Magnet Assembly Research Articles

Transforming Static Barrier Tissue Models into Dynamic Microphysiological Systems.

Microphysiological systems are miniaturized cell culture platforms used to mimic the structure and function of human tissues in a laboratory setting. However, these platforms have not gained widespread adoption in bioscience laboratories where open-well, membrane-based approaches serve as the gold standard for mimicking tissue barriers, despite lacking fluid flow capabilities. This issue can be primarily attributed to the incompatibility of existing microphysiological systems with standard protocols and tools developed for open-well systems. Here, we present a protocol for creating a reconfigurable membrane-based platform with an open-well structure, flow enhancement capability, and compatibility with conventional protocols. This system utilizes a magnetic assembly approach that enables reversible switching between open-well and microfluidic modes. With this approach, users have the flexibility to begin an experiment in the open-well format using standard protocols and add or remove flow capabilities as needed. To demonstrate the practical usage of this system and its compatibility with standard techniques, an endothelial cell monolayer was established in an open-well format. The system was reconfigured to introduce fluid flow and then switched to the open-well format to conduct immunostaining and RNA extraction. Due to its compatibility with conventional open-well protocols and flow enhancement capability, this reconfigurable design is expected to be adopted by both engineering and bioscience laboratories.

Magnetic Assembly of Eu-Doped NaYF4 Nanorods for Field-Responsive Linearly and Circularly Polarized Luminescence.

Colloidal assembly has emerged as an effective avenue for achieving polarized light emission. Here, we showcase the efficacy and versatility of the magnetic colloidal assembly in enabling both linearly and circularly polarized luminescence. Colloidal europium-doped NaYF4 nanorods with surface-bound Fe3O4 nanoparticles are magnetically assembled into linear or chiral superstructures using corresponding fields created in permanent magnets. In a uniform magnetic field generated by opposing poles, the assemblies exhibit photoluminescence with intensity tunable in response to the magnetic field direction, which is higher when the nanorods are perpendicular to light propagation than when they are parallel. The obtained superstructures display strong linearly polarized luminescence when the nanorods are aligned vertically, exhibiting a high degree of polarization up to 0.61. In a quadrupole chiral field generated by permanent magnets, the assemblies emit left-handed or right-handed polarized light depending on the position of the sample placement, attaining a g-factor of 0.04. Furthermore, the superstructures immobilized in a hydrogel film are found to retain their chirality, exhibiting opposite chiroptical responses depending on the sample orientation. The magnetic colloidal assembly approach facilitates the convenient and efficient generation of polarized light emissions from nonmagnetic luminescent materials, thus creating opportunities for tailoring light behavior in developing innovative optoelectronic devices.

Magnetic assembly of plasmonic chiral superstructures with dynamic chiroptical responses.

Plasmonic nanostructures exhibiting dynamically tunable chiroptical responses hold great promise for broad applications such as sensing, catalysis, and enantioselective analysis. Despite the successful fabrication of chiral structures through diverse templates, creating dynamic chiroptical materials with fast and reversible responses to external stimuli is still challenging. This work showcases reversible magnetic assembly and active tuning of plasmonic chiral superstructures by introducing a chiral magnetic field from a cubic permanent magnet. Manipulating the strength and direction of the magnetic field controls both the chiral arrangement and plasmonic coupling of the nanoparticle assembly, enabling fast and reversible tunability in not only the handedness of the superstructures but also the spectral characteristics of their chiroptical properties. The dynamic tunability further enables the fabrication of color-changing optical devices based on the optical rotatory dispersion effect, showcasing their potential for application in anti-counterfeiting and stress sensors.

A force-neutral adjustable phase undulator for a compact x-ray FEL

The magnetic and mechanical designs of a force-neutral adjustable phase undulator (FNAPU) are presented. The FNAPU combines two magnetic assemblies with equal periods, one with an undulator magnetic structure and one with a force compensation magnet structure. The latter is used to neutralize the magnetic force affecting the undulator magnetic structure and vice versa in all undulator phases. Assembling in proximity a group of different FNAPUs is discussed.

Five-Meter Nonmagnetic Telescopic Tubular Mast: Design, Test, and On-Orbit Application

Space deployable masts, as one of the most widely used branches of space deployable structures, can provide driving, positioning, and transmission functions for spacecraft in orbit, which are irreplaceable in complex space activities. The nonmagnetic telescopic tubular mast (NMTTM) is designed and manufactured by the Shenyang Institute of Automation, Chinese Academy of Sciences, aboard the SATech-01 satellite to keep the magnetic probe assembly away from magnetic interference and realize global magnetic field measurement. The NMTTM can withstand complicated vibration and shock during rocket launching in the retracted state of 0.95 m, while it can be stably released and deployed to 5.28 m in orbit. NMTTM was successfully launched into Sun-synchronous orbit on 27 July 2022, fully deployed, and generated the positioning signal after a duration of 19 min and 16 s for the deployment process on 7 November. This paper focuses on the whole process of NMTTM from mission requirements to structure design and manufacture, through to releasing, deployment, and locking technology, environmental simulation tests, up to on-orbit deployment verification, which provides valuable experience for the subsequent development and application of large-scale space deployable masts.

Optimization of Solenoid Parameters for a Magnetic Nozzle Assembly Using Design of Experiments

Optimization of Solenoid Parameters for a Magnetic Nozzle Assembly Using Design of Experiments

Optimal Magnet Assembly for Error Field Reduction

Optimal Magnet Assembly for Error Field Reduction

Efficient Preparation of Homogeneous Chromogenic Glucose-responsive Photonic Crystal Gels by Magnetic Assembly Method

Efficient Preparation of Homogeneous Chromogenic Glucose-responsive Photonic Crystal Gels by Magnetic Assembly Method

Multienzymatic disintegration of DNA-scaffolded magnetic nanoparticle assembly for malarial mitochondrial DNA detection

Early diagnosis of malaria can prevent the spread of disease and save lives, which, however, remains challenging in remote and less developed regions. Here we report a portable and low-cost optomagnetic biosensor for rapid amplification and detection of malarial mitochondrial DNA. Bioresponsive magnetic nanoparticle assemblies are constructed by using nucleic acid scaffolds containing endonucleolytic DNAzymes and their substrates, which can be activated by the presence of target DNA and self-disintegrated to release magnetic nanoparticles for optomagnetic quantification. Specifically, target molecules can induce padlock probe ligation and subsequent one-pot homogeneous cascade reactions consisting of nicking-enhanced rolling circle amplification, DNAzyme-assisted nucleic acid recycling, and strand-displacement-driven disintegration of the magnetic assembly. With an optimized magnetic actuation process for reaction acceleration, a detection limit of 1 fM can be achieved by the proposed biosensor with a total assay time of ca. 90 min and a dynamic detection range spanning 3 orders of magnitude. The robustness of the system was validated by testing target molecules spiked in 5% serum samples. Clinical sample validation was conducted by testing malaria-positive clinical blood specimens, obtaining quantitative results concordant with qPCR measurements.

Electrodeposition of Multi-Segment Nanowires and Site-Selective Solder Deposition for Magnetic Assembly and Nanoscale Joining

Electronic device packaging involves complex wiring assemblies for transport of electrical and thermal energy, enabling increasingly sophisticated circuit designs in an industry favoring aggressive device miniaturization. Nanoscale miniaturization of the wire morphology has become increasingly sophisticated in recent years with regards to synthesis; however, the ability to arrange and manufacture these small-scale materials to fully exploit their novel properties has been quickly outpaced. The purpose of this investigation is the establishment of a synthesis technique for a core/shell nanowire structure with tunable compositional templating via electrodeposition which can pass through this bottleneck via directed matrix assembly. A gold-nickel-gold nanowire structure was utilized as the core, synthesized via electrochemical deposition into an anodic aluminum oxide (AAO) template; the nickel segment was chosen to act as a magnetic vehicle for directed assembly, while the bordering gold tips were coated with a solder shell. Gold-selective deposition of this tin solder shell was achieved by establishing a chemisorbed nickel-protective monolayer via immersion in azelaic acid solution. Next, the protected nanowires were dispersed in an aqueous reaction vessel with excess sodium borohydride reducing agent. Controlled addition of tin sulfate and sodium dodecyl sulfate solution to the vessel resulted in the formation of tin seeds which deposited along the gold tips of the nanowires, growing into a “dumbbell” shape nanowire with tin deposited on both gold tips. Composition and confirmation of the solder deposition was performed with scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopic (EDS) analysis. Crystal structure of the core/shell nanowires was performed with x-ray diffraction (XRD) to identify intermetallic formation between the tin and gold. The core/shell nanowires were arranged magnetically across a conductive interdigitated electrode and melted by an infrared-driven reflow procedure under flux atmosphere, establishing ohmic contact tip-to-tip between nanowires and in wire-to-pad morphologies. This work establishes an effective and scalable method for site-specific nanowire functionalization while simultaneously addressing miniaturization-associated assembly issues in its desired applications.

Effect of dipolar interaction on magnetic properties of magnetite nanoparticles system: a simulation study

Superparamagnetic iron oxide nanoparticles are a potential candidate for novel research. The inter-particle interactions play a significant role in determining the overall magnetic behavior of a magnetic nanoparticle assembly, especially in dipolar interaction. In this paper, we have synthesized a practical sample and then applied an atomistic spin model simulation study with input parameters obtained from experimental measurements to investigate the influence of the dipolar interaction on the magnetic properties of Fe3O4 magnetite nanoparticles.

Computation of the Strain Induced Critical Current Reduction in the 16 T Nb3Sn Test Facility Dipole

A test facility dipole is being developed at LBNL, targeting a 16 T field in a 144 mm wide aperture. The magnet uses a block design, with two double-pancake coils. In order to minimize motion under the large Lorentz forces, the coils are preloaded against a thick aluminum shell and iron yoke using bladder and key technology. It is then crucial to verify that the performance of the magnet is not degraded due to strain induced on the Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn conductor during assembly, cool-down and powering. The critical current of extracted strands was measured in a varying background magnetic field and as a function of the applied longitudinal strain. Finite element analysis was used to extract the strain state inside the superconducting strands during magnet assembly and operation. This strain was then compared to the measurements to evaluate potential reversible and irreversible effects on the magnet performances. The results suggest that the magnet can reach 16 T with sufficient margin, with no irreversible degradation in the high field region.

Status of the MQXFB Nb3Sn Quadrupoles for the HL-LHC

The cold powering test of the first two prototypes of the MQXFB quadrupoles (MQXFBP1, now disassembled, and MQXFBP2), the Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn inner triplet magnets to be installed in the HL-LHC, has validated many features of the design, such as field quality and quench protection, but has found performance limitations. In fact, both magnets showed a similar phenomenology, characterized by reproducible quenches in the straight part inner layer pole turn, with absence of training and limiting the performance at 93% (MQXFBP1) and 98% (MQXFBP2) of the nominal current at 1.9 K, required for HL-LHC operation at 7 TeV. Microstructural inspections of the quenching section of the limiting coil in MQXFBP1 have identified fractured Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn sub-elements in strands located at one specific position of the inner layer pole turn, allowing to determine the precise origin of the performance limitation. In this paper we outline the strategy that has been defined to address the possible sources of performance limitation, namely coil manufacturing, magnet assembly and integration in the cold mass.

Reconfigurable Magnetic Liquid Building Blocks for Constructing Artificial Spinal Column Tissues.

All-liquid molding can be used to transform a liquid into free-form solid constructs, while maintaining internal fluidity. Traditional biological scaffolds, such as cured pre-gels, are normally processed in solid state, sacrificing flowability and permeability. However, it is essential to maintain the fluidity of the scaffold to truly mimic the complexity and heterogeneity of natural human tissues. Here, this work molds an aqueous biomaterial ink into liquid building blocks with rigid shapes while preserving internal fluidity. The molded ink blocks for bone-like vertebrae and cartilaginous-intervertebral-disc shapes, are magnetically manipulated to assemble into hierarchical structures as a scaffold for subsequent spinal column tissue growth. It is also possible to join separate ink blocks by interfacial coalescence, different from bridging solid blocks by interfacial fixation. Generally, aqueous biomaterial inks are molded into shapes with high fidelity by the interfacial jamming of alginate surfactants. The molded liquid blocks can be reconfigured using induced magnetic dipoles, that dictated the magnetic assembly behavior of liquid blocks. The implanted spinal column tissue exhibits a biocompatibility based on in vitro seeding and in vivo cultivating results, showing potential physiological function such as bending of the spinal column.

Fingerprints of super spin-glass state in two-dimensional nanoscopic system

Novel two-dimensional magnetic assembly was designed, manufactured, and its static and dynamic magnetic response was investigated. The assembly contains Fe3O4 nanoparticles of nominal size 7 nm which were deposited on plasma-treated polypropylene substrate using a grafting technique. The nanoparticles create agglomerates with size distribution ranging nominally from 10 nm to 110 nm. The temperature dependence of zero-field and field-cooled susceptibility is consistent with glassy behavior. The relative shift of maximum in alternating susceptibility Γ ≈ 0.075 and zυ = 10 obtained from critical slowing down analysis also support the formation of the collective states akin to super spin-glass. However, the absence of collapse in dynamic scaling of alternating susceptibility data using predictions for three-dimensional spin-glass with Gaussian distribution of magnetic coupling and two-dimensional bimodal spin-glass suggests that the studied system is not representative of the used limiting models. The investigation of memory effects revealed the coexistence of relaxation phenomena of collective degrees of freedom and individual nanoparticles. The obtained results suggest that the studied assembly is appropriate for the investigation of super spin-glass state in two-dimensional magnetic system with dominant dipolar interaction.

A magnetic assembly approach to chiral superstructures

Colloidal assembly into chiral superstructures is usually accomplished with templating or lithographic patterning methods that are only applicable to materials with specific compositions and morphologies over narrow size ranges. Here, chiral superstructures can be rapidly formed by magnetically assembling materials of any chemical compositions at all scales, from molecules to nano- and microstructures. We show that a quadrupole field chirality is generated by permanent magnets caused by consistent field rotation in space. Applying the chiral field to magnetic nanoparticles produces long-range chiral superstructures controlled by field strength at the samples and orientation of the magnets. Transferring the chirality to any achiral molecules is enabled by incorporating guest molecules such as metals, polymers, oxides, semiconductors, dyes, and fluorophores into the magnetic nanostructures.

Rugged Forest Morphology of Magnetoplasmonic Nanorods that Collect Maximum Light for Photoelectrochemical Water Splitting.

A feasible nanoscale framework of heterogeneous plasmonic materials and proper surface engineering can enhance photoelectrochemical (PEC) water-splitting performance owing to increased light absorbance, efficient bulk carrier transport, and interfacial charge transfer. This article introduces a new magnetoplasmonic (MagPlas) Ni-doped Au@Fex Oy nanorods (NRs) based material as a novel photoanode for PEC water-splitting. A two stage procedure produces core-shell Ni/Au@Fex Oy MagPlas NRs. The first-step is a one-pot solvothermal synthesis of Au@Fex Oy . The hollow Fex Oy nanotubes (NTs) are a hybrid of Fe2 O3 and Fe3 O4 , and the second-step is a sequential hydrothermal treatment for Ni doping. Then, a transverse magnetic field-induced assembly is adopted to decorate Ni/Au@Fex Oy on FTO glass to be an artificially roughened morphologic surface called a rugged forest, allowing more light absorption and active electrochemical sites. Then, to characterize its optical and surface properties, COMSOL Multiphysics simulations are carried out. The core-shell Ni/Au@Fex Oy MagPlas NRs increase photoanode interface charge transfer to 2.73 mAcm-2 at 1.23V RHE. This improvement is made possible by the rugged morphology of the NRs, which provide more active sites and oxygen vacancies as the hole transfer medium. The recent finding may provide light on plasmonic photocatalytic hybrids and surface morphology for effective PEC photoanodes.

Magnetically Induced Anisotropic Interaction in Colloidal Assembly.

The wide accessibility to nanostructures with high uniformity and controllable sizes and morphologies provides great opportunities for creating complex superstructures with unique functionalities. Employing anisotropic nanostructures as the building blocks significantly enriches the superstructural phases, while their orientational control for obtaining long-range orders has remained a significant challenge. One solution is to introduce magnetic components into the anisotropic nanostructures to enable precise control of their orientations and positions in the superstructures by manipulating magnetic interactions. Recognizing the importance of magnetic anisotropy in colloidal assembly, we provide here an overview of magnetic field-guided self-assembly of magnetic nanoparticles with typical anisotropic shapes, including rods, cubes, plates, and peanuts. The Review starts with discussing the magnetic energy of nanoparticles, appreciating the vital roles of magneto-crystalline and shape anisotropies in determining the easy magnetization direction of the anisotropic nanostructures. It then introduces superstructures assembled from various magnetic building blocks and summarizes their unique properties and intriguing applications. It concludes with a discussion of remaining challenges and an outlook of future research opportunities that the magnetic assembly strategy may offer for colloidal assembly.

An analytical method and practical verification for evaluating the undulator performance

The mechanical performance of an undulator has a significant effect on the on-axis magnetic field and thus a directly affect the performance of photon flux and stable operation in a storage ring. During the phase of mechanical design and construction, it becomes important to develop a method to evaluate the effects of magnetic fields caused by mechanical properties. This paper reveals a method to predict the distribution of a magnetic field utilizing the practice that mechanical performance combined with an ideal magnet assembly enables identification whether the magnet array structure is satisfactory. Moreover, the systematic errors expected from the mechanical inspection can be confirmed in the magnetic field measurement data. This scheme could be used to predict the systematic effects and then to apply effective remedies before the entire machine is completed.

Radial Magnetic Levitation and Its Application to Density Measurement, Separation, and Detection of Microplastics.

This work describes the development of radial magnetic levitation (MagLev) using two radially magnetized ring magnets to solve the problem of limited operational spaces in standard MagLev and the major shortcoming of a short working distance in axial MagLev. Interestingly and importantly, we demonstrate that for the same magnet size, this new configuration of MagLev doubles the working distance over the axial MagLev without significantly sacrificing the density measurement range, whether for linear or nonlinear analysis. Meanwhile, we develop a magnetic assembly method to fabricate the magnets for the radial MagLev, where multiple magnetic tiles with single-direction magnetization are used as assembly elements. On this basis, we experimentally demonstrate that the radial MagLev has good applicability in density-based measurement, separation, and detection and show its advantages in improving separation performance compared with the axial MagLev. The open structure of two-ring magnets and good levitation characteristics make the radial MagLev have great application potential, and the performance improvement brought by adjusting the magnetization direction of magnets provides a new perspective for the magnet design in the field of MagLev.