive biofluid from its hydrophobic side to hydrophilic side, thereby preventing the biofluid from wetting the wound. In an infected wound model, we demonstrated a faster wound healing treated by this self-pumping dressing than the conventional dressing. This study provides a new clue to manage excess biofluid around wounds to promote faster wound healing.Medical gauze is a conventional dressing for its economic cost, flexible and tough network structure, and super absorbing capability. [15] Bundles (diameter = 259.0 ± 59.3 µm) of cotton microfibers (diameter = 16.9 ± 2.6 µm) interpenetrate each other (Figure 1b-d) and form a superhydrophilic network (Figure 1d, inset) in medical gauze, suitable for serving as a supporting framework and the source of pumping force as well. PU is a hydrophobic (Figure 1g, inset) biocompatible medical material with easy processing property, [16] expected to be an ideal candidate for preparing a separate layer to prevent biofluid wetting. Here we electrospan a thin layer of hydrophobic PU nanofiber array (diameter = 220.0 ± 40.0 nm; Figure 1e-g) onto a cotton medical gauze (Figure 1b-d) to form a self-pumping dressing Excessive biofluid around wounds often causes infection and hinders wound healing. However, the intrinsic hydrophilicity of the conventional dressing inevitably retains excessive biofluid at the interface between the dressing and the wound. Herein, a self-pumping dressing is reported, by electrospinning a hydrophobic nanofiber array onto a hydrophilic microfiber network, which can unidirectionally drain excessive biofluid away from wounds and finall...

Solution-processed solar cells are appealing because of the low manufacturing cost, the good compatibility with flexible substrates, and the ease of large-scale fabrication. Whereas solution-processable active materials have been widely adopted for the fabrication of organic, dye-sensitized, and perovskite solar cells, vacuum-deposited transparent conducting oxides (TCOs) such as indium tin oxide, fluorine-doped tin oxide, and aluminum-doped tin oxide are still the most frequently used transparent electrodes (TEs) for solar cells. These TCOs not only significantly increase the manufacturing cost of the device, but also are too brittle for future flexible and wearable applications. Therefore, developing solution-processed TEs for solar cells is of great interest. This paper provides a detailed discussion on the recent development of solution-processed TEs, including the chemical synthesis of the electrode materials, the solution-based technologies for the electrode fabrication, the optical and electrical properties of the solution-processed TEs, and their applications on solar cells.

Flexible and wearable electronics is one major technology after smartphones. It shows remarkable application potential in displays and informatics, robotics, sports, energy harvesting and storage, and medicine. As an indispensable part and the cornerstone of these devices, soft metal electrodes (SMEs) are of great significance. Compared with conventional physical processes such as vacuum thermal deposition and sputtering, chemical approaches for preparing SMEs show significant advantages in terms of scalability, low-cost, and compatibility with the soft materials and substrates used for the devices. This review article provides a detailed overview on how to chemically fabricate SMEs, including the material preparation, fabrication technologies, methods to characterize their key properties, and representative studies on different wearable applications.

Soft electronics are rising electronic technologies towards applications spanning from healthcare monitoring to medical implants. However, poor adhesion strength and significant mechanical mismatches inevitably cause the interface failure of devices. Herein we report a self-adhesive conductive polymer that possesses low modulus (56.1-401.9 kPa), high stretchability (700%), high interfacial adhesion (lap-shear strength >1.2 MPa), and high conductivity (1-37 S/cm). The self-adhesive conductive polymer is fabricated by doping the poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) composite with a supramolecular solvent (β-cyclodextrin and citric acid). We demonstrated the solution process-based fabrication of self-adhesive conductive polymer-based electrodes for various soft devices, including alternating current electroluminescent devices, electromyography monitoring, and an integrated system for the visualization of electromyography signals during muscle training with an array of alternating current electroluminescent devices. The self-adhesive conductive polymer-based electronics show promising features to further develop wearable and comfortable bioelectronic devices with the physiological electric signals of the human body readable and displayable during daily activities.

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nanotubes [CNTs] and graphene), and metal-based materials are superior to ITO in the mechanical flexibility and the potential for roll-to-roll (R2R) manufacture. [16,17] Yet, a common drawback of FTEs made of conducting polymers, CNTs, and graphene is the inferior electrical conductivity. [18][19][20][21][22][23][24] Po l y ( 3 , 4 -e t h y l e n e d i o x y t h i o p h e n e )poly(styrene sulfonate) (PEDOT:PSS) is one of the most widely used conducting polymers. PEDOT:PSS shows the lowest cost among various transparent electrode materials, [25] but the low intrinsic conductivity, poor environmental stability (upon exposure to high temperature, high humidity, or UV irradiation), and self-emission of blue/green tinge limit its applications in flexible optoelectronics. [1,26] Whereas individual CNT and graphene may exhibit excellent conductivity, thin films made of multijunctional assembly of these nanomaterials show high contact resistance at the junctions. [27,28] The surface defects and polycrystallinity of these carbon materials, which are difficult to eliminate, further decrease the conductivity. [28][29][30][31][32][33] On the other hand, metals possess the highest electrical conductivity among all kinds of materials. [34] Thin and surface-structured metal electrodes are optically transparent and mechanically flexible. The combinatorial attributes of high conductivity, tunable transmittance, and engineerable flexibility make metal-based materials the most promising candidates for FTEs. [3,35] To date, there are three major types of metal-based FTEs (m-FTEs), including ultrathin metal films, metal nanowire networks, and metal meshes. Each type of m-FTEs shows unique advantages and critical challenges toward large-scale applications as summarized in Figure 1.This article discusses the characteristics and major challenges of each type of m-FTEs, and reviews their research advances in recent years. It then discusses the ability to achieve scalable production of these m-FTEs from the point of view of materials choice and fabrication technology. Finally, it provides perspectives on the transition from lab study to industry fabrication of m-FTEs in the future. Metal-Based-Flexible Transparent Electrodes Made of Ultrathin Metal FilmsUltrathin and homogeneous metal (such as Ag, Au, Cu, or Al) films with a thickness of 10-20 nm exhibit good electrical Flexible transparent electrodes (FTEs) with high optical transmittance, low sheet resistance, and high flexibility are critical and indispensable components of emerging flexible optoelectronic devices. Indium tin oxide (ITO), the major transparent conductive material used for optoelectronics nowadays, is not suitable for flexible applications because of its brittleness. In the past decade, researchers have developed a wide variety of new transparent conductive materials to replace ITO, among which metal-based FTEs (m-FTEs) including ultrathin metal films, metal nanowire networks, and metal meshes appear to be particularly promising. In this review, the authors summarize ...

Liquid metal (LM) has recently been used as an advanced stretchable material for constructing stretchable and wearable electronics. However, due to the poor wettability of LM and the large dimensional change during stretching, it remains very challenging to obtain a high conductivity with minimum resistance increase over large tensile strains. To address the challenge, an LM‐superlyophilic and stretchable fibrous thin‐film scaffold is reported, on which LM can be readily coated or printed to form permeable superelastic conductors. In contrast to conventional LM‐based conductors where LM particles are filled into an elastic matrix or printed on the surface of an elastic thin film, the LM can quickly infuse into the LM‐superlyophilic scaffold and form bi‐continuous phases. The LM‐superlyophilic scaffold shows unprecedented advantages of an extremely high uptake of the LM and a conductivity‐enhancement characteristic when stretched. As a result, the LM‐based conductor displays and ultrahigh conductivity of 155 900 S cm−1 and a marginal resistance change by only 2.5 fold at 2 500% strain. The conductor also possesses a remarkable durability over a period of 220 000 cycles of stretching tests. The printing of LM onto the LM‐superlyophilic scaffold for the fabrication of various permeable and wearable electronic devices is demonstrated.

Our results provide evidence that SLC30A8 is a susceptible locus for type 2 diabetes in Chinese population, and its variant can influence insulin secretion.