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Direct air capture (DAC) is a sustainable technology to alleviate the greenhouse effect and a reliable pathway to acquire inexhaustible CO2 for the production of costly chemicals and energy products. Current DAC technologies with amine‐related sorbents rely on chemisorption, while they consume intensive energy for CO2 release and sorbent regeneration by heating. Developing new DAC processes with weak, reversible adsorption can substantially reduce the regeneration energies. Herein, the design of CO2 breathing paper (CBP) is demonstrated toward spontaneous CO2 extraction from ambient air and solar‐driven regeneration. The CBP is fabricated by coupling 2‐ethyl‐4‐methylimidazole to carbon nanotube paper on the basis of density functional theory calculations. At ambient conditions, CBP spontaneously captures atmospheric CO2 with a capacity of 0.14–1.75 mmol g–1 at 0–35 °C through non‐covalent electrostatic interaction. Upon exposure to sunlight, all adsorbed CO2 can be released and converted to concentrated gas for storage. Attractively, the efficiency of solar‐driven CO2 release is much higher than the traditional temperature‐swing method owing to the IR sensitivity of CO2. Besides the reversibility, the mild conditions also ensure the durability of CBP. These findings suggest that the CBP is a promising candidate for cost‐effective DAC. [ABSTRACT FROM AUTHOR]

Paper‐based cultural relics are of great value and have been facing irreversible damage caused by multiple factors, among which acid hydrolysis and ultraviolet photodegradation are the main processes leading to paper deterioration. Paper protection highly relies on a limited range of materials with single functions, and the design of new materials that ensure long‐term safety and efficiency by simultaneously addressing the issues of acidification and UV degradation in paper is highly desired. In this study, the introduction of carbon dots (CDs)‐enhanced layered double hydroxides (LDH) 0D/2D nanohybrids (CDs/Mg‐Al LDH)  is proposed as novel dual‐functional materials for paper protection against UV degradation and acidification. Through a CDs‐assisted in situ growth strategy, CDs/Mg‐Al LDH with ultrathin thickness (≈9.1 nm) and CDs‐intercalated structure are achieved. The CDs/Mg‐Al LDH nanohybrids demonstrate high dispersibility, strong UV absorption, and remarkable photostability, resulting in protected‐paper with decelerated acidification, oxidation, and yellowing degradation processes under both accelerated UV‐aging and dry‐heat conditions. Additionally, the protected‐paper can emit uniform blue light under 365 nm UV excitation allows for easy identification of the distributed CDs/Mg‐Al LDH within the paper, marking a unique and practical feature. This research paces a new direction for the protection of paper‐based relics with emerging carbon dots‐based 0D/2D nanomaterials. [ABSTRACT FROM AUTHOR]

Self‐charging power systems (SCPSs) are envisioned as promising solutions for emerging electronics to mitigate the increasing global concern about battery waste. However, present SCPSs suffer from large form factors, unscalable fabrication, and material complexity. Herein, a type of highly stable, eco‐friendly conductive inks based on poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) are developed for direct ink writing of multiple components in the SCPSs, including electrodes for miniaturized spacer‐free triboelectric nanogenerators (TENGs) and microsupercapacitors (MSCs), and interconnects. The principle of “one ink, multiple functions” enables to almost fully print the entire SCPSs on the same paper substrate in a monolithic manner without post‐integration. The monolithic fabrication significantly improves the upscaling capability for manufacturing and reduces the form factor of the entire SCPSs (a small footprint area of ≈2 cm × 3 cm and thickness of ≈1 mm). After pressing/releasing the TENGs for ≈79000 cycles, the 3‐cell series‐connected MSC array can be charged to 1.6 V while the 6‐cell array to 3.0 V. On‐paper SCPSs are promising to serve as lightweight, thin, sustainable, and low‐cost power supplies. [ABSTRACT FROM AUTHOR]

The employment of ultra‐thin lithium metal anode with high loading cathode is the key to realizing high‐energy‐density rechargeable lithium batteries. Ultra‐thin lithium foils are routinely loaded on a copper substrate in batteries, however, the close contact of these two metals causes galvanic corrosion in the presence of electrolyte, which results in irreversible consumption of lithium and decomposition of electrolyte. Herein, a lightweight and highly conductive flexible graphite paper (GP) is applied to replace Cu foil as the current collector for lithium metal anode. It is demonstrated that the application of GP prevents galvanic corrosion and maintains intimate and steady contact between Li foil and GP current collector during cycling, thereby improving the electrochemical performance of the battery. A 1.08 Ah pouch cell assembled with Li@GP anode and LiNi0.8Co0.1Mn0.1O2 cathode exhibits a long lifetime of 240 cycles with a capacity retention of 91.6% under limited Li, high cathode loading and lean electrolyte conditions. [ABSTRACT FROM AUTHOR]

Lignin‐carbohydrate complexes (LCC) underpin the comprehensive properties of natural wood. Facile restoration of LCC analogues in paper is challenging because of the charge repulsion between negatively charged lignin and pulp fibrils. A camouflage strategy is discovered to prepare positively charged lignosulfonate–polyamide‐epichlorohydrin complex (LPC) nanoparticles, which are effectively incorporated in pulp through the "LPC–pulp" attraction instead of "lignosulfonate–pulp" repulsion. Water‐resistant LPC paper sheets are prepared in ≈20 min without pressurization. They exhibit high tensile strength (41 MPa), surviving boiling water treatment for 14 days, on par with the strength of pristine paper and certain plastics in a dry state. The camouflage strategy applies to various pulps and processing technologies, as exemplified by a paper separator showing exceptional electrolyte wettability and rate capability in lithium‐ion batteries. This work establishes advanced cellulose valorization with combined strength, water stability, and tailored microstructures replacing petroleum polymers in engineering and energy implications. [ABSTRACT FROM AUTHOR]

The growing usage and consumption of electronics‐integrated items into the daily routine has raised concerns on the disposal and proper recycling of these components. Here, a fully sustainable and green technology for the fabrication of different electronics on fruit‐waste derived paper substrate, is reported. The process relies on the carbonization of the topmost surface of different cellulose‐based substrates, derived from apple‐, kiwi‐, and grape‐based processes, by a CO2 laser. By optimizing the lasing parameters, electronic devices, such as capacitors, biosensors, and electrodes for food monitoring as well as heart and respiration activity analysis, are realized. Biocompatibility tests on fruit‐based cellulose reveal no shortcoming for on‐skin applications. The employment of such natural and plastic‐free substrate allows twofold strategies for electronics recycling. As a first approach, device dissolution is achieved at room temperature within 40 days, revealing transient behavior in natural solution and leaving no harmful residuals. Alternatively, the cellulose‐based electronics is reintroduced in nature, as possible support for plant seeding and growth or even soil amendment. These results demonstrate the realization of green, low‐cost and circular electronics, with possible applications in smart agriculture and the Internet‐of‐Thing, with no waste creation and zero or even positive impact on the ecosystem. [ABSTRACT FROM AUTHOR]

The separation of oil-water mixtures in highly acidic, alkaline, and salty environment remains a great challenge. Simple, low-cost, efficient, eco-friendly, and easily scale-up processes for the fabrication of novel materials to effective oil-water separation in highly acidic, alkaline, and salty environment, are urgently desired. Here, a facile approach is reported for the fabrication of stable hydrogel-coated filter paper which not only can separate oil-water mixture in highly acidic, alkaline, and salty environment, but also separate surfactant-stabilized emulsion. The hydrogel-coated filter paper is fabricated by smartly crosslinking filter paper with hydrophilic polyvinyl alcohol through a simple aldol condensation reaction with glutaraldehyde as a crosslinker. The resultant multiple crosslinked networks enable the hydrogel-coated filter paper to tolerate high acid, alkali, and salt up to 8 m H2SO4, 10 m NaOH, and saturated NaCl. It is shown that the hydrogel-coated filter paper can separate oil-water mixtures in highly acidic, alkaline, and salty environment and oil-in-water emulsion environment, with high separation efficiency (>99%). [ABSTRACT FROM AUTHOR]

Similar to the paper-making process, the efficient flame retardant graphene paper is conveniently obtained by using graphene oxide (GO) and hexachlorocyclotriphosphazene (HCCP) aqueous pulp. The 'paper pulp' can also conceivably be used as ink to make other hydrophilic films become flame retardant paper. Further, the as-prepared reduced GO-HCCP paper (RGO-HCCP paper), compared with GO-HCCP paper, can maintain its intact structure for a longer time in an ethanol flame. As a consequence of these preparation methods, the bearing temperature of the as-prepared graphene papers shows a significant increase. [ABSTRACT FROM AUTHOR]

Recently, actuating materials based on carbon nanotubes or graphene have been widely studied. However, present carbon-based actuating materials are mostly driven by a single stimulus (humidity, light, electricity, etc.), respectively, which means that the application conditions are limited. Here, a new kind of multiresponsive actuating material which can be driven by humidity, light, and electricity is proposed, so it can be used in various conditions. The fabrication is based on the simplest pencil-on-paper method, in which the pencil and paper are both low-cost and easily obtained daily materials. The actuation effect is more remarkable due to a dual-mode actuation mechanism, which leads to an ultralarge actuation (bending curvature up to 2.6 cm−1). Elaborately designed, the actuator can further exhibit a bidirectional bending actuation, which is a significant improvement compared with previous reported thermal actuators. What is more, a colorful biomimetic flower and a smart curtain are also fabricated, fully utilizing the printable characteristic of the paper and multiresponsive characteristic of the actuator. It is assumed that the newly designed actuating material has great potential in the fields of lab-on-paper devices, artificial muscles, robotics, biomimics, and smart household materials. [ABSTRACT FROM AUTHOR]

On‐paper microsupercapacitors (MSCs) are a key energy storage component for disposable electronics that are anticipated to essentially address the increasing global concern of electronic waste. However, nearly none of the present on‐paper MSCs combine eco‐friendliness with high electrochemical performance (especially the rate capacity). In this work, highly reliable conductive inks based on the ternary composite of poly(3,4‐ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS), graphene quantum dots and graphene are developed for scalable inkjet printing of compact (footprint area ≈ 20 mm2) disposable MSCs on commercial paper substrates. Without any post treatment, the printed patterns attain a sheet resistance as low as 4 Ω ▫−1. The metal‐free all‐solid‐state MSCs exhibit a maximum areal capacitance > 2 mF cm−2 at a high scan rate of 1000 mV s−1, long cycle life (>95% capacitance retention after 10 000 cycles), excellent flexibility, and long service time. Remarkably, the "totally metal‐free" MSC arrays are fully inkjet printed on paper substrates and also exhibit high rate performance. The life cycle assessment indicates that these printed devices have much lower eco‐toxicity and global warming potential than other on‐paper MSCs. [ABSTRACT FROM AUTHOR]

Peroxidase‐mimicking nanozymes have been extensively studied, however, their application is limited by the requirement for an acidic pH. Herein, the development of Co‐doped mesoporous cerium oxide (Co‐m‐ceria) is reported, which operates optimally at a near‐neutral pH and exhibits a peroxidase‐like catalytic efficiency that is 600‐times higher than that of pristine m‐ceria. Density functional theory (DFT) calculations for the application of pristine and various metal‐doped m‐ceria in peroxidase‐like reactions under different pH environments are conducted to select Co as the appropriate dopant. The high peroxidase‐like activity of Co‐m‐ceria under neutral conditions and its mesoporous nature enable its application in a one‐pot cascade reaction system, wherein biomarkers of oxidative enzymes can be detected without altering the pH. Five different oxidative enzymes are immobilized in the pores of Co‐m‐ceria at high loadings, followed by incorporation of the enzyme‐containing Co‐m‐ceria in paper microfluidic devices for the convenient and simultaneous detection of multiple biomarkers. The Co‐m‐ceria‐incorporated paper microfluidic device enables the selective and sensitive determination of multiple biomarkers using a smartphone‐acquired image. This study demonstrates the potential of the rational design of nanozymes and their application in paper microfluidic devices, laying the groundwork for future applications of nanozymes in point‐of‐care testing environments. [ABSTRACT FROM AUTHOR]

Despite much efforts to stabilize sodium metal anodes for promoting their commercial applications, achieving a safe cycling process without intrinsic dendrite growth remains difficult owing to the unstable reaction interface and irregular sodium metal propagation. Herein, fluorine‐superdoped carbon nanotubes with a fluorine content of 14.38 at% are achieved using a new oxidation‐assisted plasma strategy, and then alternately assembled with cellulose nanofibrils to form periodical conductive/dielectric composite paper with outstanding mechanical properties. The superdoping of fluorine facilitates the construction of a NaF‐dominated solid electrolyte interphase layer, while the periodical conductive/dielectric network re‐homogenizes electric field distribution around irregular sodium protrusions, realizing a "bottom‐up" sodium orientation deposition and the "self‐correction" functionality during sodium plating/stripping process. Density functional theory calculations reveal that the specific oxygen species (CO/CO) and fluorine species (semi‐ionic CF/covalent CF2) on the surface of carbon matrix, could remarkably trap active fluorine fragments and generate NaF with sodium metal, respectively, which promotes the superdoping of fluorine and forms dendrite‐free sodium anodes. This delicate structure renders the sodium anodes a low nucleation overpotential of ≈7 mV, high Coulombic efficiency of 99.5% over 300 cycles at 3 mA cm−2, stable operation for up to 2100 h under ≈16 mV, and excellent full battery performance. [ABSTRACT FROM AUTHOR]

Solar steam generation has been extensively studied for its potential application in power generation and water treatment. Although some efficient evaporators have been developed, the challenge of the abrupt drop in the evaporator performance under outdoor environments remains to be overcome. The heteroblasty of Monstera and other climbers allows them to grow rapidly under the extreme shade of a tropical rainforest, inspiring the design of a high‐efficiency evaporator that can function even in weak light environments. Herein, artificial trees that imitate the leaf fenestration of Monstera combined with the Chinese paper cutting technique exhibit the highest evaporation rate of 2.30 kg m−2 h−1. Moreover, under oblique incidence (from 0° to 75°) and dappled sunlight, the evaporation rates of artificial trees with leaf fenestration are 1.08–1.26 and 1.34–2.78 times those of artificial trees without leaf fenestration and a 2D evaporator, respectively. The excellent performance is attributed to high‐efficiency light absorption, photothermal conversion, high evaporation area, and excellent light and thermal management abilities, which are achieved through leaf fenestration and efficient thermal recovery through multiple reflections of light and thermal radiation between the leaves. The design of the 3D hierarchical structure and leaf fenestration are also applicable for various light absorbents. [ABSTRACT FROM AUTHOR]

Nanofluidic membranes consisting of 2D materials and polymers are considered promising candidates for harvesting osmotic energy from river estuaries owing to their unique ion channels. However, micron‐scale polymer chains agglomerate in the nanochannels, resulting in steric hindrance and affection ion transport. Herein, a nanofluidic membrane is designed from MXene and xylan nanoparticles that are derived from paper‐mill waste. The demonstrated membrane reinforced by paper‐mill waste has the characteristics of green, low‐cost, and outstanding performance in mechanical properties and surface‐charge‐governed ionic transport. The MXene/carboxmethyl xylan (CMX) membrane demonstrates a high surface charge (ζ‐potential of −44.3 mV) and 12 times higher strength (284.96 MPa) than the pristine MXene membrane. The resulting membrane shows intriguing features of high surface charge, high ion selectivity, and reduced steric hindrance, enabling it high osmotic energy generation performance. A potential of the nanofluidic membrane is ≈109 mV, the corresponding current of up to 2.73 µA, and the output power density of 14.52 mW m−2 are obtained under a 1000‐fold salt concentration gradient. As the electrolyte pH increases, the power density reaches 56.54 mW m−2. This works demonstrate that CMX nanoparticles can effectively enhance the properties of the nanofluidic membrane and provide a promising strategy to design high‐performance nanofluidic devices. [ABSTRACT FROM AUTHOR]

The demand for flexible memory devices is growing due to the development of flexible neuromorphic electronics for wearable devices, soft robotics, and biologically‐inspired circuits. Described herein is a flexible memcapacitor based on a biocomposite paper composed of reduced graphene oxide (rGO) and silk fibroin (SF) via a gel‐film transformation process. The presented rGO‐SF/H3PO4‐polyvinyl alcohol (PVA)/rGO memory stack exhibits analog, reversible, and nonvolatile memcapacitance characteristics. Impressively, the stack has a broad range of high capacitance states so as to be tuned to at least four capacitive states by the operating voltages. This memcapacitive behavior is ascribed to an interfacial charge build‐up (capacitive double layer) modulated by the H+ migration, which is trapped/detrapped by the rGO‐SF paper depending on bias conditions. Further, the flexibility tests are conducted to confirm the applicability of the rGO‐SF/H3PO4‐PVA/rGO stack to flexible devices. Thus, the rGO‐SF papers can be used as electronic materials for capacitive memory in neuromorphic systems where operation at biocompatibility, low‐energy, and mechanical flexibility are important issues. [ABSTRACT FROM AUTHOR]

Using synergetic effects of various sodium storage modes and materials to construct high power, high energy, and long cycling flexible sodium anode materials is significant and still challenging. Here, by advantageous functional integration of adsorption‐intercalation‐conversion sodium storage mechanisms, a 3D flexible fiber paper anode with the composition of Nb2O5@hard carbon@MoS2@soft carbon is designed and prepared. Based on the synergetic effects, it exhibits higher specific capacity than pure Nb2O5, with more excellent rate performance (245, 201, 155, 133, and 97 mAh g−1 at the current density of 0.2, 1, 5, 10, and 20 A g−1, respectively) than pure MoS2 as well as admirable long‐term cycling characteristics (≈82% capacity retention after 20 000 cycles at 5 A g−1). Relevant kinetics mechanisms are expounded in detail. This work can be helpful for preparing other types of hybrid and flexible electrodes for energy storage systems. [ABSTRACT FROM AUTHOR]

Photodetectors, which convert the light signal into other forms of signal, have been under the spotlight of research for many years because they are widely applied in monitoring, communication, and imaging. Most of the currently available photodetectors can output electrical signals to indicate the transient light intensity, while some display color change to reveal the absorbed light dosage. However, there is no device that can tell the transient light intensity and accumulated light dosage at the same time. Here, a paper‐based wearable photodetector that can simultaneously measure transient light intensity and accumulated light dosage is reported. The phosphomolybdic acid/citric acid system, whose color change can be observed by the naked eye, is designed as the photochromic material to combine with photodetective materials (using 2D Sr2Nb3O10 and ZnO nanoparticle as examples) on paper. Such paper‐based photodetector fully utilizes natural hygroscopicity and softness of paper, showing decent flexibility. Its optoelectronic signal remains stable even after 1000 cycles of bending. To the best of one's knowledge, this is the first photodetector that can tell light intensity and dosage simultaneously. This work introduces a new type of wearable photodetector by structure design and material selection, shedding light on more novel works for convenient and practical photodetection. [ABSTRACT FROM AUTHOR]

Due to low density, extremely high electrical and thermal conductivities, graphene has great potential to construct lightweight thermal conductive paper for high-power electric devices. However, the remarkable properties of graphene are on a molecular level and difficult to achieve when processed into macroscopic paper. Here, an effective route to construct ultrahigh conductive graphene paper is developed. First, large-volume, high-concentration, plane-defect-free, few-layer graphene dispersion is fast produced from graphite at high yield through ball milling. The exfoliated graphene dispersion is further processed into graphene paper through fast filtration, thermal treatment, and mechanical compression. The electrical and thermal conductivities of the resultant graphene paper are as high as 2231 S cm−1 and 1529 W m−1 K−1, superior to previously reported graphene papers. Structural analyses confirm that the ultrahigh conductivities are attributed to high quality of graphene sheets, their compact ordered stacking, and large graphitic crystalline domain size, which improve electron and phonon transport within basal plane of graphene sheet and between graphene sheets. [ABSTRACT FROM AUTHOR]

Abstract: An eco‐friendly biodegradable starch paper is introduced for use in next‐generation disposable organic electronics without the need for a planarizing layer. The starch papers are formed by starch gelatinization using a very small amount of 0.5 wt% polyvinyl alcohol (PVA), a polymer that bound to the starch, and 5 wt% of a crosslinker that bound to the PVA to improve mechanical properties. This process minimizes the additions of synthetic materials. The resultant starch paper provides a remarkable mechanical strength and stability under repeated movements. Robustness tests using various chemical solvents are conducted by immersing the starch paper for 6 h. Excellent nonpolar solvent stabilities are observed. They are important for the manufacture of organic electronics that use nonpolar solution processes. The applicability of the starch paper as a flexible substrate is tested by fabricating flexible organic transistors using pentacene, dinaphtho[2,3‐b:2′,3′‐f]thieno[3,2‐b]thiophene, and poly(dimethyl‐triarylamine) using both vacuum and solution processes. Electrically well‐behaved device performances are identified. Finally, the eco‐friendly biodegradability is verified by subjecting the starch paper to complete degradation by fungi in fishbowl water over 24 d. These developments illuminate new research areas in the field of biodegradable green electronics, enabling the development of extremely low‐cost electronics. [ABSTRACT FROM AUTHOR]

Information recording and encryption/decryption functions are essential due to the prevalence of counterfeiting activities and information leakage in the current age. However, the development of high‐resolution information recording and multistage information protection systems to achieve high data security levels, such as self‐erasing encrypted data and time‐controlled data handling, remains limited. Herein, inspired by the information‐recording structure of paper, a multiresponsive nanofiber‐reinforced poly(N‐isopropylacrylamide) (PNIPAM) hydrogel (NCPN hydrogel) with improved mechanical properties, solvent‐induced high‐resolution reversible information recording, self‐encryption, and multi‐decryption capabilities, is proposed. Due to the unique hydrophilic and hydrophobic structures of the hydrogel matrix, ethanol and other polar analogs can be applied as special inks to record information by changing the lower critical solution temperature to achieve the repeatable transmittance variation. The recorded information can be erased via water wiping or ethanol volatilization. Additionally, self‐encryption can be achieved and adjusted based on the ethanol volatilization time and concentration difference, and confidential information can be further decrypted in a water environment or under a thermal stimulus. Furthermore, several stable, repeatable, and fast‐response hydrogel‐based information‐recognition systems are designed and investigated. Therefore, the designed hydrogel‐based informational platform provides a universal information‐handling system allowing for the reversible recording of information, with self‐encryption and multidecryption capabilities. [ABSTRACT FROM AUTHOR]

The integration of fully printed transistors on low cost paper substrates compatible with roll-to-roll processes is demonstrated here. Printed electronics promises to enable a range of technologies on paper including printed sensors, RF tags, and displays. However, progress has been slow due to the paper roughness and ink absorption. This is solved here by employing gravure printing to print local smoothing pads that also act as an absorption barrier. This innovative local smoothing process retains desirable paper properties such as foldability, breathability, and biodegradability outside of electronically active areas. Atomic force microscopy measurements show significant improvements in roughness. The polymer ink and printing parameters are optimized to minimize ink absorption and printing artifacts when printing the smoothing layer. Organic thin film transistors (OTFT) are fabricated on top of this locally smoothed paper. OTFTs exhibit performance on par with previously reported printed transistors on plastic utilizing the same materials system (pBTTT semiconductor, poly-4-vinylphenol dielectric). OTFTs deliver saturation mobility approaching 0.1 cm2V-1s-1 and on-off-ratio of 3.2 × 104. This attests to the quality of the local smoothing, and points to a promising path for realizing electronics on paper. [ABSTRACT FROM AUTHOR]

Compared with traditional paper relying on cellulose, the polymeric paper written by light can satisfy more multi‐environmental stability and reusability for sustainable development. Herein, proposed for the first time, a novel multifunctional polymeric paper with a patch‐sewing structure is designed, presenting the reversible writing/re‐writing performance. Meanwhile, a series of Fe‐based oxides with various submicron structures inherited from metal–organic framework templates are reported, in which the optimum one exhibited 95.04% absorbance from the finite difference time domain simulation and realized photothermal conversion instantaneously (soaring to 300 °C within 38 s). Given the distinguished mechanical properties (the tensile strength of 21.34 MPa and elongation at break of 546.06%), shape‐memory ability, and multi‐environmental stability, the composites are perfect for information recording. Due to the addition of the liquid crystal phase serving as the ink on the paper, the stress concentration and destruction can be recorded on the surface while it can recover to the initial situation by near‐infrared irradiation. Moreover, the remote writing with precision triggered by a focused light source can be achieved in multiple situations (air, water, and ice), which paved the way for the next generation of paper, especially in extreme conditions like deep‐water or aerospace. [ABSTRACT FROM AUTHOR]

The possibility of exfoliating graphite into graphene sheets allows the researchers to produce a material, termed "graphene paper" (G‐paper), conductive as graphite but more flexible and processable. G‐paper is already used for electronic applications, like conductors, antennas, and heaters, outperforming metal conductors thanks to its high flexibility, lightness, chemical stability, and compatibility with polymeric substrates. Here, the effectiveness in the use of G‐paper for the realization of electrodes on flexible plastic substrates and textiles, and their applicability as amperometric sensors are demonstrated. The performance of these devices is compared with commercial platforms made of carbon‐based inks, finding that they outperform commercial devices in sensing nicotinamide adenine dinucleotide (NADH), a key molecule for enzymatic biosensing; the electrodes can achieve state‐of‐the‐art sensitivity (107.2 μA mm−1 cm−2) and limit of detection (0.6 × 10−6m) with no need of additional functionalization. Thanks to this property, the stable deposition of a suitable enzyme, namely lactate dehydrogenase, on the electrode surface is used as a proof of concept of the applicability of this new platform for the realization of a biosensor. The possibility of having a single material suitable for antennas, electronics, and now sensing opens new opportunities for smart fabrics in wearable electronic applications. [ABSTRACT FROM AUTHOR]

Kirigami is the art of paper cutting, and it is emerging as an elegant design and manufacturing solution in mechanical metamaterials. Currently, the majority of kirigami designs focus on shape‐morphing, but there is little attention on the remarkable mechanical properties they can produce: high strength to weight ratio where they can bear thousands of times of their own weight. This paper proposes a kirigami‐based, strong, yet lightweight metamaterial, which is created by folding pop‐up and pop‐down from a checkerboard pattern with blocks. To transform the kirigami metamaterial into arbitrary objects, the challenge lies in how to automatically design the kirigami folding to approximate the outline of the object. Herein, a computational model that is based on deploying discretized objects onto a planar sheet is proposed. Additionally, to achieve high strength, a glue‐free connector that can lock the collocated cuts in the folded configuration is designed. The standard compression tests show that the kirigami metamaterial, weighing 12.05 g, can carry 346.4 N payloads. Meanwhile, six examples of curved surfaces are prototyped to verify the shape transforming capability of the proposed kirigami metamaterial. This study paves the way towards using the kirigami technique for weight reduction in industrial applications. [ABSTRACT FROM AUTHOR]

A solution-based fabrication of flexible and light-weight light-emitting devices on paper substrates is reported. Two different types of paper substrates are coated with a surface-emitting light-emitting electrochemical cell (LEC) device: a multilayer-coated specialty paper with an intermediate surface roughness of 0.4 μm and a low-end and low-cost copy paper with a large surface roughness of 5 μm. The entire device fabrication is executed using a handheld airbrush, and it is notable that all of the constituent layers are deposited from solution under ambient air. The top-emitting paper-LECs are highly flexible, and display a uniform light emission with a luminance of 200 cd m−2 at a current conversion efficacy of 1.4 cd A−1. [ABSTRACT FROM AUTHOR]

Plastic‐based electronics fill the gaps in conventional rigid silicon‐based devices toward the applications in soft interfaces. However, people in the future should also consider their potential environmental impact if tons of non‐degradable plastics are applied. Silk fibroin is a superior substrate alternative for the development of "green" electronics; whereas, the brittleness of silk films is still a major limitation impeding their practical use. Different from the widely reported polyphasic composite approaches, here a trace‐ion‐assisted plasticization strategy is developed, and shape‐engineerable pure silk fibroin paper (PSFP) is prepared for the first time, which can be engraved and crumpled like a sheet of paper in the dry state. The PSFPs exhibit higher tensile fracture energy (14.4 ± 4 kJ m−2) than any typical plastic‐electronic‐substrates as far as it is known. The intrinsic brittleness of pure silk films is overcome, and the PSFP can be easily engineered to form periodic meshes, electronic prototypes, and kirigami‐based devices, which are beyond the reported regenerated silk films or silk composite films. Moreover, the scrape coating method employed here is simple, highly repeatable, and suitable for scaled production of low‐cost PSFP continuously. Collectively, the PSFP is generalizable to various shapes and devices, represents an ideal substrate alternative to plastic electronics. [ABSTRACT FROM AUTHOR]

Paper‐based electronics has attracted growing interest owing to many advantages of papers including low‐cost, abundance, flexibility, biocompatibility, and environmental friendliness. Despite recent progress in paper electronics, however, development of a high‐performance paper‐based triboelectric nanogenerator (TENG), which is a power‐generating device that converts mechanical energy into electric energy by coupling triboelectrification and electrostatic induction, remains a challenge mainly due to weak electron‐donating tendency of cellulose‐based papers. In this work, highly conductive ferroelectric cellulose composite papers containing silver nanowires and BaTiO3 nanoparticles are fabricated, and their successful application for realizing a large‐area TENG with enhanced electrical output performance is demonstrated. It is found that triboelectric charge generation on the ferroelectric cellulose composite paper can be promoted by simple poling treatment, which significantly enhances TENG performance. The ferroelectric cellulose composite paper–based TENG exhibits an electrical output performance that surpasses those of aluminum‐based and pristine cellulose–based TENGs by more than two times, as well as outstanding output stability without a noticeable degradation in performance during 10 000 cycles of a repeated pushing test. The work demonstrates the great potential of multifunctional cellulose‐based papers for TENG and other self‐powered electronic applications. [ABSTRACT FROM AUTHOR]

In this work, a facile methodology is discussed, involving fluoro-silanization followed by oxygen plasma etching, for the fabrication of surfaces with extreme wettabilities, i.e., surfaces that display all four possible combinations of wettabilities with water and different oils: hydrophobic-oleophilic, hydrophilic-oleophobic, omniphobic, and omniphilic. Open-channel, paper-based microfluidic devices fabricated using these surfaces with extreme wettabilities allow for the localization, manipulation, and transport of virtually all high- and low-surface tension liquids. This in turn expands the utility of paper-based microfluidic devices to a range of applications never before considered. These include, as demonstrated here, continuous oil-water separation, liquid-liquid extraction, open-channel microfluidic emulsification, microparticle fabrication, and precise measurement of mixtures' composition. Finally, the biocompatibility of the developed microfluidic devices and their utility for cell patterning are demonstrated. [ABSTRACT FROM AUTHOR]

An adaptable stimuli responsive system is proposed based on defective graphitic carbon nitride (d‐GCN)/polyvinyl alcohol (PVA) composite attached to different substrates. Nitrogen vacancies, introduced during synthesis via potassium doping, act as internal electron donors to enhance the photoreduction of redox dyes for quick reversible photochromism. This system can be applied as visible light responsive rewritable paper that offers high resolution for printed text, rapid activation/recoloration, multicolor functionality, and high cyclability. The defects also inhibit the d‐GCN particle growth resulting in smaller particle sizes over bulk samples, which enable the formation of transparent mechanochromic films. By altering the PVA/d‐GCN ratio in the composites, two mechanical stimuli responses are introduced by taking advantage of wrinkle and crack formation on the film surface. With a low d‐GCN concentration, mechanical scratching of the film causes the formation of surface wrinkles that alter the film transparency without damaging the film, allowing for text to be written on the surface that can be erased by moisture. With a high d‐GCN concentration, cracks developed on the surface scatter light when stretched, enabling the development of a strain dependent smart window. Both these mechanochromisms can be combined with the photochromism to develop multifunctional smart materials with widespread application. [ABSTRACT FROM AUTHOR]

Manufacturing of printed electronics relies on the deposition of conductive liquid inks, typically onto polymeric or paper substrates. Among available conductive fillers for use in electronic inks, carbon nanotubes (CNTs) have high conductivity, low density, processability at low temperatures, and intrinsic mechanical flexibility. However, the electrical conductivity of printed CNT structures has been limited by CNT quality and concentration, and by the need for nonconductive modifiers to make the ink stable and extrudable. This study introduces a polymer‐free, printable aqueous CNT ink, and, via an ambient direct‐write printing process, presents the relationships between printing resolution, ink rheology, and ink‐substrate interactions. A model is constructed to predict printed feature sizes on impermeable substrates based on Wenzel wetting. Printed lines have conductivity up to 10 000 S m−1. The lines are flexible, with <5% change in DC resistance after 1000 bending cycles, and <3% change in DC resistance with a bending radius down to 1 mm. Demonstrations focus on i) conformality, via printing CNTs onto stickers that can be applied to curved surfaces, ii) interactivity using a CNT‐based button printed onto folded paper structure, and iii) capacitive sensing of liquid wicking into the substrate itself. Facile integration of surface mount components on printed circuits is enabled by the intrinsic adhesion of the wet ink. [ABSTRACT FROM AUTHOR]

Direct formic acid fuel cells (DFAFCs) possess the advantages of high power density and theoretical cell potential. Exploring robust catalysts for electrochemical formic acid electro‐oxidation (FAO) is greatly essential for the wide spread uptake of DFAFCs. However, many electrodes with attractive catalysts suffer limited mass transport due to sluggish CO2 bubble growth and departure steps on its surface. In this study, a superaerophobic electrode is developed by depositing fern‐shaped palladium nanostructured arrays on the carbon paper (Pd‐nanoarray@CP). Its unique superaerophobic feature successfully facilitates the CO2 bubble releasing from the catalyst surface in a significantly small size. With the merits of specific nanoarray morphology, superior under water superaerophobicity, and rapid gas bubble release, the Pd‐nanoarray@CP shows fast charge/mass transport rate, high electrocatalytic activity, and great stability for FAO. A direct formic acid fuel cell equipped with the Pd‐nanoarray@CP anode is successfully fabricated on a microfluidic platform. A peak power density of 35.8 mW cm−2 and limiting current density of 173.3 mA cm−2 are obtained, respectively, which are 49.2% and 33.0% higher than that of conventional Pd‐black anodes. The electrode with superaerophobic interface allows deeper insight into the mechanism of FAO efficiency and holds promise for possible applications of commercially viable DFAFCs. [ABSTRACT FROM AUTHOR]

This paper describes the design and fabrication of electrically controlled paper actuators that operate based on the dimensional changes that occur in paper when the moisture absorbed on the surface of the cellulose fibers changes. These actuators are called 'Hygroexpansive Electrothermal Paper Actuators' (HEPAs). The actuators are made from paper, conducting polymer, and adhesive tape. They are lightweight, inexpensive, and can be fabricated using simple printing techniques. The central element of the HEPAs is a porous conducting path (used to provide electrothermal heating) that changes the moisture content of the paper and causes actuation. This conducting path is made by embedding a conducting polymer (PEDOT:PSS) within the paper, and thus making a paper/polymer composite that retains the porosity and hydrophilicity of paper. Different types of HEPAs (straight, precurved, and creased) achieved different types of motions (e.g., bending motion, accordion type motion). A theoretical model for their behavior is proposed. These actuators have been used for the manipulation of liquids and for the fabrication of an optical shutter. [ABSTRACT FROM AUTHOR]

The electrochromic (EC) polymer poly (3,4‐(2,2‐dimethylpropylenedioxy)thiophene) (PProDOT‐Me2) is expected to be used in flexible e‐paper displays because of its great optical modulation ability and inherent flexibility. While the EC effect is primarily determined by the anions and cations in the electrolyte, yet suffers from inorganic salt based on monovalent Li+ cations and corresponding anions, such as lithium perchlorate(LiClO4), lithium bis(trifluoromethane sulfonyl) imide (LiTFSI), and lithium trifluoromethane sulfonate (LiTRIF), which may impact the overall EC performance of the EC device caused by insufficient ion doping/de‐doping processes. Herein, the divalent viologen cation‐based ionogel (VGE) is developed to tackle the challenge. Owing to its more anions design, the doping/de‐doping process in the PProDOT‐Me2 is more sufficient, thereby enhancing the optical modulation range (ΔR = 39.4%) of PProDOT‐Me2, compared to monovalent Li+ cation‐based ionogel (ΔR = 13.3%). Meanwhile, the VGE has good interface contact with PProDOT‐Me2 and the flexible electrode, which makes the VGE‐based EC device (V‐ECD) exhibit commendable mechanical stability. To demonstrate the potential application in flexible e‐paper displays, the simple eight‐digit EC display device is assembled from seven V‐ECDs, each of which hasa high switching speed, robust cycling stability, and low operating energy consumption. [ABSTRACT FROM AUTHOR]

The intrinsic hydrophilicity of conventional dressings cannot achieve effective management of excessive biofluid around the wound bed, which inevitably causes infection and hinders wound healing. In addition, present dressings such as medical gauze or band aids have a limited stretching capability, which does not comply well with the skin deformation during muscle movement, thus impacting patient comfort. Herein, a Janus wound dressing is reported by assembling an external hydrophobic (HP) adhesive tape, a filter paper, and a polydimethylsiloxane (PDMS) Janus film. The PDMS Janus film as the primary dressing can unidirectionally remove biofluid away from the wound bed. The mechanism of the unidirectional biofluid transport is investigated, demonstrating that the stretching or bending of the Janus dressing is beneficial for unidirectional biofluid draining. It indicates that the Janus PDMS film has potential for practical applications on stretched or bended skin surface. In addition, in order to prevent bacterial infection, amoxicillin powder is uniformly encapsulated on the HP layer of Janus film, resulting in faster wound healing. This study is valuable for designing and fabricating next‐generation dressings with high performance for clinical applications. [ABSTRACT FROM AUTHOR]

Portable and wearable sensors have attracted considerable attention in the healthcare field because they can be worn or implanted into a human body to monitor environmental information. However, sensors cannot work independently and require power. Flexible in-plane micro-supercapacitor (MSC) is a suitable power device that can be integrated with sensors on a single chip. Meanwhile, paper is an ideal flexible substrate because it is cheap and disposable and has a porous and rough surface that enhances interface adhesion with electronic devices. In this study, a new strategy to integrate MSCs, which have excellent electrochemical and mechanical performances, with sensors on a single piece of paper is proposed. The integration is achieved by printing Ni circuit on paper without using a precoating underlay. Ink diffusion is also addressed to some degree. Meanwhile, a UV sensor is integrated on a single paper, and the as-integrated device shows good sensing and self-powering capabilities. MSCs can also be integrated with a gas sensor on one-piece paper and can be charged by connecting it to a solar cell. Thus, it is potentially feasible that a flexible paper can be used for integrating MSCs with solar cell and various sensors to generate, store, and use energy. [ABSTRACT FROM AUTHOR]

A highly flexible Mn3O4/reduced graphene oxide (rGO) nanohybrid paper with high electrical conductivity and high mass loading of Mn3O4 nanofibers (0.71 g cm−3) is developed via a facile gel formation and electrochemical reduction process, which is low-cost, environmental friendly, and easy to scale up. Confined Mn3O4 nanofibers are well dispersed within the rGO sheets, which demonstrate to be a promising cathode material for flexible asymmetric supercapacitors (ASCs). When coupled with an electrochemically reduced rGO paper as the anode, a flexible ASC device, based on the Mn3O4/rGO nanohybrid paper as the cathode, is assembled; and it demonstrates remarkable electrochemical performance: a high volumetric capacitance of 54.6 F cm−3 (546.05 mF cm−2), and remarkable volumetric energy and power density (0.0055 Wh cm−3 and 10.95 W cm−3) being achieved with excellent cycling ability. The nanohybrid paper shows great improvement for flexible energy devices in terms of electrochemical properties. [ABSTRACT FROM AUTHOR]

The present development of non-wafer-based photovoltaics (PV) allows supporting thin film solar cells on a wide variety of low-cost recyclable and flexible substrates such as paper, thereby extending PV to a broad range of consumer-oriented disposable applications where autonomous energy harvesting is a bottleneck issue. However, their fibrous structure makes it challenging to fabricate good-performing inorganic PV devices on such substrates. The advances presented here demonstrate the viability of fabricating thin film silicon PV cells on paper coated with a hydrophilic mesoporous layer. Such layer can not only withstand the cells production temperature (150 °C), but also provide adequate paper sealing and surface finishing for the cell's layers deposition. The substances released from the paper substrate are continuously monitored during the cell deposition by mass spectrometry, which allows adapting the procedures to mitigate any contamination from the substrate. In this way, a proof-of-concept solar cell with 3.4% cell efficiency (41% fill factor, 0.82 V open-circuit voltage and 10.2 mA cm−2 short-circuit current density) is attained, opening the door to the use of paper as a reliable substrate to fabricate inorganic PV cells for a plethora of indoor applications with tremendous impact in multi-sectorial fields such as food, pharmacy and security. [ABSTRACT FROM AUTHOR]

Constructing sodium‐ion battery anodes with efficient ion/electron transport and high cycling stability is significantly promising for applications but still remains challenging. Here, "three‐in‐one" multi‐level design is performed to develop a carbon‐coated phosphorous‐doped MoS2 anchored on carbon nanotube paper (P‐MoS2@C/CNTP). The Na+ diffusion and electron transport, as well as the structural stability of the whole anode are simultaneously enhanced through the synergistically optimization of P‐MoS2@C/CNTP at atomic, nanoscopic, and macroscopic levels. Resulted from the multi‐level modification, the synergetic mechanism has been demonstrated by electrochemical measurement and theoretical calculation. As a result, the free‐standing P‐MoS2@C/CNTP anode presents a high rate performance (150 mA h g−1 at 5 A g−1) and a long cycling life (1 A g−1, 1200 cycles, 249 mA h g−1). This work provides a new approach to the design and fabrication of high‐performance conversion‐type electrode materials for rechargeable batteries application. [ABSTRACT FROM AUTHOR]

Self-supported electrodes comprising carbon fiber paper (CP) integrated with bifunctional nickel phosphide (Ni-P) electrocatalysts are fabricated by electrodeposition of Ni on functionalized CP, followed by a convenient one-step phosphorization treatment in phosphorus vapor at 500 °C. The as-fabricated CP@Ni-P electrode exhibits excellent electrocatalytic performance toward hydrogen evolution in both acidic and alkaline solutions, with only small overpotentials of 162 and 250 mV, respectively, attaining a cathodic current density of 100 mA cm−2. Furthermore, the CP@Ni-P electrode also exhibits superior catalytic performance toward oxygen evolution reaction (OER). An exceptionally high OER current of 50.4 mA cm−2 is achieved at an overpotential of 0.3 V in 1.0 m KOH. The electrode can sustain 10 mA cm−2 for 180 h with only negligible degradation, showing outstanding durability. Detailed microstructural and compositional studies reveal that upon OER in alkaline solution the surface Ni-P is transformed to NiO covered with a thin Ni(OH) x layer, forming a Ni-P/NiO/Ni(OH) x heterojunction, which presumably enhances the electrocatalytic performance for OER. Given the well-defined bifunctionality, a full alkaline electrolyzer is constructed using two identical CP@Ni-P electrodes as cathode and anode, respectively, which can realize overall water splitting with efficiency as high as 91.0% at 10 mA cm−2 for 100 h. [ABSTRACT FROM AUTHOR]

As a low dimensional crystal, graphene attracts great attention as heat dissipation material due to its unique thermal transfer property exceeding the limit of bulk graphite. In this contribution, flexible graphene-carbon fiber composite paper is fabricated by depositing graphene oxide into the carbon fiber precursor followed by carbonization. In this full-carbon architecture, scaffold of one-dimensional carbon fiber is employed as the structural component to reinforce the mechanical strength, while the hierarchically arranged two-dimensional graphene in the framework provides a convenient pathway for in-plane acoustic phonon transmission. The as-obtained hierarchical carbon/carbon composite paper possesses ultra-high in-plane thermal conductivity of 977 W m−1 K−1 and favorable tensile strength of 15.3 MPa. The combined mechanical and thermal performances make the material highly desirable as lateral heat spreader for next-generation commercial portable electronics. [ABSTRACT FROM AUTHOR]

Along with reduced graphene oxide (RGO), water soluble Prussian blue nanoparticles (PBNPs, around 6 nm) are synthesized and broadly characterized. These two types of highly stable, low-cost and chemically compatible nanomaterials are exploited as building ingredients to prepare electrically enhanced and functionally endorsed nanohybrid electrocatalysts, which are further transformed into free-standing graphene papers. PBNPs doped graphene papers show highly efficient electrocatalysis towards reduction of hydrogen peroxide and can be used alone as flexible chemical sensors for potential applications in detection of hydrogen peroxide or/and other organic peroxides. The as-prepared PBNPs-RGO papers are further capable of biocompatible accommodation of enzymes for development of free-standing enzyme based biosensors. In this regard, glucose oxidase is used as an example for electrocatalytic oxidation and detection of glucose. The present work demonstrates a facile and highly reproducible way to construct free-standing and flexible graphene paper doped with electroactive catalyst. Thanks to high stability, low-cost and efficient electrocatalytic characteristics, this kind of nanohybrid material has potential to be produced on a large scale, and offers a broad range of possible applications, particularly in the fabrication of flexible sensing devices and as a platform for electrocatalytic energy conversion. [ABSTRACT FROM AUTHOR]

Freestanding, robust electrodes with high capacity and long lifetime are of critical importance to the development of advanced lithium–sulfur (Li–S) batteries for next‐generation electronics, whose potential applications are greatly limited by the lithium polysulfide (LiPS) shuttle effect. Solutions to this issue have mostly focused on the design of cathode hosts with a polar, sulfurphilic, conductive network, or the introduction of an extra layer to suppress LiPS shuttling, which either results in complex fabrication procedures or compromises the mechanical flexibility of the device. A robust Ti3C2Tx/S conductive paper combining the excellent conductivity, mechanical strength, and unique chemisorption of LiPSs from MXene nanosheets is reported. Importantly, repeated cycling initiates the in situ formation of a thick sulfate complex layer on the MXene surface, which acts as a protective membrane, effectively suppressing the shuttling of LiPSs and improving the utilization of sulfur. Consequently, the Ti3C2Tx/S paper exhibits a high capacity and an ultralow capacity decay rate of 0.014% after 1500 cycles, the lowest value reported for Li–S batteries to date. A robust prototype pouch cell and full cell of Ti3C2Tx/S paper // lithium foil and prelithiated germanium are also demonstrated. The preliminary results show that Ti3C2Tx/S paper holds great promise for future flexible and wearable electronics. [ABSTRACT FROM AUTHOR]

Paper has remained the world's most-widely accessible information medium even as sustainable and reusable paper replacements have attracted increasing attention. Here, an ink-free rewritable paper concept is developed that combines recent developments in photonic crystals, shape memory polymers, and electroactive polymers in a nanocomposite that matches the benefits of paper as a zero-energy, long-term data storage medium, but provides the additional advantage of rewritability. The rewritable paper consists of a ferroferric oxide-carbon (Fe3O4@C) core-shell nanoparticle (NP)-based photonic crystal embedded in a bistable electroactive polymer (BSEP). Electrical actuation induces large deformation in the z-axis of the nanocomposite, creating distinct color change in the actuated area. This nanocomposite stores high fidelity color images without inks, the images remain stable after more than a year of storage in ambient conditions, and the stored images can then be rewritten over 500 times without degrading. A seven-segment numerical display is also demonstrated. [ABSTRACT FROM AUTHOR]

Abstract: A low‐cost and easy‐to‐fabricate microchip remains a key challenge for the development of true point‐of‐care (POC) diagnostics. Cellulose paper and plastic are thin, light, flexible, and abundant raw materials, which make them excellent substrates for mass production of POC devices. Herein, a hybrid paper–plastic microchip (PPMC) is developed, which can be used for both single and multiplexed detection of different targets, providing flexibility in the design and fabrication of the microchip. The developed PPMC with printed electronics is evaluated for sensitive and reliable detection of a broad range of targets, such as liver and colon cancer protein biomarkers, intact Zika virus, and human papillomavirus nucleic acid amplicons. The presented approach allows a highly specific detection of the tested targets with detection limits as low as 102 ng mL−1 for protein biomarkers, 103 particle per milliliter for virus particles, and 102 copies per microliter for a target nucleic acid. This approach can potentially be considered for the development of inexpensive and stable POC microchip diagnostics and is suitable for the detection of a wide range of microbial infections and cancer biomarkers. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) papers are candidates for structural materials in modern technology due to their high specific strength and stiffness. The relationship between their mechanical properties and structure needs to be systematically investigated before they can be applied to the broad range fields where they have potential. Herein, the mechanical properties of GO papers with various thicknesses (0.5-100 μm) are investigated using bulge and tensile test methods; this includes the Young's modulus, fracture strength, fracture strain, and toughness. The Young's modulus, fracture strength, and toughness are found to decrease with increasing thickness, with the first two exhibiting differences by a factor of four. In contrast, the fracture strain slightly increases with thickness. Transmission electron, scanning electron, and atomic force microscopy indicate that the mechanical properties vary with thickness due to variations in the inner structure and surface morphology, such as crack formation and surface roughness. Thicker GO papers are weaker because they contain more voids that are produced during the fabrication process. Surface wrinkles and residual stress are found to result in increased fracture strain. Determination of this structure-property relationship provide improved guidelines for the use of GO-based thin-film materials in mechanical structures. [ABSTRACT FROM AUTHOR]

In the last couple decades, several viral outbreaks resulting in epidemics and pandemics with thousands of human causalities have been witnessed. The current Covid‐19 outbreak represents an unprecedented crisis. In stopping the virus' spread, it is fundamental to have personal protective equipment and disinfected surfaces. Here, the development of a TiO2 nanowires (TiO2NWs) based filter is reported, which it is believed will work extremely well for personal protective equipment (PPE), as well as for a new generation of air conditioners and air purifiers. Its efficiency relies on the photocatalytic generation of high levels of reactive oxygen species (ROS) upon UV illumination, and on a particularly high dielectric constant of TiO2, which is of paramount importance for enhanced wettability by the water droplets carrying the germs. The filter pore sizes can be tuned by processing TiO2NWs into filter paper. The kilogram‐scale production capability of TiO2NWs gives credibility to its massive application potentials. [ABSTRACT FROM AUTHOR]

Colorful blue phase liquid crystal (BPLC) patterns have attracted wide research attention owing to their intriguing and advantageous properties and promising applications. However, it remains a challenge to develop novel and high‐resolution patterns from BPLC owing to the complicated synthetic procedure for the functional molecules. This study reports a high‐resolution "live" pattern by well‐designed diffusion of 5CB ink on the wettability‐modified BPLC networks. Interestingly, the shape and color of the as‐prepared pattern change with time, which results in unique spectra change of the printed pattern, "first red‐shift and subsequent blue‐shift of the stopband position" and "continuous growth in reflectivity intensity" with time. The hydrophobic substrate greatly suppresses the random spreading and diffusion of ink, contributing to high‐resolution patterns. The promising applications of live patterns for program display and active labels are demonstrated. Various high‐resolution erasable colorful patterns are obtained. The structure reconfiguration of the writing and erasing processes is proved by transmitted electronic microscope images and Kossel diffraction diagrams, which ensures the reversible writing/erasing of the pattern on the membrane. This work is of significance for the development of novel rewritable paper and high‐quality optic devices based on BPLC materials. [ABSTRACT FROM AUTHOR]

Due to the high blood glucose and low oxygen environment in diabetes wounds, complex pathological problems arise, such as failure to upregulate healing factors, biological barriers generation, microvascular lesions, and skin neuropathy. Inspired by nature and traditional Chinese paper‐cutting technology, polypeptide deoxyribonucleic acid (DNA) hydrogel microneedles (MNs) (P‐DNA gel MNs) are prepared. The obtained P‐DNA gel MNs possess optimized structure and large deformability, providing excellent clamping, stability, skin penetration, large deformation, tissue adhesion, and antibacterial properties. By incorporating extracellular vesicles (EVs) extracted under hypoxia (H‐EVs‐hypoxia), P‐DNA gel MNs can regulate tissue microenvironment, scavenge free radicals, and reduce inflammation. Notably, P‐DNA gel MNs integration system activates immune regulation and beneficial pathways, promoting neurogenesis and angiogenesis, reducing pathological pain, and achieving high‐quality healing. Overall, P‐DNA gel MNs system presents a fundamental mechanism for clinical transformation in treating diabetes wounds. [ABSTRACT FROM AUTHOR]

Paper has been utilized as an ideal platform for chemical, biological, and mechanical sensing for its fibrous structures and properties in addition to its low cost. However, current studies on pressure‐sensitive papers have not fully utilized the unique advantages of papers, such as printability, cuttability, and foldability. Moreover, the existing resistive, capacitive, and triboelectric sensing modalities have long‐standing challenges in sensitivity, noise‐proofing, response time, linearity, etc. Here, a novel flexible iontronic sensing mechanism, referred to as iontronic sensing paper (ISP), is introduced to the classic paper substrates by incorporating both ionic and conductive patterns into an all‐in‐one flexible sensing platform. The ISP can then be structured into 2D or 3D tactile‐sensitive origamis only by the paper‐specific manipulations of printing, cutting, folding, and gluing. Notably, the ISP device possesses a device sensitivity of 10 nF kPa−1 cm−2, which is thousands of times higher than that of the commercial counterpart, a resolution of 6.25 Pa, a single‐millisecond response time, and a high linearity (R2 > 0.996). Benefiting from the unique properties of the fibrous paper structures and its remarkable performances, the ISP devices hold enormous potential for the emerging human–machine interfaces, including smart packaging, health wearables, and pressure‐sensitive paper matrix. A flexible iontronic sensing paper with both ionic and conductive patterns as an all‐in‐one flexible sensing platform, with direct printability, custom cuttability, and 3D foldability is structured into a pressure‐sensing device by paper‐specific manipulations in the forms of a 2D device or a 3D tactile‐sensing‐enabled origami with remarkable sensitivity, resolution, response linearity, and response time. [ABSTRACT FROM AUTHOR]

Using an innovative, tissue-independent approach to decellularized tissue processing and biomaterial fabrication, the development of a series of 'tissue papers' derived from native porcine tissues/organs (heart, kidney, liver, muscle), native bovine tissue/organ (ovary and uterus), and purified bovine Achilles tendon collagen as a control from decellularized extracellular matrix particle ink suspensions cast into molds is described. Each tissue paper type has distinct microstructural characteristics as well as physical and mechanical properties, is capable of absorbing up to 300% of its own weight in liquid, and remains mechanically robust ( E = 1-18 MPa) when hydrated; permitting it to be cut, rolled, folded, and sutured, as needed. In vitro characterization with human mesenchymal stem cells reveals that all tissue paper types support cell adhesion, viability, and proliferation over four weeks. Ovarian tissue papers support mouse ovarian follicle adhesion, viability, and health in vitro, as well as support, and maintain the viability and hormonal function of nonhuman primate and human follicle-containing, live ovarian cortical tissues ex vivo for eight weeks postmortem. 'Tissue papers' can be further augmented with additional synthetic and natural biomaterials, as well as integrated with recently developed, advanced 3D-printable biomaterials, providing a versatile platform for future multi-biomaterial construct manufacturing. [ABSTRACT FROM AUTHOR]