High Thermal Conductive Liquid Crystal Elastomer Nanofibers.

Liquid crystal elastomers (LCEs), consisting of polymer networks and liquid crystal mesogens, show a reversible phase change under thermal stimuli. However, the kinetic performance is limited by the inherently low thermal conductivity of the polymers. Transforming amorphous bulk into a fiber enhances thermal conductivity through the alignment of polymer chains. Challenges are present due to their rigid networks, while cross-links are crucial for deformation. Here, we employ hydrodynamic alignment to orient the LCE domains assisted by controlled in situ cross-linking and to remarkably reduce the diameter to submicrons. We report that the intrinsic thermal conductivity of LCE fibers at room temperature reaches 1.44 ± 0.32 W/m-K with the sub-100 nm diameter close to the upper limit determined in the quasi-1D regime. Combining the outstanding thermal conductivity and thin diameters, we anticipate these fibers to exhibit a rapid response and high force output in thermomechanical systems. The fabrication method is expected to apply to other cross-linked polymers.

A review of various strategies in e-waste management in line with circular economics.

Waste management of electrical and electronic equipment has become a key challenge for electronics manufacturers due to globalization and the rapid expansion of information technology. As the volume of e-waste grows, legal departments lack the infrastructure, technology, and ability to collect and manage it environmentally soundly. Government laws, economic reasons, and social issues are important considerations in e-waste management. The circular economy concept is built on reusing and recycling goods and resources. A novel idea called the circular economy might prevent the negative consequences brought on by the exploitation and processing of natural resources while also having good effects such as lowering the demand for raw materials, cutting down on the use of fundamental resources, and creating jobs. To demonstrate the significance of policy implementation, the necessity for technology, and the need for societal awareness to build a sustainable and circular economy, the study intends to showcase international best practices in e-waste management. This study uses circular economy participatory implementation methods to provide a variety of possible approaches to assist decision-makers in e-waste management. The purpose of this article is to review the most accepted methods for e-waste management to emphasize the importance of implementing policies, technology requirements, and social awareness in creating a circular economy. To conclude, this paper highlights the necessity of a common legal framework, reform of the informal sector, the responsibility of different stakeholders, and entrepreneurial perspectives.

Marine plastics, circular economy, and artificial intelligence: A comprehensive review of challenges, solutions, and policies.

Global plastic production is rapidly increasing, resulting in significant amounts of plastic entering the marine environment. This makes marine litter one of the most critical environmental concerns. Determining the effects of this waste on marine animals, particularly endangered organisms, and the health of the oceans is now one of the top environmental priorities. This article reviews the sources of plastic production, its entry into the oceans and the food chain, the potential threat to aquatic animals and humans, the challenges of plastic waste in the oceans, the existing laws and regulations in this field, and strategies. Using conceptual models, this study looks at a circular economy framework for energy recovery from ocean plastic wastes. It does this by drawing on debates about AI-based systems for smart management. In the last sections of the present research, a novel soft sensor is designed for the prediction of accumulated ocean plastic waste based on social development features and the application of machine learning computations. Plus, the best scenario of ocean plastic waste management with a concentration on both energy consumption and greenhouse gas emissions is discussed using USEPA-WARM modeling. Finally, a circular economy concept and ocean plastic waste management policies are modeled based on the strategies of different countries. We deal with green chemistry and the replacement of plastics derived from fossil sources.

A Self-Powered Piezoelectric Nanofibrous Membrane as Wearable Tactile Sensor for Human Body Motion Monitoring and Recognition.

Wearable sensors have drawn vast interest for their convenience to be worn on body to monitor and track body movements or exercise activities in real time. However, wearable electronics rely on powering systems to function. Herein, a self-powered, porous, flexible, hydrophobic and breathable nanofibrous membrane based on electrospun polyvinylidene fluoride (PVDF) nanofiber has been developed as a tactile sensor with low-cost and simple fabrication for human body motion detection and recognition. Specifically, effects of multi-walled carbon nanotubes (CNT) and barium titanate (BTO) as additives to the fiber morphology as well as mechanical and dielectric properties of the piezoelectric nanofiber membrane were investigated. The fabricated BTO@PVDF piezoelectric nanogenerator (PENG) exhibits the high ß-phase content and best overall electrical performances, thus selected for the flexible sensing device assembly. Meanwhile, the nanofibrous membrane demonstrated robust tactile sensing performance that the device exhibits durability over 12,000 loading test cycles, holds a fast response time of 82.7 ms, responds to a wide pressure range of 0-5 bar and shows a high relative sensitivity, especially in the small force range of 11.6 V/bar upon pressure applied perpendicular to the surface. Furthermore, when attached on human body, its unique fibrous and flexible structure offers the tactile sensor to present as a health care monitor in a self-powered manner by translating motions of different movements to electrical signals with various patterns or sequences. Supplementary Information: The online version contains supplementary material available at 10.1007/s42765-023-00282-8.

Transistor-Based Biomolecule Sensors: Recent Technological Advancements and Future Prospects.

Transistor-based sensors have been widely recognized to be highly sensitive and reliable for point-of-care/bed-side diagnosis. In this line, a range of cutting-edge technologies has been generated to elevate the role of transistors for biomolecule detection. Detection of a wide range of clinical biomarkers has been reported using various configurations of transistors. The inordinate sensitivity of transistors to the field-effect imparts high sensitivity toward wide range of biomolecules. This overview has gleaned the present achievements with the technological advancements using high performance transistor-based sensors. This review encloses transistors incorporated with a variety of functional nanomaterials and organic elements for their excellence in selectivity and sensitivity. In addition, the technological advancements in fabrication of these microdevices or nanodevices and functionalization of the sensing elements have also been discussed. The technological gap in the realization of sensors in transistor platforms and the resulted scope for research has been discussed. Finally, foreseen technological advancements and future research perspectives are described.

Recent Advancement in Biofluid-Based Glucose Sensors Using Invasive, Minimally Invasive, and Non-Invasive Technologies: A Review.

Biosensors have potentially revolutionized the biomedical field. Their portability, cost-effectiveness, and ease of operation have made the market for these biosensors to grow rapidly. Diabetes mellitus is the condition of having high glucose content in the body, and it has become one of the very common conditions that is leading to deaths worldwide. Although it still has no cure or prevention, if monitored and treated with appropriate medication, the complications can be hindered and mitigated. Glucose content in the body can be detected using various biological fluids, namely blood, sweat, urine, interstitial fluids, tears, breath, and saliva. In the past decade, there has been an influx of potential biosensor technologies for continuous glucose level estimation. This literature review provides a comprehensive update on the recent advances in the field of biofluid-based sensors for glucose level detection in terms of methods, methodology and materials used.

Flexible free-standing Ni-Mn oxide antenna decorated CNT/nanofiber membrane for high-volumetric capacitance supercapacitors.

There is growing demand for lightweight flexible supercapacitors with high electrochemical performance for wearable and portable electronics. Here, we spun nanoparticles of nickel-manganese oxides along with carbon nanotubes into carbon nanofibers and engineered a 3D networked Ni-Mn oxides/CNT@CNF free-standing membrane for flexible supercapacitor applications. The electrospinning process controlled the nanoparticle aggregation while subsequent heat treatment generates nanochannels in the fibres, resulting in a very porous tubular nanocomposite structure. The preparation process also enabled good interfacial contact between the nanoparticles and the conductive carbon network. The resulting Ni-Mn oxides/CNT@CNF membrane displays high mass loading (Ni-Mn oxides) of 855 mg cm-3 and low CNT incorporation of ∼0.4%. The outstanding porous structure, synergy of the carbon with Ni-Mn oxides, and fast and facile faradaic reactions on the electrode were responsible for the superior volumetric capacitance of 250 F cm-3 at 1 A cm-3, energy density as high as 22 mW h cm-3 and an excellent power density of 12 W cm-3. Despite the low CNT loading, the hybrid electrode exhibits excellent cycling performance with capacitance retention of 96.4% after 10 000 cycles evidencing a well-preserved Ni-manganese oxide nanostructure throughout the cycling. The resulting outstanding electrochemical performances of the Ni-Mn oxides/CNT@CNF synergic system offer new insights into effective utilization of transition metal oxides for establishing high-performance flexible supercapacitors within a confined volume.

A Review on Electrospun Nanofibers Based Advanced Applications: From Health Care to Energy Devices.

Electrospun nanofibers have been exploited in multidisciplinary fields with numerous applications for decades. Owing to their interconnected ultrafine fibrous structure, high surface-to-volume ratio, tortuosity, permeability, and miniaturization ability along with the benefits of their lightweight, porous nanofibrous structure, they have been extensively utilized in various research fields for decades. Electrospun nanofiber technologies have paved unprecedented advancements with new innovations and discoveries in several fields of application including energy devices and biomedical and environmental appliances. This review article focused on providing a comprehensive overview related to the recent advancements in health care and energy devices while emphasizing on the importance and uniqueness of utilizing nanofibers. A brief description regarding the effect of electrospinning techniques, setup modifications, and parameters optimization on the nanofiber morphology was also provided. The article is concluded with a short discussion on current research challenges and future perspectives.

Fabrication of Pressure Sensor Using Electrospinning Method for Robotic Tactile Sensing Application.

Tactile sensors are widely used by the robotics industries over decades to measure force or pressure produced by external stimuli. Piezoelectric-based pressure sensors have intensively been investigated as promising candidates for tactile sensing applications. In contrast, piezoelectric-based pressure sensors are expensive due to their high cost of manufacturing and expensive base materials. Recently, an effect similar to the piezoelectric effect has been identified in non-piezoelectric polymers such as poly(d,l-lactic acid (PDLLA), poly(methyl methacrylate) (PMMA) and polystyrene. Hence investigations were conducted on alternative materials to find their suitability. In this article, we used inexpensive atactic polystyrene (aPS) as the base polymer and fabricated functional fibers using an electrospinning method. Fiber morphologies were studied using a field-emission scanning electron microscope and proposed a unique pressure sensor fabrication method. A fabricated pressure sensor was subjected to different pressures and corresponding electrical and mechanical characteristics were analyzed. An open circuit voltage of 3.1 V was generated at 19.9 kPa applied pressure, followed by an integral output charge (ΔQ), which was measured to calculate the average apparent piezoelectric constant dapp and was found to be 12.9 ± 1.8 pC N-1. A fabricated pressure sensor was attached to a commercially available robotic arm to mimic the tactile sensing.

Intelligent Polymers, Fibers and Applications.

Intelligent materials, also known as smart materials, are capable of reacting to various external stimuli or environmental changes by rearranging their structure at a molecular level and adapting functionality accordingly. The initial concept of the intelligence of a material originated from the natural biological system, following the sensing-reacting-learning mechanism. The dynamic and adaptive nature, along with the immediate responsiveness, of the polymer- and fiber-based smart materials have increased their global demand in both academia and industry. In this manuscript, the most recent progress in smart materials with various features is reviewed with a focus on their applications in diverse fields. Moreover, their performance and working mechanisms, based on different physical, chemical and biological stimuli, such as temperature, electric and magnetic field, deformation, pH and enzymes, are summarized. Finally, the study is concluded by highlighting the existing challenges and future opportunities in the field of intelligent materials.

A self-cleaning zwitterionic nanofibrous membrane for highly efficient oil-in-water separation.

The oil and bacteria adhesion during membrane separation process brings great challenges to the operation costs and membrane service life. Meantime, the strong chemical corrosion in sewage seriously limits the durability of membrane as well. Herein, a facile strategy is developed for fabricating highly stable and efficient zwitterionic nanofibrous membrane (NFM) with self-cleaning feature via the combination of in-situ cross-linking of poly (sulfobetaine methacrylate) (PSBMA) and electrospun poly (ether sulfone) (PES) nanofibers. Owing to the introduction of zwitterionic functional groups, the PSBMA/PES NFM exhibits superior antifouling ability (over 3 cycles of crude oil fouling/self-cleaning and up to 7 days of bacteria adhesion/repelling tests). Moreover, the membrane also presents remarkable chemical stability in acidic, alkaline and salty environments; and exhibits excellent separation performance for both layered oil/water mixture and oil-in-water emulsion as well. Furthermore, the membrane is capable to remove bacteria during the continuous oil/water mixture separation. Overall, the proposed strategy provides a new perspective into developing long-term antifouling membrane materials for complicated oily wastewater remediation in various corrosive environments.

Flower-like 3-dimensional hierarchical Co3O4/NiO microspheres for 4-nitrophenol reduction reaction.

Aromatic nitro compounds are toxic and not biodegradable. Therefore, the elimination of nitro groups is very important. Metal catalysts play an important role in the catalytic transformation. We present here flower-like 3D hierarchical Co3O4/NiO microspheres, which are prepared by a chemical precipitation method. The as-prepared catalyst is characterized by FTIR, SEM, TEM, EDS, XRD, XPS and N2 sorption isotherms. They have shown different morphologies such as flower, nanocubes, and hexagonal structure at different calcined temperatures. The synthesized catalyst is tested and used for the reduction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride as a reducing agent. The reaction takes place in an aqueous medium at room temperature. The bimetallic catalyst Co3O4/NiO showed good performance and reusability.

Significance of Nanomaterials in Wearables: A Review on Wearable Actuators and Sensors.

Together with the evolution of digital health care, the wearable electronics field has evolved rapidly during the past few years and is expected to be expanded even further within the first few years of the next decade. As the next stage of wearables is predicted to move toward integrated wearables, nanomaterials and nanocomposites are in the spotlight of the search for novel concepts for integration. In addition, the conversion of current devices and attachment-based wearables into integrated technology may involve a significant size reduction while retaining their functional capabilities. Nanomaterial-based wearable sensors have already marked their presence with a significant distinction while nanomaterial-based wearable actuators are still at their embryonic stage. This review looks into the contribution of nanomaterials and nanocomposites to wearable technology with a focus on wearable sensors and actuators.

Synthesis and Characterization of AlCl3 Impregnated Molybdenum Oxide as Heterogeneous Nano-Catalyst for the Friedel-Crafts Acylation Reaction in Ambient Condition.

Aluminum trichloride (AlCl3) impregnated molybdenum oxide heterogeneous nano-catalyst was prepared by using simple impregnation method. The prepared heterogeneous catalyst was characterized by powder X-ray diffraction, FT-IR spectroscopy, solid-state NMR spectroscopy, SEM imaging, and EDX mapping. The catalytic activity of this protocol was evaluated as heterogeneous catalyst for the Friedel-Crafts acylation reaction at room temperature. The impregnated MoO4(AlCl2)2 catalyst showed tremendous catalytic activity in Friedel-Crafts acylation reaction under solvent-free and mild reaction condition. As a result, 84.0% yield of acyl product with 100% consumption of reactants in 18 h reaction time at room temperature was achieved. The effects of different solvents system with MoO4(AlCl2)2 catalyst in acylation reaction was also investigated. By using optimized reaction condition various acylated derivatives were prepared. In addition, the catalyst was separated by simple filtration process after the reaction and reused several times. Therefore, heterogeneous MoO4(AlCl2)2 catalyst was found environmentally benign catalyst, very convenient, high yielding, and clean method for the Friedel-Crafts acylation reaction under solvent-free and ambient reaction condition.