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The British Journal of Radiology Sep 2019Quantitative Susceptibility Mapping (QSM) and Susceptibility Weighted Imaging (SWI) are MRI techniques that measure and display differences in the magnetization that is... (Review)
Review
Quantitative Susceptibility Mapping (QSM) and Susceptibility Weighted Imaging (SWI) are MRI techniques that measure and display differences in the magnetization that is induced in tissues, . their magnetic susceptibility, when placed in the strong external magnetic field of an MRI system. SWI produces images in which the contrast is heavily weighted by the intrinsic tissue magnetic susceptibility. It has been applied in a wide range of clinical applications. QSM is a further advancement of this technique that requires sophisticated post-processing in order to provide quantitative maps of tissue susceptibility. This review explains the steps involved in both SWI and QSM as well as describing some of their uses in both clinical and research applications.
Topics: Diffusion Magnetic Resonance Imaging; Humans; Magnetic Resonance Imaging; Magnetics
PubMed: 30933548
DOI: 10.1259/bjr.20181016 -
Journal of Medicine and Life Apr 2023Magnets have been widely used in dentistry as a means of retention in various prosthodontic applications. This review summarizes the historical background, types, and... (Review)
Review
Magnets have been widely used in dentistry as a means of retention in various prosthodontic applications. This review summarizes the historical background, types, and modes of action of magnets in dentistry, including their uses in conventional removable prostheses, sectional dentures, overdentures, maxillofacial prostheses, and implant-supported prostheses. A comprehensive electronic literature search was performed through multiple databases, including Medline via Pubmed, Wiley Online Library, Ebscohost, Science Direct, and Google Scholar. We used the following keywords: "magnets", "retention", "overdenture", and "maxillofacial prosthesis", with a focus on articles published between October 1953 and March 2016. We found 20 articles, and 16 were selected for inclusion in this review based on their relevance to the topic at hand. Recent advancements in magnetic technology have resulted in newer magnets that exhibit superior biological compatibility and corrosion resistance. These properties have made magnets an effective retentive aid intra- and extra-orally.
Topics: Humans; Magnets; Artificial Limbs; Electronics; PubMed
PubMed: 37305814
DOI: 10.25122/jml-2020-0012 -
Theranostics 2021The theranostics paradigm is based on the concept of combining therapeutic and diagnostic modalities into one platform to improve the effectiveness of treatment.... (Review)
Review
The theranostics paradigm is based on the concept of combining therapeutic and diagnostic modalities into one platform to improve the effectiveness of treatment. Combinations of multiple modalities provide numerous medical advantages and are enabled by nano- and micron-sized mediators. Here we review recent advancements in the field of ultrasound theranostics and the use of magnetic materials as mediators. Several subdisciplines are described in detail, including controlled drug delivery and release, ultrasound hyperthermia, magneto-ultrasonic heating, sonodynamic therapy, magnetoacoustic imaging, ultrasonic wave generation by magnetic fields, and ultrasound tomography. The continuous progress and improvement in theranostic materials, methods, and physical computing models have created undeniable possibilities for the development of new approaches. We discuss the prospects of ultrasound theranostics and possible expansions of other studies to the theranostic context.
Topics: Animals; Drug Delivery Systems; Humans; Magnetic Field Therapy; Magnetic Fields; Magnetics; Nanoparticles; Neoplasms; Precision Medicine; Theranostic Nanomedicine; Ultrasonic Therapy; Ultrasonic Waves; Ultrasonography
PubMed: 34815806
DOI: 10.7150/thno.62218 -
Chemical Reviews Mar 2022In conventional classification, soft robots feature mechanical compliance as the main distinguishing factor from traditional robots made of rigid materials. Recent... (Review)
Review
In conventional classification, soft robots feature mechanical compliance as the main distinguishing factor from traditional robots made of rigid materials. Recent advances in functional soft materials have facilitated the emergence of a new class of soft robots capable of tether-free actuation in response to external stimuli such as heat, light, solvent, or electric or magnetic field. Among the various types of stimuli-responsive materials, magnetic soft materials have shown remarkable progress in their design and fabrication, leading to the development of magnetic soft robots with unique advantages and potential for many important applications. However, the field of magnetic soft robots is still in its infancy and requires further advancements in terms of design principles, fabrication methods, control mechanisms, and sensing modalities. Successful future development of magnetic soft robots would require a comprehensive understanding of the fundamental principle of magnetic actuation, as well as the physical properties and behavior of magnetic soft materials. In this review, we discuss recent progress in the design and fabrication, modeling and simulation, and actuation and control of magnetic soft materials and robots. We then give a set of design guidelines for optimal actuation performance of magnetic soft materials. Lastly, we summarize potential biomedical applications of magnetic soft robots and provide our perspectives on next-generation magnetic soft robots.
Topics: Magnetic Phenomena; Magnetics; Robotics
PubMed: 35104403
DOI: 10.1021/acs.chemrev.1c00481 -
Molecules (Basel, Switzerland) Jun 2022Magnetic composites and self-healing materials have been drawing much attention in their respective fields of application. Magnetic fillers enable changes in the... (Review)
Review
Magnetic composites and self-healing materials have been drawing much attention in their respective fields of application. Magnetic fillers enable changes in the material properties of objects, in the shapes and structures of objects, and ultimately in the motion and actuation of objects in response to the application of an external field. Self-healing materials possess the ability to repair incurred damage and consequently recover the functional properties during healing. The combination of these two unique features results in important advances in both fields. First, the self-healing ability enables the recovery of the magnetic properties of magnetic composites and structures to extend their service lifetimes in applications such as robotics and biomedicine. Second, magnetic (nano)particles offer many opportunities to improve the healing performance of the resulting self-healing magnetic composites. Magnetic fillers are used for the remote activation of thermal healing through inductive heating and for the closure of large damage by applying an alternating or constant external magnetic field, respectively. Furthermore, hard magnetic particles can be used to permanently magnetize self-healing composites to autonomously re-join severed parts. This paper reviews the synthesis, processing and manufacturing of magnetic self-healing composites for applications in health, robotic actuation, flexible electronics, and many more.
Topics: Magnetic Fields; Magnetics; Robotics
PubMed: 35744920
DOI: 10.3390/molecules27123796 -
ACS Applied Materials & Interfaces Mar 2022The giant magnetoresistance (GMR) effect has seen flourishing development from theory to application in the last three decades since its discovery in 1988. Nowadays,... (Review)
Review
The giant magnetoresistance (GMR) effect has seen flourishing development from theory to application in the last three decades since its discovery in 1988. Nowadays, commercial devices based on the GMR effect, such as hard-disk drives, biosensors, magnetic field sensors, microelectromechanical systems (MEMS), etc., are available in the market, by virtue of the advances in state-of-the-art thin-film deposition and micro- and nanofabrication techniques. Different types of GMR biosensor arrays with superior sensitivity and robustness are available at a lower cost for a wide variety of biomedical applications. In this paper, we review the recent advances in GMR-based biomedical applications including disease diagnosis, genotyping, food and drug regulation, brain and cardiac mapping, etc. The GMR magnetic multilayer structure, spin valve, and magnetic granular structure, as well as fundamental theories of the GMR effect, are introduced at first. The emerging topic of flexible GMR for wearable biosensing is also included. Different GMR pattern designs, sensor surface functionalization, bioassay strategies, and on-chip accessories for improved GMR performances are reviewed. It is foreseen that combined with the state-of-the-art complementary metal-oxide-semiconductor (CMOS) electronics, GMR biosensors hold great promise in biomedicine, particularly for point-of-care (POC) disease diagnosis and wearable devices for real-time health monitoring.
Topics: Biosensing Techniques; Electronics; Magnetics; Micro-Electrical-Mechanical Systems; Wearable Electronic Devices
PubMed: 35167743
DOI: 10.1021/acsami.1c20141 -
Sensors (Basel, Switzerland) Sep 2020Biosensors based on magneto-impedance (MI) effect are powerful tools for biomedical applications as they are highly sensitive, stable, exhibit fast response, small in... (Review)
Review
Biosensors based on magneto-impedance (MI) effect are powerful tools for biomedical applications as they are highly sensitive, stable, exhibit fast response, small in size, and have low hysteresis and power consumption. However, the performance of these biosensors is influenced by a variety of factors, including the design, geometry, materials and fabrication procedures. Other less appreciated factors influencing the MI effect include measuring circuit implementation, the material used for construction, geometry of the thin film sensing element, and patterning shapes compatible with the interface microelectronic circuitry. The type magnetic (ferrofluid, Dynabeads, and nanoparticles) and size of the particles, the magnetic particle concentration, magnetic field strength and stray magnetic fields can also affect the sensor sensitivity. Based on these considerations it is proposed that ideal MI biosensor sensitivity could be achieved when the sensor is constructed in sandwich thick magnetic layers with large sensing area in a meander shape, measured with circuitry that provides the lowest possible external inductance at high frequencies, enclosed by a protective layer between magnetic particles and sensing element, and perpendicularly magnetized when detecting high-concentration of magnetic particles.
Topics: Biosensing Techniques; Electric Impedance; Magnetic Fields; Magnetics; Nanoparticles
PubMed: 32932740
DOI: 10.3390/s20185213 -
Journal of Comparative Physiology. A,... Jan 2022In addition to providing animals with a source of directional or 'compass' information, Earth's magnetic field also provides a potential source of positional or 'map'... (Review)
Review
In addition to providing animals with a source of directional or 'compass' information, Earth's magnetic field also provides a potential source of positional or 'map' information that animals might exploit to assess location. In less than a generation, the idea that animals use Earth's magnetic field as a kind of map has gone from a contentious hypothesis to a well-established tenet of animal navigation. Diverse animals ranging from lobsters to birds are now known to use magnetic positional information for a variety of purposes, including staying on track along migratory pathways, adjusting food intake at appropriate points in a migration, remaining within a suitable oceanic region, and navigating toward specific goals. Recent findings also indicate that sea turtles, salmon, and at least some birds imprint on the magnetic field of their natal area when young and use this information to facilitate return as adults, a process that may underlie long-distance natal homing (a.k.a. natal philopatry) in many species. Despite recent progress, much remains to be learned about the organization of magnetic maps, how they develop, and how animals use them in navigation.
Topics: Animal Migration; Animals; Birds; Magnetic Fields; Magnetics; Turtles
PubMed: 34999936
DOI: 10.1007/s00359-021-01529-8 -
Proceedings of the National Academy of... Jan 2022Various physical tweezers for manipulating liquid droplets based on optical, electrical, magnetic, acoustic, or other external fields have emerged and revolutionized...
Various physical tweezers for manipulating liquid droplets based on optical, electrical, magnetic, acoustic, or other external fields have emerged and revolutionized research and application in medical, biological, and environmental fields. Despite notable progress, the existing modalities for droplet control and manipulation are still limited by the extra responsive additives and relatively poor controllability in terms of droplet motion behaviors, such as distance, velocity, and direction. Herein, we report a versatile droplet electrostatic tweezer (DEST) for remotely and programmatically trapping or guiding the liquid droplets under diverse conditions, such as in open and closed spaces and on flat and tilted surfaces as well as in oil medium. DEST, leveraging on the coulomb attraction force resulting from its electrostatic induction to a droplet, could manipulate droplets of various compositions, volumes, and arrays on various substrates, offering a potential platform for a series of applications, such as high-throughput surface-enhanced Raman spectroscopy detection with single measuring time less than 20 s.
Topics: Acoustics; Magnetics; Optical Tweezers; Spectrum Analysis, Raman; Static Electricity
PubMed: 34992136
DOI: 10.1073/pnas.2105459119 -
Saudi Medical Journal Aug 2021To systematically review the occurrence of magnet or receiver/stimulator displacement following cochlear implant (CI) placement complication and evaluate the existing...
OBJECTIVES
To systematically review the occurrence of magnet or receiver/stimulator displacement following cochlear implant (CI) placement complication and evaluate the existing literature on this topic.
METHODS
A systematic literature search was conducted using PubMed, Scopus, Web of Science, Virtual Health Library (VHL), and Cochrane Library. Original studies reporting cases of magnet or receiver-stimulator migration occurring as a complication after CI placement were included. The quality of the included studies was evaluated using the National Institutes of Health Quality Assessment Tool for observational studies and CARE checklist for case studies.
RESULTS
A total of 36 studies, including 6469 patients, were included. Magnet migration was reported in 82 (1.3%) patients, while receiver/stimulator was reported in 4 (0.1%) cases. The cause of magnet migration was identified in 78 cases; MRI-induced movement was the most frequently reported cause (n=43, 55.1%), followed by head trauma (n=25, 32.1%). A total of 20 studies involving 35 patients with magnet migration performed skull radiography to diagnose magnet migration. Revision/exploratory surgery with surgical repositioning or replacement was the most frequent management procedure (n=46).
CONCLUSIONS
Further research on magnet pocket design and standard protocols for MRI in CI users is needed. Early diagnosis of magnet migration and instant referral to specialized CI centers is necessary for proper management and prevention of major complications. PROSPERO REG. NO. CRD: 42020204514.
Topics: Cochlear Implantation; Cochlear Implants; Humans; Magnetic Resonance Imaging; Magnets; Reoperation
PubMed: 34344804
DOI: 10.15537/smj.2021.42.8.20210294