Search

The wide range of pressure detection and the exceptional linearity are essential performance parameters for flexible pressure sensors, enabling them to adapt to diverse scenarios and acquire information accurately. However, currently available "ultra‐wide range" piezoresistive sensors lack an optimal solution that effectively balances sensing properties, device thickness, and process cost. This study proposes a distinctive approach by introducing a Janus conductive structure assembled with dual resistive sensitive layers. The design allows for a pressure‐induced staged transformation of the current transport path, effectively mitigating variations and saturation in sensor resistance over a wide pressure range. The resulting piezoresistive sensor demonstrates an unprecedented detection range of 0–3800 kPa, showcasing remarkable sensitivity of 4.11 kPa−1 and outstanding linearity of 99.9% within the range of 0–1000 kPa. Additionally, the sensor boasts a thickness of only ≈200 µm, made possible through the utilization of a cellulose nanofibers material matrix. These performance achievements stand at the forefront when compared to existing reports. This research explores the potential applications of these sensors and extended arrays in the domains of human health and motion monitoring. It investigates their utility in gait analysis for assisted posture correction, as well as in the assessment and rehabilitation of gait instability. [ABSTRACT FROM AUTHOR]

A simple, environmentally friendly and efficient montmorillonite (MMT)‐metal ion (Me: Mg2+, Ca2+, Fe3+ and Zn2+)‐carboxymethyl cellulose (CMC) organic–inorganic hybrid film is successfully applied to flame retardant cellulose paper through layer‐by‐layer self‐assembly (LbL) technology. Using SEM, TGA, XPS, air permeability test and horizontal flammability test to characterize its surface morphology, thermal stability, air permeability and flame retardancy. The results show that MMT‐Me‐CMC system can endow cellulose paper with high flame retardancy properties, and different metal ions have different contributions to the flame retardancy. MMT with multi‐layer structure and high specific surface area is beneficial to reduce the air permeability of paper, thereby effectively reducing the flammability of flammable pyrolysis gas and the transfer of heat. The XPS analysis shows that the Zn2+ flame retardant system promotes the formation of graphitized char in the condensed phase. Meanwhile, the possible flame‐retardant mechanism of the system is clarified. Zn2+ replaces Al3+ in MMT, thus increasing the active acidic catalytic sites on MMT. This promotes the carbonization of degradation products and forms graphitized clay‐rich char. This work provides a simple and efficient LbL preparation strategy and provides a reference for the catalytic role of metal ions in the flame retardancy of cellulose paper. [ABSTRACT FROM AUTHOR]

DNA is a promising material for high density and long‐term archival data storage. In addition to algorithms for encoding digital information into DNA sequences, the DNA writing (chemical synthesis) and reading (DNA sequencing), the preservation of DNA mixtures with high sequence diversity is another critical issue for sustainable, long‐term, and large‐scale DNA data storage. Here, this work demonstrates a method for low‐cost, convenient and sustainable DNA data storage on cellulose paper. A DNA pool comprising thousands of sequences, in which archival data are encoded, is conveniently stored on a cellulose paper with a calculated density as high as 15 TB per mm3 through electrostatic adsorption. This work demonstrates that these digitally encoded DNA pools can be stable for years on the cellulose paper after drying even when directly exposed to air. Furthermore, the reversible electrostatic adsorption enables repeated loading/retrieval of DNA on/off cellulose paper. Therefore, this sustainable DNA preservation on cellulose paper through the convenient electrostatic adsorption exhibits a great advantage in terms of storage capacity and cost that is crucial for practical systems to achieve large‐scale and long‐time data storage. [ABSTRACT FROM AUTHOR]

A novel strategy is proposed to enhance the electrochemical performance of polypyrrole (PPy)‐coated cellulose paper (PCP)‐based supercapacitor by increasing the reaction interface between hydrophobic pyrrole and hydrophilic FeCl3 solution. Paper is pretreated with regenerated cellulose (RC) to increase its specific surface area, which lays the foundation for increasing the reaction interface between pyrrole and FeCl3 in the following in situ polymerization while providing more adsorption sites for PPy. The RC‐pretreated paper is first impregnated with pyrrole, followed by removing surplus pyrrole occupied by the internal pores of paper prior to the impregnation of FeCl3 solution, aiming to increase the reaction interface between pyrrole and FeCl3 solution. Consequently, the as‐prepared PCP electrode exhibits a PPy loading of 4.2 mg cm−2, which is twofold higher than unpretreated PCP electrodes (2 mg cm−2). Moreover, a solid‐state supercapacitor assembled with PCP electrodes presents a 58 mF cm−2 areal capacitance at 2 mA cm−2 (equivalent to 140.5 F g−1 at 0.5 A g−1), a 33.1 µWh cm−2 energy density at a power density of 0.60 mW cm−2, and excellent cycling stability with a capacitance retention of 91.6% after 10 000 CV cycles. This work offers a new insight toward improving the electrochemical performance of PCP‐based supercapacitor. [ABSTRACT FROM AUTHOR]

Developing highly efficient electromagnetic interference (EMI) shielding materials with outstanding mechanical properties are urgently desirable for portable device hardware and flexible electronic devices. Herein, a highly conductive and flexible silver nanowires/graphene nanosheets/cellulose (AgNWs/GNSs/cellulose) composite paper with particular three‐layered structures is fabricated via vacuum assisted filtered and coating method. The prepared composites exhibit excellent EMI shielding property due to the unique layered structure. By changing the order of the conductive layers, the overall shielding performance can be further improved. An outstanding EMI shielding effectiveness (SE) of 53.3 dB is achieved with a thickness of only 0.17 mm. The composites show prominent bending resistance, which is proved by 1000 times of repeated bending leading to no obvious changes in structure. Moreover, the prepared composites exhibit excellent mechanical properties. Therefore, it is expected that this work will open up a facile strategy for exploiting materials with excellent EMI shielding properties and mechanical performance. [ABSTRACT FROM AUTHOR]

Developing new energy technology is a significant challenge in the context of the energy crisis. As a novel energy conversion device to convert mechanical energy into electricity, the triboelectric nanogenerator (TENG) has attracted significant attention in the past few years. The choice of component materials directly affects the cost, environmental performance, output performance, and preparation process of a TENG. In recent years, cellulose paper has become an ideal material for fabricating a TENG due to its lightweight, biodegradability, low‐cost, high flexibility, environmental friendliness, porosity, and easy modification. Cellulose paper‐based TENG has become a hot topic in the field of green energy. This paper systematically summarizes the research progress of the cellulose paper‐based TENG. The advantages of cellulose paper as raw material to fabricate a TENG, followed by introducing the different roles of cellulose paper in paper‐based TENGs, are first discussed. Then the recent progress in energy storage, performance optimization methods, hybridization, and applications of cellulose paper‐based TENGs is successively elaborated. Finally, some perspectives and challenges for the future development of cellulose paper‐based TENG are discussed to provide guidance. [ABSTRACT FROM AUTHOR]

The high‐efficiency conversion of water drop mechanical energy into electrical energy has always been an urgent issue in the development and utilization of raindrop energy. In this work, a novel drum‐like triboelectric nanogenerator (D‐TENG) with robust self‐cleaning superhydrophobic features is developed to harvest water drop energy. An elastic superhydrophobic cellulose paper is created by spray‐coating nanofumed silica dispersed in a thermoplastic elastomer solution, followed by treatment with triethoxy‐1H,1H,2H,2H‐tridecafluoro‐n‐octylsilane. When raindrops hit the D‐TENG surface, the superhydrophobic cellulose paper will vibrate and periodic contact and separation with polytetrafluoroethylene will occur to generate electricity. The results demonstrate that when a 6 mm water drop falls from a height of 2.5 m and hits the D‐TENG, the generated voltage output can reach a peak of 21.6 V and charge transfer of 10 nC. The output power of the D‐TENG can reach 16 µW per droplet, which is more than 13.3 times that generated from the previous TENGs based on the electrostatic induction of water droplets. These results indicate that the superhydrophobic cellulose paper‐based D‐TENG is potentially a strong candidate for harvesting energy from raindrops, thereby making it a promising sustainable energy source for next‐generation electronics. [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]

A rhodamine‐based colorimetric and fluorescent pH chemosensor (RhA) was designed and synthesized via a coupling reaction between rhodamine ethylenediamine and succinic anhydride. RhA showed excellent pH response in aqueous solutions. In addition, common cations (Na+, K+, Ag+, Mg2+, Ca2+, Pb2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, Al3+, Cr3+, Fe3+, Au3+, Pt2+, and Ru2+) did not interfere with the pH response. As it has the potential to be used as a portable pH sensor, RhA was immobilized on activated cellulose paper using N,N'‐dicyclohexylcarbodiimide (DCC) and N,N'‐dimethylpyridin‐4‐amine (DMAP) as the coupling reagent to obtain a composite pH sensor (CP‐RhA). CP‐RhA was characterized by ATR‐FTIR, UV–vis, and fluorescence spectroscopy, and by scanning electron microscopy (SEM). CP‐RhA showed a rapid response in the pH range 1–8 through color and fluorescence changes. DFT calculations showed a blue‐shifted spectrum in the protonated form compared to the neutral form. Moreover, the pH sensor paper could be reused by dipping in NaOH. Thus, our work demonstrates the potential of the rhodamine dye composite for visualizing pH changes in real systems. [ABSTRACT FROM AUTHOR]

The existing research on furfural analysis mainly focuses on the relationship between the furfural content in oil and the degree of polymerization (DP) of the paper, which are always obtained by accelerated thermal aging at high temperatures. However, the operating temperature of a winding is relatively low, approximately 60°C to 90°C. Thus, the relationship established at high temperature may be not suitable for the operating temperatures. In this research, aging tests of oil‐paper systems at different temperatures (from 100°C to 130°C) were carried out, with the DP, furfural content in oil and furfural content in paper being measured regularly to analyze the effect of temperature variation on the production and diffusion behavior of furfural in oil–paper insulation. The results show that temperature influences the production of furfural, i.e., there is no obvious difference in the amount of furfural produced by paper in the initial aging periods; however, a higher temperature results in more furfural being produced when the DP decreases to values below 600. An obvious diffusion process occurs after furfural is produced in paper in accelerated aging experiments, resulting in most of the furfural content remaining in the cellulose paper in the initial aging period. [ABSTRACT FROM AUTHOR]

A general anion-sensing platform is reported based on a portable and cost-effective ion-selective optode and a smartphone detector equipped with a color analysis app. In contrast to traditional anion-selective optodes using a hydrophobic polymer and/or plasticizer to dissolve hydrophobic sensing elements, the new optode relies on hydrophilic cellulose paper. The anion ionophore and a lipophilic pH indicator are inkjet-printed and adsorbed on paper and form a 'dry' hydrophobic sensing layer. Porous cellulose sheets also allow the sensing site to be modified with dried buffer that prevents any sample pH dependence of the observed color change. A highly selective fluoride optode using an AlIII-porphyrin ionophore is examined as an initial example of this new anion sensing platform for measurements of fluoride levels in drinking water samples. Apart from Lewis acid-base recognition, hydrogen bonding recognition is also compatible with this sensing platform. [ABSTRACT FROM AUTHOR]

Flexible broadband photodetectors based on 2D MoS2 have gained significant attention due to their superior light absorption and increased light sensitivity. However, pristine MoS2 has absorption only in visible and near IR spectrum. This paper reports a paper-based broadband photodetector having ZnS-MoS2 hybrids as active sensing material fabricated using a simple, cost effective two-step hydrothermal method wherein trilayer MoS2 is grown on cellulose paper followed by the growth of ZnS on MoS2. Optimization in terms of process parameters is done to yield uniform trilayer MoS2 on cellulose paper. UV sensing property of ZnS and broadband absorption of MoS2 in visible and IR, broadens the range from UV to near IR. ZnS plays the dual role for absorption in UV and in the generation of local electric fields, thereby increasing the sensitivity of the sensor. The fabricated photodetector exhibits a higher responsivity toward the visible light when compared to UV and IR light. Detailed studies in terms of energy band diagram are presented to understand the charge transport mechanism. This represents the first demonstration of a paper-based flexible broadband photodetector with excellent photoresponsivity and high bending capability that can be used for wearable electronics, flexible security, and surveillance systems, etc. [ABSTRACT FROM AUTHOR]

A new approach exploiting the dual properties of thiol-grafted cellulose paper for promoting copper-catalyzed [3+2]-cycloadditions of organic azides with alkynes and adsorbing residual copper species in solution was developed. The thiol-grafted cellulose paper, used as a paper strip, effects the reduction of CuII to catalytically active CuI and acts as a powerful adsorbent for copper, thereby facilitating the work-up process and leaving the crude mixture almost free of copper residues after a single filtration. [ABSTRACT FROM AUTHOR]

Cellulose paper (CP)-based asymmetrical thin film supercapacitors (ATFSCs) have been considered to be a novel platform for inexpensive and portable devices as the CP is low-cost, lightweight, and can be rolled or folded into 3D configurations. However, the low energy density and poor cycle stability are serious bottlenecks for the development of CP-based ATFSCs. Here, sandwich-structured graphite/Ni/Co2NiO4-CP is developed as positive electrode and the graphite/Ni/AC-CP as negative electrode for flexible and high-performance ATFSCs. The fabricated graphite/Ni/Co2NiO4-CP positive electrode shows a superior areal capacitance (734 mF/cm2 at 5 mV/s) and excellent cycling performance with ≈97.6% Csp retention after 15 000 cycles. The fabricated graphite/Ni/AC-CP negative electrode also exhibits large areal capacitance (180 mF/cm2 at 5 mV/s) and excellent cycling performance with ≈98% Csp retention after 15 000 cycles. The assembled ATFSCs based on the sandwich-structured graphite/Ni/Co2NiO4-CP as positive electrode and graphite/Ni/AC-CP as negative electrode exhibit large volumetric Csp (7.6 F/cm3 at 5 mV/s), high volumetric energy density (2.48 mWh/cm3, 80 Wh/kg), high volumetric power density (0.79 W/cm3, 25.6 kW/kg) and excellent cycle stability (less 4% Csp loss after 20 000 cycles). This study shows an important breakthrough in the design and fabrication of high-performance and flexible CP-based electrodes and ATFSCs. [ABSTRACT FROM AUTHOR]

Flexible, biocompatible, and light‐weight power sources are urgently required due to their promising application in wearable electronics. Organic‐inorganic hybrid lead halide perovskite solar cells (PSCs) with their impressive efficiency and scalable processing capability have emerged as promising candidates for efficient and reliable power sources for wearable electronics. However, the progress in developing low‐cost and efficient flexible PSCs has been confined to Poly(ethylene terephthalate) or metal foil substrates and difficulty to design PSCs on other easily accessible low‐cost substrates such as cellulose paper. Herein, the authors report the hole transport material (HTM)‐free flexible PSCs fabricated on abundant, low‐cost, and biocompatible cellulose paper substrate for the first time. The highest PCE of 9.05% for the paper based flexible HTM‐free PSC is achieved and the device could maintain over 75% of its initial PCE after 1000 bending cycles, demonstrating good stability against bending deformation. Our findings provide an avenue to fabricate reliable power source for wearable electronics. Cellulose paper, as one of the four great inventions of China, possesses admirable properties such as biocompatible, biodegradable, and low‐cost, making it a promising alternative to conventional substrates for perovskite solar cells (PSCs). A flexible hole‐transport‐material (HTM)‐free PSC with PCE of 9.05% is fabricated successfully on the cellulose paper for the first time, which could be utilized in wearable devices. [ABSTRACT FROM AUTHOR]