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Heart Rhythm Oct 2021Implantable pacemakers and implantable cardioverter-defibrillators (ICDs) are designed to include a "magnet mode" feature that can be activated from magnets stronger...
Static magnetic field measurements of smart phones and watches and applicability to triggering magnet modes in implantable pacemakers and implantable cardioverter-defibrillators.
BACKGROUND
Implantable pacemakers and implantable cardioverter-defibrillators (ICDs) are designed to include a "magnet mode" feature that can be activated from magnets stronger than 10 G. This feature is designed to be used when a patient is undergoing a procedure where electromagnetic interference is possible, or anytime suspension of tachycardia detection and therapy is needed. A publication in Heart Rhythm demonstrates an iPhone 12 triggering the magnet mode of a Medtronic ICD.
OBJECTIVE
The purpose of this study is to determine the separation distance between consumer electronic devices that may create magnetic interference, including cell phones and smart watches, and implantable pacemakers and ICDs where magnet mode can be triggered.
METHODS
The static magnetic fields of the iPhone 12 models and Apple Watch were measured at several planes in 1 cm resolution using an FW Bell 5180 Gauss Meter with STD18-0404 Transverse probe (unidirectional probe).
RESULTS
All iPhone 12 and Apple Watch 6 models tested have static magnetic fields significantly greater than 10 G in close proximity (1-11 mm), which attenuates to below 10 G between 11 and 20 mm.
CONCLUSION
The findings of this study support the US Food and Drug Administration recommendation that patients keep any consumer electronic devices that may create magnetic interference, including cell phones and smart watches, at least 6 inches away from implanted medical devices, in particular pacemakers and cardiac defibrillators.
Topics: Arrhythmias, Cardiac; Defibrillators, Implantable; Electromagnetic Fields; Equipment Design; Humans; Magnets; Pacemaker, Artificial; Smartphone
PubMed: 34600610
DOI: 10.1016/j.hrthm.2021.06.1203 -
The Laryngoscope Mar 2021Review safety and effectiveness of magnetic resonance imaging (MRI) of patients implanted with a cochlear implant (CI) containing a diametric magnet housed within the...
OBJECTIVES/HYPOTHESIS
Review safety and effectiveness of magnetic resonance imaging (MRI) of patients implanted with a cochlear implant (CI) containing a diametric magnet housed within the undersurface of the device.
STUDY DESIGN
Retrospective chart review with additional review of MRI at a tertiary-care children's hospital.
METHODS
Seven patients with mean age of 8.4 years (range = 1.3-19 years) with a diametric magnet in situ during MRI. The intervention comprised one or more sessions of 1.5 T or 3.0 T MRI without a head wrap. The main outcome measures were the occurrence of magnet-related complications including discomfort and magnet displacement, use of anesthesia or sedation, and clinical usefulness of MRI studies.
RESULTS
Seven CI recipients underwent 17 episodes of 1.5 or 3.0 T MRI with an in situ diametric magnet. Thirteen of 17 (76%) MRI sessions were completed in awake patients. No patients had device-related discomfort. No magnet-related complications occurred. Thirteen of 14 (93%) brain studies were clinically useful despite artifacts.
CONCLUSIONS
The diametric magnet enabled MRI with magnet in situ without the discomfort or magnet displacement associated with removable axial magnets. The reduction in MRI magnet-related complications occurred because torque is not directed perpendicular and outward from the plane of the magnet, and the magnet is securely contained within its housing. The design of this device increased access and reduced the need for sedation or anesthesia.
LEVEL OF EVIDENCE
4 Laryngoscope, 131:E952-E956, 2021.
Topics: Adolescent; Artifacts; Child; Child, Preschool; Cochlear Implants; Equipment Design; Female; Humans; Infant; Magnetic Resonance Imaging; Magnets; Male; Retrospective Studies; Treatment Outcome; Young Adult
PubMed: 32569426
DOI: 10.1002/lary.28854 -
Scientific Reports Aug 2022Two major technical challenges facing parallel nuclear magnetic resonance (NMR) spectroscopy, at the onset, include the need to achieve exceptional [Formula: see text]...
Two major technical challenges facing parallel nuclear magnetic resonance (NMR) spectroscopy, at the onset, include the need to achieve exceptional [Formula: see text] homogeneity, and good inter-detector radiofrequency signal decoupling, and have remained as technical obstacles that limit high throughput compound screening via NMR. In this contribution, we consider a compact detector system, consisting of two NMR 'unit cell' resonators that implement parallel [Formula: see text] shimming with parallel radiofrequency detection, as a prototype NMR environment, pointing the way towards achieving accelerated NMR analysis. The utility of our approach is established by achieving local field correction within the bore of a 1.05T permanent magnet MRI. Our forerunner platform suppresses signal cross-coupling in the range of [Formula: see text] dB to [Formula: see text] dB, under a geometrically decoupled scheme, leading to a halving of the necessary inter-coil separation. In this permanent magnet environment, two decoupled parallel NMR detector sites simultaneously achieve narrow spectral linewidth, overcoming the spatial inhomogeneity of the magnet from 400 to 28 Hz.
Topics: Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Magnets; Radio Waves
PubMed: 35986044
DOI: 10.1038/s41598-022-17694-y -
BioMed Research International 2020Recent developments regarding cochlear implant magnets (e.g., a bipolar diametral magnet) and refined surgical techniques (e.g., implant positioning) have had a... (Comparative Study)
Comparative Study
INTRODUCTION
Recent developments regarding cochlear implant magnets (e.g., a bipolar diametral magnet) and refined surgical techniques (e.g., implant positioning) have had a significant impact on the relation between cochlear implants and MRIs, making the reproducible visibility of cochlea and IAC possible. MRI scanning has changed from a contraindication to a diagnostic tool. Magnet artifact size plays a central role in the visual assessment of the cochlea and IAC.
OBJECTIVE
The aim of this study is to compare the CI magnet-related maximum artifact sizes of various cochlea implant systems.
MATERIALS AND METHODS
We performed an in vivo measurement of MRI artifacts at 1.5 and 3 Tesla with three cochlear implant magnet systems (AB 3D, Medel Synchrony, and Oticon ZTI). The implant, including the magnet, was positioned with a head bandage 7.0 cm and 120° from the nasion, external auditory canal. We used a TSE T2w MRI sequence on the axial and coronal plains and compared the artifacts in two volunteers for each tesla strength.
RESULTS
Intraindividual artifact size differences between the three magnets are smaller than interindividual maximum artifact size differences. 3 T MRI scans, in comparison to 1.5 T MRI scans, show a difference between soft artifact areas.
CONCLUSION
We observed no major difference between maximum implant magnet artifact sizes of the three implant magnet types.
Topics: Artifacts; Cochlear Implants; Ear, Inner; Humans; Magnetic Resonance Imaging; Magnets
PubMed: 32420348
DOI: 10.1155/2020/5086291 -
International Journal of Molecular... Dec 2023Anchoringsingle-molecule magnets (SMMs) on the surface of nanostructures is gaining particular interest in the field of molecular magnetism. The accurate organization of... (Review)
Review
Anchoringsingle-molecule magnets (SMMs) on the surface of nanostructures is gaining particular interest in the field of molecular magnetism. The accurate organization of SMMs on low-dimensional substrates enables controlled interactions and the possibility of individual molecules' manipulation, paving the route for a broad range of nanotechnological applications. In this comprehensive review article, the most studied types of SMMs are presented, and the quantum-mechanical origin of their magnetic behavior is described. The nanostructured matrices were grouped and characterized to outline to the reader their relevance for subsequent compounding with SMMs. Particular attention was paid to the fact that this process must be carried out in such a way as to preserve the initial functionality and properties of the molecules. Therefore, the work also includes a discussion of issues concerning both the methods of synthesis of the systems in question as well as advanced measurement techniques of the resulting complexes. A great deal of attention was also focused on the issue of surface-molecule interaction, which can affect the magnetic properties of SMMs, causing molecular crystal field distortion or magnetic anisotropy modification, which affects quantum tunneling or magnetic hysteresis, respectively. In our opinion, the analysis of the literature carried out in this way will greatly help the reader to design SMM-nanostructure systems.
Topics: Magnets; Nanostructures; Nanotechnology; Anisotropy
PubMed: 38203222
DOI: 10.3390/ijms25010052 -
ACS Applied Materials & Interfaces Apr 2024Living organisms inspire the design of microrobots, but their functionality is unmatched. Next-generation microrobots aim to leverage the sensing and communication...
Living organisms inspire the design of microrobots, but their functionality is unmatched. Next-generation microrobots aim to leverage the sensing and communication abilities of organisms through magnetic hybridization, attaching magnetic particles to them for external control. However, the protocols used for magnetic hybridization are morphology specific and are not generalizable. We propose an alternative approach that leverages the principles of negative magnetostatics and magnetophoresis to control nonmagnetic organisms with external magnetic fields. To do this, we disperse model organisms in dispersions of FeO nanoparticles and expose them to either uniform or gradient magnetic fields. In uniform magnetic fields, living organisms align with the field due to external torque, while gradient magnetic fields generate a negative magnetophoretic force, pushing objects away from external magnets. The magnetic fields enable controlling the position and orientation of larvae and flagellated bacteria through directional interactions and magnitude. This control is diminished in live spermatozoa and adult due to stronger internal biological activity, i.e., force/torque. Our study presents a method for spatiotemporal organization of living organisms without requiring magnetic hybridization, opening the way for the development of controllable living microbiorobots.
Topics: Animals; Caenorhabditis elegans; Magnetics; Magnets; Magnetic Fields; Nanoparticles
PubMed: 38531044
DOI: 10.1021/acsami.4c02325 -
Scientific Reports Feb 2024Over the past 15 years, there has been a noticeable uptick in incidents involving children ingesting multiple magnetic foreign bodies which can cause injuries and... (Observational Study)
Observational Study
Over the past 15 years, there has been a noticeable uptick in incidents involving children ingesting multiple magnetic foreign bodies which can cause injuries and gastrointestinal complications including death. The current study aimed to identify the prevalence, clinical presentation, and management of single or multiple magnet ingestions. A retrospective multi-central cross-sectional study was conducted to include all pediatric patients < 18 years presented to the emergency department with ingestion of single or multiple magnets and admitted across hospitals in Qatar, UAE, KSA, Tunisia, and Turkey between January 2011 and December 2021. Demographics, symptoms, management, and outcomes were analyzed. There were 189 magnet ingestions, of which 88 (46.6%) were multiple magnet ingestions. Most patients (55.6%) were male, and the median age was 3.9 (IQR 2-7) years. An abdominal X-ray was obtained in all cases. 119 (62%) patients were conservatively treated, 53 (28%) required surgical intervention and 17 (8.9%) underwent gastroscopy. None of the patients with single magnet ingestions experienced morbidity or severe outcomes. Multiple magnet ingestions led to significant morbidity including hospitalizations, perforations (44.3%), severe intestinal necrosis (19.3%), peritonitis (13.6%), severe abdominal infection (10.2%), and septic shock (4.5%). The rate of surgical intervention (59.1% vs. 1.0%) and gastroscopy (15.9% vs. 3.0%) was significantly higher in the multiple ingestion group compared to the single magnet ingestion group. No deaths were identified. A high risk of serious complications, including the need for surgery to remove the magnets and substantial morbidity may result from swallowing more than one magnet. Magnet safety requirements, public education, and improved legislation are urgently required.
Topics: Humans; Child; Male; Child, Preschool; Female; Magnets; Retrospective Studies; Cross-Sectional Studies; Foreign Bodies; Eating
PubMed: 38403623
DOI: 10.1038/s41598-024-55127-0 -
Reports on Progress in Physics.... Jan 2015Magnetic sorting using magnetic beads has become a routine methodology for the separation of key cell populations from biological suspensions. Due to the inherent... (Review)
Review
Magnetic sorting using magnetic beads has become a routine methodology for the separation of key cell populations from biological suspensions. Due to the inherent ability of magnets to provide forces at a distance, magnetic cell manipulation is now a standardized process step in numerous processes in tissue engineering, medicine, and in fundamental biological research. Herein we review the current status of magnetic particles to enable isolation and separation of cells, with a strong focus on the fundamental governing physical phenomena, properties and syntheses of magnetic particles and on current applications of magnet-based cell separation in laboratory and clinical settings. We highlight the contribution of cell separation to biomedical research and medicine and detail modern cell-separation methods (both magnetic and non-magnetic). In addition to a review of the current state-of-the-art in magnet-based cell sorting, we discuss current challenges and available opportunities for further research, development and commercialization of magnetic particle-based cell-separation systems.
Topics: Animals; Cell Separation; Humans; Magnetic Phenomena; Magnets
PubMed: 25471081
DOI: 10.1088/0034-4885/78/1/016601 -
Sensors (Basel, Switzerland) Oct 2022This paper presents a fast design optimization using an effective characteristic analysis for linear permanent magnet motors (LPMMs) with techniques for improving motor...
This paper presents a fast design optimization using an effective characteristic analysis for linear permanent magnet motors (LPMMs) with techniques for improving motor performance such as using an auxiliary tooth, permanent magnet (PM) skew, and overhang structures. These techniques have different effects on the characteristics of the LPMM depending on the combinations of each other, resulting in complexity in the design optimization process. In particular, the three-dimensional (3-D) effect of the PM skew and overhang structure takes a lot of time to be analyzed. To deal with this problem, an effective magnetic field analysis method and a novel optimization algorithm are proposed. Preferentially, the field reconstruction method is used for a fast and accurate evaluation of the magnetic field of the LPMM. In the proposed magnetic field analysis method, the change of magnetic field distribution due to the addition of an auxiliary tooth is predicted, and the 3-D magnetic field effect of PM skew and overhang structure is considered. By reducing the computational burden in the magnetic field analysis, the electromagnetic characteristics of LPMMs can be calculated quickly, such as detent force, end force, thrust force, and back-EMF. The effect of the auxiliary tooth and overhang structure on the optimal PM skew length is investigated with comparative study results. Subsequently, the proposed optimization algorithm has the advantage of reducing time cost by providing multimodal optimization and robustness evaluation of local peaks at the same time. The proposed method is verified via comparison with finite element analysis and experimental results.
Topics: Algorithms; Electromagnetic Phenomena; Finite Element Analysis; Magnetic Fields; Magnets
PubMed: 36236667
DOI: 10.3390/s22197568 -
Cells Oct 2021The idea of remote magnetic guiding is developed from the underlying physics of a concept that allows for bijective force generation over the inner volume of magnet... (Review)
Review
The idea of remote magnetic guiding is developed from the underlying physics of a concept that allows for bijective force generation over the inner volume of magnet systems. This concept can equally be implemented by electro- or permanent magnets. Here, permanent magnets are in the focus because they offer many advantages. The equations of magnetic fields and forces as well as velocities are derived in detail and physical limits are discussed. The special hydrodynamics of nanoparticle dispersions under these circumstances is reviewed and related to technical constraints. The possibility of 3D guiding and magnetic imaging techniques are discussed. Finally, the first results in guiding macroscopic objects, superparamagnetic nanoparticles, and cells with incorporated nanoparticles are presented. The constructed magnet systems allow for orientation, movement, and acceleration of magnetic objects and, in principle, can be scaled up to human size.
Topics: Animals; Cells; Humans; Imaging, Three-Dimensional; Magnetic Fields; Magnetic Phenomena; Magnets; Nanoparticles
PubMed: 34685688
DOI: 10.3390/cells10102708