Flexural Bending Research Articles

Development of a mussel-inspired conductive graphene coated cotton yarn for wearable sensors.

Graphene-based flexible yarn sensors are promising due to their exceptional conductivity and user-friendly properties, but ensuring stable graphene adsorption on fibers for long-term durability remains challenging. Herein, we produce a flexible polydopamine (PDA)-modified cotton yarn via a simple dip-coating process using a self-made sodium deoxycholate (SDC)-modified graphene dispersion, avoiding non-biodegradable, corrosion-prone metallic coatings. The resulting sensor exhibits low electrical resistance (as low as 21.1Ω± 0.2/cm), high bending sensitivity (resistance change rate of 3.557± 0.002 for bending ranges from 40% to 100%), and outstanding durability over 2,000 flexural bending cycles. It can monitor various human body movements and physiological states and be integrated into wearable electronic textiles (e-textiles) for applications like monitoring knee movements, recognizing hand gestures, and detecting thoracic respiratory status. This work highlights the sensor's potential in personal and public healthcare applications.

Mechanical Twisting-Induced Enhancement of Second-Order Optical Nonlinearity in a Flexible Molecular Crystal.

Flexible molecular crystals are essential for advancing smart materials, providing unique functionality and adaptability for applications in next-generation electronics, pharmaceuticals, and energy storage. However, the optical applications of flexible molecular crystals have been largely restricted to linear optics, with nonlinear optical (NLO) properties rarely explored. Herein, we report on the application of mechanical twisting of flexible molecular crystals for second-order nonlinear optics. The crystal formed through the self-assembly of the model compound 9-anthraldehyde (AA) features an intrinsic chiral and noncentrosymmetric structure, demonstrating high efficiency second harmonic generation (SHG) and NLO circular dichroism, which could be greatly enhanced by macroscopic mechanical twisting. The anisotropic molecular stacking imparts the AA crystal with mechanical flexibility of combined elastic bending and plastic twisting. The isochiral mechanical twisting could greatly enhance the SHG intensities by an order of magnitude depending on their M- or P-configuration. Meanwhile, the SHG circular dichroism factor gSHG-CD of the isochiral twisted crystal is greatly increased, achieving the highest reported NLO anisotropy factor among organic NLO materials. These boosted NLO performances of SHG intensity and nonlinear chiroptical response are expected to greatly expand the photonic applications of flexible molecular crystals.

Study of Flexural Strength of Epoxy Composites Reinforced with Opuntia Ficus Indica Fibers

This study investigates the potential of Opuntia ficus indica (cactus) fiber as a reinforcing material in composite applications, particularly in combination with an epoxy matrix. Despite being a naturally abundant resource, cactus fiber remains underutilized in engineering. The research focuses on evaluating the flexural strength of cactus fiber-reinforced composites, with particular attention to how variations in fiber volume fraction influence bending strength. As a member of the Cactaceae family, which includes over 130 genera and nearly 1,500 species, cactus fiber offers a sustainable and eco-friendly alternative to conventional materials. With the growing demand for high-performance composite materials, this study underscores the potential of cactus fiber to enhance the mechanical properties and environmental sustainability of composite materials. Composites are prepared using cactus fibers of two lengths (8 mm and 10 mm) and varying weight fractions (20%, 25%, and 30%). The fibers are treated with a 5% Sodium Hydroxide (NaOH) solution by soaking it for 24 hours. The study investigates how fiber treatment, length, and loading affects the flexural strength or bending strength of cactus fibers. Results indicate that alkali-treated cactus fiber composites exhibit superior mechanical properties compared to untreated composites. Composites reinforced with 10 mm fibers show improved mechanical behavior over those reinforced with shorter fibers.

Fabrication of Nano Copper Highly Conductive and Flexible Printed Electronics by Direct Ink Writing.

Nanoscale metals have emerged as crucial materials for conductive inks in printed electronics due to their unique physical and chemical properties. However, the synthesis of high-precision and highly conductive copper ink remains a challenge. Herein, a high-precision, highly conductive, and oxidation-resistant nanocopper ink was synthesized to fabricate highly conductive and flexible printed electronic devices. Copper nanoparticles with a particle size of only 8.5 nm, a controllable structure, and excellent oxidation resistance were synthesized by the alcohol phase reduction method. The conductive ink was formulated with ethylene glycol, ethanol, and isopropanolamine (IPA) as the solvent, exhibiting excellent printability and sintering reducibility. Fluid dynamics simulations were employed to investigate the influence of printing parameters on the circuit forming performance, enabling precise control over the printing process. The sintering behavior of copper nanoparticles with varying particle sizes was investigated by combining experiments with molecular dynamics (MD) simulations. Highly conductive and flexible circuits were fabricated using direct ink writing (DIW) under low-temperature sintering, exhibiting a low resistance level as low as 1.9 μΩ·cm. Moreover, the circuit demonstrated an excellent adhesion performance and bending flexibility. The developed copper ink demonstrates outstanding printing potential for applications in flexible electronics, advancing the field of flexible printing and wearable electronic devices.

Mechanical Properties of Cobalt Chromium Alloy Manufactured by Direct Energy Deposition Technology

Abstract Cobalt chromium (CoCr), a well-known biocompatible material, is additively manufactured using direct energy deposition (DED) technology in this study. This study investigates some important mechanical characteristics of the additively manufactured CoCr using two different numerical simulation methods in addition to mechanical tests and experiments. Mechanical experiments such as hardness, wear, and flexural bending test were conducted on DED-processed samples. All experiments were also conducted on conventionally processed CoCr specimens for comparison purposes. DED-processed CoCr samples exhibited a complex microstructure with a variety of features such as cellular, columnar, and equiaxed grains within their melt pools. While the DED-processed sample had a lower hardness compared to the conventionally processed one, it exhibited a higher wear resistance. The tensile strength obtained from resonance frequency testing was higher for the DED-processed CoCr sample compared to the conventionally fabricated one. The out-of-plane mechanical strength of CoCr samples was measured by conducting flexural bending test, and the conventional sample showed a higher flexural modulus than the DED sample. The bend tests were also numerically simulated using two different finite element analysis (FEA) procedures. The FEA results for the conventionally processed samples are in good agreement with the ones obtained from the experimental flexural bending test. The results of the FEA studies on the DED-processed samples were within 10-20 % of the experimental ones, showing the potential of numerical methods in estimating this property without the need of mechanical testing.

Finite Modelling and Analysis on the Flexural Behaviour of Reclaimed Timber Reinforced Steel Beams

Timber-steel composites are used widely for various construction such as roofs, floors, bridges and multistory buildings due to its strength, ultimate load capacity and ductility advantages. This study investigated the structural behaviour of hollow steel and reclaimed timber reinforced steel specimens under static loading. The timber reinforcement is not only to enhance flexural behaviour but encourage the recycling of old timber materials as a way of natural resource maintainability and sustainability in the developing countries, Nigeria inclusive. A total number of eight (12) specimens were prepared in which four replicates for each set of reclaimed timber, hollow steel and reclaimed timber reinforced steel specimens, respectively. Each of these specimens was loaded slowly and statically tested using a Universal Testing Machine (UTM) with displacement control, until failure occurred and the test results were computed and analysed. Thereafter, ANSYS R.19 was used for the finite modelling and numerical analysis. The experimental results showed that reclaimed timber reinforced steel (RTRS) beams have performed better than hollow steel (SH) beams under bending. That is the reinforcement has significantly improved the ultimate load capacity and strength of RTRS beams with 31.37% experimentally. In addition, the ultimate loads, deformations, equivalent stresses and failure modes of the beams under flexural bending were accurately predicted and well agreed with experimental data. It was concluded that reclaimed timbers can be used as reinforcement materials in composite construction to increase the flexural capacity of steel hollow section.

Omnidirectional Bending Sensor with Bianisotropic Structure for Wearable Electronics.

Bending sensors are critical to the advancement of wearable electronics and can be applied in the dynamic monitoring of flexible object morphology. However, current bending sensors are constrained by sensing range and precision, especially in full-range detection. The maximum sensing range of existing flexible bending sensors is 0-240°. This study introduces a bianisotropic responsive structure into the design of an all-textile bending sensor, thereby realizing 0-360° full-range omnidirectional bending sensing. First, the project elucidated the sensing mechanism of the piezoresistive bianisotropic structured bending sensor and identified critical factors through a numerical simulation method. Then, the bianisotropic structured bending sensors were produced through the stitch method and analyzed on their electromechanical performance. Further, the recognition model for both bending angle and direction parameters was developed via numerical calculation, achieving a high accuracy with an error rate of 2.82%. Last, according to the ergonomics of body joints, the sensors were customized and validated in body joint monitoring scenarios. This work significantly enhances the performance of flexible bending sensors in sensing range, accuracy, and comfort for the wearer. The versatility of this bending sensor positions it as a promising candidate to supplant traditional heavy equipment or rigid devices, particularly in wearable joint motion monitoring and soft robotics.

Impacts of Transition Piece Designs on the Resilience of Large Offshore Wind Turbines Subject to Combined Earthquake, Wind and Wave Loads and Soil‐Structure Interaction

ABSTRACTThe urgent global drive to mitigate greenhouse gas emissions has significantly boosted renewable energy production, notably expanding offshore wind energy across the globe. With the technological evolution enabling higher‐capacity turbines on larger foundations, these installations are increasingly situated in earthquake‐prone areas, underscoring the critical need to ensure their seismic resilience as they become a pivotal component of the global energy infrastructure. This study scrutinises the dynamic behaviour of a 15 MW offshore wind turbine (OWT) under concurrent earthquake, wind and wave loads, focusing on the performance of the ultra‐high‐strength cementitious grout that bonds the monopile to the transition piece. Employing LS DYNA for numerical simulations, we explored the seismic responses of four OWT designs with diverse transition piece cone angles, incorporating nonlinear soil springs to model soil‐structure interactions (SSIs) and conducting a site response analysis (SRA) to account for local site effects on ground motion amplification. Our findings reveal that transition pieces with larger cone angles exhibit substantially enhanced stress distribution and resistance to grout damage, evidenced by decreased ovalisation in the coned sections of the transition piece and monopile, and improved bending flexibility. The observed disparities in damage across different cone angles highlight shortcomings in current design guidelines pertaining to the prediction of grout stresses in conical transition piece designs, with the current code‐specified calculations predicting higher stresses for transition piece designs with larger cone angles. This study also highlights the code's limitations when accounting for grout damage induced by stress concentrations in the grouted connections under seismic dynamic loading conditions. The results of the study demonstrate the need for refinement of these guidelines to improve the seismic robustness of OWTs, thereby contributing to the resilience of renewable energy infrastructure against earthquake‐induced disruptions.

Posture Monitoring During Breastfeeding: Smart Underwear Integrated with an Accelerometer and Flexible Sensors.

The position that a woman adopts during breastfeeding is important for both infant and maternal health; however, many women experience musculoskeletal pain due to poor posture during breastfeeding, which is a known factor in low exclusive breastfeeding rates. Posture monitoring is an effective intervention, but existing wearable devices do not consider the ergonomics of nursing mothers and breastfeeding scenarios. In this study, nursing underwear was developed with posture monitoring and a real-time feedback system using accelerometers and flexible bending sensors targeting the neck and upper thoracic spine. Semi-structured interviews were conducted with 12 Chinese mothers to identify key challenges and inform the design. After designing and producing the prototype, wear trials were conducted with two participants who tested both the prototype and a commercial sample while holding a 4 kg baby doll. Video recordings and questionnaires were used to assess the underwear's effectiveness. The results showed improvements in postural alignment and an increase in the frequency and duration of relaxation periods. Participants reported that the prototype surpassed the commercial sample in functionality, comfort, and aesthetics. These findings are significant for postpartum health and provide guidelines for future smart nursing garment development.

Cofilin-Mediated Filament Softening and Crosslinking Counterbalance to Enhance Actin Network Flexibility.

Filamentous-actin (F-actin) crosslinking within the cell cytoskeleton mediates the transmission of mechanical forces, enabling changes in cell shape, as occurs during cell division and cell migration. Crosslinking by actin binding proteins (ABPs) generally increases the connectivity of the F-actin network, but also increases network rigidity. As a result, there is a narrow range in the concentration of crosslinker protein at which F-actin networks are both connected and labile. Another ABP, cofilin, severs F-actin filaments at high pH through increasing their bending flexibility and concentrating mechanical stress, inducing fragmentation. By contrast, at lower pH, cofilin increases filament flexibility yet does not sever. Instead, it forms disulfide bonds, which crosslink F-actin into bundles, and bundles into networks. Here, we combine light microscopy and rheology to determine the impact of two potentially opposing effects on the mechanics of F-actin networks-increased flexibility at the filament level, and increased connectivity at the network level. Indeed, by linear rheology, we find that these mechanisms are counterbalanced, such that cofilactin network moduli are only weakly dependent on cofilin concentration over a broad range, in contrast to the dramatic stiffening that occurs with F-actin crosslinking protein. Further, by nonlinear rheology, the network stiffens at a higher stress than crosslinking protein, indicative of a broader range in which the material remains flexible. These results may enable F-actin networks to increase connectivity without heavy penalties to rigidity, and thus provide a new route to modulating active polymer mechanics unseen using traditional F-actin accessory proteins.

Strongly toughened heat‐resistant cyanate ester resin‐based coatings doped by Tb3+‐complex anchored‐uCNTs with green fluorescent properties

AbstractThermally stable polymeric coatings are widely used for metal protection at high temperatures, but their brittle weakness makes them unavailable to durable environment. To overcome that, we report properties of cyanate ester resin (CER) coating doped with unzipped carbon nanotubes (uCNTs) loaded with terbium complex (TBP) as nanofiller. The performance of the coating showed that the bending flexibility, adhesion, and impact resistance of the doped coatings was significantly improved. The cylinder bending test showed that the minimal bending diameter of CER doped with TBP‐uCNTs coating reached 6 mm without failure, which represents a significant improvement compared to the pure CER coating (18 mm). Surprisingly, the impact resistance reached the highest value of 50 cm without any failure of the coating. X‐ray diffraction, Fourier transform infrared spectroscopy, Raman, x‐ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy studies of CNTs, uCNTS, TBP‐uCNTs, and properties of CER indicate that formation of CER/TBP‐uCNTs composite is supported by a chemical reaction between hydroxyl groups of TBP‐uCNTs and the cyanate groups of CER resulting in fabrication of a solid cross‐linked structure. The thermal decomposition temperature of the coating increases from 409°C for pure CER to 453°C for CER/TBP‐uCNTs. The fluorescence spectra show that CER/TBP‐uCNTs exhibits strong luminescence at 550 nm.

Sub-modelling based fatigue evaluation of welded details in composite trapezoidal corrugated web girders under coupled thermal-structural loading

Exploring the long-term performance of welded details in composite trapezoidal corrugated web (TCW) girders is a significant focus for the service life of these structures exposed to atmospheric environment and traffic flow. The majority of the present studies have been conducted without accounting for thermal stresses induced by temperature differences and accurately reflecting internal force transfers for the composite girders in flexural bending. The fatigue behaviour of the welded details in these girders under coupled thermal-structural loading is investigated herein through experimental and numerical methods. The results indicated three stages for the structural degradation from the test performance and justified a proper allowance of the cross-sectional stress in coordination with the flexural curvature in the derivation of S-N relations comparable to similar details in related design codes. A sub-modelling procedure is implemented to capture the thermal gradient, the local stress concentration, and the crack distribution in global modelling while replicate the semi-elliptical surface crack at the external side of the fillet weld toe in local modelling. The fatigue lives predicted from the proposed analytical model match reasonably well with experimental and numerical results, indicating its good applicability incorporating characteristic geometric correction factors into classical theoretical calculation for fatigue evaluation.

Investigation of higher-order springing of a ship in regular waves by experimental analysis and two-way CFD-FEA coupled method

In this paper, the higher-order springing phenomenon is addressed for a segmented barge ship model through experimental and numerical measures. An efficient in-house two-way coupled numerical solver between Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) is developed and validated against experimental results. The coupling method is based on a domain-separated approach and necessitates the resolution of individual boundary value problems in distinct domains. To ensure convergence within these individual domains, an implicit numerical scheme is employed and further facilitated exchange of variables for coupling. The current approach emphasizes the overall convergence between two solvers, maintaining a strongly coupled setup to comprehensively address fluid-structure interaction phenomena, including added mass and damping effects. A series of tank tests were conducted first to measure the wave-induced sectional loads and motions, during which the springing responses to very high-order harmonics of wave load were observed. By comparing the numerical prediction with the tank test results for rigid body motion and flexible vertical bending moment (VBM), the proposed numerical method demonstrated agreement with experimental results, affirming its validity and robustness. Finally, the springing response up to 14th order harmonics is discussed and investigated.

Improving the Fatigue Performance of Binder Jet Manufactured 316L by Severe Shot Peening Surface Modification

Binder jetting is a rapidly evolving additive manufacturing technique, challenging the dominance of laser powder bed fusion in metal fabrication. This study focuses on the material properties of austenitic stainless steel 316L produced via binder jet technology. Porosity remains a significant challenge across additive manufacturing methods, adversely affecting material properties and fatigue life. To address this issue, we propose a novel approach employing severe shot peening as a post-processing treatment to enhance the material's characteristics. Microstructural analysis, including electron backscatter diffraction (EBSD), coupled with tensile testing, was conducted to evaluate the mechanical properties. Additionally, fatigue behavior was investigated under both axial and flexural bending loading conditions. The results revealed a substantial increase in material strength achievable through the post-treatment. Notably, the fatigue limit of the material in bending fatigue was elevated from 120 MPa to 190 MPa, indicating a significant enhancement in fatigue performance. This study contributes new insights into the enhancement of fatigue resistance in binder jet-manufactured 316L stainless steel through surface modification techniques. The findings underscore the potential of severe shot peening as an effective strategy to improve material properties and expand the applicability of binder jet printing in demanding industrial applications.

Flexible and Extensible Ribbon-Cable Interconnects for Implantable Electrical Neural Interfaces.

The design and characterization of thin-film ribbon cables as electrical interconnects for implanted neural stimulation and recording devices are reported. Our goal is to develop flexible and extensible ribbon cables that integrate with thin-film, cortical penetrating microelectrode arrays (MEAs). Amorphous silicon carbide (a-SiC) and polyimide were employed as the structural elements of the ribbon cables and multilayer titanium/gold thin films as electrical traces. Using photolithography and thin-film processing, ribbon cables with linear and serpentine electrical traces were investigated. A cable design with an open lattice geometry was also investigated as a means of achieving high levels of extensibility while preserving the electrical function of the cables. Multichannel ribbon cables were fabricated with 50 mm lengths and metallization trace widths of 2-12 μm. The ribbon cables tolerate flexural bending to a radius of 50 μm with no change in trace impedance but tolerate less than 5% tensile elongation without trace failure. Ribbon cables with a lattice structure exhibit 300% elongation without failure. The high elongation tolerance is attributed to a lattice design that results in an out-of-plane displacement that avoids fracture or plastic deformation. Extensible ribbon cables underwent up to 50,000 tensile elongation cycles to 45% extension without failure. An electrical interconnect process using through-holes in the distal gold bond pads of the ribbon cables was used to connect to an a-SiC-based MEA. The electrical connection was created by stenciling a conductive epoxy into the through-holes, bridging metallization between the traces, and MEA. The interconnect was tested using a ribbon cable connected to an a-SiC MEA implanted acutely in rat cortex and used to record neuronal activity. These highly flexible and extensible ribbon cables are expected to accommodate large extensions and facilitate cable routing during surgical implantation. They may also reduce tethering forces on implanted electrode arrays, potentially improving chronic neural recording performance.

A 3-D modelling of monopile behaviour under laterally applied loading

Deploying higher-capacity offshore wind turbines to meet the growing energy demand poses a significant challenge in designing their foundations. Monopiles currently constitute 80% of the foundation installations for these turbines. This study utilizes a nonlinear three-dimensional (3D) finite element model to explore the behavior of monopiles underpinning a five megawatt wind turbine under horizontal loads. The findings reveal that the performance of monopiles is influenced by the strength of the soil and the ratio of pile depth of embedment to diameter (L/D). Examination of flexural bending profiles at/close to failure loads demonstrates the flexible behavior of monopiles, even with a low L/D ratio. The L/D ratio exhibits varying degrees of impact on the normalized ultimate lateral capacity of monopiles, with a notable effect observed in soft clays, resulting in an increase of up to five times for L/D ratios ranging from 3.33 to 13.33. Stiff clays show comparatively lesser effects. Under serviceability loading, an increase in the L/D ratio leads to a 3–6% rise in the maximum flexural moment of monopiles, while the maximum shear force experiences a decrease of 20–30%. Furthermore, a significant reduction, up to five-fold, in the maximum tower tip displacements and rotations at the mudline is observed with an increasing L/D ratio. However, this reduction is more pronounced for higher foundation rigidity.

Effects of Anisotropic Mechanical Behavior on Nominal Moment Capability of 3D Printed Concrete Beam with Reinforcement

In this study, 3D-printed reinforced concrete beams were tested for flexural performance and compared with the analytical model based on the material test results. Two cementitious mixes (PSU and GCT) were designed for concrete printing and were mechanically tested and compared. Anisotropies in the compressive strength and modulus of elasticity of printed concrete were observed, applied to the analytical prediction of flexural bending behavior, and validated by actual test results. Significant differences between analytical predictions and experimental tests of the bending behaviors of the printed concrete beams were observed. Furthermore, higher compressive strengths and moduli of elasticity were observed when the loading direction was perpendicular to the printed layers or with the PSU mix. The effect of anisotropic mechanical properties on a reinforced beam was compared to the flexural bending tests for both mixes. The analytical model based on the material test results was compared to the flexural bending test results. The significant errors in the prediction of printed concrete’s structural performance, from 10% to 50%, suggest that factors other than reduced compressive strengths may influence the structural behaviors of printed concrete beams.

Flexible supercapacitors based on in-situ synthesis of composite nickel manganite@reduced graphene oxide nanosheets cathode: An integration of high mechanical flexibility and energy storage

Supercapacitors have attracted considerable attention in the context of electric vehicles, renewable energy storage, and industrial equipment. Nevertheless, further work is required to enhance the energy storage performance and improve the adaptability of supercapacitors under mechanical loads. To address these challenges, we propose a novel design strategy for composite micro-nano structures of reduced graphene oxide coated in situ growth of nickel manganite nanoarrays on the carbon fiber surface (CF@NiMn2O4@rGO). This design enables the fabrication of flexible supercapacitor electrodes with optimised electrochemical and mechanical properties. The CF@NiMn2O4@rGO cathode exhibits a synergistic effect that enhances energy storage, as evidenced by a high specific capacitance of 1003.35 F g−1 (at 10 mA cm−2) and exceptional cycling stability over more than 4000 cycles. Furthermore, the flexible carbon fiber (CF) and in-situ grown nickel manganite@reduced graphene oxide (NiMn2O4@rGO) contribute to improved mechanical properties of the electrode. The assembled supercapacitor exhibits both high energy density and cycling stability. Notably, the flexible bending angle ranging from 0° to 180° has minimal impact on the energy storage performance of this flexible supercapacitor. Even under a bending angle of 180°, it successfully powers a small light bulb. This novel nanostructured material presents an innovative approach for designing flexible supercapacitors.

CORC® wires allowing bending to 20 mm radius with 97.5% retention in critical current and having an engineering current density of 530 A mm−2 at 20 T

Abstract Low-inductance, high-field insert solenoid magnets and 20 T dipole magnets for particle accelerators require flexible cables, wound from high-temperature superconductors (HTS) such as RE-Ba2Cu3O7-δ (REBCO) coated conductors, that allow bending to a 20 mm radius without significant degradation in performance. They require an operating current of at least 5 kA and a high engineering current density (Je) exceeding 500 A/mm2 at 20 T. HTS cable technologies that target such demanding magnet applications so far haven’t been able to meet the combination of these requirements.
Here we present the development of the next generation of Conductor on Round Core (CORC®) wires that improves their bending flexibility by factor of more than 2 compared to previous generation CORC® wires. CORC® wires now allow for a bending radius of 20 mm with only 2 – 3 % performance degradation. They allow bending to a radius of 15 mm with a performance retention of 83.5 %. The performance of 30-tape CORC® wires wound from 2 mm wide REBCO tapes from SuperPower Inc, SuperOx and Shanghai Superconductor Technologies was measured at magnetic fields up to 12 T. The overall performance at high magnetic fields of the next generation of CORC® wires improved by a factor of 1.5 – 1.8, depending on the REBCO tape manufacturer. CORC® wires wound from production REBCO tapes achieved a new record Je of 751 A/mm2 at a current of 8.3 kA at 12 T, and a Je of 530 A/mm2 at a current of 5.8 kA when extrapolated to 20 T. 

Enhancing flexibility of smart bioresorbable vascular scaffolds through 3D printing using polycaprolactone and polylactic acid

With the growing use of stent implantations, the risk of in-stent restenosis represents a major concern for cardiovascular patients. Herein, we propose a hybrid bioresorbable vascular scaffold (H-BVS) integrated with a wireless sensor that could enable significant advances in cardiovascular therapeutics. The H-BVS was carefully manufactured using a state-of-the-art customized 3D printer equipped with dual nozzles to achieve a synergistic combination of polycaprolactone (PCL) and polylactic acid (PLA), both of which are known for their bioresorbable properties. This characteristic is particularly valuable in medical applications where the scaffold is gradually absorbed by the body, eliminating the need for a second procedure to remove it. Furthermore, the H-BVS was integrated with a wireless, battery-less LC-type pressure sensor for real-time monitoring of in-stent restenosis. This wireless sensor was meticulously connected with the H-BVS framework through engineered microstructures, which not only ensured a robust bond but also significantly enhanced the overall integrity and functionality of the device. Additionally, the combination of the H-BVS and sensor was optimized to exhibit superior bending flexibility and radial strength, which are key factors in ensuring effectiveness and patient safety. The feasibility of the smart H-BVS (SH-BVS) was verified through comprehensive testing within a phantom system designed to simulate real blood flow conditions. We believe that the SH-BVS system holds strong potential to significantly improve patient monitoring and treatment strategies within the cardiovascular healthcare domain.