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Deformable alternating-current electroluminescent (ACEL) devices are of increasing interest because of their potential to drive innovation in soft optoelectronics. Despite the research focus on efficient white ACEL devices, achieving deformable devices with high luminance remains difficult. In this study, this challenge is addressed by fabricating white ACEL devices using color-conversion materials, transparent and durable hydrogel electrodes, and high-k nanoparticles. The incorporation of quantum dots enables the highly efficient generation of red and green light through the color conversion of blue electroluminescence. Although the ionic-hydrogel electrode provides high toughness, excellent light transmittance, and superior conductivity, the luminance of the device is remarkably enhanced by the incorporation of a high-k dielectric, BaTiO3. The fabricated ACEL device uniformly emits very bright white light (489 cd m-2) with a high color-rendering index (91) from both the top and bottom. The soft and tough characteristics of the device allow seamless operation in various deformed states, including bending, twisting, and stretching up to 400%, providing a promising platform for applications in a wide array of soft optoelectronics.
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Thermal stiffening materials are commonly applied in the aerospace and automotive industries, among others, since their dimensional stabilities and stiffness characteristics improve at high temperatures. In this study, temperature-triggered modulus-tunable hydrogels were prepared by combining Pluronic F-127 with charged polymers. Pluronic F-127, a triblock copolymer micelle, provided three-dimensional printing capabilities of fine resolution with high viscosity, while hydrophobic and ionic interactions among polymer networks provided thermal stiffening. The hydrogel ink's printability was demonstrated by successfully creating complex 3D structures. A calcium ion carrying a hydrophobic propionate and carboxylate group in polymer chains was used to form additional physical crosslinking at high temperature, ultimately leading to the thermal stiffening effect without volume change. The thermal stiffening behavior was found to be fully reversible and repeatable. Finally, to demonstrate the versatility of this work, graphene oxide was added to produce a light-controllable modulus based on its photothermal properties.
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High-resolution 3D-printable hydrogels with high mechanical strength and biocompatibility are in great demand because of their potential applications in numerous fields. In this study, a material system comprising Pluronic F-127 dimethacrylate (FDMA) is developed to function as a direct ink writing (DIW) hydrogel for 3D printing. FDMA is a triblock copolymer that transforms into micelles at elevated temperatures. The transformation increases the viscosity of FDMA and preserves its structure during DIW 3D printing, whereupon the printed structure is solidified through photopolymerization. Because of this viscosity shift, various functionalities can be incorporated through the addition of other materials in the solution state. Acrylic acid is incorporated into the pregel solution to enhance the mechanical strength, because the carboxylate group of poly(acrylic acid) ionically crosslinks with Fe3+ , increasing the toughness of the DIW hydrogel 37 times to 2.46 MJ m-3 . Tough conductive hydrogels are also 3D printed by homogenizing poly(3,4-ethylenedioxythiophene) polystyrene sulfonate into the pregel solution. Furthermore, the FDMA platform developed herein uses DIW, which facilitates multicartridges 3D printing, and because all the materials included are biocompatible, the platform may be used to fabricate complex structures for biological applications.
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Hidrogéis , Poloxâmero , Tinta , Polímeros , Impressão TridimensionalRESUMO
Ionogels are crosslinked polymeric networks swollen in ionic liquids (ILs) with coupled cation-anion structures. Notably, ionogels are promising candidates for a wide range of applications owing to their biocompatibility, high electrical conductivity, mechanical durability, and chemical stability. The thermal behavior of ionogels can be tuned based on the chemical structure of the polymer network. However, the modification of the swelling behavior and thermo-responsiveness depending on the properties of the IL for a given polymer network has been rarely reported. To better understand the thermal behavior of ionogels based on the chemical structure of the ILs, in this study, a series of poly(N-isopropylacrylamide-co-N,N'-diethylacrylamide) ionogels were prepared and swollen in various ILs and their mixtures. By measuring the temperature-dependent swelling ratio change of the prepared ionogels, it was revealed that the chemical structure of the IL is the major factor governing their swelling and thermal behavior. Variations in the cationic and/or anionic structures led to changes in the transition temperature range and degree of volume change upon heating; this was owing to variations in the interactions between the IL and the polymer network. Furthermore, the volume phase transition of the ionogels could be finely tuned by adjusting the composition of the medium, which was controlled by the mixing of ILs.
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Hydrogels in the shape of double-walled microtubes possess great potential for development into artificial human blood vessels. In this work, we have prepared temperature-responsive tubular hydrogels with selectively controllable wall diameters, by using alginate templated photopolymerization in a triple channel microfluidic device. These tubular hydrogels mimic human blood vessels because of the separate thermally active inner and passive outer walls. The different behavior of each wall leads to the expansion of the hollow center volume with increasing temperature. This temperature-based control of the hollow center volume cannot be achieved in the case of conventional hydrogel microtubes. Furthermore, through this method, the hydrogels can be modified to achieve a controllable outer diameter while maintaining the hollow center dimensions simply by changing the position of the hydrogel walls. The ability to change the layer properties of the developed system indicates that the preparation of hydrogels with various monomers is possible.
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Stimuli-responsive hydrogel microfibers and microtubes are in great demand for biomedical applications due to their similarity to the native extracellular matrix. In this study, we prepared pH- and temperature-responsive hydrogel microfibers and microtubes using a microfluidic device through alginate-templated photopolymerization. Hydrogel monomer solutions containing N-isopropylacrylamide (NIPAm) and sodium acrylate (SA) or allyl amine (AA) were irradiated with UV light to invoke in situ photopolymerization. A repulsive force between the ionized SA or AA groups caused by protonation/deprotonation of the acrylate or amine groups, respectively, led to changes in the diameters and wall thicknesses of the fibers and/or tubes depending on the pH of the medium. Poly(NIPAm) is a well-known thermally responsive polymer wherein the NIPAm-based copolymer microfibers exhibited a thermal behavior close to the lower critical solution temperature. We have demonstrated that these multistimuli-responsive volume changes are fully reversible and repeatable. Furthermore, the positively charged microfibers were shown to exhibit cell adhesion, and the number of cells attached to the microfibers could be further increased by supplying nutrients, presenting the possibility of their application in tissue engineering and other biomedical fields.
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Microfluídica , Hidrogéis , Polímeros , Temperatura , Engenharia TecidualRESUMO
Ionogels are crosslinked polymer networks that swell in ionic liquids (ILs) and exhibit high conductivity and chemical stability. Combined with a representative thermally responsive polymer, poly(N-isopropylacrylamide) (PNIPAm), previously studied ionogels fulfilled the requirements for smart responsive materials, but their transition temperature in hydrophobic ILs exceeded that which could be used for practical applications. In this study, we prepared transition temperature tunable ionogels via copolymerization of NIPAm with solvatophilic N,N'-diethylacrylamide (NDEAm). The hydrophobic diethyl moiety in NDEAm promoted ionogel solvatophilicity toward the IL, resulting in a larger swelling ratio, lower volume phase transition temperature, and narrower transition range with increase in NDEAm content in the prepared ionogels. Based on these fundamental observations, ionogels that exhibit a volume phase transition near room temperature were prepared. We also studied the swelling and deswelling kinetics of the prepared ionogels, revealing that the deswelling rate is much slower than swelling due to the formation of a dense skin layer on the ionogel surface.
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Extensive research efforts have been devoted to the development of hydrogel microfibers for tissue engineering, because the vascular structure is related to the transport of nutrients and oxygen as well as the control of metabolic and mechanical functions in the human body. Even though stimuli-responsive properties would enhance the potential applicability of hydrogel microfibers for artificial tissue architectures, previous studies of their fabrication have not considered changes in the microfibers in response to external stimuli. In this work, we prepared temperature-responsive poly(N-isopropylacrylamide) (PNIPAm) microfibers with controlled shapes and sizes by the in situ photo-polymerization of aqueous monomers loaded in calcium alginate templates generated from microcapillary devices. We found that the shape and size of the hydrogel microfibers could be controlled by adjusting the injection positions of the solutions and varying the diameters of the inner capillary, respectively. We further fabricated light-responsive materials by incorporating photothermal magnetite nanoparticles (MNPs) within the temperature-responsive PNIPAm hydrogel microfibers. Because the MNPs incorporated into the PNIPAm microfibers generated heat upon the absorption of visible light, we could demonstrate volume changes in the microfibers triggered by both visible light irradiation and temperature.
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Resinas Acrílicas/química , Hidrogel de Polietilenoglicol-Dimetacrilato/química , Nanopartículas de Magnetita/química , Resinas Acrílicas/síntese química , Hidrogel de Polietilenoglicol-Dimetacrilato/síntese química , Hidrogel de Polietilenoglicol-Dimetacrilato/efeitos da radiação , Luz , Nanopartículas de Magnetita/efeitos da radiação , Polimerização/efeitos da radiação , TemperaturaRESUMO
Conductive hydrogels (CHs) have received significant attention for use in wearable devices because they retain their softness and flexibility while maintaining high conductivity. CHs are well suited for applications in skin-contact electronics and biomedical devices owing to their high biocompatibility and conformality. Although highly conductive hydrogels for smart wearable devices are extensively researched, a detailed summary of the outstanding results of CHs is required for a comprehensive understanding. In this review, the recent progress in the preparation and fabrication of CHs is summarized for smart wearable devices. Improvements in the mechanical, electrical, and functional properties of high-performance wearable devices are also discussed. Furthermore, recent examples of innovative and highly functional devices based on CHs that can be seamlessly integrated into daily lives are reviewed.
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Hidrogéis , Dispositivos Eletrônicos Vestíveis , Eletrônica , Condutividade ElétricaRESUMO
The fabrication of environmentally benign, solvent-processed, efficient, organic photovoltaic sub-modules remains challenging due to the rapid aggregation of the current high performance non-fullerene acceptors (NFAs). In this regard, design of new NFAs capable of achieving optimal aggregation in large-area organic photovoltaic modules has not been realized. Here, an NFA named BTA-HD-Rh is synthesized with longer (hexyl-decyl) side chains that exhibit good solubility and optimal aggregation. Interestingly, integrating a minute amount of new NFA (BTA-HD-Rh) into the PM6:L8-BO system enables the improved solubility in halogen-free solvents (o-xylene:carbon disulfide (O-XY:CS2)) with controlled aggregation is found. Then solar sub-modules are fabricated at ambient condition (temperature at 25 ± 3 °C and humidity: 30-45%). Ultimately, the champion 55 cm2 sub-modules achieve exciting efficiency of >16% in O-XY:CS2 solvents, which is the highest PCE reported for sub-modules. Notably, the highest efficiency of BTA-HD-Rh doped PM6:L8-BO is very well correlated with high miscibility with low Flory-Huggins parameter (0.372), well-defined nanoscale morphology, and high charge transport. This study demonstrates that a careful choice of side chain engineering for an NFA offers fascinating features that control the overall aggregation of active layer, which results in superior sub-module performance with environmental-friendly solvents.
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Dopant-free polymeric hole transport materials (HTMs) have attracted considerable attention in perovskite solar cells (PSCs) due to their high carrier mobilities and excellent hydrophobicity. They are considered promising candidates for HTMs to replace commercial Spiro-OMeTAD to achieve long-term stability and high efficiency in PSCs. In this study, we developed BDT-TA-BTASi, a conjugated donor-π-acceptor polymeric HTM. The donor benzo[1,2-b:4,5-b']dithiophene (BDT) and acceptor benzotriazole (BTA) incorporated pendant siloxane, and alkyl side chains led to high hole mobility and solubility. In addition, BDT-TA-BTASi can effectively passivate the perovskite layer and markedly decrease the trap density. Based on these advantages, dopant-free BDT-TA-BTASi-based PSCs achieved an efficiency of over 21.5%. Furthermore, dopant-free BDT-TA-BTASi-based devices not only exhibited good stability in N2 (retaining 92% of the initial efficiency after 1000 h) but also showed good stability at high-temperature (60 °C) and -humidity conditions (80 ± 10%) (retaining 92 and 82% of the initial efficiency after 400 h). These results demonstrate that BDT-TA-BTASi is a promising HTM, and the study provides guidance on dopant-free polymeric HTMs to achieve high-performance PSCs.
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Background/purpose: Human dental pulp stem cells (hDPSCs) possess excellent proliferative and osteogenic differentiation potentials. This study aimed to elucidate the role of lysophosphatidic acid (LPA) signaling in the proliferation and osteogenic differentiation of hDPSCs. Materials and methods: hDPSCs were treated with LPA and proliferation was measured using the cell counting kit-8 assay. Following the osteogenic differentiation of hDPSCs using osteogenic medium in the presence or absence of LPA, alkaline phosphatase (ALP) staining, ALP activity measurements, and RT-qPCR were performed to analyze the osteoblast differentiation. Small interfering RNA (siRNA)-mediated LPAR3 silencing and extracellular signal-regulated (ERK)/mitogen-activated protein (MAP) kinase inhibitors were used to elucidate the molecular mechanisms underlying LPA-induced proliferation and differentiation of hDPSCs. Results: LPA treatment significantly induced proliferation and osteogenic differentiation of hDPSCs. The depletion of LPAR3 expression by LPAR3-speicifc siRNA in hDPSCs diminished LPA-induced proliferation and osteogenic differentiation. The LPAR3-mediated proliferation and osteogenic differentiation of hDPSCs in response to LPA were significantly suppressed by U0126, a selective inhibitor of ERK. Conclusion: These findings suggest that LPA induces the proliferation and osteogenic differentiation of hDPSCs via LPAR3-ERK-dependent pathways.
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A new nonfullerene acceptor (NFA), BTA-ERh, was synthesized and integrated into a PM6:Y7:PC71BM ternary system to regulate the blend film morphology for enhanced device performance. Due to BTA-ERh's good miscibility with host active blend films, an optimized film morphology was obtained with appropriate phase separation and fine-tuning of film crystallinity, which ultimately resulted in efficient exciton dissociation, charge transport, lower recombination loss, and decreased trap-state density. The resulting additive-free quaternary devices achieved a remarkable efficiency of 18.90%, with a high voltage, fill factor, and current density of 0.87 V, 76.32%, and 28.60 mA cm-2, respectively. By adding less of a new small molecule with high crystallinity, the favorable nanomorphology shape of blend films containing NFAs might be adjusted. Consequently, this strategy can enhance photovoltaic device performance for cutting-edge NFA-based organic solar cells (OSCs). In contrast, the additive-free OSCs exhibited good operational stability. More importantly, large-area modules with the quaternary device showed a remarkable efficiency of 12.20%, with an area as high as 55 cm2 (substrate size, 100 cm2) in an air atmosphere via D-bar coating. These results highlight the enormous research potential for a multicomponent strategy for future additive-free OSC applications.
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The cerebellum is associated with balance control and coordination, which might be important for gliding on smooth ice at high speeds. A number of case studies have shown that cerebellar damage induces impaired balance and coordination. As a positive model, therefore, we investigated whether plastic changes in the volumes of cerebellar subregions occur in short-track speed skating players who must have extraordinary abilities of balance and coordination, using three-dimensional magnetic resonance imaging volumetry. The manual tracing was performed and the volumes of cerebellar hemisphere and vermian lobules were compared between short-track speed skating players (n=16) and matched healthy controls (n=18). We found larger right cerebellar hemisphere volume and vermian lobules VI-VII (declive, folium, and tuber) in short-track speed skating players in comparison with the matched controls. The finding suggests that the specialized abilities of balance and coordination are associated with structural plasticity of the right hemisphere of cerebellum and vermian VI-VII and these regions play an essential role in balance and coordination.
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Cerebelo/fisiologia , Imageamento por Ressonância Magnética/métodos , Desempenho Psicomotor/fisiologia , Patinação/fisiologia , Adolescente , Humanos , Masculino , Destreza Motora/fisiologia , Adulto JovemRESUMO
Visible light induces switching of surface chemical patterns based on hybrid gels of thermally responsive poly(N-isopropyl acrylamide) copolymer networks containing iron oxide nanoparticles. The swelling of these hybrid gels is reduced upon illumination (see picture), allowing controlled unfolding of creased features formed owing to an elastic surface instability.
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(1) Background: The amount of physical activity most adults perform is less than the recommended amount, and the resulting decrease in physical strength makes them vulnerable to various diseases. A decrease in muscle size and strength due to damage caused by disease or aging negatively affects functional strength. Muscle evaluation in adults can yield results that are predictive indicators of aging and unexpected disability. In addition, balance ability is essential to prevent falls and injuries in daily life and maintain functional activities. It is important to develop and strengthen balance in the lower extremities and core muscles to maintain and enhance overall body balance. This study aimed to analyze the effects of core balance training on muscle tone and balance ability in adults. (2) Methods: The participants of this study were 32 adult male and female university students (male: mean age = 21.3 ± 1.9 years, weight = 74.2 ± 12.6 kg, BMI = 23.4 + 2.5, n = 14; female: mean age = 21.0 ± 1.4 years, weight = 64.6 + 1.2 kg, BMI = 22.4 ± 2.4, n =18). Thirty-two adults (training group: 16, control group: 16; male: 16, female: 16) participated in the Myoton PRO (gastrocnemius lateral/medial, tibialis anterior), Pedalo balance system, and Y-balance test. (3) Results: The following results were obtained for muscle elasticity, stiffness, and dynamic/static balance ability after 10 weeks of core balance training. 1. There was no significant difference in muscle elasticity (gastrocnemius lateral/medial, tibialis anterior) (p < 0.05). 2. Muscle stiffness (gastrocnemius lateral/medial, tibialis anterior) significantly increased (p < 0.05). 3. Dynamic/static balance ability significantly increased (p < 0.05). (4) Conclusions: In future, data for the age and sex of various participants, should be accumulated by recruiting participants to study muscle characteristics, such as muscle elasticity and stiffness. Estimating the appropriate injury range and optimal exercise capacity is possible through follow-up studies. The findings can then be used as a basis for predicting injuries or determining and confirming the best time to resume exercise.
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Tono Muscular , Equilíbrio Postural , Adulto , Estabilidade Central , Exercício Físico , Feminino , Humanos , Masculino , Força Muscular/fisiologia , Músculo Esquelético/fisiologia , Equilíbrio Postural/fisiologia , Adulto JovemRESUMO
End group engineering on the side chain of π-conjugated donor polymers is explored as an effective way to develop efficient photovoltaic devices. In this work, we designed and synthesized three new π-conjugated polymers (PBDT-BZ-1, PBDT-S-BZ, and PBDT-BZ-F) with terminal aryl end groups on the side chain of chlorine-substituted benzo[1,2-b:4,5b']dithiophene (BDT). End group modifications showed notable changes in energy levels, dipole moments, exciton lifetimes, energy losses, and charge transport properties. Remarkably, the three new polymers paired with IT-4F (halogen-free solvent processed/toluene:DPE) displayed high power conversion efficiencies (PCEs) compared to a polymer (PBDT-Al-5) without a terminal end group (PCE of 7.32%). Interestingly, PBDT-S-BZ:IT-4F (PCE of 13.73%) showed a higher PCE than the benchmark PM7:IT-4F. The improved performance of PBDT-S-BZ well correlates with its improved charge mobility, well-interdigitated surface morphology, and high miscibility with a low Flory-Huggins interaction parameter (1.253). Thus, we successfully established a correlation between the end group engineering and bulk properties of the new polymers for realizing the high performance of halogen-free nonfullerene organic solar cells.
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When the intensity of the incident light increases, the photocurrents of organic photodiodes (OPDs) exhibit relatively early saturation, due to which OPDs cannot easily detect objects against strong backlights, such as sunlight. In this study, this problem is addressed by introducing a light-intensity-dependent transition of the operation mode, such that the operation mode of the OPD autonomously changes to overcome early photocurrent saturation as the incident light intensity passes the threshold intensity. The photoactive layer is doped with a strategically designed and synthesized molecular switch, 1,2-bis-(2-methyl-5-(4-cyanobiphenyl)-3-thienyl)tetrafluorobenzene (DAB). The proposed OPD exhibits a typical OPD performance with an external quantum efficiency (EQE) of <100% and a photomultiplication behavior with an EQE of >100% under low-intensity and high-intensity light illuminations, respectively, thereby resulting in an extension of the photoresponse linearity to a light intensity of 434 mW cm-2 . This unique and reversible transition of the operation mode can be explained by the unbalanced quantum yield of photocyclization/photocycloreversion of the molecular switch. The details of the operation mechanism are discussed in conjunction with various photophysical analyses. Furthermore, they establish a prototype image sensor with an array of molecular-switch-embedded OPD pixels to demonstrate their extremely high sensitivity against strong light illumination.
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Emerging organic solar cells based on a ternary strategy is one of the most effective methods for improving the blend film morphology, absorption ability, and device performances. On the other hand, this strategy has had very limited success in all-polymer solar cells (all-PSCs) because of the scarcity of new polymers and the challenges faced during third component optimization. Herein, highly efficient ternary all-PSCs were developed from siloxane-functionalized side chains with a wide-band-gap (Eg) polymer, Si-BDT, which is blended with a medium and ultra-narrow Eg polymer donor and acceptor, PTB7-Th, and DCNBT-TPIC. An impressive power conversion efficiency (PCE) of 13.45% was achieved in the ternary all-PSCs [PTB7-Th(0.6):Si-BDT(0.4):DCNBT-TPIC(0.6)] with the addition of 0.4 wt equivalent Si-BDT into binary all-PSCs [PTB7-Th(1):DCNBT-TPIC(0.6) PCE of 10.11%]. In contrast, the binary all-PSCs with a Si-BDT(1):DCNBT-TPIC(0.6) active layer only exhibited a good PCE of 9.92%. More importantly, the siloxane-functionalized side chains increase the light-absorption ability, carrier mobility, blend miscibility, and film morphology in ternary devices compared to those of the binary devices. Hence, exciton dissociation, charge carrier transport, and suppressed recombination properties were facilitated. In the presence of Si-BDT, both binary and ternary all-PSCs PCEs are significantly improved. Indeed, 13.45% PCE is one of the best values reported for all-PSCs except for those based on polymerized small molecule acceptors. In addition, the ternary all-PSCs showed excellent environmental and thermal stabilities with 95 and 84% of the initial PCE retained after 900 and 500 h, respectively. These results offer effective device engineering, providing a new avenue for improving the device performance in ternary all-PSCs.
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Surfaces with physicochemical properties that can be modulated using external stimuli offer great promise for designing responsive or adaptive materials. Here, we describe biocompatible dynamic scaffolds based on thin hydrogel coatings that reversibly hide and display surface chemical patterns in response to temperature changes. At room temperature, the gel absorbs water, triggering an elastic creasing instability that sequesters functionalized regions within tight folds in the surface. Deswelling at approximately 37 degrees C causes the gel surface to unfold, thereby regenerating the biomolecular patterns. Crease positions are directed by topographic features on the underlying substrate, and are translated into two-dimensional micrometre-scale surface chemical patterns through selective deposition of biochemically functionalized polyelectrolytes. We demonstrate specific applications of these dynamic scaffolds--selective capture, sequestration and release of micrometre-sized beads, tunable activity of surface-immobilized enzymes and reversible encapsulation of adherent cells--which offer promise for incorporation within lab-on-a-chip devices or as dynamic substrates for cellular biology.