Wide Range Of Strains Research Articles

Highly Sensitive and Wide Detection Range Thermoplastic Polyurethane/Graphene Nanoplatelets Multifunctional Strain Sensor with a Porous and Crimped Network Structure.

High-performance flexible strain sensors have tremendous potential applications in wearable devices and health monitoring. However, developing a flexible strain sensor with high sensitivity over a wide strain range remains a significant challenge. In this study, a fibrous membrane with a porous and crimped structure was designed as the substrate material for TPU/GNPs flexible strain sensors. This structural design effectively balances sensitivity with the strain range. The TPU-PEO fibrous membrane prepared using electrospinning with water washing, resulted in a porous fibrous membrane with a TPU framework. Subsequently, the fibrous membrane was subjected to anhydrous ethanol stimulation to obtain a porous and crimped network structure. GNPs were modified on the TPU fibrous membrane through ultrasonic treatment. The produced flexible strain sensor exhibited high sensitivity (GF = 4047.5) within a large strain range (350%) and demonstrated excellent sensing performance, stability, and durability (>10,000 cycles). It not only captured basic movements but also efficiently recognized and measured bending angles, enabling a more sophisticated human-machine interaction experience. This advancement opens up possibilities for future intelligent wearable technology and human-machine interaction, contributing to the evolution of these fields.

Bioinspired Multifunctional Self-Sensing Actuated Gradient Hydrogel for Soft-Hard Robot Remote Interaction

HighlightsThe bioinspired self-sensing actuated gradient hydrogel was developed by a wettability-based method via precipitation of MoO2 nanosheets.Self-sensing actuated gradient hydrogel combined ultrafast thermo-responsive actuation (21° s–1), exceptional photothermal efficiency (3.7 °C s–1) and high sensing properties (GF = 3.94).The first self-sensing remote interaction system based on gradient hydrogel actuators and robotic hands was constructed.

Electronic properties and modulation effects on edge-modified GeS<sub>2</sub> nanoribbons

GeS<sub>2</sub> monolayers have been successfully prepared in this work. To further expand their applications and discover new physical properties, we construct armchair-type GeS<sub>2</sub> nanoribbons (AGeS<sub>2</sub>NR) and use different concentrations of H and O atoms for the edge modificationand their structural stabilities, electronic properties, carrier mobilities, and physical field modulation effects are studied in depth. The results show that the edge-modified nanoribbon has a higher energy and thermal stability. The bare edge nanoribbon is a nonmagnetic semiconductor, while the edge modification can change the bandgap of AGeS<sub>2</sub>NR and make it a wide or narrowed bandgap semiconductor, or a metal, which is closely related to the elimination or partial elimination of the edge states or the creation of hybridization bands. Thus edge modification extends the application range of nanoribbons in the fields of electronic devices and optical devices. In addition, the carrier mobility is found to be very sensitive to the edge modification: the carriers’ (electrons’ and holes’) mobilities of nanoribbons can be adjusted to a difference of up to one order of magnitude, and the difference in carrier mobility polarization can be tuned to one order of magnitude. Strain effect studies reveal that the semiconducting nanoribbons are robust in keeping the electronic phase unchanged over a wide strain range, which is useful for maintaining the stability of the electron transport in the related device. Most of the semiconducting nanoribbons have the stability to keep the semiconducting properties unchanged under high external electric field, but the bandgap can be reduced significantly with the increase of the electric field. In short, this study provides a theoretical analysis and reference for understanding the property of GeS<sub>2</sub> nanoribbons and developing related devices.

A topological nodal line semi-metal with a negative Poisson's ratio in a three-dimensional carbon network with sp2 hybridization.

In carbon allotropes, a series of topological semi-metals have been predicted, but both novel electronic properties and mechanical characteristics, e.g., a negative Poisson's ratio (NPR), are rarely discovered in the same sp2 type system. Here, a new three-dimensional carbon network, named WZGN, constructed from distorted one-dimensional zigzag graphene nanoribbons is proposed. The stability of the system is fully ensured by the phonon dispersion, AIMD simulation, and binding energy calculations. Besides, it is found that the system holds both topologically protected nodal line semi-metal properties together with an NPR property. Especially, the value of the NPR can exceed -0.36 when 21% uniaxial tensile strain along the c'-direction is applied. Our findings point out that nodal line semi-metals can be compatible with intrinsic NPR properties in a wide strain range in carbon systems with sp2 hybridization, suggesting possible applications in mechanical and electronics fields.

Hyper strength, high sensitivity integrated wearable signal sensor based on non-covalent interaction of an ionic liquid and bacterial cellulose for human behavior monitoring.

Ion-sensing hydrogels exhibit electrical conductivity, softness, and mechanical and sensory properties akin to human tissue, rendering them an ideal material for mimicking human skin. In the realm of fabricating sensors for detecting human physiological activities, they present an ideal alternative to traditional rigid metal conductors. Nevertheless, achieving ionic hydrogels with outstanding tensile properties, toughness, ionic conductivity, and transport stability poses a significant challenge. This paper describes a simple method of forming a basic network by free radical polymerization of acrylamide, and then bacterial cellulose (BC) and 1-ethyl-3-methylimidazolium chloride ([EMIM]Cl) were introduced into the basic network. The polyhydrogen bonds and electrostatic interactions in the system gave the hydrogel notable tensile properties (3271 ± 37%), toughness (7.39 ± 0.13 MJ m-3), and high ultimate tensile stress (385.1 ± 7.2 kPa). In addition, the combination of BC and [EMIM]Cl collaboratively enhanced the mechanical properties and electrical conductivity. Ion sensing hydrogels have a wide operating strain range (≈1000%) and high sensitivity (gage factor (GF) = 11.85), and are therefore considered promising candidates for next-generation gel-based strain sensor platforms.

Cold-resistant, highly stretchable ionic conductive hydrogels for intelligent motion recognition in winter sports.

Conductive hydrogels have attracted much attention for their wide application in the field of flexible wearable sensors due to their outstanding flexibility, conductivity and sensing properties. However, the weak mechanical properties, lack of frost resistance and susceptibility to microbial contamination of traditional conductive hydrogels greatly limit their practical application. In this work, multifunctional polyvinyl alcohol (PVA)/carboxymethyl cellulose (CMC)/poly(acrylamide-co-1-vinyl-3-butylimidazolium bromide) (P(AAm-co-VBIMBr)) (PCPAV) ionic conductive hydrogels with high strength and good conductive, transparent, anti-freezing and antibacterial properties were constructed by introducing a network of chemically crosslinked AAm and VBIMBr copolymers into the base material of PVA and CMC by in situ free radical polymerization. Owing to the multiple interactions between the polymers, including covalent crosslinking, multiple hydrogen bonding interactions, and electrostatic interactions, the obtained ionic conductive hydrogels exhibit a high tensile strength (360.6 kPa), a large elongation at break (810.6%), good toughness, and fatigue resistance properties. The introduction of VBIMBr endows the PCPAV hydrogels with excellent transparency (∼92%), a high ionic conductivity (15.2 mS cm-1), antimicrobial activity and good flexibility and conductivity at sub-zero temperatures. Notably, the PCPAV hydrogels exhibit a wide strain range (0-800%), high strain sensitivity (GF = 3.75), fast response, long-term stability, and fantastic durability, which enable them to detect both large joint movements and minute muscle movements. Based on these advantages, it is believed that the PCPAV-based hydrogel sensors would have potential applications in health monitoring, human motion detection, soft robotics, ionic skins, human-machine interfaces, and other flexible electronic devices.

Multifunctional organohydrogel via the synergy of dialdehyde starch and glycerol for motion monitoring and sign language recognition

Conductive hydrogel which belongs to a type of soft materials has recently become promising candidate for flexible electronics application. However, it remains difficult for conductive hydrogel-based strain sensors to achieve the organic unity of large stretchability, high conductivity, self-healing, anti-freezing, anti-drying and transparency. Herein, a multifunctional conductive organohydrogel with all of the above superiorities is prepared by crosslinking polyacrylamide (PAM) with dialdehyde starch (DAS) in glycerol-water binary solvent. Attributing to the synergy of abundant hydrogen bonding and Schiff base interactions caused by introducing glycerol and dialdehyde starch, respectively, the organohydrogel achieved balanced mechanical and electrical properties. Besides, the addition of glycerol promoted the water-locking effects, making the organohydrogel retain the superior mechanical properties and conductivity even at extreme conditions. The resultant organohydrogel strain sensor exhibits desirable sensing performance with high sensitivity (GF = 6.07) over a wide strain range (0–697 %), enabling the accurate monitoring of subtle body motions even at −30 °C. On the basis, a hand gesture monitor system based on the organohydrogel sensors arrays is constructed using machine learning method, achieving a considerable sign language recognition rate of 100 %, and thus providing convenience for communications between the hearing or speaking-impaired and general person.

Highly Stretchable and Fluorescent Visualizable Thermoplastic Polyurethane/Tetraphenylethylene Plied Yarn Strain Sensor with Heterogeneous and Cracked Structure for Human Health Monitoring.

Smart wearable technology has been more and more widely used in monitoring and prewarning of human health and safety, while flexible yarn-based strain sensors have attracted extensive research interest due to their ability to withstand greater external strain and their significant application potential in real-time monitoring of human motion and health signals. Although several strain sensors based on yarn structures have been reported, it remains challenging to strike a balance between high sensitivity and wide strain ranges. At the same time, visual signal sensing is expected to be used in strain sensors thanks to its intuitiveness. In this work, thermoplastic polyurethane (TPU) and tetraphenylethylene (TPE) were wet-spun to fabricate flexible fluorescent fibers used as the substrate of the sensor, followed by the drop addition of polydimethylsiloxane (PDMS) beads and curing to produce a heterogeneous structure, which were further twisted into a plied yarn. Finally, a visualizable flexible yarn strain sensor based on solidified liquid beads and crack structure was obtained by loading polydopamine (PDA) and polypyrrole (PPy) in situ. The sensor exhibited high sensitivity (the GF value was 58.9 at the strain range of 143-184%), a wide working strain range (0-184%), a low monitoring limit (<0.1%), a fast response (58.82 ms), reliable responses at different frequencies, and excellent cycle durability (over 2000 cycles). At the same time, the yarn strain sensor also had excellent photothermal characteristics and a fluorescence crack visualization effect. These attractive advantages enabled yarn strain sensors to accurately monitor various human activities, showing great application potential in health monitoring, personalized medical diagnosis, and other aspects.

StenM_174: A Novel Podophage That Infects a Wide Range of Stenotrophomonas spp. and Suggests a New Subfamily in the Family Autographiviridae.

Stenotrophomonas maltophilia was discovered as a soil bacterium associated with the rhizosphere. Later, S. maltophilia was found to be a multidrug-resistant hospital-associated pathogen. Lytic bacteriophages are prospective antimicrobials; therefore, there is a need for the isolation and characterization of new Stenotrophomonas phages. The phage StenM_174 was isolated from litter at a poultry farm using a clinical strain of S. maltophilia as the host. StenM_174 reproduced in a wide range of clinical and environmental strains of Stenotrophomonas, mainly S. maltophilia, and it had a podovirus morphotype. The length of the genomic sequence of StenM_174 was 42,956 bp, and it contained 52 putative genes. All genes were unidirectional, and 31 of them encoded proteins with predicted functions, while the remaining 21 were identified as hypothetical ones. Two tail spike proteins of StenM_174 were predicted using AlphaFold2 structural modeling. A comparative analysis of the genome shows that the Stenotrophomonas phage StenM_174, along with the phages Ponderosa, Pepon, Ptah, and TS-10, can be members of the new putative genus Ponderosavirus in the Autographiviridae family. In addition, the analyzed data suggest a new subfamily within this family.

Microchannel‐Confined Chinese Ink‐Based Highly Stretchable Liquid‐State Strain Sensor for Early Warning of Road Collapse

AbstractStretchable strain sensors are widely used in the fields of wearable devices, soft robotics, healthcare monitoring, and more. Despite tremendous efforts, strain sensors capable of detecting large‐scale soil deformation for urban geological hazard prevention have not yet been demonstrated. In this paper, a soft strain sensor of a highly stretchable Ecoflex‐0030 elastomeric matrix with microchannel‐confined environmentally benign conductive Chinese ink as the liquid‐state strain‐sensitive material that can reliably detect a wide range of working strain up to 300% is demonstrated. The sensor exhibits a negligible hysteresis error of 2.1%, with a considerably good gauge factor of 1.95. The sensor performance is evaluated under both creep and cyclic loading tests, indicating superior stability (0.65% fluctuation), and repeatability (0.28% variation in 1000 cycles), even under a lower underground environment temperature of 18°C. As a proof‐of‐concept demonstration, a liquid‐state strain sensor array with a strain amplification mechanism capable of accurately monitoring the formation of various underground cavities and providing timely demanded information for early warning of catastrophic road collapse is demonstrated and verified by the computer vision‐based particle image velocimetry (PIV) method.

Ternary Liquid Metal Polymer Composite for Stretchable Electronics

AbstractThe small strain characteristics of the traditional flexible conductive composites hinder their realization of skin‐like properties and multi‐scenario applications. The value of liquid metal (LM)‐based elastomers is demonstrated in flexible electronics. Attempts in this area include the development of multifunctional LM‐based elastomers with controllable morphology, superior mechanical performances, and excellent stability. In this work, an efficient strategy is proposed to achieve the fast preparation of the LM patch by uniformly distributing eutectic gallium–indium–tin alloy in deionized water and by constructing the LM‐iron particles‐Ecoflex (LMIE) ternary composite system. In this study, the fabricated LMIE large strain sensor exhibits high sensitivity (the gage factor (GF) = 0.98 when strain ranges from 0% to 60%; GF = 1.91 when strain ranges from 60% to 100%), high linearity (correlation coefficient (R2) = 0.96 when strain ranges from 0% to 60%; R2 = 0.99 when strain ranges from 60% to 100%), a wide strain range of detection (e.g., 1%–100%) and breaking elongation (e.g., 450%), a fast response time (80 ms), excellent repeatability and stability. This work exhibits the excellent potential of multifunctional liquid metal composites in wearable electronics and prediction devices of structural collapse.

Strain and stacking induced topological phase transition in bipolar ferromagnetic semiconductor OsClBr

The combination of valleytronics and topology has great potential significance in condensed matter and material physics. Here, based on first-principles calculations, we predict a dipolar ferromagnetic semiconductor OsClBr. Benefiting from strong spin–orbit coupling and the intrinsic exchange interaction of localized d electrons, spontaneous valley polarization occurs. In addition, the tensile strain can induce topological phase transitions between ferrovalley, half-valley-metal, and valley-polarization quantum anomalous Hall (VQAH) phases, which can be attributed to the band inversion between dz2 and dxy/dx2−y2 orbitals of Os atom. Moreover, stacking-dependent topological phase transitions can be found in bilayer OsClBr, and the robustness of VQAH phase in b − 1 configuration under a wide strain range has been proved, which is greatly beneficial for the regulation of quantum states. Our work provides a potential opportunity for the preparation and application of low-power consumption electronics devices.

Spatial hetero-structured composites with ultrawide linear range for positive-negative pressure sensing and e-skin of bionic fish

For impelling practical applications of flexible sensors or electronic skins, it is challenging and urgent to fabricate multifunctional flexible mechanical sensors with good linearity over a wide working range in an economical and scalable manner. Currently, it is immensely difficult to simultaneously detect tension, pressure and bending with high linearity over a wide strain range by using one film without sensor integration. Herein, we present a porous flexible mechanical sensor with a spatial electron transport network consisting of ethylene-α-octene random copolymer (ORC) elastic skeleton with surface embedded carbon black (CB) and carbon fiber (CF) bridges. Such an interesting spatial hetero-structure can shunt the electron transport effectively to regulate the resistance change of the sensor during strain loading, resulting in linear electrical signal response to mechanical deformation for a tensile strain up to 320% and a pressure up to 1.3 MPa, as well as a bending angle ranging from− 90 o to 90 o, respectively. Besides, it shows the detection capability of ambient pressure ranging from −0.09 MPa to 0.4 MPa continuously. Such a multifunctional film sensor with ultrawide linear working range demonstrates potential applications for monitoring body motions of athletics and underwater soft robots.

25 Years Responding to Respiratory and Other Viruses with Mass Spectrometry.

This review article presents the development and application of mass spectrometry (MS) approaches, developed in the author's laboratory over the past 25 years, to detect; characterise, type and subtype; and distinguish major variants and subvariants of respiratory viruses such as influenza and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). All features make use of matrix-assisted laser desorption ionisation (MALDI) mass maps, recorded for individual viral proteins or whole virus digests. A MALDI-based immunoassay in which antibody-peptide complexes were preserved on conventional MALDI targets without their immobilisation led to an approach that enabled their indirect detection. The site of binding, and thus the molecular antigenicity of viruses, could be determined. The same approach was employed to study antivirals bound to their target viral protein, the nature of the binding residues, and relative binding affinities. The benefits of high-resolution MS were exploited to detect sequence-conserved signature peptides of unique mass within whole virus and single protein digests. These enabled viruses to be typed, subtyped, their lineage determined, and variants and subvariants to be distinguished. Their detection using selected ion monitoring improved analytical sensitivity limits to aid the identification of viruses in clinical specimens. The same high-resolution mass map data, for a wide range of viral strains, were input into a purpose-built algorithm (MassTree) in order to both chart and interrogate viral evolution. Without the need for gene or protein sequences, or any sequence alignment, this phylonumerics approach also determines and displays single-point mutations associated with viral protein evolution in a single-tree building step.

A novel viscoelastic fractional damage model of thermosetting polymers for dynamic responses

Thermosets-polymeric materials play a key role in the modern plastics and polymers composites, which are increasingly used in the areas subject to dynamic loading condition. The materials will experience an amount of micro-damage under such circumstances, while the damage softening behaviors cannot be well captured by viscoelastic or elasto-viscoplastic constitutive models. In this paper, a viscoelastic fractional damage model depended on strain rate is formulated to depict the dynamic responses of thermosetting polymers. A dynamic damage evolution law related to strain and strain rate is developed by means of the fractional calculus. The relationship between fractional order and damage evolution for materials is theoretically investigated. It is observed that the fractional order can be able to characterize the intensity of damage evolution, and the variation of order function is in line with the evolution with damage of material properties. The model applicability is verified by the compressive loading experimental data under different strain rates and temperatures of thermosets. The influences of temperatures on the proposed model and the damage evolution are analyzed by the fitting results. Furthermore, a corresponding thermo-viscoelastic model is developed by considering the temperature effect, of which the predictive ability is tested and the comparisons with the existing model are also presented. The results indicate the proposed model can better capture the stress-strain responses over a wider range of strain.

Anisotropy reduction and mechanical property improvement of additively manufactured stainless steel based on cyclic phase transformation

Owing to the special layer-by-layer deposition process of directed energy deposition (DED), columnar coarse grains, produced by cyclic reheating with intrinsic directional heat flow along the building direction, are difficult to avoid. These grains result in strong anisotropic characteristics with poor mechanical properties, which restrict the application of DED products. This work proposes a novel fabrication strategy based on the cyclic-phase-transformation behavior, which can reduce the anisotropy and improve the mechanical properties of DED-printed stainless steel. Using this fabrication strategy, 316 L powder (austenitic stainless steel) and 17–4PH powder (martensitic stainless steel) were mixed in different mass ratios to fabricate five types of DED-printed stainless steels. Among the five samples, P70 (mixture of 70 wt% 17–4PH powder and 30 wt% 316 L powder) showed the weakest anisotropy and the best mechanical properties, which can be attributed to the cyclic phase transformation under cyclic reheating treatment and the transformation-induced plasticity (TRIP) effect over a wide range of strains, respectively. Compared with the pure 316 L printed material, the tensile test results of P70 showed that the yield strength (YS) and ultimate tensile strength (UTS) increased by 35.4% and 34.5%, respectively, whereas the uniform elongation (UE) and total elongation (TE) were improved by 63.9% and 31.4%, respectively. In addition, the strength–ductility balance (UTS × UE) increased by as much as 120.4%. The proposed fabrication strategy is expected to reduce the anisotropy in other materials that undergo cyclic-phase-transformation phenomena during additive manufacturing.

Effect of ultrasonication on the properties of carnauba wax-based soybean oleogel

In this study, the ultrasonication treatment was applied to develop a carnauba wax-based soybean oleogel with improved functional and physical properties. Oleogel was prepared by adding carnauba wax (8 % w/w) in soybean oil. The response surface methodology was used to optimize the ultrasonication conditions. Ultrasonic amplitude percentage and time were kept as independent variables. Oil binding capacity, hardness, and adhesiveness of the oleogel were the responses for the study. The effect of the ultrasonication condition was obtained at 35.40 % amplitude and 16.33 min ultrasonication time. The oil binding capacity of the oleogel increased from 91.4 % to 98.7 %, hardness increased from 52.56 to 290.22 N/mm2, and similarly, adhesiveness varied from − 20.30 to − 101.72 N/mm2. According to the rheological data, ultrasonication strengthened the oleogels and made it more stable over a wider strain range than the control oleogel sample. Thermographs revealed a minor rise in the ultrasonicated oleogel samples enthalpy, but there was no discernible change between the ultrasonicated and control samples on-set or melting temperatures. The use of oleogels as an alternative to traditional fats and oils in food products is gaining popularity due to their unique rheological properties and potential health benefits. Ultrasonication as a green technology increased the oil binding capacity, hardness, and adhesiveness of the oleogel. FT-IR analysis also confirmed that ultrasonication did not affect the chemical structure of the oleogel as there was no significant difference in the observed peaks of both samples. There was no significant change observed in the smoke point of the samples. Statement of Novelty and SignificanceThe improvement in the structure of the oleogel can be achieved by varying the process parameters and types of oleogelators in general. Techniques like ultrasonication can be beneficial for improving the structure of the oleogel by physical mode of action. The studies on the effect of ultrasound on the structure improvement of oleogels have not been extensively studied and that too for a carnauba wax-based soybean oleogel. Hence this study was conducted and the outcomes of the research are having industrial significance. Significant improvements in structural integrity, emulsion stability, and texture optimization are shown in Carnauba Wax-Based Soybean Oleogel, making it a viable formulation for a range of uses in the food and pharmaceutical industries.

Linear Strain Sensors via a Spatial Heteromodulus Tricontinuous Structure Design for High-Resolution Recording of Snoring Breath.

Porous conductive elastomer composites are very attractive for designing flexible and air-permeable mechanical sensors for healthcare, while it is challenging to achieve a linear and sensitive electromechanical response over a wide strain range for high-resolution recording of physiological activities and body motions. Here, a scalable strategy is developed to construct porous elastomer composites with a bamboo-shaped heteromodulus microstructure in the pores for the fabrication of linear stretchable strain sensors. Such a spatial heteromodulus microstructure is fabricated via phase separation and selective location of high-modulus phase during melt compounding of elastomers and thermoplastics, together with green etching of the water-soluble plastic in the tricontinuous elastomer composites. The bamboo-shaped heteromodulus microstructure is constructed on the pore struts via the fracture of a high-modulus polymer self-assembled on the pore surface and relaxation recovery of the elastomer matrix after prestretching, which blocks the propagation of cut-through microcracks upon stretching. The composites with super low resistance after in situ growth of silver nanoparticles sustain up to 110% tensile strain with a linear and sensitive electromechanical response, demonstrating potential applications in discriminating respiration status and monitoring snoring breath. This work unveils a new approach to fabricate high-performance air-permeable strain sensors in a simple and scalable way.

Dynamic high-order buckling and spontaneous recovery of active epithelial tissues

Active epithelial tissues can adapt to quasi-static compressive forces through buckling instability, but their responses to dynamic forces at shorter timescales remain elusive. We firstly establish a cytoarchitectural model that can accurately capture the experimentally observed high-order buckling and postbuckling (e.g., spontaneous flattening and stress recovery) behaviors of epithelia under fast compression. It is found that the stress evolution of epithelia can be divided into three stages: loading, phase transition, and stress recovery. In the loading stage, we observe the high-order instability with a buckling mode highly correlated with the strain rate, and derive its analytical relation, showing that the rate-dependent buckling mode is quantitatively determined by the viscoelastic and geometrical characteristics of epithelia. In the phase transition and stress recovery stages, we demonstrate that the postbuckling process is governed by the active tension generated by the actomyosin network. Furthermore, by proposing a minimal model, we obtain the explicit solutions of the flattening time and stress recovery extent as functions of the applied strain or strain rate, which are in quantitative agreement with our simulations and relevant experiments. In addition, depending on the stress evolution route, we construct a universal phase diagram for the morphology evolution of the epithelia in a wide range of strain and strain rate. This study elucidates the dominative roles of the activity and rheological characteristics of active soft materials in their dynamic mechanical behaviors, offering an approach for studying the complex morphology evolution.

Healable Ionic Conductors with Extremely Low-Hysteresis and High Mechanical Strength Enabled by Hydrophobic Domain-Locked Reversible Interactions.

Extremely low hysteresis, high mechanical strength, superior toughness, and excellent healability are essential for stretchable ionic conductors to enhance their reliability and meet for cutting-edge applications. However, the fabrication of stretchable ionic conductors with such mutually exclusive properties remains challenging. Herein, extremely low-hysteresis and healable ionic conductors with a tensile strength of ≈8.9MPa and toughness of ≈23.2MJ m-3 are fabricated through the complexation of 4-carboxybenzaldehyde (CBA) grafted poly(vinyl alcohol) (PVA) (denoted as PVA-CBA) and poly (allylamine hydrochloride) (PAH) followed by acidification and ion-loading steps. The acidification step generates the PVA-CBA/PAH ionic conductors with in situ formed dynamic hydrophobic domains that lock and stabilize noncovalent interactions. This significantly minimizes the energy dissipation of the ionic conductors during cyclic mechanical loading (≤200% strain), resulting in ionic conductors with extremely low hysteresis (≈5%). The fractured ionic conductors can be healed at 60°C to restore their original properties. Because of the extremely low hysteresis, the PVA-CBA/PAH ionic conductors show a highly stable and reproducible electrical response over 5000 uninterrupted loading-unloading cycles at a strain of 200%. The ionic conductor based sensors exhibit a high sensitivity to a wide range of strains (1-500%).