Scalable Fabrication Strategy Research Articles

Facile and Scalable Fabrication of Regenerated Cellulose Microspheres with High Strength and Porosity as a Potential Matrix for Hemoperfusion

For acquiring an ideal sorbent for hemoperfusion, three crucial problems should be addressed: 1. The gap between the stacked sorbents should be larger than the blood cells, around 600 μm, for a continuous pass-through of blood in a hemoperfusion device. 2. The hemoperfusion device should maintain at least a 190 ml/min flow rate. 3. Specific binding on the sorbents is required to absorb the harmful agent in blood. In this research we developed a low-surfactant emulsification technique to prepare physically crosslinked cellulose microspheres (CMs). The particle size of the CMs could be tuned from 150 μm to 1000 μm. Three dehydration methods also regulated the mechanical properties of the CMs. The perfusion column stacked by physically crosslinked CMs, after being treated by an ethanol bath, could withstand pressure induced by a flow rate of 190 ml/min. The adsorption processes of hydrophobic alkyl carbon chain (C18) modified CMs for bilirubin conformed to the Langmuir isothermal adsorption model, which indicated that the bilirubin adsorption by C18 grafted CMs mainly relied on the interaction between C18 and bilirubin. In summary, a facile, scalable and low-surfactant fabrication strategy was developed to synthesize regenerated cellulose microspheres with high strength and porosity as a promising absorbent for hemoperfusion.

Scalable exothermic synthesis of sprout-like Ni-Co-Fe trimetallic oxide nanoparticles anchored on N-doped carbon nanotubes as bifunctional oxygen catalysts for zinc-air batteries

Zn-air batteries (ZABs) offer a high specific energy density, cost-effectiveness, and eco-friendliness. Hence, they are attractive candidates for use as sustainable energy-storage devices. However, their practical applications are limited by their high bifunctional oxygen evolution reaction/oxygen reduction reaction (OER/ORR) overpotential and sluggish kinetics. To address these limitations, in this study, a highly active bifunctional oxygen catalyst, TNPs@N-CNT, is developed, in which Ni-Co-Fe trimetallic nanoparticles are anchored on N-doped carbon networks. TNPs@N-CNT is synthesized via the thermally driven combustion of collodion fuel. The carbonization of melamine foam containing pyridinic N in TNPs@N-CNT enhances the ORR and affords a high catalytic surface area and high electrical conductivity. Morphological studies and chemical characterization aid in finely tuning the thermal processing conditions, affording a TNPs@N-CNT suitable for charge transfer. TNPs@N-CNT shows enhanced ORR activity (half-wave potential = 0.62 V and onset potential = 1.49 V) in alkaline media. A ZAB with TNPs@N-CNT as the air cathode exhibits an output power density of 90 mW cm−2 and excellent cycling stability for over 200 h, outperforming previously reported carbon-supported precious-metal catalysts. This tunable and scalable fabrication strategy could promote the development of novel mesoporous structures combined with high-efficiency multi-metallic catalysts for applications in energy-storage systems.

Eco-friendly bamboo pulp foam enabled by chitosan and phytic acid interfacial assembly of halloysite nanotubes: Toward flame retardancy, thermal insulation, and sound absorption

Lightweight, porous cellulose foam is an attractive alternative to traditional petroleum-based products, but the intrinsic flammability impedes its use in construction. Herein, an environmentally friendly strategy for scalable fabrication of flame-retardant bamboo pulp foam (BPF) using a foam-forming technique followed by low-cost ambient drying is reported. In the process, a hierarchical structure of halloysite nanotubes (HNT) was decorated onto bamboo pulp fibers through layer-by-layer assembling of chitosan (CS) and phytic acid (PA). This modification retained the highly porous microcellular structure of the resultant BPF (92 %–98 %). It improved its compressive strength by 228.01 % at 50 % strain, endowing this foam with desired thermal insulation properties and sound absorption coefficient comparable to commercial products. More importantly, this foam possessed exceptional flame retardancy (47.05 % reduction in the total heat release and 95.24 % reduction in the total smoke production) in cone calorimetry, and it showed excellent extinguishing performance, indicating considerably enhanced fire safety. These encouraging results suggest that the flame retardant BPF has the potential to serve as a renewable and cost-effective alternative to traditional foam for applications in acoustic and thermal insulation.

Highly-Efficient and Robust Zn Anodes Enabled by Sub-1-µm Zincophilic CrN Coatings.

For exploring advanced Zn-ion batteries (ZIBs) with long lifespan and high Coulombic efficiency (CE), the critically important point is to limit the undesired Zn dendrite and parasitic reactions. Among the coating for electrode is a promising strategy, relying on the trade-off between its thickness and stability to achieve the ultra-stable Zn anodes in ZIBs. Herein, a submicron-thick (≈0.4µm) zincophilic CrN coatings are fabricated by a facile and industry-compatible magnetron sputtering approach. It is exhilarating that the ultrathin and dense CrN coatings with strong adsorption ability for Zn2+ exhibit an impressive lifespan up to 3700h with ≈100% CE at 1mAcm-2 . Along with the experiments and theoretical calculations, it is verified that the introduced CrN coatings cannot only effectively suppress the dendrite growth and notorious parasitic reactions, but also allow the uniform Zn deposition due to the reduced nucleation energy. Moreover, the as-assembled Zn@CrN‖MnO2 full cell delivers a high specific capacity of 171.1mAhg-1 after 1000 cycles at 1Ag-1 , much better than that of Zn‖MnO2 analog (97.8mAhg-1 ). This work provides a facile strategy for scalable fabrication of ultrathin zincophilic coating to push forward the practical applications of ZIBs.

Graphene-based ultralow-profile microwave Fresnel lens

The development of ultrathin Fresnel lenses has revolutionized the lens technology and provided great prospects for the miniaturization of electromagnetic systems. Despite considerable advances in microtechnology, a scalable fabrication strategy to achieve ultralow profile microwave lenses is yet to be developed. Here, we report on a novel strategy to create ultrathin and essentially flat Fresnel lenses using graphene rings. We show that monolayer or multilayer graphene can be microstructured into a Fresnel lens to utilize the unique transmission properties of graphene. We design different Fresnel lenses and investigate their performance in the microwave regime both numerically and experimentally. It is shown that one can change the intensity of the focused wave without shifting the focusing point by altering the number of the graphene layers. The good agreement between our experimental results and the results of numerical simulations demonstrates the feasibility of atom-thick (about 10−7 of the operating wavelength) graphene-based lenses and shows their potential for ultra-compact integration.

High performance strain sensor based on leather activated by micro-cracking conductive layer

Flexible strain sensors are capable to detect external force induced strain change owing to their unique ability to convert deformation into electrical signals. Generally, micro/nano patterning of conductive layer in strain sensor is an effective method to improve its sensitivity, however the sophisticated manipulation process is limited only in laboratory scale. In this report, a simple and scalable fabrication strategy was used to create micro-cracking conductive layer as an alternative patterning method to achieve high performance of strain sensor. In details, the sensor was fabricated using leather as the substrate to filtrated acidified multi-walled carbon nanotubes (a-MWCNTs)/layered double hydroxides (LDHs) suspension. During stretching process, micro-cracking structure emerged on the percolated a-MWCNTs/LDHs layer, causing a rise up of resistance according to increasing strain and generated a detectable electrical signal. The prepared sensor had a large detecting range (60%), high sensitivity (GF of 7238.92 at strain 30–60%), fast response (tensile response time of 270 ms), good stability and repeatability. The sensor also inherited the advantages of leather, such as biodegradability and good air permeability, and the introduction of a-MWCNTs/LDHs further enhanced its fire retardancy properties. These features ensured the sensor as an eco-friendly, comfortable and safe electronic device for human motion detection.Graphical abstract

Flexible, durable, green thermoelectric composite fabrics for textile-based wearable energy harvesting and self-powered sensing

Textile-based wearable thermoelectric (TE) devices which could realize electricity harvesting and self-powered sensing using body heat attract great attention as they combine flexibility and skin conformality, yet do not require an external power supply. However, the challenge remains in developing durable TE fabrics which could generate sufficient power. Herein, a novel and scalable fabrication strategy that realizes simultaneous carbon nanotube (CNT) electrospray on poly (lactic acid) (PLA) fabric electrospinning is proposed to fabricate flexible TE composite fabrics. The optimal TE fabrics demonstrate a high Seebeck coefficient of 62.9 ± 6.2 μV K−1 and a maximum power density of 37.3 nW cm−2 is achieved at a temperature difference of 17 K with flexible textile TE generator assembled with CNT/PLA TE composite fabrics on neat PLA textile. The device further demonstrated superior capability in electricity harvesting from the human body and self-powered temperature and/or breath sensing. Moreover, the device exhibited excellent durability after 500 times bending and 100 times water dip-wash, which is ascribed to the uniform CNT electrospray among the PLA nanofibers and strong adhesion between the CNT and PLA. This work provides a novel fabrication strategy for green, durable and wearable TE composites and textiles in emerging power generation and smart sensing applications.

Digital light processing 3D printing for microfluidic chips with enhanced resolution via dosing- and zoning-controlled vat photopolymerization

Conventional manufacturing techniques to fabricate microfluidic chips, such as soft lithography and hot embossing process, have limitations that include difficulty in preparing multiple-layered structures, cost- and labor-consuming fabrication process, and low productivity. Digital light processing (DLP) technology has recently emerged as a cost-efficient microfabrication approach for the 3D printing of microfluidic chips; however, the fabrication resolution for microchannels is still limited to sub-100 microns at best. Here, we developed an innovative DLP printing strategy for high resolution and scalable microchannel fabrication by dosing- and zoning-controlled vat photopolymerization (DZC-VPP). Specifically, we proposed a modified mathematical model to precisely predict the accumulated UV irradiance for resin photopolymerization, thereby providing guidance for the fabrication of microchannels with enhanced resolution. By fine-tuning the printing parameters, including optical irradiance, exposure time, projection region, and step distance, we can precisely tailor the penetration irradiance stemming from the photopolymerization of the neighboring resin layers, thereby preventing channel blockage due to UV overexposure or compromised bonding stability owing to insufficient resin curing. Remarkably, this strategy can allow the preparation of microchannels with cross-sectional dimensions of 20 μm × 20 μm using a commercial printer with a pixel size of 10 μm × 10 μm; this is significantly higher resolution than previous reports. In addition, this method can enable the scalable and biocompatible fabrication of microfluidic drop-maker units that can be used for cell encapsulation. In general, the current DZC-VPP method can enable major advances in precise and scalable microchannel fabrication and represents a significant step forward for widespread applications of microfluidics-based techniques in biomedical fields.

A Stretchable, Breathable, And Self‐Adhesive Electronic Skin with Multimodal Sensing Capabilities for Human‐Centered Healthcare

AbstractElectronic skins (E‐skins) capable of biomechanical/bioelectrical signal acquisition are intensively pursued for human‐centered healthcare of daily life. For practical use, it is highly desired, yet challenging, to mass‐produce E‐skins that are soft and breathable for wearing comfort, skin‐adhesive for robust signal acquisition, multi‐signal sensing for enhanced healthcare data. Herein, a scalable fabrication strategy for a bioinspired E‐skin (SPRABE‐skin) with a multi‐layered architecture is reported that integrates skin‐like softness, self‐protection, self‐adhesion, breathability, and bimodal sensing in a single patch. The fibrous thermoplastic polyurethane (TPU) scaffold endows the SPRABE‐skin with tissue‐like softness (Young's modulus of 3.36 MPa) and stretchability, good permeability to water vapor, and self‐protection against adverse loading events. A strain sensing layer composed of MXene‐carbon nanotubes@TPU (MXene‐CNT@TPU) composition exhibits ultra‐high sensitivity in a wide sensing range (gauge factor at strain of 485% reaches 63 494). An electrode layer made of MXene‐waterborne polyurethane (MXene‐WPU) provides a highly adhesive electrode‐skin interface, which enables the acquisition of biopotentials, such as electrocardiograph (ECG), electromyograph (EMG), electroencephalo‐graph (EEG), with improved fidelity even under various dynamic interferences. Finally, a SPRABE‐skin based human‐centered healthcare system is demonstrated that realizes the wireless, long‐duration, and dynamic monitoring of ECG and running activities.

Mammalian-brain-inspired neuromorphic motion-cognition nerve achieves cross-modal perceptual enhancement

Perceptual enhancement of neural and behavioral response due to combinations of multisensory stimuli are found in many animal species across different sensory modalities. By mimicking the multisensory integration of ocular-vestibular cues for enhanced spatial perception in macaques, a bioinspired motion-cognition nerve based on a flexible multisensory neuromorphic device is demonstrated. A fast, scalable and solution-processed fabrication strategy is developed to prepare a nanoparticle-doped two-dimensional (2D)-nanoflake thin film, exhibiting superior electrostatic gating capability and charge-carrier mobility. The multi-input neuromorphic device fabricated using this thin film shows history-dependent plasticity, stable linear modulation, and spatiotemporal integration capability. These characteristics ensure parallel, efficient processing of bimodal motion signals encoded as spikes and assigned with different perceptual weights. Motion-cognition function is realized by classifying the motion types using mean firing rates of encoded spikes and postsynaptic current of the device. Demonstrations of recognition of human activity types and drone flight modes reveal that the motion-cognition performance match the bio-plausible principles of perceptual enhancement by multisensory integration. Our system can be potentially applied in sensory robotics and smart wearables.

Toward the Scalable Fabrication of Fully Bio-Based Antimicrobial and UVB-Blocking Transparent Polylactic Acid Films That Incorporate Natural Coatings and Nanopatterns.

Microbial transmissions via membrane surface and single-use plastic-induced pollution are two urgent societal problems. This research introduces a scalable fabrication strategy for fully biobased antibacterial and ultraviolet-B block polylactic acid (PLA) films integrating natural coatings and nanopatterns via ultrasonic atomization spray coating and thermal nanoimprinting lithography (TNIL) techniques, respectively. Tannic acid (TA) and gallic acid (GA) were formulated prior to TNIL using anode aluminum oxide template. Results reveal that TA and GA inks display intense adsorption in the UVB region. Plasma increases the hydrophilicity of PLA films for fast spreading of ink droplets. Micron-sized pillars observed on film confirm the successful structural replication. TA-coated PLA films display higher transparency than GA-coated ones. Nanopatterned PLA films have a modest antibacterial resistance of c. 45% against Escherichia coli. TA/GA coatings, however, impart PLA films with a bacterial reduction rate of over 80%. The integration of a TA or GA coating with nanopatterns further promotes the antibacterial rate up to 98%. The cytocompatibility of TA and GA demonstrates that the engineered film can potentially be applied as food packaging. Finally, a continuous mass production strategy is proposed along with an outline of the associated challenges and costs. This study provides a scalable strategy to the sustainable development of eco-benign and functional films.

Ultra-foldable integrated high-performance in-plane micro-supercapacitors from laser-induced selective metallization

The popularity of flexible and wearable electronic devices has stimulated the development of flexible energy storage devices, in which micro-supercapacitor (MSCs) are the most promising. Herein, we demonstrated a novel strategy for scalable fabrication of copper-nickel-polypyrrole (Cu-Ni-PPy) MSCs devices through laser-induced selective metallization of Cu interdigitated electrode combined with electroplating Ni and electrochemical deposition active material of PPy. The prepared Cu-Ni current collector exhibit high electrical conductivity and mechanical flexibility. Moreover, the obtained Cu-Ni-PPy MSCs devices display a large areal capacitance of 126.67 mF/cm2 and a high volume energy density of 31.78 and 5.39 mWh/cm3 at the corresponding power density of 0.15 and 7.5 W/cm3, respectively. Besides, the MSCs exhibit remarkable capacity retention of 94.8% after 10,000 bending cycles and 89.3% after 10,000 cycles. The wireless charging of the MSCs device can be realized by reasonably designing the wireless charging coil (WCO) for electromagnetic conversion. It is believed that this work provides insight into the manufacture of portability and flexibility of miniaturized energy storage devices.

Metallothermic-synchronous construction of compact dual-two-dimensional MoS2-graphene composites for high-capacity lithium storage

Addressing structural degradation of two-dimensional materials is of vast significance for improving their energy storage efficiency and cyclability in alkali metal-ion batteries. Here we propose a one-step metallothermic-synchronous construction strategy of Mo+CS2 =MoS2 +C that can simultaneously generate crystalline MoS2 wrapped by few-layer graphene, forming a compact dual-two-dimensional MoS2-graphene core-shell structure. XPS analysis reveals that dual-two-dimensional components are connected by chemical bonding of C−S, which promotes electronic and ionic transport and accommodates volumetric change. Notably, electrochemical studies disclose the relationship between storage efficiency and electrode dynamics, as well as cycle stability and volumetric effect of MoS2-graphene, where the improved electrode dynamics and volumetric efficiency enable high capacity (800 mAh g−1) and excellent cyclability (550 mAh g−1 after 500 cycles at 5.0 A g−1) for reversible lithium storage. This facile and scalable fabrication strategy makes dual-two-dimensional composite materials potentially viable for the commercialization in high-capacity energy storage.

Biomimetic color‐changing skin based on temperature‐responsive hydrogel microspheres with the photonic crystal structure

AbstractThe responsive color‐changing bionic skin imitation of certain organisms such as chameleons has potential applications in the fields of chemical sensing and information transfer. Inspired by the cellular structure of the chameleon iridophores, a flexible and scalable fabrication strategy was proposed in the present study, which centers on the modular assembly of miniature color‐changing pixel dots. The color‐changing pixel dots were formed by self‐assembling charged silica particles inside hydrogels and fabricated in bulk using microfluidic methods. The pixel dots were immobilized in hydrogels to encapsulate in a membrane structure similar to biological skin. With thermal stimulation, the bionic color‐changing skin can change color from green to red and has an angle‐independent color display with good environmental adaptability.

Highly efficient and eco-friendly InP-based quantum dot light-emitting diodes with a synergetic combination of a liquid metal cathode and size-controlled ZnO nanoparticles

Colloidal quantum dot light-emitting diodes (QLEDs) are the most promising candidates for next-generation displays due to wide color gamut, high contrast ratio, and narrow bandwidth emission. However, high-efficiency QLEDs based on toxic cadmium-based quantum dots (QDs) are strictly regulated by environmental law, and therefore environmentally friendly fabrication methods using non-cadmium-based QDs are indispensable for industrial applications. In this study, an eco-friendly and scalable fabrication strategy based on a synergetic combination of colloidal InP QDs, a eutectic gallium-indium liquid metal, and size-controlled ZnO nanoparticles was developed to produce highly efficient, environmentally friendly, solution-processable QLEDs. The cathode electrode of a gallium alloy liquid metal was applied using a simple screen-printing method, and the InP/GaP/ZnS green QDs with an excellent photoluminescence quantum yield of 85% were facilely prepared and incorporated into the device through spin coating process, ensuring that high device efficiency of InP-based QLED was achieved through uniform electroluminescence of active area. In addition, a size-controlled synthetic method for ZnO nanoparticles as the electron transfer layer was developed to improve the quantum efficiency of InP QDs, and consequently the optoelectronic performance of the resulting device was higher than that of conventional device in terms of current density, luminance, and external quantum efficiency.

Ultrasensitive flexible NO2 gas sensors via multilayer porous polymer film

Micro-nano structure engineering of active materials in sensors have attracted broad attention for hazardous component detection, which enables creating electronic noses that could detect gas analytes efficiently without introducing abundant functional groups and defects. However, challenges still remain on realizing flexible gas sensors with both decent sensing performance and good mechanical robustness, which are extremely important for wearable electronics. Here we present a scalable and facile manufacturing method to construct the three-dimensional (3D) multilayer porous organic semiconductors (OSCs) structure for transistor based gas sensor, showing largely enhanced gas sensing properties as well as bendability down to 1 mm radius with stable operation. The multilayer porous film of OSCs is assembled via breath figure method, followed by layer-by-layer transferring process. The formed 3D porous structure provides efficient hazardous gas diffusion pathways, abundant gas molecules adsorption active sites and immunity towards mechanical deformation simultaneously. Consequently, an obvious increase of responsivity (from 122% to 1053% at 30 ppm) was achieved for NO2 detection, along with an ultralow limit of detection (∼2.3 ppb), and good gas selectivity. This work demonstrates a scalable and low-cost fabrication strategy for high-performance flexible sensors, which delivers an alternative way for next-generation wearable electronics.

Printable and Versatile Superhydrophobic Paper via Scalable Nonsolvent Armor Strategy.

Despite great scientific and industrial interest in waterproof cellulosic paper, its real world application is hindered by complicated and costly fabrication processes, limitations in scale-up production, and use of organic solvents. Furthermore, simultaneously achieving nonwetting properties and printability on paper surfaces still remains a technical and chemical challenge. Herein, we demonstrate a nonsolvent strategy for scalable and fast fabrication of waterproofing paper through in situ surface engineering with polysilsesquioxane nanorods (PSNRs). Excellent superhydrophobicity is attained on the functionalized paper surface with a water contact angle greater than 160°. Notably, the engineered paper features outstanding printability and writability, as well as greatly enhanced strength and integrity upon prolonged exposure to water (tensile strength ≈ 9.0 MPa). Additionally, the PSNRs concurrently armor paper-based printed items and artwork with waterproofing, self-cleaning, and antimicrobial functionalities without compromising their appearance, readability, and mechanical properties. We also demonstrate that the engineered paper holds the additional advantages of easy processing, low cost, and mechanochemical robustness, which makes it particularly promising for real world applications.

Flame-Retardant PEDOT:PSS/LDHs/Leather Flexible Strain Sensor for Human Motion Detection.

Flexible piezoresistive sensors have demonstrated great potential in human-motion-detection applications. However, it still remains a challenge to fabricate strain sensors with high sensitivity, broad sensing range, and good linear response to strain. In this report, a simple and scalable fabrication strategy is developed to construct high performance strain sensors by using leather as the substrates to filtrate poly(3,4-ethylenedioxythiophene): poly(4-styrenesulfonate) (PEDOT:PSS) modified layered double hydroxides (LDHs) suspensions. The naturally aligned collagen fibers in leather enable size selection for the 2D conductive materials and as such dual-conductive pathways are effectively formed on the surface and in the matrix of leather. Due to the unique design of conductive networks, the prepared sensor possesses high gauge factor (maximum value of 2326.84), tunable strain range (0-70%), fast tensile response time (160ms), and good stability in 1000 stretching-relaxing/compression-relaxing cycles, making it suitable for various human motion detections including coughing and large-scale motions of joint bending. In addition, the incorporated LDHs is a non-toxic flame retardant, which is helpful to reduce electronic fire risk and can bring added value to the sensor.

Scalable fabrication of efficient p-n junction lead sulfide quantum dot solar cells

Nowadays, the best lead sulfide (PbS) colloidal quantum dot (CQD) solar cells are primarily demonstrated in the n-p structure, while the p-n structure is significantly less developed. This technological gap between the n-p and p-n structures is much more distinct than in cases of other solution-processable photovoltaic technologies like perovskites and polymers. Here, we propose a scalable fabrication strategy for efficient PbS QD solar cells with p-n structure. An industrially suited blade-coating technique has been used to deposit both n-type and p-type QD layers. The obtained solar cells demonstrated power conversion efficiency of 9%, thus, commensurate to the record device efficiency with this architecture fabricated with a non-scalable technique. The availability of both p-n and n-p structures fabricated from scalable methods may promote the future integration of the PbS QDs into tandem devices together with other solution-processable materials to exploit the most prominent benefits of the PbS QDs, such as infrared absorption.

Pruney fingers-inspired highly stretchable and sensitive piezoresistive fibers with isotropic wrinkles and robust interfaces

Scalable construction of robust and isotropic wrinkles on fiber surface is crucial for the development of highly sensitive piezoresistive fibers, which still remains a challenge. Herein, inspired by the typical morphology and formation of pruney fingers, we develop a novel core–shell “pruney fiber” with both isotropic wrinkles and robust interfaces via a scalable and facile fabrication strategy. Briefly, the robust isotropic wrinkles are constructed through the core thermoplastic polyurethane (TPU) molecular chain’s constriction and the sheath pyrrole monomer’ synergistic interfacial polymerization. As a result, the robust interfaces enable the pruney fiber high stabilities under a remark stretchability (200%). Two as-prepared pruney fibers are overlapped vertically for piezoresistive sensing. Owe to the interlocking of the surface isotropic wrinkles, the piezoresistive fibers show high sensitivity (0.15 kPa−1), fast response time (47 ms), low detection limit (0.2 g), and high stability. For practical applications, the piezoresistive fibers can be easily weaved and integrated into a smart glove for wearable sensors and human–machine interfaces (HMI). At last, the novel structure and its unique scalable developing process would pave a new way in stable surface structure engineering on variable surface in the future.