Linear Control of Moisture Permeability and Anti-adhesion of Bacteria in a Broad Temperature Region Realized by Cross-Linking Thermoresponsive Microgels onto Cotton Fabrics

Enhanced anti-bacterial properties and thermal regulation via photothermal conversion with localized surface plasmon resonance effect in cotton fabrics

Enhanced anti-bacterial properties and thermal regulation are realized in cotton fabrics cross-linked with hybrid poly(di(ethylene glycol) methyl ether methacrylate-co-oligo(ethylene glycol) methyl ether methacrylate-co-ethylene glycol methacrylate) nanogels containing gold nanoparticles (Au NPs), denoted as hybrid P(MA-co-MA300-co-EGMA)/Au nanogels. Pure P(MA-co-MA300-co-EGMA) nanogels are synthesized by emulsion polymerization as carriers and then embedded with Au NPs via in-situ reduction. By applying 1,2,3,4-butanetetracarboxylic acid as a cross-linker and changing the amount of hybrid P(MA-co-MA300-co-EGMA)/Au nanogels in solution, the weight gain ratios of hybrid nanogels on cotton fabrics are set as 10 % (CHN-10) and 20 % (CHN-20). Due to the densely packed structure of the hybrid nanogels on the surface, the localized surface plasmon resonance (LSPR) effect of the Au NPs improves the photothermal conversion capability and converts the absorbed light energy into thermal energy. Simply illuminating with visible light, the surface temperature of CHN-20 pronouncedly increases from 20.4 to 43.0 °C in 50 s. The increased local temperature induces the denaturation of protein and the death of bacteria on the surface. Thus, an illumination with visible light for 2 h results in an anti-bacterial rate for S. aureus of 100 % for CHN-20. Additionally, it presents an excellent thermal regulation capability via photothermal conversion and can be used for continuously maintaining human body temperature in cold areas. Because no additional chemical agents and external power source are required for the anti-bacterial properties and thermal regulation, the obtained cotton fabrics cross-linked with hybrid P(MA-co-MA300-co-EGMA)/Au nanogels are eco-friendly and suitable for smart textiles in daily wear.

Scalable Preparation of Superdurable, Self-Healing, and Biocompatible Superhydrophobic Poly(ethylene terephthalate) Fabrics

The chemical inertness of poly(ethylene terephthalate) (PET) fabrics poses challenges in achieving superhydrophobic coatings with durable adhesion on their surfaces. Conventional surface modification methods such as alkali etching and plasma etching typically compromise the favorable mechanical properties of PET. In this study, polydopamine (PDA) was utilized to functionalize the PET fabric nondestructively by creating robust and reactive hydroxyl and amine groups on its surface, which were subsequently used as a binder of superhydrophobic modifiers such as fluorine-free octadecyltrichlorosilane (OTS). By utilizing PDA to provide reactive groups, OTS undergoes self-assembly through hydrolysis on the surface of the PET fabric without introducing any inorganic nanoparticles while simultaneously forming low surface energy, strong covalent bonds, and rough surfaces. This robust material system provides a novel strategy to design and prepare superhydrophobic PET fabrics that can withstand extreme conditions and maintain superb water repellency even after 1000 times of abrasion and 100 washing cycles. Additionally, the room-temperature self-assembly properties of OTS provide the modified PET fabrics with efficient and repeatable room-temperature self-healing capability. This entire process through an environmentally friendly two-step immersion method enables large-scale production of superhydrophobic PET fabrics with wide applications in sports shoes and clothing.

Bioinspired Polydopamine Modification for Interface Compatibility of PDMS-Based Responsive Structurally Colored Textiles

Textiles that can repeatedly change color in the presence of external stimuli have attracted great interest. Effectively designing to produce such functional textiles is essential, yet there remain challenges like producing stable coloration, rapid response, and reverse color changing. Here, the preparation of a magnetic field response (MFR) textile with a fast magnetic field response, brilliant structural coloration, and mechanical robustness is reported. The MFR textile is knitted by incorporating magnetic particles' ethylene glycol (EG) suspension within polydimethylsiloxane (PDMS)-based fibers. A surface modification strategy is designed to prevent EG from seeping out along the PDMS polymer chains. A PDMS fiber is encapsulated in waterborne polyurethane, and a polydopamine joint layer is used. The MFR textile demonstrates magnetic field-triggered structural colors, and the breaking strength and elongation at break of each composite fiber are improved. In addition, multishaped patterns can be printed on the MFR textile with the help of the photo etching technology, which enhances the applications of the new functional textiles.

Bacterial Adhesion to Natural and Synthetic Fibre-Forming Polymers: Influence of Material Properties

Polymer-based textiles have a major impact on human well-being, as they provide the desired functional protection and aesthetic comfort when worn. However, natural and synthetic polymer-based textiles can also pose serious health risks, as they are surfaces that allow the adhesion of various bacteria, including pathogenic bacteria. To minimise these problems, antibacterial chemical treatments are generally applicable in the case of polymer-based textiles. However, to avoid the use of potentially toxic chemicals, sustainable approaches require the customised design of non-adhesive polymer-based textiles, considering their chemical, physicochemical, constructional, and textural properties. Before designing, several articles are required to gain sufficient knowledge of the described object. Despite the urgent need to combat bacteria (on polymer-based textiles), which pose a serious global health risk, only a few review articles have been published that address bacterial adhesion in the context of superhydrophobic and antibacterial textile materials, while only one review article holistically addresses the textile factors and their influence on this phenomenon. The aim of this review article is to expand the insufficient knowledge about bacterial adhesion to polymer-based textiles on the basis of theoretical findings and real examples through a high degree of structuring, simplification, holistic consideration, and visualization. Therefore, this review provides an insight into the mechanisms involved in bacterial adhesion and a comprehensive overview of the influence of different textile factors, such as chemical composition, hydrophilicity/hydrophobicity, surface charge, surface free energy, roughness, and porosity, on bacterial adhesion. To emphasise the importance of the synergistic effect of the combined textile factors, examples of the influence of hydrophilicity/hydrophobicity in combination with surface charge, surface roughness, and porosity are discussed. From the review, it can be concluded that the combination of hydrophilicity/hydrophobicity and the surface charge of textile fibres and bacteria is crucial for bacterial adhesion, with roughness and porosity being the most important factors among the constructive and textural properties of polymer-based textiles.

Enhanced UV protection in silk fibroin based electrospun fabrics realized via orientation induced high efficiency of azobenzene isomerization

Due to the poor UV protection capability, natural silk fabrics not only suffer from easy damage by sunshine but also induce possible sunburn in the human body. Efficient azobenzene isomerization and enhanced UV shielding are realized by replacing the natural silk with natural protein silk fibroin (SF) and electrospinning together with light-responsive copolymer P(MEO2-co-OEG300-co-AHMA). Compared to a solution cast film, the absorption peak intensity at 355 nm is 60 % higher in UV-Vis spectra of the electropsun SF/P(MEO2-co-OEG300-co-AHMA) fabrics. This improvement is related to the highly oriented chains, inducing more space and higher efficiency for azobenzene isomerization. Only exposure to visible light for 20 min, the absorption peak corresponding to the trans- state at 355 nm recovers to 92.5 % in the electrospun fabrics, which is at least 100 % faster than that in the solution cast film (50 min). It is related to the zip effect of the isomerization in the oriented chain structure. Thus, not only the absorption of UV radiation, but also the isomerization rate is enhanced. Based on these unique absorption and recovery capabilities, the SF based electrospun fabrics can be used to replace the natural silk fabrics for UV shielding in summer, especially for cyclic use.

Photothermoelectric Synergistic Hydrovoltaic Effect: A Flexible Photothermoelectric Yarn Panel for Multiple Renewable-Energy Harvesting

The human body is in a complex environment affected by body heat, light, and sweat, requiring the development of a wearable multifunctional textile for human utilization. Meanwhile, the traditional thermoelectric yarn is limited by expensive and scarce inorganic thermoelectric materials, which restricts the development of thermoelectric textiles. Therefore, in this paper, photothermoelectric yarns (PPDA-PPy-PEDOT/CuI) using organic poly(3,4-ethylenedioxythiophene) (PEDOT) and inorganic thermoelectric material cuprous iodide (CuI) are used for the thermoelectric layer and poly(pyrrole) (PPy) for the light-absorbing layer. With the introduction of PPy, the temperature difference of the photothermoelectric yarn can be increased for a better voltage output. Subsequently synergizing the photothermoelectric effect with the hydrovoltaic effect to create higher electric potentials, a single wet photothermoelectric yarn obtained by preparation can be irradiated under an infrared lamp at a voltage of up to 0.47 V. Finally, the photothermoelectric yarn PPDA-PPy-PEDOT/CuI was assembled in a series and parallel to obtain a photothermoelectric yarn panel, which was able to output 41.19 mV under an infrared lamp, and the synergistic photothermoelectric and hydrovoltaic effects of the photothermoelectric panel were tested outdoors on human body, and we found that the voltage was able to reach approximately 0.16 V under sunlight. Therefore, the voltage values obtained from the photothermoelectric yarns in this study are competitive and provide a new research idea for the study of photothermoelectric yarns.

Multiresponsive Self-Healing Lanthanide Fluorescent Hydrogel for Smart Textiles

Lanthanide organometallic complexes exhibit strong luminescence characteristics, owing to their antenna effects. The f-d energy level transition causes this phenomenon, which occurs when ligands and the external electrons of lanthanide metals coordinate. Based on this phenomenon, we used two lanthanide metals, europium (Eu) and terbium (Tb), in the present study as the metal center for iminodiacetic acid ligands. Further, we developed the resulting fluorescent organometallic complex as a smart material. The ligand-metal bond in the material functioned as a metal chelating agent and a cross-linking agent in a dynamically coordinated form, thereby prompting the material to self-heal. Temperature-sensitive poly-N-isopropylacrylamide was incorporated into the material as the polymer backbone. Afterward, we combined it with water-soluble poly(vinyl alcohol) and an additional ligand from poly(acrylic acid) to fabricate a high-performance hydrogel composite material. The shrinkage and expansion of the polymer form a grid between the materials. Because of the different coordination stabilities of Eu3+ and Tb3+, the corresponding material exhibits environmental responses toward excitation wavelength, temperature, and pH, thus generating different colors. When used in fabrics, the cross-linking mechanism of the material effectively looped the material between fabric fibers; furthermore, the temperature sensitivity of the polymer adjusted the size of pores between fabric fibers. At relatively higher temperatures (>32 °C), the polymer structure shrank, fiber pores expanded, and air permeability improved. Thus, this material appears to be promising for use in smart textiles.

Dual-Layer All-Textile Flexible Pressure Sensor Coupled by Silver Nanowires with Ti3C2-Mxene for Monitoring Athletic Motion during Sports and Transmitting Information

At present, wearable flexible pressure sensors have broad application prospects in fields such as motion monitoring and information transmission. However, it is still a challenge to design flexible pressure sensors with high sensitivity over a large sensing range and simple fabrication. Here, we use a simple "dipping-drying" method to fabricate a fabric-based flexible pressure sensor by coupling silver nanowires (AgNWs) with Ti3C2-MXene. The interaction between MXene and AgNWs helps realize a dual-layer sensing network, achieving good synergistic effects between pressure sensitivity and sensing range. The effects of the material combination and dip-coating sequence on the sensor's performance are systematically studied. The results show that the sensor was impregnated sequentially with AgNWs solution, and the MXene solution has the highest sensitivity (0.168 kPa-1) over a wide range (190 kPa). Meanwhile, it has the advantages of low response hysteresis and detection limit, as well as good linearity and durability. We further demonstrate the application of this sensor in human physiological signal monitoring and motion pattern recognition. It can also encrypt and transmit information according to different pressing states. In addition, the proposed pressure sensor array exhibits spatial resolution detection capabilities, laying the foundation for applications in the fields of motion monitoring and human-computer interaction.

Asymmetric Multienergy-Coupled Radiative Warming Textiles for Personal Thermal-Moisture Management

In order to address the requirements for warmth and energy conservation in cold climates, the development of personal thermal management textiles that regulate local human thermal comfort has emerged as a promising solution in recent times. Nevertheless, existing warming textile strategies often rely on a singular energy source, exhibit inadequate air/moisture permeability, and lack adaptability to dynamic and intricate climate variations. Herein, a novel multienergy-coupled radiative warming Janus textile has been effectively designed and fabricated via screen printing and foam finishing. Taking advantage of the synergistic effects of directional water transport capability of polyester-covered cotton (with a directional water-transport index of R = 577.5%), high mid-infrared radiant reflection (at 60%), electrothermal conversion of copper coating (with a sheet resistance of 0.01 Ω sq-1), and strong solar absorption of the nanoporous structure TA@APTES@Fe(III)@CNT (TAFC) coating (at 98.5%), the Janus fabric exhibits exceptional performance in expelling out one-way sweat/moisture (R = 329.3%) and solar heating (86.9 °C)/Joule heating (226.4 °C at 3.0 V)/heat retention (2.4 °C higher than that of cotton fabric). Furthermore, the fabric is also provided with exceptional mechanical, washing, flame-retardant, and antibacterial performance. This research holds the potential to revolutionize the development and production of warming textiles by incorporating desirable sweat/moisture permeability and multienergy-coupled heating.

Polylactic Acid/Calcium Stearate Hydrocharging Melt-Blown Nonwoven Fabrics for Respirator Applications

Non-biodegradable polypropylene, which poses a serious threat to the environment, is the most utilized material in air filtration systems. Moreover, under conditions of high temperature and high humidity, the electrostatic charge in melt-blown nonwoven fabrics treated with traditional corona electrets will quickly dissipate. Here, biodegradable polylactic acid, calcium stearate, and an innovative hydrocharging technique are reported to develop environmentally friendly polylactic acid/calcium stearate hydrocharging melt-blown nonwoven fabrics with high charge stability. Compared with polylactic acid melt-blown nonwoven fabrics, the crystallization structure and charge storage of polylactic acid/calcium stearate melt-blown nonwoven fabrics have been greatly improved due to the presence of calcium stearate. In PM0.3, it exhibited a high filtration efficiency (96.78%), a low pressure drop (65.20 Pa), and a good quality factor (0.053 Pa-1), which can meet the N95 respirator standard. Furthermore, it is worth mentioning that the filtration performance remained at a high level (>95.00%) after 2 months. Importantly, based on the test and analysis of surface electrostatic potential, crystallization, and charge storage and distribution, we proposed plausible charge generation and stable storage mechanisms. It demonstrated more potential for electret air filtration and smart respirators as the further possible step of research in the field.

Soft Self-Assembled Mechanoelectrical Transducer Films from Conductive Microgel Waterborne Dispersions

The present study aims in the developing of new soft transducers based on sophisticated stimuli-responsive microgels that exhibit spontaneous self-assembly forming cohesive films with conductive and mechanoelectrical properties. For that, oligo(ethylene glycol)-based stimuli-responsive microgels have been synthesized using bio-inspired catechol cross-linkers by one-step batch precipitation polymerization in aqueous media. Then, 3,4-ethylene dioxyyhiophene (EDOT) has been directly polymerized onto stimuli-responsive microgels using catechol groups as the unique dopant. PEDOT location is dependent on the cross-linking density of microgel particles and EDOT amount used. Moreover, the spontaneous cohesive film formation ability of the waterborne dispersion after evaporation at soft application temperature is demonstrated. The films obtained present conductivity and enhanced mechanoelectrical properties triggered by simple finger compression. Both properties are function of the cross-linking density of the microgel seed particles and PEDOT amount incorporated. In addition, to obtain maximum electrical potential generated and the possibility to amplify it, several films in series were demonstrated to be efficient. The present material can be a potential candidate for biomedical, cosmetic, and bioelectronic applications.

Construction of Wash-Resistant Photonic Crystal-Coated Fabrics based on Hydrogen Bonds and a Dynamically Cross-Linking Double-Network Structure

Structural coloration as the most possible way to realize the ecofriendly dying process for textiles or fabrics has attracted significant attention in the past decades. However, photonic crystals (PCs) are a typical example of materials with structural color usually located on the surface of the fabrics or textiles, which make them not stable when rubbed, bent, or washed due to the weak interaction between the PC coatings and fabrics. Here, double networks were constructed between the PC coatings and the fabrics for the first time via a hydrogen bond by introducing tannic acid (TA) and dynamic cross-linking with 2-formylphenylboronic acid to increase the wash resistance of the structural colored fabrics. On modifying the monodispersed SiO₂ nanoparticles, poly(dimethylsiloxane), and the fabrics, the interaction between the PC coatings and the fabrics increased by the formation of double networks. The structural color, wash, and rub resistance of the PC-coated fabrics were systematically studied. The obtained fabrics with the TA content at 0.030% (SiDT30) showed the best wash and rub resistance. The construction of double networks not only improved the wash and rub resistance of PCs but also retained the bright structural color of the PC coatings, facilitating the practical application of structural coloration in the textile industry.

Nonwoven Membranes with Infrared Light-Controlled Permeability

This study presents the development of the first composite nonwoven fiber mats (NWFs) with infrared light-controlled permeability. The membranes were prepared by coating polypropylene NWFs with a photothermal layer of poly(N-isopropylacrylamide) (PNIPAm)-based microgels impregnated with graphene oxide nanoparticles (GONPs). This design enables "photothermal smart-gating" using light dosage as remote control of the membrane's permeability to electrolytes. Upon exposure to infrared light, the GONPs trigger a rapid local increase in temperature, which contracts the PNIPAm-based microgels lodged in the pore space of the NWFs. The contraction of the microgels can be reverted by cooling from the surrounding aqueous environment. The efficient conversion of infrared light into localized heat by GONPs coupled with the phase transition of the microgels above the lower critical solution temperature (LCST) of PNIPAm provide effective control over the effective porosity, and thus the permeability, of the membrane. The material design parameters, namely the monomer composition of the microgels and the GONP-to-microgel ratio, enable tuning the permeability shift in response to IR light; control NWFs coated with GONP-free microgels displayed thermal responsiveness only, whereas native NWFs showed no smart-gating behavior at all. This technology shows potential toward processing temperature-sensitive bioactive ingredients or remote-controlled bioreactors.

Effect of Thermal Stimulus on Kinetic Rehydration of Thermoresponsive Poly(diethylene glycol monomethyl ether methacrylate)-block-poly(poly(ethylene glycol) methyl ether methacrylate) Thin Films Probed by In Situ Neutron Reflectivity

The kinetic rehydration of thin di-block copolymer poly(diethylene glycol monomethyl ether methacrylate)-block-poly(poly(ethylene glycol) methyl ether methacrylate) (PO₂-b-PO₃₀₀) films containing two thermoresponsive components is probed by in situ neutron reflectivity (NR) with different thermal stimuli in the D₂O vapor atmosphere. The transition temperatures (TTs) of PO₂ and PO₃₀₀ blocks are 25 and 60 °C, respectively. After the one-step stimulus (rapid decrease in temperature from 60 to 20 °C), the film directly switches from a collapsed to a fully swollen state. The rehydration process is divided into four steps: (a) D₂O condensation, (b) D₂O absorption, (c) D₂O evaporation, and (d) film reswelling. However, the film presents a different rehydration behavior when the thermal stimulus is separated into two smaller steps (first decrease from 60 to 40 °C and then to 20 °C). The film first switches from a collapsed to a semiswollen state caused by the rehydrated PO₃₀₀ blocks after the first step of thermal stimulus (60 to 40 °C) and then to a swollen state induced by the rehydrated PO₂ blocks after the second step (40 to 20 °C). Thus, the kinetic responses are distinct from that after the one-step thermal stimulus. Both the time and extent of condensation as well as evaporation processes are significantly reduced in these two smaller steps. However, the final states of the rehydrated PO₂-b-PO₃₀₀ films are basically identical irrespective of the applied thermal stimulus. Thus, the final state of thermoresponsive di-block copolymer films is not affected by the external thermal stimuli, which is beneficial for the design and preparation of sensors or switches based on thermoresponsive polymer films.

Preparation of Structural Color on Cotton Fabric with High Color Fastness through Multiple Hydrogen Bonds between Polyphenol Hydroxyl and Lactam

Structural coloration is an important way to realize eco-friendly dyeing of textiles. Structural colored cotton fabric was obtained by fabricating a polydopamine (PDA) film on the white cotton fabric at different polymerization reaction times. PDA is prone to generate capillary tension during film formation, which damages the uniformity and interfacial bonding force of the film. Multiple hydrogen bonds will form between the lactam group of polyvinylpyrrolidone (PVP) and the phenolic hydroxyl group of PDA. The introduced hydrogen bonds will effectively enhance the interfacial bond strength and lead to structural color with high color fastness. The surface morphology of double-layer aggregates of the PDA film on structural colored cotton fabric was revealed by scanning electron microscopy. The chemical constitution of the PDA film and PVP was investigated by Fourier transform infrared spectroscopy and X-ray diffraction. The color characteristics of structural colored cotton fabrics were analyzed by UV-vis reflectance spectroscopy and spectrophotometry.

Ionic Hydrogels Based Wearable Sensors to Monitor the Solar Radiation Dose for Vitamin D Production and Sunburn Prevention

Wearable solar radiation sensors based on ionic hydrogels are facilely prepared to simultaneously monitor the radiation dose for the production of vitamin D and the prevention of sunburn. Tetramethylethylenediamine (TEMED) is neutralized with acrylic acid (AA) to obtain tetramethylethylenediamine acrylate (TEMEDA), which is further polymerized with acrylamide by a free radical reaction. By simply adding MB or NR during the polymerization, the final obtained ionic hydrogels can indicate solar radiation. Due to the extent of discoloration, the discoloration speed of MB and NR is correlated to the radiation dose. This wearable sensor can indicate the solar radiation dose required by the human body to synthesize vitamin D through the discoloration of the ionized hydrogel of MB, whereas those with NR are able to illustrate the threshold of radiation dose that causes potential skin hurt. Therefore, the benefit and drawback of solar radiation can be well balanced by optimizing the exposure time to solar irradiation. In addition, polyurethane cross-linked with a thermoresponsive coating is used as band for this wearable sensor. Due to the hydrophilicity below its transition temperature, the cross-linked band possesses the easy cleaning capability of stains after the daily wear. Such type of wearable sensor can be broadly used for monitoring the solar radiation, especially in outdoor activities.

Alternatives to Conventional Antibiotic Therapy: Potential Therapeutic Strategies of Combating Antimicrobial-Resistance and Biofilm-Related Infections

Antibiotics have been denoted as the orthodox therapeutic agents for fighting bacteria-related infections in clinical practices for decades. Nevertheless, overuse of antibiotics has led to the upsurge of species with antimicrobial resistance (AMR) or multi-drug resistance. Bacteria can also grow into the biofilm, which accounts for at least two-thirds of infections. Distinct gene expression and self-produced heterogeneous hydrated extracellular polymeric substance matrix architecture of biofilm contribute to their tolerance and externally manifest as antibiotic resistance. In this review, the difficulties in combating biofilm formation and AMR are introduced, and novel alternatives to antibiotics such as metal nanoparticles and quaternary ammonium compounds, chitosan and its derivatives, antimicrobial peptides, stimuli-responsive materials, phage therapy and other therapeutic strategies, from compounds to hydrogel, from inorganic to biological, are discussed. We expect to provide useful information for the readers who are seeking for solutions to the problem of AMR and biofilm-related infections.

Two-Dimensional MOF Modulated Fiber Nanogenerator for Effective Acoustoelectric Conversion and Human Motion Detection

The real-time application of piezoelectric nanogenerators (PNGs) under a harsh environment remains a challenge due to lower output performance and poor durability. Thus, the development of flexible, sensitive, and stable PNGs became a topic of interest to capture different human motions including gesture monitoring to speech recognition. Herein, a scalable approach is adapted where naphthylamine bridging a [Cd(II)-μ-I₄] two-dimensional (2D) metal-organic framework (MOF)-reinforced poly(vinylidene fluoride) (PVDF) composite nanofibers mat is prepared to fabricate a flexible and sensitive composite piezoelectric nanogenerator (C-PNG). The needle-shaped MOF was successfully synthesized by the layering and diffusion of two different solutions. The incorporation of single-crystalline 2D MOF ensures a large content of electroactive phases (98%) with a resultant high-magnitude piezoelectric coefficient of 41 pC/N in a composite nanofibers mat due to the interfacial specific interaction with -CH₂-/-CF₂- dipoles of PVDF. As an outcome, C-PNG generates high electrical output (open-circuit voltage of 22 V and maximum power density of 24 μW/cm²) with a very fast response time (t_r ≈ 5 ms) under periodic pressure imparting stimuli. Benefiting from bending and twisting functionality, C-PNG is capable of scavenging biomechanical energy by mimicking complex musculoskeletal motions that broaden its application in wearable electronics and fabric integrated medical devices. In addition, C-PNG also demonstrates an efficient acoustic vibration to electric energy conversion capability with an improved power density and acoustic sensitivity of 6.25 μW and 0.95 V/Pa, respectively. The overall energy conversion efficiency is sufficient to operate several consumer electronics without any energy storage unit. This acoustic observation is further validated by the finite element method-based theoretical simulation. Overall, the 2D MOF-based device design strategy opens up a new possibility to develop a human-motion compatible energy generator and a self-powered acoustic sensor to power up electronic gadgets as well as low-frequency noise detection.

Hydration and Thermal Response Kinetics of a Cross-Linked Thermoresponsive Copolymer Film on a Hydrophobic PAN Substrate Coating Probed by In Situ Neutron Reflectivity

The hydration and thermal response kinetics of the cross-linked thermoresponsive copolymer poly((diethylene glycol monomethyl ether methacrylate)-co-poly(ethylene glycol) methyl ether methacrylate), abbreviated as P(MEO₂MA-co-OEGMA₃₀₀), thin film on a hydrophobic polyacrylonitrile (PAN) substrate coating, which resembles a synthetic fabric, is probed by in situ neutron reflectivity (NR). The PAN and monomer (MEO₂MA and OEGMA₃₀₀) solutions are sequentially spin-coated onto a silicon (Si) substrate. Afterward, plasma treatment is applied to realize the cross-linking of PAN and monomers. The as-prepared cross-linked P(MEO₂MA-co-OEGMA₃₀₀) film on the hydrophobic PAN substrate coating presents a two-layer structure: a substrate-near layer, which is a mixture of PAN and P(MEO₂MA-co-OEGMA₃₀₀), and a main layer, which is composed of pure hydrophilic P(MEO₂MA-co-OEGMA₃₀₀). During hydration in D₂O vapor atmosphere, the hydrophobic PAN component prevents the formation of D₂O enrichment in the substrate-near layer. However, an additional vapor-near layer is observed on top of the main layer, which is enriched with D₂O. The hydration process is constrained by the cross-linking points in the film, inducing the relaxation time to be longer than that in a spin-coated P(MEO₂MA-co-OEGMA₃₀₀) film. Because the as-prepared cross-linked film presents a transition temperature (TT) at 38 °C, the hydrated film switches to the collapsed state when the temperature is increased from 23 to 50 °C. The response to a thermal stimulus is also slower due to the existence of the internal cross-linking points as compared to the spin-coated film. Interestingly, no reswelling is observed at the end of the thermal stimulus, which can be also attributed to the presence of internal cross-linking points.

Highly swelling pH-responsive microgels for dual mode near infra-red fluorescence reporting and imaging

Near infra-red (NIR) fluorescence is a desirable property for probe particles because such deeply penetrating light enables remote reporting of the local environment in complex surroundings and imaging. Here, two NIR non-radiative energy transfer (NRET) fluorophores (Cy5 and Cy5.5) are coupled to preformed pH-responsive poly(ethylacrylate-methacrylic acid-divinylbenzene) microgel particles (PEA-MAA-5/5.5 MGs) to obtain new NIR fluorescent probes that are cytocompatible and swell strongly. NIR ratiometric photoluminescence (PL) intensity analysis enables reporting of pH-triggered PEA-MAA-5/5.5 MG particle swelling ratios over a very wide range (from 1-90). The dispersions have greatly improved colloidal stability compared to a reference temperature-responsive NIR MG based on poly(N-isopropylacrylamide) (PNP-5/5.5). We also show that the wavelength of maximum PL intensity (λ _max) is a second PL parameter that enables remote reporting of swelling for both PEA-MAA-5/5.5 and PNP-5/5.5 MGs. After internalization the PEA-MAA-5/5.5 MGs are successfully imaged in stem cells using NIR light. They are also imaged after subcutaneous injection into model tissue using NIR light. The new NIR PEA-MAA-5/5.5 MGs have excellent potential for reporting their swelling states (and any changes) within physiological settings as well as very high ionic strength environments (e.g., waste water).

Infrared Thin Film Detectors Based on Thermoresponsive Microgels with Linear Shrinkage Behavior and Gold Nanorods

To overcome the drawbacks of existing infrared detectors, infrared thin film detectors based on microgels and gold nanorods (Au NRs) are investigated. The microgels with a linear shrinkage of the hydrodynamic diameter between 10 and 55 °C are copolymerized by monomers di(ethylene glycol) methyl ether methacrylate, oligo(ethylene glycol) methyl ether methacrylate, and acrylic acid with a molar ratio of 1:1:1. Homogenous thin films are obtained by spin coating from an aqueous solution on silicon substrates. Upon heating in a water vapor atmosphere, the film thickness of the hybrid films linearly decreases. Heat generation from a plasmon resonance enhanced absorption of the infrared radiation by the Au NRs triggers a linear shrinkage in the hybrid microgel-Au NR films as well. A linear correlation between the film thickness and the applied infrared power density is observed. The sensitivity is enhanced by a slight increase in the amount of Au NRs in the films. Infrared detectors are constructed from the hybrid microgel-Au NR films by adding two electrodes via deposition of two silver layers at the film ends. By monitoring the ohmic resistance, the intensity of the incident infrared light can be obtained. The detectors not only possess a good reversibility and fast response rate but also show a high stability after the resistance measurements. Compared with the traditional infrared detectors, the infrared thin film detectors based on microgels are sensitivity adjustable. Thus, they can be promising candidates for replacing expensive inorganic infrared detectors in areas of daily life applications.

Highly Wearable, Breathable, and Washable Sensing Textile for Human Motion and Pulse Monitoring

At present, pressure sensor textiles are of great significance in the area of wearable electronics, especially for making smart or intelligent textiles. However, the design of these textile-based devices with sensitive ability, simple fabrication, and low cost is still challenging. In this study, we developed a triboelectric sensing textile constructed with core-shell yarns. Nylon filament and polytetrafluoroethylene filament were selected as the positive and negative layers, respectively, in the woven structure while the built-in helical stainless steel yarn was serving as the inner electrode layer. The sensitivity of the sensing textile can reach up to 1.33 V·kPa^-1 and 0.32 V·kPa^-1 in the pressure range of 1.95-3.13 kPa and 3.20-4.61 kPa, respectively. This sensing textile presented good mechanical stability and sensing capability even after 4200 cycles of continuous operation or after 4 h continuous water washing. Benefiting from the favorable merits of being highly flexible, breathable, lightweight, and even dyeable, the fabricated device was capable of being placed on any desired body parts for quantifying the dynamic human motions. It can be effectively used to measure and monitor various human movements associated with different joints, such as the hand, elbow, knee, and underarm. Moreover, the sensing textile was able to capture real-time pulse signals and reflect the current health status for human beings. This study affords an innovative and promising track for multifunctional pressure sensor textiles with wide applications in smart textiles and personalized healthcare.

Three-Dimensional Conformal Porous Microstructural Engineering of Textile Substrates with Customized Functions of Brick Materials and Inherent Advantages of Textiles

The conventional use of textiles as substrates for the incorporation of brick materials (i.e., polymers and nanomaterials) is ubiquitously developed with primary purposes for introducing desired technical/functional performance rather than maintaining the aesthetic/decorative characteristics and inherent advantages (i.e., flexibility and permeability) of textiles. Such kinds of modified textiles with typical solid coating layers, however, are becoming more and more unsuitable for some emerging applications, such as smart wearable devices. Herein, we presented a brand-new kind of modified textiles with brick materials formed contouring to the nonplanar fiber surfaces of a fabric substrate as a three-dimensional (3D) conformal layer of porous microstructures by a unique breath figure self-assembling strategy of employing water microdroplet arrays as soft dynamic templates that can be controlled, formed, and removed spontaneously. In this paper, the main influential factors such as solution concentration, relative humidity, temperature, brick materials, and fabric substrates were studied systematically to control and adjust the formation of 3D conformal porous microstructures (3CPMs). The obtained 3D conformal porous microstructured textiles (3CPMTs) hierarchically combining the inherent texture features of the porous network of textiles and honeycomb porous microstructures templated from water microdroplet arrays not only possess new functions of introduced brick materials (such as triboelectric performance and wettability) and maintain the excellent inherent advantages (such as flexibility, air permeability, water vapor permeability, and unique texture features) of fabrics but also enhance the tensile strength and thermal insulation performance of substrates. Taking advantage of the introduced functions, they can be either used for conventional applications (i.e., oil/water separation) with enhanced performance or explored for new applications (i.e., self-powered sensors with textile breathability and comfort) with truly wearable potential. We believe this efficient, robust, and versatile strategy opens up numerous possibilities for designing and developing a broad range of advanced multifunctional textiles upon end uses.

Highly Flexible, Efficient, and Sandwich-Structured Infrared Radiation Heating Fabric

Controlling thermal energy is one of the biggest concerns along with the progress of human civilization for thousands of years. Current thermal comfort devices are mainly based on materials that are bulky, rigid, and heavy, largely limiting their widespread practical applications. It still remains a challenge to develop highly lightweight, flexible, and efficient electrical heaters for personal thermal management and local climate control. In this work, we present a high-performance composite infrared radiation heating fabric (IRHF), which mainly consists of two layers of poly(ethylene terephthalate) (PET) fabrics and one sandwiched layer of carbon nanofibers embedded with different inorganic nanoparticles. A copper electrode sheet was connected with the carbon nanofibers to form a conductive heating circuit. The permanent spontaneous polarization of both carbon nanofibers and infrared radiation nanoparticles can facilitate an enhanced current in the heater by creating an additional electrical field, which results in a fast electrothermal response and favorable heat preservation. The constructed IRHF could achieve an increase in the temperature to 43 °C from room temperature in 1 min under a voltage of 30 V, with an electrothermal conversion efficiency up to 78.99%. With a collection of compelling features such as good thermal stability, excellent flexibility and breathability, and high electrical conductivity and energy conversion efficiency, the fabricated sandwich-structured IRHF can open up new opportunities to develop smart heating textiles and wearable heating clothes in many fields.

Construction of antimicrobial and biocompatible cotton textile based on quaternary ammonium salt from rosin acid

Antimicrobial cotton textiles (CT) show great promise for wound dressings. However, modifying CTs to have antimicrobial properties requires balancing the killing of microbes while protecting normal cells. In this study, the surface of CT was modified using maleopimaric acid quaternary ammonium cations (MPA-N⁺) from rosin acid. The surfaces morphology and chemical composition were determined by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), which confirmed that the MPA-N⁺ modified CT (CT-g-MPA-N⁺) was prepared. CT-g-MPA-N⁺ shows strong and broad spectrum antimicrobial activities against Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus). It also exhibits prominent durability of antimicrobial capability even after soaking in PBS for 6 days, and can effectively inhibit bacterial biofilm formation. Most importantly, the excellent biocompatibility of CT-g-MPA-N⁺ was verified by hemocompatible and cytotoxic assays. This work is believed to be promising method to prepare antimicrobial cotton textiles by surface modification and suggest the great potential application in wound dressing.

Hierarchically Rough Structured and Self-Powered Pressure Sensor Textile for Motion Sensing and Pulse Monitoring

Nowadays, real-time human motion sensing and pulse monitoring can provide significant basis for health assessment and medical diagnosis. Nevertheless, it is still a big challenge to design a lightweight, flexible, and energy-sustainable pressure sensor with high sensitivity and breathability. Here, we fabricated a triboelectric all-fiber structured pressure sensor via a facile electrospinning technique. The constructed sensor textile holds a composite structure made up of a polyvinylidene fluoride/Ag nanowire nanofibrous membrane (NFM), an ethyl cellulose NFM, and two layers of conductive fabrics. This wearable device with high shape adaptability exhibited excellent sensing capability because of the introduced hierarchically rough structure on the nanofibers. The sensitivity can reach up to 1.67 and 0.20 V·kPa^-1 in the pressure range of 0-3 and 3-32 kPa, respectively. The fabricated sensor textile also showed a superior mechanical stability even after continuous operation of 7200 working cycles. This sensor textile was easily conformable on different desired body parts for dynamic motion sensing and real-time pulse monitoring. It can work in a self-powered manner to detect and quantify various human motions associated with joints, such as elbows, knees, and ankles. Additionally, it can be placed on the carotid artery to capture the pulse signals, serving as a reliable way to reflect the state of health. This work has great possibilities to promote the rapid advancement and broad applications of multifunctional pressure sensors and next-generation wearable electronics.

Infrared-Radiation-Enhanced Nanofiber Membrane for Sky Radiative Cooling of the Human Body

Extreme heat events are mainly responsible for weather-related human mortality due to climate change. However, there is a lack of outdoor thermal management for protecting people from extreme heat events. We present a novel infrared-radiation-enhanced nanofiber membrane (NFM) that has good infrared resonance absorption and selectively radiates thermal radiation of the human body through the atmosphere and into the cold outer space. The NFM comprises polyamide 6 (PA6) nanofibers and randomly distributed SiO₂ submicron spheres and has sufficient air permeability and thermal-moisture comfortability because of its interconnect nanopores and micropores. We measure the sky radiative cooling performance under a clear sky, and PA6/SiO₂ NFM produces temperatures that are about 0.4-1.7 °C lower than those of commercial textiles when covering dry and wet hands and temperatures 1.0-2.5 °C lower than the ambient temperature when thermal conduction and convection are isolated in a closed device. Our processed PA6/SiO₂ NFM combines sky radiative cooling with thermal management of the human body very well, which will promote the development of radiative cooling textiles.