Wide Range Of Strains Research Articles

Piezotronic Strain Sensor with Uniform and Switchable Sensitivity by Conductivity Transformation

Piezotronic strain sensors that convert mechanical deformation into electrical signals are becoming increasingly important in artificial intelligence, human-machine interfaces, and robotic technologies. These applications require piezotronic sensor with the integration of high-sensitivity, high-stability, and versatile-functionality, which are limited by the single conductivity mechanism. In this study, we propose a piezotronic strain sensor with uniform and switchable sensitivity in a short channel field effect junction.The strain-induced piezo-potential can be used to switch the conductivity between Schottky and Ohmic regime, leading to an exponential (linear) piezotronic modulation in Schottky (Ohmic) conductivity elucidated by Fermi occupation theory. Local gauge factor reaches a high value of 1330 in Schottky conductivity and a low value of 320 in Ohmic regime, yielding a higher ratio of 4.2. The stable conductivity makes these high and low sensitivity uniform over a wide strain range. This study gives a deep insight into the correlation of strain-sensing performance and conductive mechanism in piezotronic sensors, and offers a new avenue to develop multifunctional and high-sensitivity sensors.

Cutting-edge Bioinformatics strategies for synthesizing Cyclotriazadisulfonamide (CADA) analogs in next-Generation HIV therapies

Cyclotriazadisulfonamide (CADA) is a macrocyclic compound known for its unique mechanism in inhibiting HIV infection by downregulating the CD4 T-cell receptor, a crucial entry point for the virus. Unlike other antiretrovirals, CADA exhibits activity against a wide range of HIV strains, as all HIV variants require CD4 binding for infection. Furthermore, CADA has shown a synergistic effect with clinically approved anti-HIV drugs, offering potential for enhanced therapeutic strategies (Vermeire & Schols, [65]). One proposed mechanism for CADA’s inhibition of the CD4 receptor involves blocking the gates of the Sec61 channel, thereby preventing its translocation. However, CADA suffers from poor solubility and bioavailability. To address this, the study aimed to design CADA analogs with improved binding to the Sec61 channel, enhanced bioavailability, and reduced toxicity. The analogs were designed using SeeSAR, with Avogadro and Meeko used for 3D configuration and pseudoatom placement, respectively. AutoDock Vina version 1.2.4 was employed to predict the binding energies of these analogs. Of the 113 analogs designed, 93 demonstrated a more negative binding energy to the Sec61 channel compared to CADA. Structure-binding energy analyses were done to the top-binding analogs to show favorable structural modifications. Enzyme-ligand interactions were analyzed to elucidate the forces contributing to these binding energies. Additionally, 33 of the 113 analogs were deemed bioavailable using a bioavailability criteria specific for macrocycles. Toxicity predictions using PASS Online and StopTox identified analogs JGL023, JGL024, JGL032, and JGL047 as potential drug candidates. Molecular dynamics simulations using Gromacs-2020.4 revealed that JGL023 and JGL032 exhibited the most favorable binding to the Sec61 channel, as determined by evaluating ligand and residue flexibility, compactness, contact frequency, motion pathways, free energy, and other relevant parameters. Synthetic routes for these four analogs were proposed for future studies. The results of this study offer a new perspective on developing drugs to inhibit HIV entry.

Full range fragmentation simulation of nanoflake filler-matrix composite coatings on a polymer substrate

This paper presents a comprehensive experimental and computational study to explore the damage evolution mechanisms of polymer matrix nanocomposite films consisting of rigid ceramic fillers coated on a polymer substrate. The weight ratio of montmorillonite (MMT) fillers in the polyvinyl alcohol (PVA) matrix ranges from 30 % to 70 %, and these are applied onto a polyethylene terephthalate (PET) substrate. Through experiments, apart from damage behaviors, the water vapor transmission rates are also measured to gain insight into moisture diffusion characteristics with varying weight ratios of fillers. The optimal weight ratio of nanocomposite films consisting of a PVA matrix with MMT fillers can vary depending on the purpose of damage resistance and moisture barrier characteristics. A peridynamic theory is employed to simulate various damage scenarios of bi-layer nanocomposite films. The solution strategy presented incorporates the use of the cut-boundary and finite element methods to reduce substrate thickness and make initial predictions of crack onset strains, respectively, under quasi-static loading conditions. Several damage scenarios are considered for thin and thick PVA films on the PET substrate, as well as weak to strong interfaces between the PET-PVA and PVA-MMT layers. Additionally, different distributions of MMT fillers are also considered by varying the distances between them and inserting inclusions. The peridynamic damage analyses encompass crack initiation, propagation, and final failure stages across a wide range of strains, including various damage modes such as matrix cracking, cracking at the filler-matrix, or matrix-substrate interfaces, leading to the cohesive film cracking and delamination.

Reexamination of the Sida Micrantha Mosaic Virus and Sida Mottle Virus Complexes: Classification Status, Diversity, Cognate DNA-B Components, and Host Spectrum.

Sida mottle virus (SiMoV) and Sida micrantha mosaic virus (SiMMV) are major Brazilian begomoviruses (Geminiviridae). However, the range of DNA-A identity of isolates of these viruses (81-100%) is not in agreement with the current criteria for Begomovirus species demarcation (<91%). To clarify this putative classification problem, we performed a comprehensive set of molecular analyses with all 53 publicly available isolates (with complete DNA-A genomes) designated as either SiMoV or SiMMV (including novel isolates obtained herein from nationwide metagenomics-based studies). Two well-defined phylogenetic clusters were identified. The SiMMV complex (n = 47) comprises a wide range of strains (with a continuum variation of 88.8-100% identity) infecting members of five botanical families (Malvaceae, Solanaceae, Fabaceae, Oxalidaceae, and Passifloraceae). The SiMoV group now comprises eight isolates (90-100% identity) restricted to Malvaceae hosts, including one former reference SiMMV isolate (gb|NC_077711) and SP77 (gb|FN557522; erroneously named as "true SiMMV"). Iteron analyses of metagenomics-derived information allowed for the discovery of the missing DNA-B cognate of SiMoV (93.5% intergenic region identity), confirming its bipartite nature. Henceforth, the correct identification of SiMoV and SiMMV isolates will be a crucial element for effective classical and biotech resistance breeding of the viral host species.

Activated Charcoal-Alginate Platform for Simultaneous Local Delivery of Bioactive Agents: At the Nexus of Antimicrobial and Cytotoxic Activity of Zn2+ Ions.

Antimicrobial resistance (AMR) is a global public health threat that affects cancer patients more than the general population. In this work, a composite system based on Zn-alginate hydrogel and activated charcoal (AC) particles that, upon contact with physiological fluids, simultaneously releases bioactive agents (Zn2+ and AC particles impregnated with povidone-iodine) was designed to locally address specific problems characteristic for malignant wounds (MWs). This composite was comprehensively investigated in vitro regarding its morphology (field-emission scanning electron microscopy), Zn2+ release (flame atomic absorption spectrometry), iodine adsorption and desorption from AC particles (energy dispersive X-ray analysis and UV-visible spectroscopy) as well as its antimicrobial and antitumor activity. With respect to the ongoing AMR crises, antimicrobial activity was tested against a wide range of wild multi-drug resistant bacterial and yeast strains, all isolated from patient wounds. Since Zn2+ ions proved to be selectors of resistant strains of bacteria, the synergistic activity of AC particles and adsorbed iodine was shown to be crucial for excellent antibacterial activity. On the other hand, the synergy of AC particles and Zn2+ ions showed an equally strong antifungal effect. In addition, antimicrobial concentrations of Zn2+ ions showed cytotoxic activity against two cancer cell lines derived from cancers affecting skin either as metastatic cancer (breast cancer MDA-MB-453 cell line) or primary cancer of the skin (malignant melanoma Fem-X cell line), which enables Zn2+ ions to be further investigated as potent local agents targeting malignant cells.

Mechanoresponsive self‐powered piezoelectric energy‐generating composite hydrogels based on carbon nanotube‐reinforced fungal‐carboxymethyl chitosan‐bacterial cellulose nanofibers for wearable electronics

AbstractDeveloping conductive hydrogels with both enhanced mechanical properties and superior sensing capabilities for wearable, flexible electronics remains challenging. Here, we developed mechanoresponsive self‐powered piezoelectric energy‐generating composite hydrogels. These hydrogels were prepared by blending fungal‐derived carboxymethyl chitosan (FC), carboxylate‐bacterial cellulose nanofibers (CBC‐NFs), and carbon nanotubes (CNTs) within a covalently crosslinked polyacrylamide (PAM) network (CNT‐FBCNF). The resulting hydrogels showed remarkable mechanical properties due to the molecular interactions between polymer chains. The hydrogels showed a self‐recoverable property and high stability under compressive mechanical force at 40% of strain (2000 cycles). The maximum compressive load (N) of 27.8 N was obtained for the optimized hydrogel, CNT‐FBCNF (1% CNT content). This hydrogel exhibited a good conductivity of 1.3 S/m, which was attributed to the homogeneous dispersion of CNTs within the hydrogel matrix and sufficient biocompatibility with skin fibroblasts. The hydrogel also exhibited impressive performance as a strain sensor, boasting a wide strain range (10–40%), excellent stability, and repeatability. Furthermore, strategic cutting and assembly of the hydrogel generated a flexible strain sensor capable of accurately monitoring finger and thumb pressure in real‐time. This study will significantly accelerate the development of hydrogel‐based sensors within the rapidly advancing field of wearable soft electronics.Highlights CNT‐reinforced composite hydrogel was developed The optimized hydrogel showed good electrical conductivity (1.3 S/m) The optimized hydrogel showed good self‐recovery properties The optimized hydrogel exhibited impressive strain‐sensing capability between 10% and 40% strain

Highly sensitive and stretchable CB/GNPs-TPU strain sensor with porous microstructure for multifunctional strain sensing

Multifunctional flexible strain sensors have garnered significant attention in recent years, particularly in the fields of smart wearable devices and human health monitoring. However, the trade-off between high sensitivity and a wide strain range limits their practical applications. This study presents a porous TPU/CB framework prepared using a water vapor-induced phase separation method, which can deform like a spring when stretched, thereby providing the sensor with a greater strain range. The graphene nanoplatelets (GNPs) were subsequently incorporated into the pores of the porous framework through ultrasonic treatment, which enhanced the sensor's sensitivity while preventing increased brittleness caused by the aggregation of conductive fillers. This structure establishes a stable conductive network, enabling the sensor to achieve high sensitivity (GF = 5902.4) across a wide strain range (327 %) while also demonstrating excellent stability and durability (over 7000 stretching/releasing cycles). The sensor can detect not only simple limb movements, such as bending of the arms and knees but also subtle muscle activities, including facial expressions and throat vocalization, thus bringing excellent human-computer interaction experience. These remarkable features position the sensor for promising applications in smart wearables and human health monitoring.

Speckle-decoded temperature-insensitive strain identification in a multimode optical fiber.

Fiber-optic sensing systems are significant tools for measuring various physical or biochemical parameters. However, temperature cross-sensitivity prevents accurate recognition of the target input signal when optical sensors are applied in practical scenarios. Herein, leveraging a deep learning algorithm, a speckle-decoded temperature-insensitive strain sensor is proposed and experimentally demonstrated. Scattering patterns are utilized to estimate the axial strain since the external force could change the coherent superposition of the amplitudes of propagating modes. The experimental results show that the recognition accuracy of the sensing system based on a classification model can reach 99.28% within a wide strain range of 0-0.3 N in the presence of temperature cross talk. In addition, the strain prediction demonstrates an average root-mean-square error of 1.02 N%. Such an intelligent speckle sensing strategy has the potential to broaden the applications of fiber-optic sensors in various engineering applications.

Enhancement and mechanism of mechanical properties and functionalities of polyacrylamide/polyacrylic acid hydrogels by 1D and 2D nanocarbon

Highly flexible hydrogels are widely used in fields such as agriculture, drug delivery, and tissue engineering. However, the simultaneous integration of excellent mechanical properties, swelling properties, and high electrical conductivity into a hydrogel is still a great challenge. This work introduces 1D tubular multi-walled carbon nanotubes (MWCNTs) and 2D layered graphene oxide (GO) into polyacrylamide/poly-acrylic acid (PAM/PAA) hydrogels. The high specific surface area and oxygen-containing groups of GO contribute to excellent mechanical properties and water absorption of the PAM/PAA hydrogels, but the conductivity is poorly affected due to the presence of defects on GO surface. However, MWCNTs with large aspect ratios benefit to form continuous conductive paths in PAM/PAA hydrogels which further improves conductivity of the hydrogels. MWCNTs are entangled with PAM/PAA molecular chains to form a dense three-dimensional (3D) network structure, and this special structure improves the water absorption of PAM/PAA hydrogels by 3.7 g g−1. What’s more, the MWCNTs/PAM/PAA hydrogel not only provides excellent mechanical properties (compressive strength up to 2.7 MPa), but also has high conductivity (2.3 S m−1). In particular, a strain sensor based on MWCNTs/PAM/PAA hydrogel exhibits exceptional sensitivity (gauge factor = 3.9 at 230–300 % strain) with a rapid response (200 ms) over a wide strain range (50 ∼ 200 %) which enables the ability to precisely and reliably monitor human motion. Therefore, the work provides a new insight into the design of multifunctional hydrogels with application on anatomical water plugging, electronic skin, and biosensors.

An adhesive, highly stretchable and low-hysteresis alginate-based conductive hydrogel strain sensing system for motion capture

A strain sensor stands as an indispensable tool for capturing intricate motions in various applications, ranging from human motion monitoring to electronic skin and soft robotics. However, existing strain sensors still face difficulties in simultaneously achieving superior sensing performance sufficing for practical applications like high stretchability and low hysteresis, as well as seamless device fabrication like desirable interfacial adhesion and system-level integration. Herein, we develop a highly stretchable and low-hysteresis strain sensor with adhesive poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/polyacrylamide (PAAm)–sodium alginate (SA) composite hydrogel, allowing the successful construction of a wireless motion capture sensing system that can provide precise data collection within a large deformation range. The resultant composite hydrogel displays favorable interfacial adhesion and robust mechanical stability, and the fabricated strain sensor demonstrates a wide working strain range (up to 500%) with high sensitivity (gauge factor = 11) and ultra-low hysteresis (1.52%), outperforming previous PEDOT-based hydrogel strain sensors. Enabled by the intriguing material properties and high sensing performance, we further demonstrate the fabrication and integration of a wireless motion capture sensing system for diverse applications like human motion monitoring, gesture recognition, and interactive communication.

Facilely prepared extreme environments tolerable PIF /c-CNTx composites for piezoresistive sensor based on powder foaming strategy

Polyimide foams (PIF) are widely used in piezoresistive sensors due to their light weight and weather resistance to weathering at extreme temperatures. Nevertheless, the mechanical strength of PIF prepared by freeze-drying method is poor, with only tens to hundreds of kPa ranging from 50 % to 80 % compression. Herein, a polyimide composite reinforced with –COOH functionalized multi-walled carbon nanotubes (PIF/c-CNTx) was produced via a thermal foaming process using a powder-based method. The PIF/c-CNTx composites exhibit ultra-low density (0.165 g/cm3), excellent mechanical properties (compressive strength of up to 2.5 MPa at 60 % compressive strain, tens to hundreds of times higher than similar materials) as well as stable compressive properties and recoverability in liquid nitrogen and at high temperatures up to 200 ℃. The PIF/c-CNTx piezoresistive sensor achieves excellent sensing capability over a wide strain range, high sensitivity (GF = 12.9) and exhibit good stability over 5000 s of cyclic compression at a compression rate of 10 mm/min. The stability and reproducibility of the strong piezoresistive signal at extreme temperatures shows the great potential of PIF/c-CNTx composites as structural components under extreme conditions for applications in aerospace and polar exploration.

Sustainable and high performance MXene hydrogel with interlocked structure for machine learning-facilitated human-interactive sensing

Wearable epidermal electronics fabricated from MXene-based conductive hydrogels have attracted considerable interest because of their promising prospects in real-time health monitoring and human–computer interaction sensing. However, the development of a sustainable hydrogel with exceptional mechanical toughness, high conductivity, and self-adhesion is crucial to reliably capture signals through polymer network designs that establish robust interactions between MXene nanosheets and network substrates while minimizing electronic waste generated by discarded sensors. This study presents the fabrication of a sustainable conductive MXene-based dual-network hydrogel through skillful assembly of MXene nanosheets, β-cyclodextrin with azobenzene-modified polyacrylic acid chains, and poly (vinyl alcohol) polymer networks. The hydrogel demonstrates exceptional mechanical properties (strength at breaking ∼ 625 kPa, elongation at break ∼ 630 %) attributed to the presence of numerous hydrogen bonds and host–guest interactions, along with superior electrical conductivity (23.65 S/cm) and self-adhesion. The hydrogel demonstrates exceptional sensitivity across a wide range of strains, enabling the detection of various human movements and achieving successful applications in handwriting recognition and sign language translation. Under acidic condition and UV irradiation, the disassembly of AZO and β-CD as well as the untangling of PVA chains entanglement facilitate the release and recycling of MXene. This study presents a technological platform that holds promise for developing conductive hydrogels with enhanced sensing capabilities, catering to the requirements of stretchable electronic skin and intelligent robotic systems.

Wearable fiber-based visual strain sensors with high sensitivity and excellent cyclic stability for health monitoring and thermal management

Visual strain sensors have attracted significant attention in the smart wearables field due to their ability to intuitively monitor human health and movement through color displays. However, their development is limited by restricted sensitivity over a large strain range and poor cyclic stability. The conductivity and electricity-induced heating performance can be enhanced by filling microcracks with conductive nanoparticles to increase the conductive paths. Inspired by this concept, nanocarbon powder/silver nanoparticles@carboxylic multi-walled carbon nanotubes/polyurethane (NAMP) fiber-based visual strain sensors were developed using wet spinning, in-situ polymerization, and ultrasonic impregnation techniques. The NAMP sensors exhibit high sensitivity (GF=3528), a wide strain range (0–107 %), and excellent cyclic stability (over 5000 cycles), demonstrating high reusability, stability, and durability. Meanwhile, a wide temperature range from 27.8 °C to 75.2 °C and corresponding color display changes triggered by applied voltages from 0 to 2.5 V were achieved, indicating excellent visualization performance. In addition, the integration of NAMP fibers into temperature-adjustable electrothermal fabric can be utilized for human thermal management therapy and deicing. This work provides valuable insights into the design and potential applications of intelligent fibrous sensor, paving the way for the development of wearable textiles from fibers to fabrics.

Elastomeric Sensor-Triboelectric Nanogenerator Coupled System for Multimodal Strain Sensing and Organic Vapor Detection.

Stretchable, flexible sensors are one of the most critical components of smart wearable electronics and Internet of Things (IoT), thereby attracting multipronged research interest in the last decades. Following miniaturization and multicomponent development of several sensors in one could further propel the demand for wireless, multimodal platforms. Greener substitutes to conventional sensors that can operate in a self-powered configuration are highly desirable in terms of all-in-one sensor utilities. However, fabrication of composite-based ultrastretchable, self-powered sensors with multifunctionality, robustness, and conformability is still only partially achieved and, therefore, demands further investigation. In this work, we report a triboelectric nanogenerator (TENG)-based multifunctional strain and organic vapor sensor using cross-linked ethylene propylene diene monomer (EPDM) elastomer and conducting carbon black as active fillers in the presence of an ionic liquid. The resulting piezoresistive sensor demonstrates ultrahigh gauge factor (GF > 220k) and wide range strain sensitivity and is, therefore, suitable for subtle-to-high frequency motion detection devices. Supported by excellent triboelectric outputs (force sensitivity 0.5 V/N in the range of 50-300 N, maximum output voltage VOC ∼ 178 V, short circuit current ISC ∼ 18 μA, maximum power density 0.11 mW/cm2), the hybrid sensors offer remarkable mechanical toughness and seamless voltage generation under contact-separation, even after several thousand cycles of operations. Furthermore, the sensor substrates exhibited reproducible organic vapor-sensing behavior, with high responsivity of 1.92 and 1 for ethanol and acetone, respectively, under flowing vapor conditions. This work lays a strong foundation for developing a truly multimodal, TENG-based, self-powered organic vapor and strain sensors.

Strain-Controlled Electronic and Magnetic Properties of Janus Nitride MXene Monolayer MnCrNO2

Two-dimensional (2D) van der Waals (vdW) magnetic materials show potential for the advancement of high-density, energy-efficient electronic and spintronic applications in future memory and computation. Here, by using first-principles density functional theory (DFT) calculations, we predict a new 2D Janus nitride MXene MnCrNO2 monolayer. Our results suggest that the optimized MnCrNO2 monolayer possesses a hexagonal structure and exhibits good dynamical stability. The intrinsic monolayer MnCrNO2 exhibits semiconductive properties and adopts a ferromagnetic ground state with an out-of-plane easy axis. It can sustain strain effects within a wide range of strains from −10% to +8%, as indicated by the phonon dispersion spectra. Under the biaxial tensile strain, a remarkable decrease in the bandgap of the MnCrNO2 is induced, which is attributed to the distinct roles played by Mn and Cr in the VBM or CBM bands. Furthermore, when the compressive strain reaches approximately −8%, the magnetic anisotropy undergoes a transition from an out-of-plane easy axis to an in-plane easy axis. This change is mainly influenced by the efficient hybridization of the d orbitals, particularly in Mn atoms. Our study of the Janus MXene MnCrNO2 monolayer indicates its potential as a promising candidate for innovative electronic and spintronic devices; this potential is expected to create interest in its synthesis.

Multifunctional 1D/2D silver nanowires/MXene-based fabric strain sensors for emergency rescue

Abstract Monitoring the vital signs of the injured in accidents is crucial in emergency rescue process. Fabric-based sensing devices show a vast range of potential applications in wearable healthcare monitoring, human motion and thermal management due to their wearable flexibility and high sensitivity. Nevertheless, flexible electronic devices for both precise monitoring of health under low strain and motion under large strain are still a challenge in extremely harsh environment. Therefore, development of sensors with both high sensitivity and wide strain range remains a formidable challenge. Herein, a wearable flexible strain sensor with a one-dimensional/two-dimensional (1D/2D) composite conductive network was developed for healthcare and motion monitoring and thermal management by coating 1D silver nanowires (AgNWs) and 2D Ti3C2Tx MXene composite films on nylon/spandex blended knitted fabric (MANS). The MANS strain sensor can simultaneously achieve high sensitivity (gauge factor for up to 267), a wide range of detection (1–115%), excellent repeatability and cycling stability (1000 cycles). The sensor can be utilized for human health monitoring including heartbeat, pulse detection, breathing and various human motion. Moreover, the MANS sensor also has the electrical heating properties and voltage control temperature between 20-110 °C can achieved at low voltage. In addition, the MANS shows hydrophobicity with water contact angle of 137.1°. The MXene/AgNWs composite conductive layer with high sensitivity under low and large strains, electrical thermal conversion, and hydrophobicity has great potential for precisely monitoring health and motion of the injured in emergency rescue in harsh environment.

Flexible and robust polyaniline/cross-linked collagen sponge with fibrils network structure as a piezoresistive sensing material

The polyaniline/cross-linked collagen sponge (PANI/CCS) was synthesized by polymerizing PANI onto the collagen skeleton using mesoscopic collagen fibrils (CFs) as building blocks, serving as a piezoresistive sensing material. The structure and morphology of PANI/CCS were characterized using scanning electron microscopy (SEM), Fourier infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and thermal analysis (TA). The mechanical properties of PANI/CCS could be controlled by adjusting the CFs content and polymerization conditions. PANI/CCS treated with pure water exhibited exceptional compressive elasticity under 1000 compression cycles, demonstrating a wide strain range (0–85 %), rapid response time (200 ms), recovery time (90 ms), and high sensitivity (6.72 at 40–50 % strain). The treatment of the ionic liquid further improved the elasticity and the strain sensing range (0–95 %). The presence of PANI nanoparticles and mesoscopic collagen fibrils imparted antibacterial properties, stability in solvents, and biodegradability to PANI/CCS. Utilizing PANI/CCS as a piezoresistive sensing material enabled monitoring human movement behavior through the assembled sensor, showing significant potential for flexible wearable devices.

Cyclic mechanical response of LPBF Hastelloy X over a wide temperature and strain range: Experiments and modelling

Additive manufacturing (AM) of high-temperature alloys through processes such as laser powder bed fusion (LPBF) has gained significant interest and is rapidly expanding due to its exceptional design freedom, which enables the fabrication of complex parts that contribute to the increased efficiency of aerospace and energy systems. The materials produced through this process exhibit unique microstructures and mechanical properties, which necessitate dedicated study and characterization. In this context, our research focuses on the experimental characterization of the isothermal cyclic viscoplastic mechanical response of Hastelloy X (HX) over the temperature range of 22 to 1000 °C and at various strain rates, addressing a current gap in the literature. Recognizing the need for material models that can accurately represent the cyclic mechanical response of LPBF HX across a broad temperature range, we developed a robust extension of the viscoplastic isotropic-kinematic hardening Chaboche model, intended for applications in the thermomechanical simulation of the LPBF process for the analysis of residual stress and distortion, as well as for assessing the mechanical integrity of LPBF components. The extension involves expressing the entire set of model parameters explicitly with analytical functions to account for their temperature dependence. Consequently, the model includes a relatively large number of parameters to represent the isotropic-kinematic hardening viscoplastic response of the alloy over a wide temperature range, and hence to overcome the endeavor of its systematic calibration, a dedicated calibration approach was introduced. The model ultimately demonstrated its capability to precisely represent the isothermal response of the alloy over the examined temperatures and strain rates. To evaluate the model’s predictiveness for non-isothermal conditions, out-of-phase thermomechanical cyclic experiments were also conducted as independent benchmark tests, where the model’s predictions were fairly consistent with the experimental results. As a part of this study, the derived material model has been integrated into the UMAT subroutine, complete with an analytical derivation of the consistent Jacobian matrix.

Highly conductive copper-coated polyamide yarn for wearable sensing and Joule heating applications

A highly conductive yarn was developed by electroless deposition of copper metal particles on the polyamide 6 yarn. The successful incorporation of Cu particles into the substrate was revealed by surface and elemental characterizations. The Cu/PA 6 yarn exhibited superior electrical conductivity (2.3 Ω/cm) with improved mechanical properties. The excellent electromechanical properties demonstrated by the Cu/PA 6 composite revealed its sensing capacity for a wide range of strains. Therefore, the composite yarn was affixed to the different regions of the human body and was capable of successfully monitoring various human motions, including finger bending, wrist bending, knee bending, drinking, and writing. In addition, rapid heat generation with high and uniform surface temperature (66.3 °C at 4.0 V in 45 s) validated the potential of the Cu/PA 6 yarn for wearable thermal heating devices. Moreover, rapid heating at a lower voltage, when attached to a wristband, revealed the capability of the composite yarn for localized heating or region-specific temperature regulation for personalized healthcare or comfort. This study informs a facile and effective strategy for developing robust yarn-shaped e-textiles for advanced wearable sensing and thermal heating.

Simultaneously enhancing the strength and ductility of Fe–Mn–C twinning-induced plasticity steel via Cr/N alloying

The effect of Cr/N alloying on the tensile deformation behavior of Fe–Mn–C twinning-induced plasticity steel was investigated through monotonic tensile tests, X-ray diffraction, electron back-scattered diffraction, transmission electron microscopy, and digital image correlation technique. The results demonstrate that the addition of Cr/N significantly enhances both the strength and ductility of Fe–18Mn-0.6C steel while dynamic strain aging (DSA) behavior weakens or even disappears. Compared with that in the Fe–18Mn-0.6C steel, more densely-spaced, thinner deformation twins were formed in the Cr/N-alloyed steel. Moreover, the Cr/N additions promote deformation twins to form over a wider strain range. This unique twinning behavior leads to a sustained high strain-hardening rate at higher strains, thereby delaying plastic instability and concurrently enhancing strength and ductility.