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The increasingly intimate contact between electronics and the human body necessitates the development of stretchable energy storage devices that can conform and adapt to the skin. As such, the development of stretchable batteries and supercapacitors has received significant attention in recent years. This review provides an overview of the general operating principles of batteries and supercapacitors and the requirements to make these devices stretchable. The following sections provide an in-depth analysis of different strategies to convert the conventionally rigid electrochemical energy storage materials into stretchable form factors. Namely, the strategies of strain engineering, rigid island geometry, fiber-like geometry, and intrinsic stretchability are discussed. A wide range of materials are covered for each strategy, including polymers, metals, and ceramics. By comparing the achieved electrochemical performance and strain capability of these different materials strategies, we allow for a side-by-side comparison of the most promising strategies for enabling stretchable electrochemical energy storage. The final section consists of an outlook for future developments and challenges for stretchable supercapacitors and batteries.
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Electrically conductive metal-organic frameworks (cMOFs) have become a topic of intense interest in recent years because of their great potential in electrochemical energy storage, electrocatalysis, and sensing applications. Most of the cMOFs reported hitherto are 2D structures, and 3D cMOFs remain rare. Herein we report FeTHQ, a 3D cMOF synthesized from tetrahydroxy-1,4-quinone (THQ) and iron(II) sulfate salt. FeTHQ exhibited a conductivity of 3.3 ± 0.55 mS cm-1 at 300 K, which is high for 3D cMOFs. The conductivity of FeTHQ is valence-dependent. A higher conductivity was measured with the as-prepared FeTHQ than with the air-oxidized and sodium naphthalenide-reduced samples.
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Condutividade Elétrica , Estruturas Metalorgânicas/química , Quinonas/química , Eletroquímica , Ferro/química , Modelos Moleculares , OxirreduçãoRESUMO
Flame-retardant coatings are widely used in a variety of personnel or product protection, and many applications would benefit from film stretchability if suitable materials are available. It is challenging to develop flame-retardant coatings that are stretchable, eco-friendly, and capable of being integrated on mechanically dynamic devices. Here, a concept is reported that uses pretextured montmorillonite (MMT) hybrid nanocoatings that can undergo programed unfolding to mimic the stretchability of elastomeric materials. These textured MMT coatings can be transferred onto an elastomeric substrate to achieve an MMT/elastomer bilayer device with high stretchability (225% areal strain) and effective flame retardancy. The bilayer composite is utilized as flame-retardant skin for a soft robotic gripper, and it is demonstrated that the actuated response can manipulate and rescue irregularly shaped objects from a fire scene. Furthermore, by depositing the conformal MMT nanocoatings on nitrile gloves, the firefree gloves can endure direct flame contact without ignition.
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Bentonita/química , Materiais Revestidos Biocompatíveis/química , Retardadores de Chama/análise , Nanoestruturas/química , Dispositivos Eletrônicos Vestíveis , Elastômeros/química , Luvas Protetoras , Álcool de Polivinil/químicaRESUMO
Gut microbiota play a key role in health maintenance and disease pathogenesis in animals. Dietary phytochemicals are crucial factors shaping gut bacteria. Here, we investigated the function and mechanism of a phytogenic formulation, EUBIO-BPSG (BP), in laying hens. We found that BP dose-dependently improved health and egg production in 54-week-old hens. Furthermore, BP was correlated with increased fecal Lactobacillus, decreased Escherichia coli and Salmonella enterica, and reduced antibiotic resistance (AR) and antibiotic resistance genes (ARG) in chicken stools. The 16S rDNA data showed that BP increased seven genera of probiotics and reduced 13 genera of pathogens in chicken feces. In vitro co-culture experiments showed that BP at 4 µg/mL and above promoted growth of L. reuteri while large 100- and 200-fold higher doses suppressed growth of E. coli and S. enterica, respectively. Mechanistic studies indicated that L. reuteri and its supernatants antagonized growth of E. coli and S. enterica but not vice-versa. Five short-chain fatty acids and derivatives (SCFA) produced from L. reuteri directly killed both pathogens via membrane destruction. Furthermore, BP inhibited conjugation and recombination of ARG via interference with conjugation machinery and integrase activity in E. coli. Collectively, this work suggests that BP promotes host health and reproductive performance in laying hens through regulation of gut microbiota through increasing probiotics and decreasing pathogens and spreading ARG.
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Flame-retardant coatings are crucial for intelligent systems operating in high-temperature (300-800°C) scenarios, which typically involve multi-joint discrete or continuous kinematic systems. These multi-segment motion generation systems call for conformable yet resilient skin for dexterous work, including firefighting, packaging inflammable substances, encapsulating energy storage devices, and preventing from burning. In fire scenes, a flame-retardant soft robot shall protect integrated electronic components safely and work for navigation and surveillance effectively. Here, we establish fire-resistant robotic mechanisms with montmorillonite (MMT)-biocompatible hydrogel skin, offering effective flame retardancy (â¼78°C surface temperature after 3 min in fire) and high post-fire stretchability (â¼360% uniaxial tensile strain). Fatigue test results in the MMT-hydrogel polymer matrix to portray a change in post-fire energy consumption of â¼21% (between the first cycle and the 200th cycle), further indicating robustness. MMT-hydrogel synthetic skin medium is then applied to everyday household items and electronics, offering appealing protections in fire scenes (≤10% capacitance loss after 3 min and ≤14% diode light-intensity loss after 1 min in fire). We deploy shape memory alloy (SMA) actuated inchworm-, starfish-, and snail-like locomotion (average velocity â¼12 mm·min-1) for translating inside fire applications. With the stretchable and flame-retardant translucent barriers, the MMT-hydrogel skinned soft robots demonstrate stable compression/relaxation cycles (25 cycles) within flames (4 min 10 s) while protecting the electronic components inside in fire scene. We solve the agility vs. endurance conundrum in this article with SMA actuation independently via Joule heating without a cross-talk from the surrounding high-temperature arena.
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Retardadores de Chama , Robótica , Bentonita , Eletrônica , HidrogéisRESUMO
Mismatched deformation in a bilayer composite with rigid coating on a soft substrate results in complex and uniform topographic patterns, yet it remains challenging to heterogeneously pattern the upper coatings with various localized structures. Herein, a heterogeneous, 3D microstructure composed of Ti3C2Tx titanium carbide (MXene) and single-walled carbon nanotubes (SWNTs) was fabricated using a one-step deformation of a thermally responsive substrate with designed open holes. The mechanically deformed SWNT-MXene (s-MXene) structure was next transferred onto an elastomeric substrate, and the resulting s-MXene/elastomer bilayer device exhibited three localized surface patterns, including isotropic crumples, periodic wrinkles, and large papillae-like microstructures. By adjusting the number and pattern, the s-MXene papillae arrays exhibited superhydrophobicity (>170°), strong and tunable adhesive force (52.3-110.6 µN), and ultra-large liquid capacity (up to 35 µL) for programmable microdroplet manipulation. The electrically conductive nature of s-MXene further enabled proper thermal management on microdroplets via Joule heating for miniaturized antibacterial tests. The s-MXene papillae were further fabricated in a piezoresistive pressure sensor with high sensitivity (11.47 kPa-1). The output current changes of s-MXene sensors were highly sensitive to voice vibrations and responded identically with prerecorded profiles, promising their application in accurate voice acquisition and recognition.
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Nanopartículas Multifuncionais/química , Nanotubos de Carbono/química , Estresse Mecânico , Titânio/química , Elastômeros/química , Interações Hidrofóbicas e Hidrofílicas , Microscopia Eletrônica de Varredura , Nanopartículas Multifuncionais/ultraestrutura , Propriedades de Superfície , Temperatura , Vibração , VozRESUMO
Origami structures have been widely applied in various technologies especially in the fields of soft robotics. Metal oxides (MOs) have recently emerged as unconventional backbone materials for constructing complex origamis with distinct functionalities. However, the MO origami structures reported in the literature were rigid and not deformable, thus limiting their applications to soft robotics. Herein, we reported a graphene oxide (GO)-enabled templating synthesis to produce complex MO origami structures from their paper origami templates with high structural replication. The MO origami structures were next stabilized with elastomer, and the MO-elastomer origamis were able to be adapted into multiple actuation systems (including magnetic fields, shape-memory alloys, and pneumatics) for the fabrication of MO origami robots. Compared with conventional paper origami robots, the MO robots were lightweight, mechanically compliant, fire-retardant, magnetic responsive, and power efficient. We further demonstrated the legendary phoenix-fire-reborn concept in the soft robotics fields: a paper origami robot sacrificed itself in a fire scene and transformed itself into a downsized Al2O3 robot; the Al2O3 robot was able to crawl through a narrow tunnel where the original paper robot was unfit. These MO reconfigurable origamis provide an expanded material library for building soft robotics, and the functionalities of MO robots can be systematically engineered via the intercalation of various metal ions during the GO-enabled synthesis.
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Stretchable skin-like pressure sensing with minimized and distinguishable strain-induced interference is essential for the development of collision-aware surgical robotics to improve the safety and efficiency of minimally invasive surgery in a confined space. Inspired by the multidimensional wrinkles of Shar-Pei dog's skin for tactile sensing, we developed a stretchable pressure sensor consisting of reduced graphene oxide (rGO) electrodes with biomimetic topographies to improve the robot-tissue collision detections. A facile fabrication route for stretchable rGO electrodes was first demonstrated by harnessing the surface instability during the sequential deformation processes. The wrinkle-crumple rGO electrodes exhibited high stretchability (â¼100%) and strain-insensitive resistance profiles [a gauge factor (GF) < 0.05], which were next utilized to fabricate piezoresistive pressure sensors. The rGO pressure sensors were highly stretchable and exhibited high sensitivity under uniaxial strains (1.37, 1.30, and 0.98 kPa-1 at 0, 30, and 50% stretching states, respectively) along with distinguishable and reduced stretching responsiveness (a small GF â¼0.2 under 40% strains). The stretchable pressure sensors were next integrated with two surgical robots for the transoral robotic surgery procedure. During the cadaveric testing, the rGO sensors can detect the robot-tissue contacts under joint stretches in real time to enhance the surgeon's awareness for collision avoidance. The stretchable rGO pressure sensor that is highly sensitive under large strains provides great potential in the fields of wearable sensing and collision-aware humanoid robots to improve the human-machine interactions.
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The tight integration of actuation, sensing, and communication capabilities into origami robots enables the development of new-generation functional robots. However, this task is challenging because the conventional materials (e.g., papers and plastics) for building origami robots lack design opportunities for incorporating add-on functionalities. Installing external electronics requires high system integration and inevitably increases the robotic weight. Here, a graphene oxide (GO)-enabled templating synthesis was developed to produce reconfigurable, compliant, multifunctional metallic backbones for the fabrication of origami robots with built-in strain sensing and wireless communication capabilities. The GO-enabled templating synthesis realized the production of complex noble metal origamis (such as Pt) with high structural replication of their paper templates. The reproduced Pt origami structures were further stabilized with thin elastomer, and the Pt-elastomer origamis were reconfigurable and served as the multifunctional backbones for building origami robots. Compared with traditional paper and plastic materials, the reconfigurable Pt backbones were more deformable, fire retardant, and power efficient. In addition, the robots with conductive Pt-elastomer backbones (Pt robots) demonstrated distinct capabilities-such as on-demand resistive heating, strain sensing, and built-in antennas-without the need for external electronics. The multifunctionality of Pt robots was further demonstrated to extend beyond the capabilities of traditional paper-based robots, such as melting an ice cube to escape, monitoring/recording robotic motions in real time, and wireless communications between robots. The development of multifunctional metallic backbones that couple actuation, sensing, and communication enriches the material library for the fabrication of soft robotics toward high functional integration.
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Human skin serves as a multifunctional organ with remarkable properties, such as sensation, protection, regulation, and mechanical stretchability. The mimicry of skin's multifunctionalities via various nanomaterials has become an emerging topic. 2D materials have attracted much interest in the field of skin mimicry due to unique physiochemical properties. Herein, recent developments of using various 2D materials to mimic skin's sensing, protecting, and regulating capabilities are summarized. Next, to endow high stretchability to 2D materials, the approaches for fabrication of stretchable bilayer structures by integrating higher dimensional 2D materials onto soft elastomeric substrates are introduced. Accordion-like 2D material structures can elongate with elastomers and undergo programmed folding/unfolding processes to mimic skin's stretchability. That stretchable 2D material devices can achieve effective tactile sensing and protecting capabilities under large deformation is then highlighted. Finally, multiple key directions and existing challenges for future development are discussed.
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Biomimética , Pele Artificial , Humanos , Equipamento de Proteção Individual , Robótica , Fenômenos Fisiológicos da Pele , Dispositivos Eletrônicos VestíveisRESUMO
Two-dimensional MXene materials have demonstrated attractive electrical and electrochemical properties in energy storage applications. Adding stretchability to MXene remains challenging due to its high mechanical stiffness and weak intersheet interaction, so the assembling techniques for mechanically stable MXene architectures require further development. We report a simple fabrication by harnessing the interfacial instability to generate higher dimensional MXene nanocoatings capable of programmed crumpling/unfolding. A sequential patterning approach enabled the design of sequence-dependent MXene textures across multiple length scales, which were utilized for controllable wetting surfaces and high-areal-capacitance electrodes. We next transferred the crumpled MXene nanocoating onto an elastomer to fabricate an MXene/elastomer electrode with high stretchability. The accordion-like MXene can be reversibly folded/unfolded and still preserve efficient specific capacitances. We further fabricated asymmetric MXene supercapacitors, and the devices demonstrated efficient electrochemical performance and large deformability (180° bendability, 100% stretchability). Our texturing techniques can be applied to large MXene families for designing stretchable architectures in wearable electronics.
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Nanoporous carbon (NC) materials have attracted great research interest for supercapacitor applications, because of their excellent electrochemical and mechanical stability, good electrical conductivity, and high surface area. Although there are many reports on metal-organic framework (MOF)-derived carbon materials, previous synthetic studies have been hindered by imperfect control of particle sizes and shapes. Here, we show precise control of the particle sizes of MOF-525 from 100â nm to 750â nm. After conversion of MOF-525 to NC, the effects of variation of the particle size on the electrochemical performance have been carefully investigated. The results demonstrate that our NC is a potential candidate for practical supercapacitor applications.
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With the aim of a reliable biosensing exhibiting enhanced sensitivity and selectivity, this study demonstrates a dopamine (DA) sensor composed of conductive poly(3,4-ethylenedioxythiophene) nanotubes (PEDOT NTs) conformally coated with porphyrin-based metal-organic framework nanocrystals (MOF-525). The MOF-525 serves as an electrocatalytic surface, while the PEDOT NTs act as a charge collector to rapidly transport the electron from MOF nanocrystals. Bundles of these particles form a conductive interpenetrating network film that together: (i) improves charge transport pathways between the MOF-525 regions and (ii) increases the electrochemical active sites of the film. The electrocatalytic response is measured by cyclic voltammetry and differential pulse voltammetry techniques, where the linear concentration range of DA detection is estimated to be 2 × 10-6-270 × 10-6 m and the detection limit is estimated to be 0.04 × 10-6 m with high selectivity toward DA. Additionally, a real-time determination of DA released from living rat pheochromocytoma cells is realized. The combination of MOF5-25 and PEDOT NTs creates a new generation of porous electrodes for highly efficient electrochemical biosensing.
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Vinyl benzyl viologen (VBV) was synthesized and utilized to obtain all-in-one thermally cured electrochromic devices (ECDs). The vinyl moiety of VBV monomer could react with methyl methacrylate (MMA) to yield bulky VBV/poly(methyl methacrylate) (PMMA) chains and even cross-linked network without the assistance of additional cross-linker. Both the bulky VBV/PMMA chains and the resulting polymer network can hinder the aggregation of the viologens and reduce the possibility of dimerization, rendering enhanced cycling stability. Large transmittance changes (ΔT) over 60% at both 570 and 615 nm were achieved when the VBV-based ECD was switched from 0 V to a low potential bias of 0.5 V. Ultimately, the dual functional of VBV molecules, serving simultaneously as a promising electrochromic material and a cross-linker, is fully utilized in the proposed electrochromic system, making its fabrication process much easier. Negligible decays in ΔT at both wavelengths were observed for the cured ECD after being subjected to 1000 repetitive cycles, while 17.1% and 22.0% decays were noticed at 570 and 615 nm, respectively, for the noncured ECD. In addition, the low voltage-driven feature of the VBV-based ECD enables it to be incorporated with phenyl viologen (PV), further expanding the absorption range of the ECD. Panchromatic characteristic of the proposed PV/VBV-based ECD was demonstrated while exhibiting ΔT over 60% at both wavelengths. Only 5.3% and 6.9% decays, corresponding at 570 and 615 nm, respectively, were observed in the PV/VBV-based ECD after 10â¯000 continuous cycles at bleaching/coloring voltages of 0/0.5 V with an interval of 10 s for both bleaching and coloring processes.
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In this study, hybrid perovskite solar cells are fabricated using poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and poly(3-hexylthiophene-2,5-diyl) (P3HT) as dopant-free hole-transporting materials (HTMs), and two solution processes (one- and two-step methods, respectively) for preparing methylammonium lead iodide perovskite. By optimizing the concentrations and solvents of MEH-PPV solutions, a power conversion efficiency of 9.65% with hysteresis-less performance is achieved, while the device with 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'spirobifluorene (Spiro-OMeTAD) doped with lithium salts and tert-butylpyridine (TBP) exhibits an efficiency of 13.38%. This result shows that non-doped MEH-PPV is a suitable, low-cost HTM for efficient polymer-based perovskite solar cells. The effect of different morphologies of methylammonium lead iodide perovskite on conversion efficiency is also investigated by incident photon-to-electron conversion efficiency (IPCE) curves and electrochemical impedance spectroscopy (EIS).
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Herein, three kinds of viologens-based electrochromic devices (ECDs) (heptyl viologen (HV(BF4)2), octyl viologen (OV(BF4)2), and nonyl viologen (NV(BF4)2)) were fabricated utilizing ferrocene (Fc) as a redox mediator. Among them, the NV(BF4)2-based ECD exhibits the highest coloration efficiency (36.2 cm2/C) owing to the lowest driving energy. Besides, switching between 0 and 1.2 V, the NV(BF4)2-based ECD shows a desirable initial transmittance change (ΔT = 56.7% at 605 nm), and long-term stability (ΔT = 45.4% after 4000 cycles). Furthermore, a UV-cured polymer electrolyte containing polymeric ionic liquid (PIL, 1-allyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) and ethoxylated trimethylolpropane triacrylate (ETPTA) was introduced to the NV(BF4)2-based ECD. By controlling the weight percentage of the PIL, different curing degrees of the polymer electrolytes were obtained and led to an improved stability of the NV(BF4)2-based ECD because of the immobilization of NV(BF4)2. This observation was explained by calculating the apparent diffusivity (Dapp) of the redox species in the NV(BF4)2-based ECD under various curing degrees. In addition, increasing the amount of PIL leads to a lower driven energy needed for the NV(BF4)2-based ECD, following the same trend as the value of Dapp. Among all NV(BF4)2-based ECDs, 20 wt % of PIL addition (20-PIL ECD) exhibits large transmittance change (ΔT = 55.2% at 605 nm), short switching times (2.13 s in coloring and 2.10 s in bleaching), high coloration efficiency (60.4 and 273.5 cm2/C at 605 nm, after excluding the current density at the steady state), and exceptional cycling stability (ΔT = 53.8% after 10,000 cycles, or retained 97.5% of its initial ΔT).
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Uniform thin films of a metal-organic framework, which is constructed from free-base porphyrin linkers and hexa-zirconium nodes (MOF-525), are solvothermally grown on conducting substrates. Subsequently, solvothermal post metalations are employed to prepare the Zn-MOF-525 and Co-MOF-525 thin films. All the thin films are electroactive in aqueous media.
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B. pilosa has long been purported to have antidiabetes activity, but despite the advancement in phytochemistry and animal models of diabetes, no human clinical trials have been conducted to date. Here, we evaluated the effect of a B. pilosa formulation on fasting blood glucose (FBG), fasting serum insulin, and glycosylated hemoglobin A1c (HbA1c) in diabetic subjects. The B. pilosa formulation reduced the level of FBG and HbA1c in diabetics but increased fasting serum insulin in healthy subjects. Moreover, combination of B. pilosa formulation with antidiabetic drugs had better glycemic control in diabetics. The homeostatic model assessment (HOMA) data suggested that the antidiabetic activity of this formulation was via improvement of ß-cell function. We also tested the safety of the B. pilosa formulation in healthy subjects and observed no obvious side effects. We conclude that B. pilosa has potential as an antidiabetes treatment.
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Zr-based porphyrin metal-organic framework (MOF-525) nanocrystals with a crystal size of about 140 nm are synthesized and incorporated into perovskite solar cells. The morphology and crystallinity of the perovskite thin film are enhanced since the micropores of MOF-525 allow the crystallization of perovskite to occur inside; this observation results in a higher cell efficiency of the obtained MOF/perovskite solar cell.