Rotating Magnetic Field Research Articles

Urchin-like Fe3O4@Bi2S3 Nanospheres Enable the Destruction of Biofilm and Efficiently Antibacterial Activities.

Biofilm-associated infections (BAIs) have been considered a major threat to public health, which induce persistent infections and serious complications. The poor penetration of antibacterial agents in biofilm significantly limits the efficiency of combating BAIs. Magnetic urchin-like core-shell nanospheres of Fe3O4@Bi2S3 were developed for physically destructing biofilm and inducing bacterial eradication via reactive oxygen species (ROS) generation and innate immunity regulation. The urchin-like magnetic nanospheres with sharp edges of Fe3O4@Bi2S3 exhibited propeller-like rotation to physically destroy biofilm under a rotating magnetic field (RMF). The mild magnetic hyperthermia improved the generation of ROS and enhanced bacterial eradication. Significantly, the urchin-like nanostructure and generated ROS could stimulate macrophage polarization toward the M1 phenotype, which could eradicate the persistent bacteria with a metabolic inactivity state through phagocytosis, thereby promoting the recovery of implant infection and inhibiting recurrence. Thus, the design of magnetic-driven sharp-shaped nanostructures of Fe3O4@Bi2S3 provided enormous potential in combating biofilm infections.

Rotating magnetic field inhibits Aβ protein aggregation and alleviates cognitive impairment in Alzheimer's disease mice.

Amyloid beta (Aβ) monomers aggregate to form fibrils and amyloid plaques, which are critical mechanisms in the pathogenesis of Alzheimer's disease (AD). Given the important role of Aβ1-42 aggregation in plaque formation, leading to brain lesions and cognitive impairment, numerous studies have aimed to reduce Aβ aggregation and slow AD progression. The diphenylalanine (FF) sequence is critical for amyloid aggregation, and magnetic fields can affect peptide alignment due to the diamagnetic anisotropy of aromatic rings. In this study, we examined the effects of a moderate-intensity rotating magnetic field (RMF) on Aβ aggregation and AD pathogenesis. Results indicated that the RMF directly inhibited Aβ amyloid fibril formation and reduced Aβ-induced cytotoxicity in neural cells in vitro. Using the AD mouse model APP/PS1, RMF restored motor abilities to healthy control levels and significantly alleviated cognitive impairments, including exploration and spatial and non-spatial memory abilities. Tissue examinations demonstrated that RMF reduced amyloid plaque accumulation, attenuated microglial activation, and reduced oxidative stress in the APP/PS1 mouse brain. These findings suggest that RMF holds considerable potential as a non-invasive, high-penetration physical approach for AD treatment.

Experimental investigation into efficiency loss in rotating magnetic field thrusters

An experimental investigation into the low thrust efficiency of a rotating magnetic field (RMF) thruster is presented. This technology is a low maturity but potentially enabling candidate for high-power in-space propulsion for use with alternative propellants. Direct thrust stand measurements of a 5 kW class RMF thruster were performed and show the thrust efficiency was 0.41 ± 0.04% with a specific impulse of 292 ± 11 s—typical values for RMF thruster operation. A suite of far-field probes were used to inform a phenomenological efficiency model for RMF thruster performance that accounted for divergence, power coupling, mass utilization, and plasma/acceleration efficiency. It was found that the plasma efficiency was the critically low term at 6.4 ± 1.0%. This indicates that the majority of the energy coupled to the plasma from the RMF antennas was lost before being converted to directed kinetic energy in the thruster beam. To determine the source of these losses, time-resolved measurements of the internal plasma properties were performed using a triple Langmuir probe. It was found that collisional excitation radiation and wall losses were the two dominant loss processes. This trend can be explained by the unusually high plasma density ( >1019 m−3) exhibited by this device compared to other electric propulsion architectures. Limitations in the probing techniques and strategies for improving RMF thruster performance are discussed given the results from the efficiency analysis.

Alginate/GelMA microparticles via oil-free interface shearing for untethered magnetic microbots.

Microrobots hold broad application prospects in the field of precision medicine, such as intravenous drug injection, tumor resection, opening blood vessels and imaging during abdominal surgery. However, the rapid and controllable preparation of biocompatible hydrogel microparticles still poses challenges. This study proposes the one-step direct acquisition of biocompatible sodium alginate and gelatin methacrylate (GelMA) hydrogel microparticles using an oil-free aqueous solution, ensuring production with a controllable generation frequency. An adaptive interface shearing platform is established to fabricate alginate/GelMA microparticles using a mixture of the hydrogel, photoinitiator, and Fe3O4 nanoparticles (NPs). By adjusting the static magnetic field intensity (Bs), vibration frequency, and flow rate (Q) of the dispersed phase, the size and morphology of the hydrogel microparticles can be controlled. These hydrogel microparticle robots exhibit magnetic responsiveness, demonstrating precise rotating and rolling movements under the influence of an externally rotating magnetic field (RMF). Moreover, hydrogel microparticle robots with a specific critical frequency (Cf) can be customized by adjusting the Bs and the concentration of Fe3O4 NPs. The directional in situ untethered motion of the hydrogel microparticle robots can be successfully realized and accurately controlled in the climbing over obstacles and in vitro experiments of animals, respectively. This versatile and fully biodegradable microrobot has the potential to precisely control movement to bone tissue and the natural cavity of the human body, as well as drug delivery.

Gradient Rotating Magnetic Fields Impairing F-Actin-Related Gene CCDC150 to Inhibit Triple-Negative Breast Cancer Metastasis by Inactivating TGF-β1/SMAD3 Signaling Pathway.

Triple-negative breast cancer (TNBC) is the most aggressive and lethal malignancy in women, with a lack of effective targeted drugs and treatment techniques. Gradient rotating magnetic field (RMF) is a new technology used in oncology physiotherapy, showing promising clinical applications due to its satisfactory biosafety and the abundant mechanical force stimuli it provides. However, its antitumor effects and underlying molecular mechanisms are not yet clear. We designed two sets of gradient RMF devices for cell culture and animal handling. Gradient RMF exposure had a notable impact on the F-actin arrangement of MDA-MB-231, BT-549, and MDA-MB-468 cells, inhibiting cell migration and invasion. A potential cytoskeleton F-actin-associated gene, CCDC150, was found to be enriched in clinical TNBC tumors and cells. CCDC150 negatively correlated with the overall survival rate of TNBC patients. CCDC150 promoted TNBC migration and invasion via activation of the transforming growth factor β1 (TGF-β1)/SMAD3 signaling pathway invitro and invivo. CCDC150 was also identified as a magnetic field response gene, and it was marked down-regulated after gradient RMF exposure. CCDC150 silencing and gradient RMF exposure both suppressed TNBC tumor growth and liver metastasis. Therefore, gradient RMF exposure may be an effective TNBC treatment, and CCDC150 may emerge as a potential target for TNBC therapy.

Relaxation processes in nematic liquid crystals in the nonstationary regime of a rotation of magnetic field

The prospects of using the nonstationary regime of motion of the director for studying the relaxation properties of liquid crystals in the low-temperature interval of the nematic phase are shown. In the nonstationary regime, the phase shift between the direction and the wave vector is 45 and does not depend on the angular velocity of rotation of the magnetic field. A eutectic mixture of nematic liquid crystals with a wider temperature range of the nematic phase compared to individual components has been studied. A decrease in the anisotropy of the absorption coefficient in the nonstationary regime is associated with a partial violation of the homogeneous orientation of the sample. The nature of the dependence of the low-frequency component of the phase characteristic on the thermodynamic parameters of the state is established. Within the framework of the hydrodynamics of the nematic phase, relations were obtained that allow calculating the dissipative coefficients responsible for the performance of liquid crystal technical devices.

Dual-direction thermal conductive FG-based composite manufactured by rotating magnetic-field assisted casting

With the miniaturization of electronic components and the complication of packaging processes, operating environments with high power density are bound to generate large amounts of heat. Conventional thermal interface material (TIM) typically aims to enhance thermal conductivity (TC) in only one direction (either through-plane or in-plane), which is insufficient to meet the growing requirement for heat dissipation. Here, highly oriented and tightly fitted flake graphite (FG)-based TIM with dual-direction thermal conductive pathways were prepared via rotating magnetic field assisted casting (RMAC), which can dissipate heat quickly in both directions. The results revealed that at 50 wt% filler and 30 r/min magnetic field rotation rate, the composites with dual-direction thermal conductive pathways exhibited in-plane and through-plane TC of 12.8 and 10.1 W/mK, respectively. Notably, these values represent significant improvements of 415.4 % and 134.1 % over random composites and also demonstrate outstanding advantages over composites with filler orientation in only one direction, horizontal or vertical. This also has been confirmed by finite element simulations and actual thermal characterization. The rational structural design of the filler in TIM can efficiently direct heat away from specific directions, which provides a feasible solution to the heat dissipation problem of high-power-density electronic devices.

Assessing the Influence of a Rotating Magnetic Field on Ibuprofen Permeability from Diverse Pharmaceutical Formulations

This study introduces a novel approach for enhancing the transdermal permeability of ibuprofen through the skin by utilising a rotating magnetic field (RMF). The core objective is to systematically evaluate the influence of a 50 Hz RMF on ibuprofen’s skin permeability across various formulation types, each employing distinct physical forms and excipients. The experimental setup involved Franz cells with skin as the membrane, exposed to a 50 Hz RMF in conjunction with specific formulations. Subsequent comprehensive analysis revealed a notable increase in the transdermal transport of ibuprofen, irrespective of the formulation employed. Notably, the differences in the initial 30 min of permeation were particularly pronounced. Crucially, this investigation establishes that the application of a 50 Hz RMF resulted in a remarkable over-sevenfold increase in ibuprofen permeability compared to the control group without RMF exposure. It is noteworthy that in all semi-solid pharmaceutical formulations tested, RMF effectively reduced the delay time to zero, underscoring the efficiency of RMF in overcoming barriers to transdermal drug delivery. This research positions the application of RMF as a highly promising and innovative technology, significantly enhancing the transdermal penetration of anti-inflammatory and analgesic drugs through the skin. The demonstrated effectiveness of RMF across diverse formulations suggests its potential in transdermal drug delivery, offering a novel and efficient strategy for improving therapeutic outcomes in the administration of ibuprofen and potentially other pharmaceutical agents.

Magnetic hybrid nanospindle with an unconventional force-thermal coupling antibacterial effect

Nanoplatforms have been considered as an effective strategy to address the resistance problem of traditional antimicrobial agents. This work reports a magnetic Fe3O4@AgAu@PDA (Fe3O4@AgAu@Polydopamine) antibacterial nanomaterial which possesses magnetically induced force-thermal coupling antibacterial effect. The polydopamine shell has good biocompatibility and the AgAu nanorods immobilized on the surface of the magnetic nanospindle not only create a rough surface for the anisotropic nanospindle but also endow it with high photothermal performance and oxidase-like/peroxide-like activities. Besides the original Ag ions release antibacterial activity, Fe3O4@AgAu@PDA nanospindles (80 μg/mL) also exhibit a good photothermal antibacterial effect (>90%) against Escherichia coli and Staphylococcus aureus under near-infrared (NIR) irradiation. Interestingly, when a rotating magnetic field (RMF) is applied, the antibacterial activity of the magnetic nanospindles can be further increased to nearly 100%. More importantly, in comparison to the Fe3O4@AgAu@PDA nanospheres, the Fe3O4@AgAu@PDA nanospindles exhibit a better antibacterial effect. By exploring the interaction between different particles and bacteria under magnetic field conditions, the basic mechanism of force-thermal coupling antibacterial was deeply explored and extended to biofilm removal. The results of cytotoxicity assay show that Fe3O4@AgAu@PDA nanospindles have good biocompatibility. Thus, the proposed strategy provides broad promise in antimicrobial therapy and biomedicine.

Force effect of a circular rotating magnetic field of a cylindrical electric inductor on a ferromagnetic particle in process reactors

The object of research is the force effect of a circular magnetic field of cylindrical inductors with alternating current windings on the actuator element of technological reactors – a ferromagnetic particle. Technologies using a rotating magnetic field and ferromagnetic particles (RMF and FP) are increasingly used in industry, in devices for fine and ultra-fine grinding, mixing and activation, in the construction and chemical industries, in energy-saving and environmental systems. In previous studies, the authors proposed a method for calculating the force effect on ferromagnetic particles (FP) of an elliptical rotating magnetic field (RMF) of an external cylindrical inductor with a symmetrical alternating current winding. In this work, based on this technique, formulas for the force effect on the FP of the fundamental harmonic of RMF of cylindrical inductors with different numbers of pole pairs are derived and analyzed. It is shown that for a hard magnetic and saturated magnetically soft (soft-magnetic) particle in a circular field of a cylindrical inductor with the number of pole pairs greater than one, the magnitude of the magnetic displacement force does not depend on the orientation of the magnetic moment of the ferromagnetic particle, and the direction of action of this force is determined by the angle between the circular field induction vector and the magnetic moment of the particle. While maintaining the similarity of the inductors and the equality of the amplitude of the magnetic induction on the surface of the inductor bore, the magnetic displacement force does not retain the similarity, in particular, while maintaining the values of the magnetic moment of the particle, this force is inversely proportional to the radius of the bore of the cylindrical inductor. Examples are given of the use of formulas for calculating the ratio of displacement forces to the weight of a particle and the calculation of forces for an unsaturated soft-magnetic particle, where, due to the dependence of the magnetic moment on the field strength, the calculation formulas are modified and take on a slightly different form than the formulas for a particle with a constant modulus magnetic moment. The research results will be useful for engineers and researchers involved in the research, development, design and operation of reactors with RMF and FP technologies.

A Novel Superparamagnetic Multifunctional Nerve Scaffold: A Remote Actuation Strategy to Boost In Situ Extracellular Vesicles Production for Enhanced Peripheral Nerve Repair.

Extracellular vesicles (EVs) have inherent advantages over cell-based therapies in regenerative medicine because of their cargos of abundant bioactive cues. Several strategies are proposed to tune EVs production in vitro. However, it remains a challenge for manipulation of EVs production in vivo, which poses significant difficulties for EVs-based therapies that aim to promote tissue regeneration, particularly for long-term treatment of diseases like peripheral neuropathy. Herein, a superparamagnetic nanocomposite scaffold capable of controlling EVs production on-demand is constructed by incorporating polyethyleneglycol/polyethyleneimine modified superparamagnetic nanoparticles into a polyacrylamide/hyaluronic acid double-network hydrogel (Mag-gel). The Mag-gel is highly sensitive to a rotating magnetic field (RMF), and can act as mechano-stimulative platform to exert micro/nanoscale forces on encapsulated Schwann cells (SCs), an essential glial cell in supporting nerve regeneration. By switching the ON/OFF state of the RMF, the Mag-gel can scale up local production of SCs-derived EVs (SCs-EVs) both in vitro and in vivo. Further transcriptome sequencing indicates an enrichment of transcripts favorable in axon growth, angiogenesis, and inflammatory regulation of SCs-EVs in the Mag-gel with RMF, which ultimately results in optimized nerve repair in vivo. Overall, this research provides a noninvasive and remotely time-scheduled method for fine-tuning EVs-based therapies to accelerate tissue regeneration, including that of peripheral nerves.

Flow visualization of nanoparticles in a natural convection cavity

A two-litre natural convection cavity containing transformer oil is used to visualize the flow of nanoparticles. Transparency-wise, transformer oil resembles water. Kinematic viscosity, however, is nineteen times greater than water. Its thermophysical characteristic aids in keeping the nanoparticles suspended for a longer period. Transparency gives equal clarity like demineralized water. As a result, the flow of nanoparticles may be seen more clearly in transformer oil than in demineralized water. The following cases are seen in the motions of the natural convection nanoparticles that resemble cavities in the transformer oil due to the effects of a) gravity, b) mechanical agitation, c) temperature, d) rotational magnetic field, e) cavity tilting, etc. The random movement of nanoparticles, thermophoresis due to temperature gradient, and improvement in settling time of nanoparticles due to rotary magnetic field, shifting of vortex towards the upper tilting wall, and path line of few particles are also observed.

Nonlinear dynamics of large-amplitude, small-scale Alfvén waves

We study large-amplitude, very oblique Alfvén waves at low β, with small gradient length scales, comparable to the ion inertial scale di. Such waves have large density fluctuations and slight dispersion from finite-frequency and finite-ion sound radius effects. We derive a weakly nonlinear evolution equation governing the behavior of the waves in one dimension and categorize the different solitons appearing in different regimes: the regular solitons involve full rotations of the transverse magnetic field similar to modified Korteweg–de Vries (mKdV) solitons (our nonlinear equation reduces to the mKdV equation in the long-wavelength limit). However, for sufficiently small soliton widths, some become singular, small-amplitude solitons with density discontinuities and, are, thus expected to become strongly dissipative in a real plasma. These solutions may be useful in explaining some aspects of the sharp, ion-scale magnetic field rotations (switchbacks) observed in the near-Sun solar wind by Parker Solar Probe.

Solution of MHD-stokes flow in an L-shaped cavity with a local RBF-supported finite difference

One of the popular meshless methods for solving governing equations in applied sciences is a local radial basis function-finite difference (RBF-FD). In this paper, we proposed a new idea for an L- shaped (or like T- and Z-shaped) domain based on the domain decomposition. RBF-FD formulation is used at the interface points to get a better solution, while the classical FD is applied to all sub-regions. We use the algorithm based on the Gaussian-RBF (RBF-GA) in the stable calculation of the weights to avoid choosing optimal shape parameters. Stencil size is considered the nearest n-points (9,12,15) and benchmark results are presented for divided-lid driven cavity. Further, Navier–Stokes equations adding the Lorentz force term with Stokes approximation for a single-lid L-shaped cavity exposed to inclined magnetic field are solved by the devised numerical method. The flow structure is analyzed in aspect of streamline topology under the various magnetic field rotation (0∘≤α≤90∘ ) and its strength (M=10,30,50,100 ).

An experimental investigation on the nanofluids in a cavity under natural convection with and without the rotary magnetic field

This experimental study involves the use of two distinct categories of nanofluids, namely ferromagnetic and non-magnetic, within a square cavity that facilitates natural convection. There are five distinct concentrations associated with each nanofluid. Natural convection arises as a consequence of the thermal gradient between the opposing surfaces of the copper cavity, which has a thickness of 18 gauge. The purpose of utilizing the constructed electro-magnet assembly is to investigate the impact of the rotational magnetic field on the process of heat transfer. The manipulation of magnetic strength can be achieved by regulating the magnetic power and direct current (DC) power. The manipulation of the electromagnet’s spin can also be regulated. In the context of a rotational magnetic field, it is seen that the magnetic flux undergoes a transition from a positive value to an almost identical negative value throughout a full rotation. The optimal heat transfer performance is observed at a nanoparticle concentration of 0.1% by volume (φ) for both nanofluids. In the absence of a rotating magnetic field, the ferromagnetic nanofluid exhibited superior performance. When the Rayleigh number (Ra) is one order smaller than the critical Rayleigh number value, the heat transfer performance is often superior with nanofluid compared to demineralized water.

Magnetic Lateral Ladder for Unidirectional Transport of Microrobots: Design Principles and Potential Applications of Cells-on-Chip.

Functionalized microrobots, which are directionally manipulated in a controlled and precise manner for specific tasks, face challenges. However, magnetic field-based controls constrain all microrobots to move in a coordinated manner, limiting their functions and independent behaviors. This article presents a design principle for achieving unidirectional microrobot transport using an asymmetric magnetic texture in the shape of a lateral ladder, which the authors call the "railway track." An asymmetric magnetic energy distribution along the axis allows for the continuous movement of microrobots in a fixed direction regardless of the direction of the magnetic field rotation. The authors demonstratedprecise control and simple utilization of this method. Specifically, by placing magnetic textures with different directionalities, an integrated cell/particle collectorcan collect microrobots distributed in a large area and move them along a complex trajectory to a predetermined location. The authors can leverage the versatile capabilities offered by this texture concept, including hierarchical isolation, switchable collection, programmable pairing, selective drug-response test, and local fluid mixing for target objects. The results demonstrate the importance of microrobot directionality in achieving complex individual control. This novel concept represents significant advancement over conventional magnetic field-based control technology and paves the way for further research in biofunctionalized microrobotics.

Inductive probe measurements in a rotating magnetic field thruster

The induced magnetic field during acceleration in a pulsed rotating magnetic field (RMF) thruster is experimentally investigated. A two-axis Bdot probe is employed to characterize the time-resolved evolution of the fields in a 5 kW-class test article. This device is operated at an average power of 4 kW with an RMF frequency of 415 kHz, pulse widths of 125 µs, and a repetition rate of 155 Hz. Plasma currents induced in the thruster are shown to reach 2500 A and to have sufficient magnitude to form a field-reversed configuration plasmoid. The Lorentz force resulting from the induced magnetic field contributes ∼25% of measured thrust at this operating condition. Of this Lorentz thrust, ∼58% is due to plasma current interaction with the steady applied bias field, while the remainder is caused by interaction with secondary induced currents in nearby structural elements. This structure force is predicted to scale quadratically with plasma current magnitude. These results are discussed in the context of the historically low performance of these devices and strategies for improving their operation are presented.

Multipoint Observations of the Dynamics at an ICME Sheath–Ejecta Boundary

The radial evolution of interplanetary coronal mass ejections (ICMEs) is dependent on their interaction with the ambient medium, which causes ICME erosion and affects their geoefficiency. Here, an ICME front boundary, which separates the confined ejecta from the mixed, interacted sheath–ejecta plasma upstream, is analyzed in a multipoint study examining the ICME at 1 au on 2020 April 20. A bifurcated current sheet, highly filamented currents, and a two-sided jet were observed at the boundary. The two-sided jet, which was recorded for the first time for a magnetic shear angle <40°, implies multiple (patchy) reconnection sites associated with the ICME erosion. The reconnection exhaust exhibited fine structure, including multistep magnetic field rotation and localized structures that were measured only by separate Cluster spacecraft with the mission inter-spacecraft separation of 0.4–1.6 R E. The mixed plasma upstream of the boundary with a precursor at 0.8 au lacked coherency at 1 au and exhibited substantial variations of southward magnetic fields over radial (transverse) distances of 41–237 R E (114 R E). This incoherence demonstrates the need for continuous (sub)second-resolution plasma and field measurements at multiple locations in the solar wind to adequately address the spatiotemporal structure of ICMEs and to produce accurate space weather predictions.

Synthesis of a magneto-chromatic tunable Fe3O4-HPAM colloid

Colloids of soft magnetic (Fe3O4) submicrometer particles, formed by magnetic nanoparticle clusters, coated with a polyelectrolyte (hydrolyzed polyacrylamide; HPAM) were fabricated successfully in situ with a highly controllable chemical approach. The formation mechanism of submicron particles was analyzed under the amounts of HPAM, urea, citrate, and metallic precursors. This mechanism was followed by SEM. The results showed that the physicochemical properties of the HPAM favored physical interactions with the reactants, promoting the formation of dense-packed magnetic micrometer clusters in one-step synthesis. The results showed that the physicochemical properties of the HPAM favored physical interactions with the reactants, promoting the formation of dense-packed magnetic micrometer clusters in one-step synthesis. The different estimated radii of these particles in solution (hydrodynamic and gyration) and dried (internal radius) decrease when the HPAM amount increases. Moreover, the particles exhibited a superparamagnetic behavior with a magnetization of 48.2 emu/g, 50.3 emu/g, and 54.3 emu/g when the amounts were 0.5 g, 1 g, and 2g of HPAM, respectively. Consequently, the optical response of the colloids to the application of a rotating magnetic field (RMF) parallel to the horizontal plane where they were located exhibited a behavior similar to photonic structures since their reflection spectrum showed a periodic diffraction color that closely matches the frequency of the RMF.

Inductive sensing of magnetic microrobots under actuation by rotating magnetic fields.

The engineering space for magnetically manipulated biomedical microrobots is rapidly expanding. This includes synthetic, bioinspired, and biohybrid designs, some of which may eventually assume clinical roles aiding drug delivery or performing other therapeutic functions. Actuating these microrobots with rotating magnetic fields (RMFs) and the magnetic torques they exert offers the advantages of efficient mechanical energy transfer and scalable instrumentation. Nevertheless, closed-loop control still requires a complementary noninvasive imaging modality to reveal position and trajectory, such as ultrasound or X-rays, increasing complexity and posing a barrier to use. Here, we investigate the possibility of combining actuation and sensing via inductive detection of model microrobots under field magnitudes ranging from 100 s of microtesla to 10 s of millitesla rotating at 1 to 100 Hz. A prototype apparatus accomplishes this using adjustment mechanisms for both phase and amplitude to finely balance sense and compensation coils, suppressing the background signal of the driving RMF by 90 dB. Rather than relying on frequency decomposition to analyze signals, we show that, for rotational actuation, phase decomposition is more appropriate. We demonstrate inductive detection of a micromagnet placed in two distinct viscous environments using RMFs with fixed and time-varying frequencies. Finally, we show how magnetostatic selection fields can spatially isolate inductive signals from a micromagnet actuated by an RMF, with the resolution set by the relative magnitude of the selection field and the RMF. The concepts developed here lay a foundation for future closed-loop control schemes for magnetic microrobots based on simultaneous inductive sensing and actuation.