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Nature Nanotechnology Feb 2022
Topics: Magnetic Fields
PubMed: 34931030
DOI: 10.1038/s41565-021-00984-3 -
The Review of Scientific Instruments Sep 2022Micro-magnetic stimulation is a research hotspot in the field of neuromodulation. However, it is difficult to measure the weak magnetic field produced by a...
Micro-magnetic stimulation is a research hotspot in the field of neuromodulation. However, it is difficult to measure the weak magnetic field produced by a millimeter-sized inductor. In this study, a mutual inductance model considering different positions and sizes was established for a common planar square spiral coil micro-magnetic stimulator. A physical model was simulated using the Comsol finite element method to verify the accuracy of the mutual inductance model. A weak magnetic field detection system was constructed using the TI AD8130 and NE5532 chips, and the magnetic field strengths of excitation micro-coils sized 3.612 × 3.612 and 5.55 × 5.55 mm were measured. The results show that when the size ratio of the detection coil (DC) to the excitation coil (EC) is under a specific ratio (DC:EC = 1:1, 2:1, 1.53:1,2.36:1), the measurement range of the magnetic field strength is in the range 0-3.06 mT with an error of 0.05 mT, and the frequency is in the range 1-120 kHz. The measurement accuracy rate reaches 97.62%. The results of this study have potential application in the measurement of the weak magnetic field.
Topics: Equipment Design; Magnetic Fields; Magnetics
PubMed: 36182471
DOI: 10.1063/5.0075990 -
Advanced Drug Delivery Reviews May 2023Tendon afflictions constitute a significant share of musculoskeletal diseases and represent a primary cause of incapacity worldwide. Unresolved/chronic inflammatory... (Review)
Review
Tendon afflictions constitute a significant share of musculoskeletal diseases and represent a primary cause of incapacity worldwide. Unresolved/chronic inflammatory states have been associated with the onset and progression of tendon disorders, contributing to undesirable immune stimulation and detrimental tissue effects. Thus, targeting persistent inflammatory events could assist important developments to solve pathophysiological processes and innovative therapeutics to address impaired healing and accomplish complete tendon regeneration. This review overviews the impact of inflammation and inflammatory mediators in tendon niches, unveiling the importance of tendon cell populations and their signature features, and the influence of microenvironmental factors on inflamed and injured tendons. The demand for non-invasive instructive strategies to manage persistent inflammatory mediators, guide inflammatory pathways, and modulate cellular responses will also be approached by exploring the role of pulsed electromagnetic field (PEMF). PEMF alone or combined with more sophisticated systems triggered by magnetic fields will be considered in the design of successful therapies to control inflammation in tendinopathic conditions.
Topics: Humans; Tendons; Wound Healing; Electromagnetic Fields; Magnetic Fields; Inflammation
PubMed: 37001644
DOI: 10.1016/j.addr.2023.114815 -
Magnetic Susceptibility Difference-Induced Nucleus Positioning in Gradient Ultrahigh Magnetic Field.Biophysical Journal Feb 2020Despite the importance of magnetic properties of biological samples for biomagnetism and related fields, the exact magnetic susceptibilities of most biological samples...
Despite the importance of magnetic properties of biological samples for biomagnetism and related fields, the exact magnetic susceptibilities of most biological samples in their physiological conditions are still unknown. Here we used superconducting quantum interferometer device to detect the magnetic properties of nonfixed, nondehydrated live cell and cellular fractions at a physiological temperature of 37°C (310 K). It is obvious that there are paramagnetic components within human nasopharyngeal carcinoma CNE-2Z cells. More importantly, the magnetic properties of the cytoplasm and nucleus are different. Although within a single cell, the magnetic susceptibility difference between cellular fractions (nucleus and cytoplasm) could only cause ∼41-130 pN forces to the nucleus by gradient ultrahigh magnetic fields of 13.1-23.5 T (92-160 T/m), these forces are enough to cause a relative position shift of the nucleus within the cell. This not only demonstrates the importance of magnetic susceptibility in the biological effects of magnetic field but also illustrates the potential application of high magnetic fields in biomedicine.
Topics: Humans; Magnetic Fields; Magnetics; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms
PubMed: 31952800
DOI: 10.1016/j.bpj.2019.12.020 -
Journal of Neural Engineering Mar 2022We present a combination of a power electronics system and magnetic nanoparticles that enable frequency-multiplexed magnetothermal-neurostimulation with rapid channel...
We present a combination of a power electronics system and magnetic nanoparticles that enable frequency-multiplexed magnetothermal-neurostimulation with rapid channel switching between three independent channels spanning a wide frequency range.The electronics system generates alternating magnetic field spanning 50 kHz to 5 MHz in the same coil by combining silicon (Si) and gallium-nitride (GaN) transistors to resolve the high spread of coil impedance and current required throughout the wide bandwidth. The system drives a liquid-cooled field coil via capacitor banks, forming three series resonance channels which are multiplexed using high-voltage contactors. We characterized the system by the output channels' frequencies, field strength, and switching time, as well as the system's overall operation stability. Using different frequency-amplitude combinations of the magnetic field to target specific magnetic nanoparticles with different coercivity, we demonstrate actuation of iron oxide nanoparticles in all three channels, including a novel nanoparticle composition responding to magnetic fields in the megahertz range.The system achieved the desired target field strengths for three frequency channels, with switching speed between channels on the order of milliseconds. Specific absorption rate measurements and infrared thermal imaging performed with three types of magnetic nanoparticles demonstrated selective heating and validated the system's intended use.The system uses a hybrid of Si and GaN transistors in bridge configuration instead of conventional amplifier circuit concepts to drive the magnetic field coil and contactors for fast switching between different capacitor banks. Series-resonance circuits ensure a high output quality while keeping the system efficient. This approach could significantly improve the speed and flexibility of frequency-multiplexed nanoparticle actuation, such as magnetogenetic neurostimulation, and thus provide the technical means for selective stimulation below the magnetic field's fundamental spatial focality limits.
Topics: Electric Impedance; Electronics; Magnetic Fields; Magnetics; Magnetite Nanoparticles
PubMed: 35259729
DOI: 10.1088/1741-2552/ac5b94 -
Bioelectromagnetics 2023Magnetic field (MF) effects have been reported in plants' growth, seed germination, gene expression, and water consumption. Accordingly, magnetic treatments have been... (Meta-Analysis)
Meta-Analysis Review
Magnetic field (MF) effects have been reported in plants' growth, seed germination, gene expression, and water consumption. Accordingly, magnetic treatments have been proposed as a sustainable alternative to improve yields. Nevertheless, a comprehensive quantitative assessment is needed to understand whether their effects are general, species-specific, or dependent on the experimental setting. We conducted a multilevel meta-analysis of 45 articles that studied 29 different plant species. A positive and neutral effect of a nonuniform MF was found on fresh weight and germination rate, respectively. A significant association was found between a uniform MF and germination. These results suggest that MFs improve plant growth. However, the effects are highly dependent on the experimental setting. This opens exciting questions about the biophysical mechanisms underlying the perception and transduction of this environmental cue and about the possible translation to agricultural practices. © 2023 Bioelectromagnetics Society.
Topics: Magnetic Fields; Germination; Seedlings; Seeds
PubMed: 37070793
DOI: 10.1002/bem.22445 -
Radiation Protection Dosimetry May 2021In this study, electric field and magnetic field strengths at 50 Hz are measured in a solar power plant located far from residential areas, and the measurement results...
In this study, electric field and magnetic field strengths at 50 Hz are measured in a solar power plant located far from residential areas, and the measurement results near various sources of the electric and magnetic fields in the power plant are presented. Although the measured values for the electric field caused by the solar panel range between 0.07 and 1.33 V/m, the measured values for the magnetic field by the solar panel range between 0.037 and 0.19 μT. In front of the inverter, the measured value of the electric field reaches 0.7 V/m, whereas the measured value of the magnetic field reaches 2.2 μT. The results are presented and evaluated in light of the exposure limits to electromagnetic fields published by international organisations.
Topics: Electricity; Electromagnetic Fields; Power Plants; Solar Energy
PubMed: 33993315
DOI: 10.1093/rpd/ncab070 -
Nature May 2024
Topics: Animals; Magnetic Fields; Drosophila melanogaster; Drosophila
PubMed: 38693416
DOI: 10.1038/s41586-024-07320-4 -
Nanoscale Feb 2022During the last decade, the possibility to remotely control intracellular pathways using physical tools has opened the way to novel and exciting applications, both in... (Review)
Review
During the last decade, the possibility to remotely control intracellular pathways using physical tools has opened the way to novel and exciting applications, both in basic research and clinical applications. Indeed, the use of physical and non-invasive stimuli such as light, electricity or magnetic fields offers the possibility of manipulating biological processes with spatial and temporal resolution in a remote fashion. The use of magnetic fields is especially appealing for applications because they can penetrate deep into tissues, as opposed to light. In combination with magnetic actuators they are emerging as a new instrument to precisely manipulate biological functions. This approach, coined as magnetogenetics, provides an exclusive tool to study how cells transform mechanical stimuli into biochemical signalling and offers the possibility of activating intracellular pathways connected to temperature-sensitive proteins. In this review we provide a critical overview of the recent developments in the field of magnetogenetics. We discuss general topics regarding the three main components for magnetic field-based actuation: the magnetic fields, the magnetic actuators and the cellular targets. We first introduce the main approaches in which the magnetic field can be used to manipulate the magnetic actuators, together with the most commonly used magnetic field configurations and the physicochemical parameters that can critically influence the magnetic properties of the actuators. Thereafter, we discuss relevant examples of magneto-mechanical and magneto-thermal stimulation, used to control stem cell fate, to activate neuronal functions, or to stimulate apoptotic pathways, among others. Finally, although magnetogenetics has raised high expectations from the research community, to date there are still many obstacles to be overcome in order for it to become a real alternative to optogenetics for instance. We discuss some controversial aspects related to the insufficient elucidation of the mechanisms of action of some magnetogenetics constructs and approaches, providing our opinion on important challenges in the field and possible directions for the upcoming years.
Topics: Electricity; Magnetic Fields; Magnetics; Neurons; Optogenetics
PubMed: 35103278
DOI: 10.1039/d1nr06303k -
Sensors (Basel, Switzerland) Jun 2023Magnetic field sensors using magnetoelectric (ME) effects in planar ferromagnetic-piezoelectric heterostructures convert a magnetic field into an output voltage. The...
Magnetic field sensors using magnetoelectric (ME) effects in planar ferromagnetic-piezoelectric heterostructures convert a magnetic field into an output voltage. The parameters of ME sensors are determined by characteristics of the magnetic constituent. In this work, the low-frequency ME effects in heterostructures comprising a layer of antiferromagnetic hematite α-FeO crystal with easy-plane anisotropy and a piezoelectric layer are studied. The effects arise due to a combination of magnetostriction and piezoelectricity because of mechanical coupling of the layers. The field dependences of magnetization and magnetostriction of the hematite crystal are measured. The resonant ME effects in the hematite-piezopolymer and hematite-piezoceramic structures are studied. The strong coupling between magnetic and acoustic subsystems of hematite results in a tuning of the acoustic resonance frequency by the magnetic field. For the hematite layer, the frequency tuning was found to be ~37% with an increase in the bias field up to 600 Oe. For the hematite-PVDF heterostructure, the frequency tuning reached ~24% and the ME coefficient was 58 mV/(Oe∙cm). For the hematite-piezoceramic heterostructure, the frequency tuning was ~4.4% and the ME coefficient 4.8 V/(Oe∙cm). Efficient generation of the second voltage harmonic in the hematite-piezoceramic heterostructure was observed.
Topics: Acoustics; Anisotropy; Magnetic Fields; Magnets
PubMed: 37447750
DOI: 10.3390/s23135901