Low Young Modulus Research Articles

Fabrication of flexible porous slide-ring polymer/carbon nanofiber composite elastomer by simultaneous freeze-casting and cross-linking reaction with dimethyl sulfoxide

To develop flexible and tough composite materials with out-of-plane aligned thermally conductive pathways, a novel freeze-casting method was developed using dimethyl sulfoxide (DMSO), carbon nanofibers (CFs), slide-ring polymers (SRs), and cross-linkers. Porous composite materials composed of SR and plasma-surface-modified CFs were obtained. Using DMSO, which has a high melting point (19 °C) and high polymer solubility, the SR cross-linking reaction was performed during freeze-casting. The CFs were treated with plasma before composite preparation for better affinity and dispersibility to the composites. The obtained porous composites contained thermally conductive pathways in the out-of-plane direction and exhibited a low Young's modulus (0.14 MPa). The composite with a thermoplastic polyurethane (TPU) elastomer embedded into its pores exhibited a low Young's modulus (3.62 MPa), high toughness (10.0 MJ/m3), and high thermal conductivity in the out-of-plane direction (0.57 W/mK). The proposed freeze-casting method can be applied for the fabrication of various polymers and fillers and is promising for the development of flexible porous composite elastomers with out-of-plane aligned thermally conductive pathways.

Role of laser powder bed fusion process parameters in crystallographic texture of additive manufactured Nb–48Ti alloy

Additive manufacturing, known as “3D printing”, is a set of manufacturing technologies that can build parts with complex geometries in a process by adding layers of powder material. The laser powder bed fusion (L-PBF) process is characterized by selectively melting layers of particulate material at a micrometer scale in repetitive patterns. This technology is expected to improve Young's modulus of metallic biomaterials, by controlling the microstructure and crystallographic texture– influenced by the laser power and scanning speed parameters which promote an oriented heat extraction. Implant materials should have low Young's modulus, to avoid a large mismatch with that of the bones. This work investigates the role of the laser power and scanning speed on microstructure and crystallographic texture formation of the Nb–48Ti alloy, fabricated by laser powder bed fusion process, using pre-alloyed plasma atomized powder. The microstructure was characterized by optical microscopy (OM), scanning electron microscopy (SEM), backscattered electron diffraction technique (EBSD) for crystallographic texture, and Young's modulus was obtained indirectly via EBSD data. The microstructure showed a cellular dendritic solidification morphology formed by epitaxy at the edge of the melt pools. Texture results indicated that higher values of power and scanning speed favored the increasing of a near-cube-on-face texture and a reduction in Young's modulus.

MODELING OF FLAGELLUM BEHAVIOR AND TWO-DIMENSIONAL SPERM CELL MOTILITY WITHIN THE CONTEXT OF FLUID–SOLID INTERACTIONS

In this study, the flagellar motility of a swimmer microorganism as a model of a human sperm cell, inside a two-dimensional channel as a model of the female reproductive tract containing a viscous fluid, is numerically investigated. The Navier–Stokes equations governing the fluid are coupled with the equations governing the models flagellum via applying a fluid–solid interaction approach and then solved using the finite element method. To stimulate the flagellum to move, a prescribed sinusoidal waveform is applied to it. The strain induced by this waveform along the flagellum initiates a continuous interaction between the flagellum and the fluid. The simulations are validated using data available in the literature. A very good agreement is seen between them. The results show that by decreasing the Young modulus of the flagellum as well as increasing the fluid viscosity, the swimming velocity of the model significantly decreases. It is found that for lower Young modulus of the flagellum, the effect of the fluid viscosity on the flagellar deformation is stronger. It is also found that for higher amplitude of the waveform applied to stimulate the flagellum, both the swimming velocity of the model and the average work rate are greater. Moreover, it is found that in a channel with a smaller height, the model swims at a higher speed and with a higher average work rate.

3D mechanical earth model for optimized wellbore stability, a case study from South of Iraq

Wellbore instability issues represent the most critical problems in Iraq Southern fields. These problems, such as hole collapse, tight hole and stuck pipe result in tremendous increasing in the nonproductive time (NPT) and well costs. The present study introduced a calibrated three-dimensional mechanical earth model (3DMEM) for the X-field in the South of Iraq. This post-drill model can be used to conduct a comprehensive geomechanical analysis of the trouble zones from Sadi Formation to Zubair Reservoir. A one-dimensional mechanical earth model (1DMEM) was constructed using Well logs, mechanical core tests, pressure measurements, drilling reports, and mud logs. Mohr–Coulomb and Mogi–Coulomb failure criteria determined the possibility of wellbore deformation. Then, the 1DMEMs were interpolated to construct a three-dimensional mechanical earth model (3DMEM). 3DMEM indicated relative heterogeneity in rock properties and field stresses between the southern and northern of the studied field. The shale intervals revealed prone to failure more than others, with a relatively high Poisson's ratio, low Young's modulus, low friction angle, and low rock strength. The best orientation for directional Wells is 140° clockwise from the North. Vertical and slightly inclined Wells (less than 40°) are more stable than the high angle directional Wells. This integration between 1 and 3DMEM enables anticipating the subsurface conditions for the proactive design and drilling of new Wells. However, the geomechanics investigations still have uncertainty due to unavailability of enough calibrating data, especially which related with maximum horizontal stresses magnitudes.

Fabrication of polyrotaxane and graphene nanoplate composites with high thermal conductivities

AbstractIn recent years, rapid progress in the development of flexible electronic devices has increased the demand for materials with low Young's modulus and high thermal conductivities. In this study, we successfully fabricated such composites with polyrotaxane (PR) by applying highly concentrated graphene nanoplates (GNPs). A high thermal conductivity of 25 W m−1 K−1 was achieved along the in‐plane direction of the composite while maintaining a low Young's modulus of 147 MPa at 35 vol% of GNPs. This thermal conductivity is higher than those achieved with PR composites containing 56 vol% of hexagonal boron nitride and 37 vol% of aligned carbon nanofiber/carbon nanotubes.

Nanocrystalline strain glass TiNiPt and its superelastic behavior

TiNi-based shape-memory alloys are known to exhibit a strain glass state under certain conditions, generally in the presence of high-density defects such as excess solute atoms or alloying elements, dislocations, and nanoprecipitates. In this paper, we report a strain glass transition in a nanocrystalline ${\mathrm{Ti}}_{50}{\mathrm{Ni}}_{35}{\mathrm{Pt}}_{15}$ alloy. The nanocrystalline strain glass state is achieved by a combined effect of high-density grain boundaries and high concentration doping of Pt atoms in the B2 matrix. The nanocrystalline ${\mathrm{Ti}}_{50}{\mathrm{Ni}}_{35}{\mathrm{Pt}}_{15}$ strain glass alloy showed a large near-complete progressive superelasticity with a recovery strain of about 6% and a low apparent Young's modulus of about 30 GPa in a wide temperature range of over 200 \ifmmode^\circ\else\textdegree\fi{}C. In situ synchrotron x-ray diffraction measurement showed that the strain glass B2 [B2(SG)] phase experienced B2(SG)\ensuremath{\rightarrow}R\ensuremath{\rightarrow}B19 transformation upon loading and B19\ensuremath{\rightarrow}B2(SG) upon unloading. The findings of this study provide insight for the development of nanocrystalline strain glass shape-memory alloys.

Zeolite ceramics with ordered microporous structure and high crystallinity prepared by cold sintering process

Abstract4A [Na96(Al96Si96O384)⋅216H2O] and 13X [Na2(Al2Si3.3O10.6)⋅7H2O] zeolite ceramics were prepared by cold sintering processes, and the physical properties were investigated together with the structure characterization. There were four primary parameters controlling the preparation process: content of NaOH, pressure, temperature, and holding time. Zeolite ceramics with the idea ordered microporous structure and high crystallinity were obtained at 393 K under 450~550 MPa with a holding time of 5 min from the solution with 20 wt% NaOH. A high compressive strength up to 60 MPa and low Young's modulus down to 76 MPa were achieved in 13X zeolite ceramics, and the present ceramics might provide potential applications in damping materials and thermal insulating materials.

Tailoring a Low Young Modulus for a Beta Titanium Alloy by Combining Severe Plastic Deformation with Solution Treatment.

The present paper analyzed the microstructural characteristics and the mechanical properties of a Ti–Nb–Zr–Fe–O alloy of β-Ti type obtained by combining severe plastic deformation (SPD), for which the total reduction was of εtot = 90%, with two variants of super-transus solution treatment (ST). The objective was to obtain a low Young’s modulus with sufficient high strength in purpose to use the alloy as a biomaterial for orthopedic implants. The microstructure analysis was conducted through X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) investigations. The analyzed mechanical properties reveal promising values for yield strength (YS) and ultimate tensile strength (UTS) of about 770 and 1100 MPa, respectively, with a low value of Young’s modulus of about 48–49 GPa. The conclusion is that satisfactory mechanical properties for this type of alloy can be obtained if considering a proper combination of SPD + ST parameters and a suitable content of β-stabilizing alloying elements, especially the Zr/Nb ratio.

Effect of N addition on nano-domain structure and mechanical properties of a meta-stable Ti-Zr based alloy

This study showed that a superior combination of high strength and ultra-low modulus can be achieved by the addition of N in a meta-stable β-type Ti–Zr based alloy undergoing stress-induced martensitic transformation. A Ti–18Zr–3Nb–2Mo–3Sn alloy exhibited a very low Young's modulus; however, the stress-induced martensitic transformation occurred at a low stress level. The addition of N facilitated the formation of nano-sized lattice modulation (nano-domain) structure and impeded the stress-induced martensitic transformation, leading to higher apparent yield stress, narrower stress hysteresis and large non-linear elasticity. A Ti–18Zr–3Nb–2Mo–3Sn–1.2N alloy exhibited an excellent combination of a low Young’s modulus of 41 GPa and a high strength of 920 MP along with a large recovery strain with negligible hysteresis.

Femtosecond laser-induced nanoporous layer for enhanced osteogenesis of titanium implants

The osteogenic activity of medical metal can be improved by lowering its surface stiffness and elastic modulus. However, it is very difficult to directly reduce the elastic modulus of medical metal surfaces. In this paper, with selected parameters, the titanium surface was treated via femtosecond laser irradiation. Micro indentation revealed that the femtosecond laser ablation can effectively reduce the surface Young's modulus and Vickers hardness of titanium. Besides, In order to explain the mechanical properties of degradation of titanium surface, Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) was used to simulate the process of laser ablation process of titanium surface, and it was found that after the ablation of titanium surface, voids were produced in the subsurface layer. The simulation showed that the voids are formed by the cavitation of metastable liquid induced by high tensile stress and high temperature during femtosecond laser irradiation. Subsurface voids with a thickness of about 40 nm were observed under the oxide layer in the experiment. Cell experiments showed that the surface with low Young's modulus was more conducive to cell proliferation and osteogenic differentiation.

Contact Guidance Effect and Prevention of Microfouling on a Beta Titanium Alloy Surface Structured by Electron-Beam Technology.

Nano- and micro-structuring of implantable materials constitute a promising approach to introduce mechanical contact guidance effect, drive cells colonization, as well as to prevent bacteria adhesion and biofilm aggregation, through antifouling topography. Accordingly, this paper aims to extend the application of e-beam surface texturing and nano-structuring to the beta titanium alloys, which are of great interest for biomedical implants because of the low Young modulus and the reduction of the stress shielding effect. The paper shows that surface texturing on the micro-scale (micro-grooves) is functional to a contact guidance effect on gingival fibroblasts. Moreover, nano-structuring, derived from the e-beam surface treatment, is effective to prevent microfouling. In fact, human fibroblasts were cultivated directly onto grooved specimens showing to sense the surface micro-structure thus spreading following the grooves’ orientation. Moreover, Staphylococcus aureus colonies adhesion was prevented by the nano-topographies in comparison to the mirror-polished control, thus demonstrating promising antifouling properties. Furthermore, the research goes into detail to understand the mechanism of microfouling prevention due to nano-topography and microstructure.

Porous Ti-based bulk metallic glass orthopedic biomaterial with high strength and low Young's modulus produced by one step SPS

Abstract To alleviate the “stress shielding” of metallic biomaterials used as artificial bone, the state of art Ti45Zr10Cu31Pd10Sn4 porous bulk metallic glass (BMG) with adequate compressive strength of 180 MPa and Young's modulus of 27.2 GPa similar to nature bone was produced by a novel partial densification method using spark plasma sintering (SPS). The thermal mechanistic (sintering temperature, sintering rate and holding time) during SPS contributions to the densification behavior and the structures and mechanical properties of porous BMG were systematically explored under low loading pressure condition to obtain the optimal sintering process. With the help of this work, the potential application value of Ti–Zr–Cu–Pd–Sn BMG as substitute of human bone will be further enhanced.

Reliability evaluation of ultra thin 3D-IC package under the coupling load effects of the manufacturing process and temperature cycling test

In the development of semiconductor packaging technology from planar to three-dimensional vertical integration, chip interconnection density has increased, and the distance of signal transmission has dropped to improve overall device performance. In this research, an architecture composed of through‑silicon via (TSV) and solder microbump (μbump) is utilized to assemble an ultra thin-type chip into a three-dimensional integrated circuit (3D-IC) package. To explore the influence of residual thermomechanical residual stress induced during the manufacture of the 3D-IC package on the subsequent reliability of the thermal cycling test (TCT), this study establishes a nonlinear simulation methodology for investigating the coupling effect of the manufacturing process and the TCT. The plastic and creep behaviors of the solder μbump are considered in the finite element modeling. The concerned geometric dimensions and underfill materials are also parametrically analyzed. Furthermore, the inelastic strain accumulated in the crucial SnAg solder μbump is examined. Results indicate that the residual strain in the manufacturing process causes an obvious packaging warpage and converges at the subsequent TCT stage. The creep of the solder μbump increases up to 50% in thermal cycling, thereby highlighting the importance of considering the creep model. Moreover, the parameterization of chip thickness can minimize the inelastic strain increment of the solder μbump, and the low Young's modulus of the underfill materials exerts a significant effect on the warpage of the packaging module and the stress compliance of the μbumps.

In Situ and Intraoperative Detection of the Ureter Injury Using a Highly Sensitive Piezoresistive Sensor with a Tunable Porous Structure.

Iatrogenic ureteral injury, as a commonly encountered problem in gynecologic, colorectal, and pelvic surgeries, is known to be difficult to detect in situ and in real-time. Consequently, this injury may be left untreated, thereby leading to serious complications such as infections, renal failure, or even death. Here, high-performance tubular porous pressure sensors were proposed to identify the ureter in situ intraoperatively. The electrical conductivity, mechanical compressibility, and sensor sensitivity can be tuned by changing the pore structure of porous conductive composites. A low percolation threshold of 0.33 vol % was achieved due to the segregated conductive network by pores. Pores also lead to a low effective Young's modulus and high compressibility of the composites and thus result in a high sensitivity of 448.2 kPa-1 of sensors, which is consistent with the results of COMSOL simulation. Self-mounted on the tip of forceps, the sensors can monitor tube pressures with different frequencies and amplitudes, as demonstrated using an artificial pump system. The sensors can also differentiate ureter pulses from aorta pulses of a Bama minipig in situ and in real-time. This work provides a facile, cost-effective, and nondestructive method to identify the ureter intraoperatively, which cannot be effectively achieved by traditional methods.

The roles of oxygen content on microstructural transformation, mechanical properties and corrosion resistance of Ti-Nb-based biomedical alloys with different β stabilities

The effects of oxygen content on phase transformation, mechanical properties and corrosion resistance of TiNb based alloys with different Nb contents (15, 32 and 38 wt%), i.e. different β stabilities were investigated. The results show that the oxygen does not change the phase constitution of α’-type Ti15Nb based alloy with low β phase stability, while the oxygen can suppress the α” martensite and ω phase, acting as β-stabilizer in the higher β phase stability of Ti32Nb and Ti38Nb based alloys. The addition of oxygen increases strength through solid solution strengthening and/or modification of deformation behavior. It has been found that simultaneous improvement in strength and ductility can be achieved in each base alloy by doping a certain content of oxygen. Young's modulus of Ti-Nb-O alloys exhibits different trends with oxygen increasing, which is related to the different effects of oxygen on phase stability. A desirable balance between low Young's modulus and high strength can be obtained through controlling oxygen and Nb content. The Ti-Nb-O alloys exhibit a high degree of corrosion resistance within simulated body fluid (SBF) at 310 K. Particularly, the Ti-38Nb-0.5O alloy exhibits low Young's modulus (52 GPa), high yield strength (1141 MPa) and good elongation (22%), which has potential in biomedical applications.

Resistive and capacitive strain sensors based on customized compliant electrode: Comparison and their wearable applications

The demand for stretchable strain sensors has increased exponentially due to their ideal interaction with the human body. However, developing stretchable strain sensors with balanced properties such as a low Young’s modulus, easy fabrication, low cost, large deformation, and fast response time remains a challenge. In this study, we simultaneously prepared two high-performance types of stretchable strain sensors (resistive and capacitive sensors) based on customized compliant electrode. The electrode was developed by embedding multi-walled carbon nanotubes (MCNTs) into plasticized polyvinyl chloride (PVC) using the solvent casting method. The resistive strain sensor was fabricated by the compliant electrode and 3 M 4905 tapes in a sandwich structure. The capacitive sensor was obtained after simple stacking steps based on the preparation of resistive sensor. Then, the performance of the resistive and capacitive sensors was investigated, compared and discussed. The results show that both resistive and capacitive sensors have good static and dynamic performance. The two types of sensors have maximum tensile strain of more than 100 %, low Young's modulus less than 200 kPa, and fast response time less than 140 ms. The linearity of capacitive sensor is better than that of resistive sensor. The repeatability of capacitive sensor is better than that of resistive sensor during a long period. The resistive sensor has higher sensitivity (1.16) than the capacitive sensor (0.44), and has better signal anti-interference capability. Finally, the developed resistive and capacitive sensor were used to monitor the motion status of human joints and the motion angle of human joint, respectively, resulting in accurate sensing of human movement.

Compressible and Stretchable Magnetoelectric Sensors Based on Liquid Metals for Highly Sensitive, Self-Powered Respiratory Monitoring.

Healthcare monitoring, especially for respiration, has attracted tremendous attention from academics considering the great significance of health information feedback. The respiratory rate, as a critical health indicator, has been used to screen and evaluate potential illness risks in early medical diagnoses. A self-powered sensing system for medical monitoring is critical and imperative due to needless battery replacement and simple assembly. However, the development of a self-powered respiratory sensor with highly sensitive performance is still a daunting challenge. In this work, a compressible and stretchable magnetoelectric sensor (CSMS) with an arch-shaped air gap is reported, enabling self-powered respiratory monitoring driven by exhaled/inhaled breath. The CSMS contains two key functional materials: liquid metals and magnetic powders both with low Young's modulus, allowing for sensing compressibility and stretchability simultaneously. More importantly, such a magnetoelectric sensor exhibits mechanoelectrical converting capacity under an external force, which has been verified by Maxwell numerical simulation. Owing to the air-layer introduction, the magnetoelectric sensors achieve high sensitivity (up to 17.73 kPa-1), fast response, and long-term stability. The highly sensitive and self-powered magnetoelectric sensor can be further applied as a noninvasive, miniaturized, and portable respiratory monitoring system with the aim of warning for potential health risks. We anticipate that this technique will create an avenue for self-powered respiratory monitoring fields.

Topologically Enhanced Dual-Network Hydrogels with Rapid Recovery for Low-Hysteresis, Self-Adhesive Epidemic Electronics.

Dual-network conductive hydrogels have drawn wide attention in epidemic electronics such as epidemic sensors and electrodes because of their inherent low Young's modulus, high skin-compliance, and tunable mechanical strength. However, it is still full of challenges to gain a dual-network hydrogel with high stretchability, low hysteresis, and skin-adhesive performance simultaneously. Herein, to address this issue, a novel dual-network hydrogel (denoted as PAa hydrogel) with polyacrylamide as the first network and topologically entangled polydopamine as the secondary network was prepared through a facile gel-phase in situ self-polymerization and soaking treatment. Benefiting from the topological enhancement as well as the synergetic effects of hydrogen bonds and metal coordination bonds, low modulus (∼10 kPa), excellent stretchability (1090.8%), high compression (90%), negligible hysteresis (η = 0.019, energy loss coefficient), rapid recovery in seconds, and self-adhesion are obtained in the PAa hydrogels. To demonstrate their practical use, a states-independent and skin-adhesive epidemic sensor was successfully attached on human skin for motion detection. What is more, by using the hydrogel as an epidemic electrode, electromyogram signals were accurately detected and wirelessly transmitted to a smart phone. This work offers a new insight to understand the strengthening mechanism of dual network hydrogels and a design strategy for both epidemic sensors and electrodes.

Multiparametric Profiling of Single Nanoscale Extracellular Vesicles by Combined Atomic Force and Fluorescence Microscopy: Correlation and Heterogeneity in Their Molecular and Biophysical Features.

Being a key player in intercellular communications, nanoscale extracellular vesicles (EVs) offer unique opportunities for both diagnostics and therapeutics. However, their cellular origin and functional identity remain elusive due to the high heterogeneity in their molecular and physical features. Here, for the first time, multiple EV parameters involving membrane protein composition, size and mechanical properties on single small EVs (sEVs) are simultaneously studied by combined fluorescence and atomic force microscopy. Furthermore, their correlation and heterogeneity in different cellular sources are investigated. The study, performed on sEVs derived from human embryonic kidney 293, cord blood mesenchymal stromal and human acute monocytic leukemia cell lines, identifies both common and cell line-specific sEV subpopulations bearing distinct distributions of the common tetraspanins (CD9, CD63, and CD81) and biophysical properties. Although the tetraspanin abundances of individual sEVs are independent of their sizes, the expression levels of CD9 and CD63 are strongly correlated. A sEV population co-expressing all the three tetraspanins in relatively high abundance, however, having average diameters of <100 nm and relatively low Young moduli, is also found in all cell lines. Such a multiparametric approach is expected to provide new insights regarding EV biology and functions, potentially deciphering unsolved questions in this field.

Effect of soft and hard inclusions in tensile deformation and damage mechanism of Aluminum: A molecular dynamics study

Abstract The current study investigates the uniaxial tensile deformation and damage mechanism in single-crystal Aluminum (Al) in the presence of soft and hard inclusions. Spherical shaped Magnesium (Mg) and Titanium (Ti) are added as inclusions within an Al single crystal. Alteration in mechanical properties has been noticed in the presence of inclusions. Softening has been observed in the presence of Mg; while hardening in the presence of Ti. Low Young modulus of Mg inclusion and lack of dislocation activity results in less deformation, higher stress concentration at the interface, and early void nucleation in Al+Mg system. While high Young modulus of Ti inclusion and substantial dislocation activity prevails the large deformation, lower stress concentration at the interface, and slow fracture in Al+Ti system. The study provides an understanding of the governing fracture mechanism influenced by the inclusion.