Magnetic Field Manipulation Research Articles

Multifunctional Magnetic Muscles for Soft Robotics

Despite recent advancements, artificial muscles have not yet been able to strike the right balance between exceptional mechanical properties and dexterous actuation abilities that are found in biological systems. Here, we present an artificial magnetic muscle that exhibits multiple remarkable mechanical properties and demonstrates comprehensive actuating performance, surpassing those of biological muscles. This artificial muscle utilizes a composite configuration, integrating a phase-change polymer and ferromagnetic particles, enabling active control over mechanical properties and complex actuating motions through remote laser heating and magnetic field manipulation. Consequently, the magnetic composite muscle can dynamically adjust its stiffness as needed, achieving a switching ratio exceeding 2.7 × 10³. This remarkable adaptability facilitates substantial load-bearing capacity, with specific load capacities of up to 1000 and 3690 for tensile and compressive stresses, respectively. Moreover, it demonstrates reversible extension, contraction, bending, and twisting, with stretchability exceeding 800%. We leverage these distinctive attributes to showcase the versatility of this composite muscle as a soft continuum robotic manipulator. It adeptly executes various programmable responses and performs complex tasks while minimizing mechanical vibrations. Furthermore, we demonstrate that this composite muscle excels across multiple mechanical and actuation aspects compared to existing actuators.

Quantum computation with electrons trapped on liquid Helium by using the centimeter-wave manipulating techniques

Surface-state electrons floating on liquid Helium have been served as one of the great potential experimental platforms to implement quantum computation, wherein the qubits are usually encoded by either the lowest two levels of the vertical vibrations (i.e., Hydrogen-like atoms) or the electronic spins. Given the relevant operations require additional techniques, such as the corresponding millimeter-wave or magnetic field manipulations, here we investigate how to implement the scalable quantum computation with a trapped electron array by alternatively using the usual centimeter-wave manipulating techniques. This is because the eigenfrequency of the present qubit, encoded by the two lowest levels of the lateral vibration of the trapped electron, is limited in the centimeter-wave band. We show that, by biasing the electrodes properly and driving the coplanar waveguide transmission line resonator, the electrons can be individually trapped in a series of anharmonic potentials on liquid Helium. Therefore, the well-developed circuit quantum electrodynamics technique for the implementation of superconducting quantum computation can be conveniently utilized here in the present quantum computing platform (proposed firstly in Phys Rev Lett 105:040503, 2010, to implement the fundamental logic gates, typically such as the single-qubit rotations of the individually addressable trapped electrons, the switchable two-qubit manipulations between the electrons trapped in the distant traps, and also the high-fidelity readouts of the target qubits. The feasibility of the proposal is also discussed by numerical simulations.

Robust parahydrogen-induced polarization at high concentrations.

Parahydrogen-induced polarization (PHIP) is a potent technique for generating target molecules with high nuclear spin polarization. The PHIP process involves a chemical reaction between parahydrogen and a target molecule, followed by the transformation of nuclear singlet spin order into magnetization of a designated target nucleus through magnetic field manipulations. Although the singlet-to-magnetization polarization transfer process works effectively at moderate concentrations, it is observed to become much less efficient at high molar polarization, defined as the product of polarization and concentration. This strong dependence on the molar polarization is attributed to interference due to the field produced by the sample magnetization during polarization transfer, which leads to complex dynamics and can severely affect the scalability of the technique. We address this challenge with a pulse sequence that suppresses the influence of the distant dipolar field, while simultaneously achieving singlet-to-magnetization polarization transfer to the desired target spins, free from restrictions on the molar polarization.

A setup for synchrotron infrared microspectroscopy and imaging under magnetic field and low temperature.

Infrared spectroscopy is a powerful spectroscopic technique for investigating the vibrational and electronic states of matter. Temperature and magnetic field provide important methods to manipulate these states by an external field. Recent advancements have underscored the necessity for investigating small samples like two-dimensional materials with high spatial resolution. In this article, we introduce a versatile setup at the synchrotron infrared beamline, which combines synchrotron infrared microspectroscopy and imaging techniques with the application of magnetic fields and low temperature conditions. This setup facilitates infrared microscopic imaging in magnetic fields up to 8T and temperatures as low as 5K, offering a distinctive tool for probing the physical properties of materials under magnetic field and temperature manipulation. This is particularly relevant for studying two-dimensional materials, single cells, and other small samples in geoscience and environmental science, as well as multi-component heterogeneous properties in quantum materials, polymer materials, energy materials, etc.

Magoctopus: Bio-inspired small-scale magnetic soft octopus with programmable shape morphing and motions

Microscale magnetic soft robots, with their tetherless propulsion capability, non-invasive interaction with the environment, and high adaptability to confined and unstructured spaces, hold tremendous promise in the field of biomedicine. These robots can navigate flexibly within narrow internal environments, such as blood vessels and organs, under remote magnetic field manipulation. However, the lack grasping capabilities in most existing microscale magnetic soft robots, has restricted their utility in medical applications. Inspired by the movement and predatory behavior of octopuses in the ocean, we have developed a microscale biomimetic magnetic octopus (Magoctopus), capable of mimicking biological functions such as movement and object grasping in liquid environments. The Magoctopus, with a total length of 17.30 mm and weight of 0.24 g, features a polystyrene head and six tentacles made of VHB (Very hard bond) material embedded with SmFeN powder for magnetic programming. By utilizing horizontally alternating magnetic fields, the six tentacles of Magoctopus can exhibit pre-programmed bending deformations to mimic the motion patterns of octopus tentacles. Furthermore, the Magoctopus has demonstrated capabilities in cargo delivery, targeted drug delivery, and other potential application, making it suitable for transportation within complex environments, biomedical applications, and beyond.

Mechanism and Study on Ball End Magnetorheological Fluid Finishing Process

The primary object of this research is to explore the capacities of BEMRF. Traditional polishing methods for glass commonly face challenges in reaching nanoscale precision and uniformity. In BEMRF, by controlling rheological properties of the MR fluid, we can tackle these challenges and potentially surpass the limitations of conventional techniques. The study includes the application of magnetorheological (MR) fluid with suspended magnetic particle abrasives to accomplish precision finishing by the manipulation of magnetic fields.

Topological excitation of exciton-polariton half-vortices and skyrmions in a magnetic field with TE-TM splitting

We explore the topological generation of skyrmions and half-vortices in a uniform spinor exciton-polariton condensate featuring TE-TM splitting and exposed to an external magnetic field. The manipulation of pump intensity and magnetic field enables precise control over the spin texture and integrated winding number. Specifically, under an excitation condition where the power applied to the vortex state surpasses that on the non-vortex state by an amount dictated by the magnetic field, skyrmions emerge. These skyrmions exhibit a distinctive spin texture characterized by a circular polarization inversion extending from the center to the periphery. Conversely, reversing the excitation condition, where the power on the vortex state is diminished with the reversal of the magnetic field direction, leads to the creation of half-vortices across the entire condensate, devoid of any circular polarization inversion. In additional to the skyrmions and half-vortices, half-skyrmions can be also generated in the same configuration without magnetic field.

Dynamics of induced optical torque via optical vortex light

This paper investigates the dynamics of induced torque in Nitrogen-Vacancy (NV) centers interacting with two weak optical vortex beams as well as a strong control field, exploring the impact of different system parameters such as control field intensity, detuning, magnetic field, and vortex beam strength. We find a dispersive torque behavior, indicating the sensitivity of NV centers to control parameters. Magnetic field induces level splitting, leading to a transformative effect on torque, with notable enhancements observed at specific intensities. Additionally, non-resonant torque is explored, demonstrating the controllability of torque peaks through magnetic field manipulation. Unequal strengths of vortex beams is found to yield substantial enhancements in torque. These results provide crucial insights into the induced torque dynamics in NV centers, presenting opportunities for optimized torque-based applications in quantum systems.

Importance of magnetic information for neuronal plasticity in desert ants

Many animal species rely on the Earth's magnetic field during navigation, but where in the brain magnetic information is processed is still unknown. To unravel this, we manipulated the natural magnetic field at the nest entrance of Cataglyphis desert ants and investigated how this affects relevant brain regions during early compass calibration. We found that manipulating the Earth's magnetic field has profound effects on neuronal plasticity in two sensory integration centers. Magnetic field manipulations interfere with a typical look-back behavior during learning walks of naive ants. Most importantly, structural analyses in the ants' neuronal compass (central complex) and memory centers (mushroom bodies) demonstrate that magnetic information affects neuronal plasticity during early visual learning. This suggests that magnetic information does not only serve as a compass cue for navigation but also as a global reference system crucial for spatial memory formation. We propose a neural circuit for integration of magnetic information into visual guidance networks in the ant brain. Taken together, our results provide an insight into the neural substrate for magnetic navigation in insects.

Nonreciprocal Terahertz Beam Steering Manipulated by Magnetic Weyl Semimetal Metasurface Based on Universal Chirality‐ Wavevector‐ Magnetic Field Relation

AbstractMagnetic Weyl semimetal shows intriguing properties in both fundamental physics and potential applications. However, the complex relationship between nonreciprocal transmission and magnetic field manipulation in magnetic Weyl semimetal systems has not been generally clarified and fully utilized. Here, a universal Chirality–Wavevector–Magnetic field (C‐K‐B) relation is established in the magnetic Weyl semimetal system, which completely describes the spin topological band and its intrinsic polarization output in full space orientation under an arbitrary magnetic vector. This relation can provide complete guidance for the device design of nonreciprocal spin manipulation. Coupling this nonreciprocal mechanism with the photonic spin Hall effect of the geometric phased metasurface, a magnetic Weyl semimetal metasurface is constructed in the terahertz (THz) range, The experiments demonstrate the flexible THz beam steerings in a broad spatial dispersion range of ±25–±55° with four different working modes by only altering the biased magnetic vectors. Moreover, all these beam steering processes are accompanied by nonreciprocal isolating transmission with the isolation ratio reaching 27 dB. This C‐K‐B relation and active nonreciprocal beam steering devices are expected to prompt magneto‐optical devices and systems combined with echo isolation function in beam scanning, wavelength division multiplexing, and spin multiplexing.

Swimmable Micro‐Battery for Targeted Power Delivery

AbstractThe boom of microelectronic devices and their diverse applications has heightened the demand for innovative and effective energy supply strategies. The longevity of contemporary microelectronic devices predominantly depends on direct human intervention power supply methods, encompassing battery replacement or recharging. However, these methods may falter in specific scenarios, such as when facing liquid conditions in vivo. Here, a concept of swimmable micro‐batteries (MBs) for targeted power delivery is presented. This is achieved through the design of a flexible polydimethylsiloxane/Fe3O4 soft‐magnetic substrate for actuation, polydimethylsiloxane/neodymium‐iron‐boron (NdFeB) hard‐magnetic tabs for precise targeting, and quasi‐solid‐state Zn//MnO2 battery for power generation. These swimmable MBs exhibit an impressive areal capacity of 102.3 µAh cm‐2, remarkable waterproofing, adjustable output voltage or capacity, rapid response, and accurate remote magnetic field manipulation, enabling targeted power supply available. This novel swimmable MB design broadens the function of MBs and may open a new avenue for their future development.

Broadband and precise reconfiguration of megahertz electromagnetic metamaterials for wireless power transfer

It is a significant challenge to construct reconfigurable electromagnetic metamaterials that can precisely manipulate broadband megahertz electromagnetic waves. Herein, we report a reconfigurable electromagnetic metamaterial (REMM) composed of a two-dimensional periodic array of spiral copper-clad unit cells, each paralleled with a micro-tunable capacitor, which has nearly linear voltage-controlled properties. Moreover, the on-board integrated sample-and-hold modules, linked to all the REMM unit cells, are activated sequentially to perform precise voltage regulation of micro-tunable capacitors for controlling the electromagnetic properties of each unit cell. The experiment results demonstrate that the REMM sample has a maximum frequency adjustment range of 2.1 MHz, ranging from 8.7 MHz to 10.9 MHz with less than 0.1 MHz adjustment step. Furthermore, in a wireless power transfer system, the proposed REMM can achieve the desirable magnetic-field manipulation by precisely adjusting the permeability distribution compared with the traditional metamaterial slab merely capable of full-negative permeability. As a result, the power transfer efficiency (PTE) can be increased from 9.53% to 11.51% (1.69% for the case without the metamaterial slab), and approximately 3.5-fold improvement (from 0.28% to 0.98%) can be achieved when coils are misaligned. This work lays the foundation for the control of electromagnetic waves through using broadband and precise reconfiguration of megahertz electromagnetic metamaterials.

Spin-Wave Spectral Analysis in Crescent-Shaped Ferromagnetic Nanorods

The research on the properties of spin waves (SWs) in three-dimensional nanosystems is an innovative idea in the field of magnonics. Mastering and understanding the nature of magnetization dynamics and binding of SWs at surfaces, edges, and in-volume parts of three-dimensional magnetic systems enables the discovery of alternative phenomena and suggests other possibilities for their use in magnonic and spintronic devices. In this work, we use numerical methods to study the effect of geometry and external magnetic field manipulations on the localization and dynamics of SWs in crescent-shaped (CS) waveguides. It is shown that changing the magnetic field direction in these waveguides breaks the symmetry and affects the localization of eigenmodes with respect to the static demagnetizing field. This, in turn, has a direct effect on their frequency. Furthermore, CS structures are found to be characterized by significant saturation at certain field orientations, resulting in a cylindrical magnetization distribution. Thus, we present chirality-based nonreciprocal dispersion relations for high-frequency SWs, which can be controlled by the field direction (shape symmetry) and its amplitude (saturation).

Reversible conversion between skyrmions and skyrmioniums

Skyrmions and skyrmioniums are topologically non-trivial spin textures found in chiral magnetic systems. Understanding the dynamics of these particle-like excitations is crucial for leveraging their diverse functionalities in spintronic devices. This study investigates the dynamics and evolution of chiral spin textures in [Pt/Co]3/Ru/[Co/Pt]3 multilayers with ferromagnetic interlayer exchange coupling. By precisely controlling the excitation and relaxation processes through combined magnetic field and electric current manipulation, reversible conversion between skyrmions and skyrmioniums is achieved. Additionally, we observe the topological conversion from a skyrmionium to a skyrmion, characterized by the sudden emergence of the skyrmion Hall effect. The experimental realization of reversible conversion between distinct magnetic topological spin textures represents a significant development that promises to expedite the advancement of the next generation of spintronic devices.

Recent Advances in Efficient Photocatalysis via Modulation of Electric and Magnetic Fields and Reactive Phase Control.

The past several years has witnessed significant progress in enhancing photocatalytic performance via robust electric and magnetic fields' modulation to promote the separation and transfer of photoexcited carriers, and phase control at reactive interface to lower photocatalytic reaction energy barrier and facilitate mass transfer. These three research directions have received soaring attention in photocatalytic field. Herein, recent advances in photocatalysis modulated by electric field (i.e., piezoelectric, pyroelectric, and triboelectric fields, as well as their coupling) with specific examples and mechanisms discussion are first examined. Subsequently, the strategy via magnetic field manipulation for enhancing photocatalytic performance is scrutinized, including the spin polarization, Lorentz force, and magnetoresistance effect. Afterward, materials with tailored structure and composition design enabled by reactive phase control and their applications in photocatalytic hydrogen evolution and carbon dioxide reduction are reviewed. Finally, the challenges and potential opportunities to further boost photocatalytic efficiency are presented, aiming at providing crucial theoretical and experimental guidance for those working in photocatalysis, ferroelectrics, triboelectrics, piezo-/pyro-/tribo-phototronics, and electromagnetics, among other related areas.

Modeling dynamic behavior of two magnetic microbubbles in ultrasonic and magnetic fields

Magnetic microbubble (microbubble coated with magnetic nanoparticles) has the advantages of hybrid encapsulated shell, non-invasive fields manipulation and drug/gene delivery, which promotes a broad application prospects in both scientific research and clinic communities. In this work, the encapsulated shell coated with magnetic nanoparticles has been translated into the equivalent problem about bubble in the magnetic fluid. Behavior of two bubbles in the magnetic fluid are theoretically studied by using Lagrange formalism. We evaluate the manipulation of acoustic and magnetic fields on two bubbles dynamics. Magnetic pressure generated by magnetic field increases the pulsating amplitude of each bubble, affects bubbles translation and enhances the gas pressure and temperature inside bubble. Besides, bubbles attraction is caused by the competition between viscous drag and attractive secondary Bjerknes force related to bubble pulsation. In addition, the attractive force caused by magnetic field is useful at very close distance between bubbles, and its effect is quite small compared to the attraction driven by ultrasound. These findings may have implications for ultrasound guided drug delivery using microbubbles coated with magnetic nanoparticles, especial their manipulation in magnetic field.

Ultra-low noise, bi-polar, programmable current sources.

We present the design process and implementation of fully open-source, ultra-low noise programmable current source systems in two configurations. Although originally designed as coil drivers for Optically Pumped Magnetometers (OPMs), the device specifications make them potentially useful in a range of applications. The devices feature a bi-directional current range of ±10 and ±250 mA on three independent channels with 16-bit resolution. Both devices feature a narrow 1/f noise bandwidth of 1Hz, enabling magnetic field manipulation for high-performance OPMs. They exhibit a low noise of 146 pA/Hz and 4.1 nA/Hz, which translates to 15 and 16 ppb/Hz noise relative to full scale.

Efficient Preparation of a Magnetic Helical Carbon Nanomotor for Targeted Anticancer Drug Delivery.

The applications of nanomotors in the biomedical field have been attracting extensive attention. However, it remains a challenge to fabricate nanomotors in a facile way and effectively load drugs for active targeted therapy. In this work, we combine the microwave heating method and chemical vapor deposition (CVD) to fabricate magnetic helical nanomotors efficiently. The microwave heating method can accelerate intermolecular movement, which converts kinetic energy into heat energy and shortens the preparation time of the catalyst used for carbon nanocoil (CNC) synthesis by 15 times. Fe3O4 nanoparticles are in situ nucleated on the CNC surface by the microwave heating method to fabricate magnetically driven CNC/Fe3O4 nanomotors. In addition, we achieved precise control of the magnetically driven CNC/Fe3O4 nanomotors through remote manipulation of magnetic fields. Anticancer drug doxorubicin (DOX) is then efficiently loaded onto the nanomotors via π-π stacking interactions. Finally, the drug-loaded CNC/Fe3O4@DOX nanomotor can accurately accomplish cell targeting under external magnetic field control. Under short-time irradiation of near-infrared light, DOX can be quickly released onto target cells to effectively kill the cells. More importantly, CNC/Fe3O4@DOX nanomotors allow for single-cell or cell-cluster-targeted anticancer drug delivery, providing a dexterous platform to potentially perform many medically relevant tasks in vivo. The efficient preparation method and application in drug delivery are beneficial for future industrial production and provide inspiration for advanced micro/nanorobotic systems using the CNC as a carrier for a wide range of biomedical applications.

Magnetic Field Manipulation of Tetrahedral Units in Spinel Oxides for Boosting Water Oxidation

Magnetic field enhanced electrocatalysis has recently emerged as a promising strategy for the development of a viable and sustainable hydrogen economy via water oxidation. Generally, the effects of magnetic field enhanced electrocatalysis are complex including magnetothermal, magnetohydrodynamic and spin selectivity effects. However, the exploration of magnetic field effect on the structure regulation of electrocatalyst is still unclear whereas is also essential for underpinning the mechanism of magnetic enhancement on the electrocatalytic oxygen evolution reaction (OER) process. Here, it is identified that in a mixed NiFe2 O4 (NFO), a large magnetic field can force the Ni2+ cations to migrate from the octahedral (Oh ) sites to tetrahedral (Td ) sites. As a result, the magnetized NFO electrocatalyst (NFO-M) shows a two-fold higher current density than that of the pristine NFO in alkaline electrolytes. The OER enhancement of NFO is also observed at 1 T (NFO@1T) under an operando magnetic field. Our first-principles calculations further confirm the mechanism of magnetic field driven structure regulation and resultant OER enhancement. These findings provide a strategy of manipulating tetrahedral units of spinel oxides by a magnetic field on boosting OER performance.

Bioinspired Microplate Arrays for Magnetically Tuned Dynamic Color

AbstractFast responding and remote controllable dynamic color is critical in many fields such as image display, senors, and camouflage. In this work, inspired by the structural color of hummingbirds, magnetic‐field driven polymer microplate arrays with dynamic iridescence are demonstrated. The microplates are coated with a layer of photonic crystal (PC) assembled by monodispersed polystyrene nanospheres. The structural color of PC is angle‐dependent, which can be dynamically switched by tuning the tilting angle of the microplates. Magnetic field manipulation is achieved by incorporating ferromagnetic NbFeB powder into the polymer film. Pattern display is also demonstrated by pre‐programing the tilting angle of microplates. This strategy enables fast remote control of high‐resolution structural color. It merits potential applications in many fields such as iridescent mark and invisible patterns for anti‐counterfeiting.