Bending Module Research Articles

Impact of Manual Addition of Vancomycin to Polymethylmethacrylate (PMMA) Cements.

(1) Background: The addition of antibiotics to bone cements is a common practice in the treatment of periprosthetic joint infections. In revision cases, the amount and type of antibiotic is often insufficient and additional antibiotics must be added. The addition, however, changes the product itself, and the surgeon becomes the "manufacturer" of the bone cement. PMMAe wished to clarify whether the admixture of antibiotics changes the mechanical stability of the bone cements used and if the added antibiotics were still functional and released in sufficient quantities. (2) Methods: We compared two industrially manufactured vancomycin-containing PMMA cements; the low-viscous VancogenX® (TECRES, Sommacampagna, Italy) and the high-viscous Copal® G+V (Heraeus Medical GmbH, Wehrheim, Germany), with two PMMA cements loaded with aminoglycosides, to which 2.0 g of vancomycin (Hexal CT1631) were manually added-the high-viscous Smartset® GHV and the medium-viscous Antibiotic Simplex with Tobramycin (antibiotic Simplex® T). Test specimens of the bone cements were used to determine mechanical stability (bending strength and bending module), and the release of the antibiotics was determined by HLPC and modified Kirby-Bauer assays. (3) Results: All tested bone cements showed an initial high release within the first hours. Repeated testing after 24 h showed a reduced efficacy of VancogenX® and Smartset® GHV in Kirby-Bauer assays. Long-time release over days showed a release of functional antimicrobial active ingredients over this period of time in anti-microbial assays, but no activity of VancogenX® from day 21 onward. No significant differences in the ISO bending modules could be detected, but in contrast to the bending module, the ISO bending strength was substantially reduced by 10-15 mPal in comparison to both cements of the reference group. The Simplex®T met just the ISO 5833; the Smartset® GHV did not after adding vancomycin. (4) Conclusions: In conclusion, the manual addition of 2 g of vancomycin to 40 g of PMMA powder is recommended for the treatment of methicillin-resistant staphylococci. Vancomycin is released over a period of 42 days with concentrations above the MIC for typical staphylococci. The mechanical properties of the PMMA just met, or did not fulfill, ISO mechanical specification. Copal® G+V showed a better elution than VancogenX® over time.

Design and Driving Performance Study of Soft Actuators for Hand Rehabilitation Training.

To address the application requirements of soft actuators in rehabilitation training gloves, and in combination with ergonomic requirements, we designed a segmented soft actuator with bending and elongation modules. This actuator can achieve independent or coupled movements of the finger joints. A finite element model of the joint actuator was established to compare the driving performance of actuators with different structural forms. Numerical calculations were used to analyze the effects of structural size parameters on the bending characteristics and end output force of the actuator. The design was then refined based on these analyses. The joint actuator designed in this study demonstrated a 71% increase in bending angle compared to the standard fast pneumatic network structure. Key factors affecting the driving performance include the thickness of the constraint layer, the inner wall thickness of the chamber, chamber height, chamber width, chamber spacing, chamber length, and the number of chambers. After improvements, the bending angle of the joint actuator increased by 60.6%, and the output force increased by 145.9%, indicating significant improvement. This study designed and improved a soft actuator for hand rehabilitation training, achieving independent and coupled joint movements. The bending angle, bending shape, and joint driving force of the soft actuator meet the requirements for finger rehabilitation training.

Study on the flexural performance and microstructure of lithium feldspar tailings cementitious filler using mixed fibers

The brittle fracture and toughness of cemented tailings backfill (CTB) are not conducive to underground mining projects. Incorporating fibers may enhance the flexural properties of the CTB. This study used glass (GS) and polypropylene (PP) fibers to fabricate fiber-reinforced cemented lithium feldspar tailing backfill (FCLTB) specimens. The flexural strengths and microstructures of the specimens were analyzed using a three-point flexure test and scanned electron microscopy (SEM). Following a three-point bending test, it was observed that Upon decreasing the amount of GS fiber, the bending strength of the FCLTB specimens initially decreased and then increased. However, with an increase in the PP fiber content, the average bending module of the FCLTB specimens initially reduced and then rose. The combined use of GS and PP fibers significantly improved the toughness of the CLTB samples after the peak. Composite fibers resist the formation of cracks under load.

Bioinspired handheld time-share driven robot with expandable DoFs

Handheld robots offer accessible solutions with a short learning curve to enhance operator capabilities. However, their controllable degree-of-freedoms are limited due to scarce space for actuators. Inspired by muscle movements stimulated by nerves, we report a handheld time-share driven robot. It comprises several motion modules, all powered by a single motor. Shape memory alloy (SMA) wires, acting as “nerves”, connect to motion modules, enabling the selection of the activated module. The robot contains a 202-gram motor base and a 0.8 cm diameter manipulator comprised of sequentially linked bending modules (BM). The manipulator can be tailored in length and integrated with various instruments in situ, facilitating non-invasive access and high-dexterous operation at remote surgical sites. The applicability was demonstrated in clinical scenarios, where a surgeon held the robot to conduct transluminal experiments on a human stomach model and an ex vivo porcine stomach. The time-share driven mechanism offers a pragmatic approach to build a multi-degree-of-freedom robot for broader applications.

Numerical simulation of bending and length-varying flapping wing using discrete vortex method

The paper aims to perform numerical simulations of flapping flight using Discrete Vortex Method (DVM) scheme. The scheme is suitable for moderately low Reynolds number [Formula: see text] and computationally less expensive as the flow domain doesn’t need to be discretized at each time step. Flapping of a one-dimensional (1D) flexible filament in a two-dimensional (2D) inviscid flow is simulated. The effect of bending by varying the wing shape along the spanwise length on aerodynamic performance was studied. It is observed that compared to rigid wings, bending wings are found to be better in generating lift. The effect of various bending wing configurations ([Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]) and different methods of imposing the bending ([Formula: see text], [Formula: see text] and [Formula: see text]) is studied. It was demonstrated that applying wing bending only during the downstroke phase ([Formula: see text]) is more effective than imposing bending throughout the flapping cycle ([Formula: see text]). Moreover, an effort is made to replicate the bending configuration observed in manta ray fish ([Formula: see text]) to investigate its impact on flow domain characteristics, lift, and thrust forces. Furthermore, the inclusion of a winglet is found to significantly enhance lift generation. In addition to the study of bending effects on aerodynamic performance, the study also seeks to emulate a unique aspect of bat flight kinematics, specifically the dynamic variation in wing span length during flapping. In a comparative analysis of two span length variation strategies, it is discerned that exclusively varying span length during the upstroke phase is the optimal approach for achieving increased lift generation. The study highlights the crucial role of wing bending and span length modulation in achieving elevated lift forces while simultaneously reducing drag. These findings are seen as holding significant promise for the design and optimization of Micro Air Vehicles (MAVs) utilizing flapping-based lift generation mechanisms, contributing substantially to the identification of optimal parameters for enhancing MAVs’ aerodynamic performance and operational efficiency.

Rare earth regulatory defect engineering: A multifunctional nanoplatform for breast cancer therapy through PANoptosis

Photocatalytic therapy (PCT) is a minimally invasive technique that utilizes reactive oxygen species (ROS) to selectively and optically impair tumor cells. However, the limited efficacy of photocatalysts hinders their more comprehensive application. In this study, we successfully synthesized Ce and S-doped Bi2O3 (BOSC) nanosheets through topological synthesis. BOSC exhibits CAT-like and POD-like enzyme activities and can generate ROS and heat upon near-infrared light irradiation, thereby amplifying tumor oxidative stress. Introducing rare earth Ce element enhances light absorption, introduces oxygen vacancies, reduces bandgap, and facilitates charge separation. This Ce-doping also modifies the band position and Fermi level of BOSC, resulting in increased band bending at the solid–liquid interface, enabling a cascade reaction of ROS and enhancing ROS production. Additionally, BOSC demonstrates multiple enzyme activities by depleting GSH and catalyzing the production of ROS and O2 from endogenous H2O2, thereby exacerbating cellular oxidative damage. The synergistic effect of BOSC post-illumination induces panoptosis, thereby improving the therapeutic efficacy against tumors. This strategy, involving the modulation of band structure and band bending through ion doping to introduce oxygen defects into the photosensitizer, provides a viable approach to enhance tumor phototherapy.

Grating lobe-free silicon optical phased array with periodically bending modulation of dense antennas.

A grating lobe-free silicon optical phased array with large field of view is demonstrated. Antennas with periodically bending modulation are spaced at half wavelength or less. The experimental results show that the crosstalk between adjacent waveguides is negligible at 1550 nm wavelength. Additionally, to reduce the optical reflection caused by the sudden change of refractive index at the output antenna of the phased array, tapered antennas are added to the output end face so that more light will be coupled into the free space. The fabricated optical phased array shows a field of view of 120° without any grating lobes.

Influence of Wetting-Drying Cycles on Wood Behaviour of Coastal Pedestrian Walkways

In the context of inspection and maintenance actions for beach walkways in the North of Portugal, some samples of wood used in their construction were collected – the <em>Pinus</em> <em>sylvestris</em> wood, widely applied in the country. The sustainability of the beach walkways over natural coastal areas is very dependent on their material durability. One of the main problems of the timber used to build those structures is its behavior under wet-drying cycles. For that reason, this work aimed to simulate the effects of weathering on the long-term bending behavior of pinewood. Weathering slab samples with two decades of service life and new, unused slabs were subjected to wetting–drying cycles and tested between each wetting or drying phase. As the bending test characterizes one of the most representative efforts in pedestrian boardwalk slabs, the bending module of rupture was used as an indicator to characterize the resistance of timber. Thus, in this study, the samples' density, dimensional stability, and mechanical strength were determined at the end of each batch of cycle repetitions. The tests were carried out before and after a set of wetting-drying cycles caused by immersion in water and placement into an oven at 80°C to simulate environmental exposure. Thus, it was intended to simulate the use in service through the realization of successive wetting-drying cycles in a laboratory environment and to evaluate its influence on the density, dimensional stability, and mechanical strength of the pine wood tested. The extreme conditions used in the laboratory pretend to accelerate the degradation of samples and simulate, in a relatively short period, what would need years to occur in service. The results showed that the wood that had never been in service is more susceptible to bending resistance variations with cycles than the one already in service. Thus, after a few wet-drying cycles, the wood without any service life tends to approximate, in terms of bending behavior, to the one with two decades of service. This indicates that the method used could satisfy the need to obtain predictions for long-time behavior in a relatively short period.

Spatially‐Modulated Silicon Interface Energetics Via Hydrogen Plasma‐Assisted Atomic Layer Deposition of Ultrathin Alumina

AbstractAtomic layer deposition (ALD) is a key technique for the continued scaling of semiconductor devices, which increasingly relies on scalable processes for interface manipulation of structured surfaces on the atomic level. While ALD allows the synthesis of conformal films with utmost control over the thickness, atomically‐defined closed coatings and surface modifications are challenging to achieve because of 3D growth during nucleation. Here, a route is presented toward the sub‐nanometer thin and continuous aluminum oxide (AlOx) coatings on silicon substrates for the spatial control of the surface charge density and interface energetics. Trimethylaluminum in combination with remote hydrogen plasma is used instead of a gas‐phase oxidant for the transformation of silicon dioxide (SiO2) into alumina. Depending on the number of ALD cycles, the SiO2 can be partially or fully transformed, which is exploited to deposit ultrathin AlOx layers in selected regions defined by lithographic patterning. The resulting patterned surfaces are characterized by lateral AlOx/SiO2 interfaces possessing 0.3 nm step heights and surface potential steps exceeding 0.4 V. In addition, the introduction of fixed negative charges of 9 × 1012 cm−2 enables modulation of the surface band bending, which is relevant to the field‐effect passivation of silicon and low‐impedance charge transfer across contact interfaces.

A soft pneumatic glove with multiple rehabilitation postures and assisted grasping modes

This article proposes a novel soft pneumatic glove with multiple rehabilitation postures and assisted grasping modes, which is composed of five segmented pneumatic networks (PneuNets) bidirectional bending actuators with a variable height structure. The metacarpophalangeal (MCP) joint chambers and the distal phalangeal (DIP) joint chambers are designed with a trapezoidal side profile, which enhances the reverse bending ability and can effectively expand the range of hand rehabilitation activities. In order to avoid hindering the forward bending, the chambers of the reverse bending module are designed as a triangular prism chamber. Experimental tests were performed and the results show that the soft actuator can produce a bending angle of 261° under an air pressure of 100 kPa, and can produce a fingertip force of 1.59 N under an air pressure of 130 kPa. In the rehabilitation mode, the designed soft rehabilitation gloves can help the hand to form four kinds of rehabilitation postures, namely full fist, straight fist, hook fist and table top. By ventilating different finger joints, and it can also help the fingers to stretch. Under the initial air pressure of 60 kPa, the design of the reverse bending module can increase the fingertip force of reverse bending by 40 %. In the assisted grasping mode, by adjusting the input air pressure, it can help the hand to grasp objects with cylindrical and large plane contour, which is very useful for the rehabilitation of patients with partial loss of hand function. • A novel soft pneumatic glove with multiple rehabilitation postures and assisted grasping modes is proposed. • The soft glove is composed of five PneuNets bidirectional bending actuators with a variable height structure. • The soft actuator can produce a angle of 261° under pressure of 100 kPa, and a force of 1.59 N under pressure of 130 kPa.

Contact property depending on radiation intensity between the perovskite semiconductor layer and electrode film

Hybrid organic–inorganic perovskites have been widely studied in high-performance optoelectronic devices. Long-term stability is a key limitation to date in restricting their further development and commercial application. In general, interface properties between a semiconductor and an electrode highly affect device performance and stability. Herein, contact characteristics between the perovskite and electrode varying with illumination status have been first investigated. The results suggest that device's contact resistance (RC), obtained from a transfer length method, decreases as the incident light intensity increases. The RC under a higher irradiation intensity (1.26 mW/cm2) is about one-tenth of that at a lower density (0.08 mW/cm2). Simulation has been performed and shows a similar trend with experimental results. The interface physical model has been discussed based on an energy band theory. The band bending and barrier modulation at the interface under light illumination are originated from the surface states and the localized charges. This work explains the interface in determining device's fundamental properties, including stability, RC variation, and charge carrier transport process. It is significant in understanding the device working mechanism and providing a potential way for perovskite optoelectronic devices with enhanced stability and performance.

Dispersionless Coupling among Optical Waveguides by Artificial Gauge Field

Coupling among closely packed waveguides is a common optical phenomenon, and plays an important role in optical routing and integration. Unfortunately, this coupling property is usually sensitive to the working wavelength and structure features that hinder the broadband and robust functions. Here, we report a new strategy utilizing an artificial gauge field (AGF) to engineer the coupling dispersion and realize a dispersionless coupling among waveguides with periodically bending modulation. The AGF-induced dispersionless coupling is experimentally verified in a silicon waveguide platform, which already has well-established broadband and robust routing functions (directional coupling and splitting), suggesting potential applications in integrated photonics. As examples, we further demonstrate a three-level-cascaded AGF waveguide network to route broadband light to desired ports with an overwhelming advantage over the conventional ones in comparison. Our method provides a new route of coupling dispersion control by AGF and benefits applications that fundamentally rely on waveguide coupling.

Modulation of the Band Bending of CdS by Fluorination to Facilitate Photoinduced Electron Transfer for Efficient H2 Evolution over Pt/CdS

The potential barrier (Schottky barrier), embodied in the upward band bending of an n-type semiconductor at the interface of a Pt-loaded semiconductor, often makes it difficult for the interfacial photoinduced electron transfer from the conduction band of the semiconductor to the loaded Pt, giving rise to the recombination probability of the photogenerated charges. In this work, we prepared fluorinated CdS by a facile hydrothermal process in the presence of NH4F. With the assistance of the noble metal Pt, the fluorinated CdS exhibits a superior photocatalytic H2 evolution to pristine CdS. Various characterization results revealed that the incorporation of the fluorine anions into the CdS lattice by fluorination apparently lowers the Fermi level to weaken the upward band bending of CdS at the Pt/CdS interface, favoring the interfacial photoinduced electron transfer from the conduction band of CdS to the loaded Pt for an efficient H2 evolution. This work highlights the role of weakening the potential barrier at the Pt/CdS interface in promoting the interfacial photoinduced electron transfer for efficient H2 evolution.

Development of Flexible Deformation Mobile Robot Composed of Multiple Units and Pneumatic Self-Excited Valve

In this study, we developed new bending modules and pneumatic self-excited valves. In a previous study, we developed a planar flexible-deformation mobile robot that combines multiple bending modules. The robot moves by a traveling wave, which is periodically generated by pressurizing air to the bending modules. Further, it can move in every direction by simultaneously combining the two directional traveling waves. However, problems such as air leakage from the bending module that constitutes the moving object and the influence of the moving operation owing to the tubes comprising the flow path were identified. To address these problems, new bending modules have been developed. To address air leak issues, we verified the materials used in the bending modules and developed an injection mechanism. To reduce the number of externally connected tubes, we developed new bending modules that could include multiple internal flow paths. In addition, because the mobile robot moves owing to the generation of traveling waves, it is a low-grade operation. However, this requires multiple solenoid valves and electronic circuits. This is useful if traveling waves can be generated by simply supplying air using a pneumatic self-excited valve. In this study, we developed bending modules with multiple internal channels and a pneumatic self-excited valve that utilizes the snap buckling of leaf springs used in the mobile robot.

Dynamic Finite Element Modeling and Simulation of Soft Robots

Soft robots have become important members of the robot community with many potential applications owing to their unique flexibility and security embedded at the material level. An increasing number of researchers are interested in their designing, manufacturing, modeling, and control. However, the dynamic simulation of soft robots is difficult owing to their infinite degrees of freedom and nonlinear characteristics that are associated with soft materials and flexible geometric structures. In this study, a novel multi-flexible body dynamic modeling and simulation technique is introduced for soft robots. Various actuators for soft robots are modeled in a virtual environment, including soft cable-driven, spring actuation, and pneumatic driving. A pneumatic driving simulation was demonstrated by the bending modules with different materials. A cable-driven soft robot arm prototype and a cylindrical soft module actuated by shape memory alley springs inspired by an octopus were manufactured and used to validate the simulation model, and the experimental results demonstrated adequate accuracy. The proposed technique can be widely applied for the modeling and dynamic simulation of other soft robots, including hybrid actuated robots and rigid-flexible coupling robots. This study also provides a fundamental framework for simulating soft mobile robots and soft manipulators in contact with the environment.

Experimental research on a novel spring-shaped fiber-optic displacement sensor for settlement monitoring

In this paper an innovative spring-shaped fiber-optic displacement sensor (SSFODS) based on optical time domain reflectometer (OTDR) technology with simple construction and cheap cost was proposed for subgrade settlement monitoring. The sensor incorporated a simple spring-shaped fiber bending modulation that increased its sensitivity in bending, light source and detector. The sensing principle between the measured external displacement and bending loss of optical fiber was theoretically explained and its expression was also derived. Sensor calibration was conducted, which showed that the SSFODS was characterized by a large measurement range of 90 mm, minimum displacement resolution of 0.173 mm, maximum hysteresis error of 2.81% and maximum repeatability error of 8.42%, respectively. A soil drainage model test with the SSFODS was performed to study its performance in determining compression deformation of the soil. At last, a simple field monitoring application with two SSFODSs connected in series was conducted and the progressive compaction behavior of the fill slope was accurately captured by two SSFODSs. Additionally, it is possible to connect these SSFODSs in series on one optical link to realize quasi-distributed sensing monitoring. This capability supports a promising application of the sensor in geotechnical engineering for real-time monitoring of the stability of fill slopes, foundation pits and so on.

Ultrafast Digital Fabrication of Designable Architectured Liquid Crystalline Elastomer.

The muscle-like activities of liquid crystalline elastomers (LCEs) offer great potential for designing future soft machines. Their motion complexity, however, relies on inflexible and cumbersome mesogen alignment techniques. Here, a digital photocuring method for ultrafast template-free fabrication of LCE artificial muscles capable of designable complex motions is reported. This method utilizes the intrinsic light attenuation in the through-plane direction to create mesogen alignment for reversible bending action. To turn this simple actuation into complex motions, the principles of muscles are borrowed which realize diverse motions through the cooperative actions of otherwise simple contraction/expansion of individual muscle bundles. Specifically, the spatiotemporal digital light is utilized to design LCE architectures composed of strategically arranged bending modules. As such, LCE capable of highly designable motions can be fabricated within 25 s light curing without employing any physical alignment templates, which offers an attractive option toward designing functionally diverse soft machines.

Research on performance of rigid-hoop-reinforced multi-DOF soft actuator

In order to improve the bearing capacity of soft actuators, this article presents the development of the rigid-hoop-reinforced (spring or steel hoop) multi-DOF soft actuator. The actuator is composed of a rotary module with spring reinforcement on the silicone rubber-based body and a bending module with steel hoop reinforcement on the body. Compared with fiber-reinforced actuators, the bearing capacities of rigid-hoop-reinforced actuators made of 65Mn spring steel are improved. The radial and the axial bearing capacity for the bending module and the rotary module is raised by 29.6%, 28.2%, 30.6%, 49.6% respectively; under the same pressure, the spring-reinforced interval increases the maximum rotary angle of the rotary module, the steel hoop-reinforced interval increases the maximum bending angle of the bending module; with the same reinforcement type, the bending module with reinforcement interval of 10 mm has good bending characteristics that the bending angle changes with the pressure gently; the lower the hardness of silicone rubber base body, the better the adaptability and flexibility of the actuator, and the higher the hardness, the greater the bearing capacity of the actuator. Due to the above advantages, the rigid-hoop-reinforced multi-DOF soft actuator can be applied to medical devices which need high load-carrying capacity.

Development of a Multi-Cable-Driven Continuum Robot Controlled by Parallel Platforms

Abstract Cable-driven continuum robots exhibit excellent capabilities in the unstructured environment due to their inherent compliance and dexterity. To improve the reliability and load capacity of continuum robots, increasing the number of cables is often used in the control of continuum robots. However, the number of actuators will increase with the cables. To tackle this challenge, this work proposes a method for increasing the number of cables without increasing actuators in a continuum robot through parallel platforms. The parallel platforms are used to control all the cables in the continuum robot and can be separated from the continuum robot to enable the remote drive of a manipulation arm by using the cable-tube structure. The manipulation arm is composed of several independent bending modules in series, which can be configured freely according to the demand of degrees-of-freedom. Further, each bending module is controlled independently by a parallel platform, which can avoid the mutual interference between the cables of one bending module and another one, improve the position accuracy and simplify the control difficulty of the manipulation arm. To evaluate the proposed method, this work develops a prototype of six-cable-driven continuum robot controlled by 3RPS parallel platforms and presents some basic kinematic models to describe its function, and then an experimental work characterizing its performance. Experimental results illustrated the importance of increasing the number of cables, the rationality of kinematic models of the continuum robot, and the feasibility of controlling multiple cables by a parallel platform.

Fiber-optic rudder position sensor for unmanned vessels

The paper presents the results of a study on the design of the rudder position sensor of a steering vessel, in which an optic fiber is a sensitive element and a data transmission line. A design of a sensitive element based on the effect of bending modulation of light transmission of an optic fiber is proposed, and a mathematical expression is obtained in ray equivalence, which describes the behavior of the sensitive element. The prototypes of the sensitive element and the laboratory setup have been developed, numerical modeling has been carried out, and experimental results have been obtained showing the potential use of the proposed approach for this class of problems.