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Magnetic fields are widely utilized for remote control of magnetic objects, with various actuation systems developed for manipulating miniature robots in research and biomedical applications. When designing a manipulation system providing a uniform magnetic field, it is also important to consider both the accessibility of the workspace and the integration of imaging tools. This article presents an electromagnetic coil system that manipulates magnetic objects within a 3D space, enhancing the magnetic field in an upward orientation. The system includes eight metal‐core coils arranged hemispherically to ensure unimpeded access to the workspace and imaging tools, along with two air‐core coils. Easier control and repeatability of the magnetic field are achieved using two joysticks and sequential programming. The versatility of the system is demonstrated by using it to manipulate a magnetic guidewire and to guide micromagnets to various targets. Additionally, using this system, oscillating magnetic fields effectively control swarms of magnetic nanoparticles, enabling operations such as dispersion, assembly, and ribbon‐like shape formation. Furthermore, the manipulation of cell‐based microrobots (cell‐bots) showcases the system's capability to handle single and multiple cell‐bots, facilitating their collection while preserving cell viability. These experiments underscore the system's potential for fundamental biomedical research and various applications. An electromagnetic manipulation system enhances magnetic field strength in the Z‐direction for 3D control of microrobots and nanoparticles. Featuring eight metal‐core coils and two air‐core coils arranged hemispherically, it ensures unimpeded workspace access and integrates imaging tools. Quantitative experiments demonstrate its efficacy in guiding micromagnets, controlling nanoparticles, and manipulating cell‐based microrobots, underscoring its potential for biomedical research.

Structural discontinuity in the spinal cord after injury results in a disruption in the impulse conduction resulting in loss of various bodily functions depending upon the level of injury. This article presents a summary of the scientific research employing electrical stimulation as a means for anatomical or functional recovery for patients suffering from spinal cord injury. Electrical stimulation in the form of functional electrical stimulation (FES) can help facilitate and improve upper/lower limb mobility along with other body functions lost due to injury e.g. respiratory, sexual, bladder or bowel functions by applying a controlled electrical stimulus to generate contractions and functional movement in the paralysed muscles. The available rehabilitative techniques based on FES technology and various Food and Drug Administration, USA approved neuroprosthetic devices that are in use are discussed. The second part of the article summarises the experimental work done in the past 2 decades to study the effects of weakly applied direct current fields in promoting regeneration of neurites towards the cathode and the new emerging technique of oscillating field stimulation which has shown to promote bidirectional regeneration in the injured nerve fibres. The present article is not intended to be an exhaustive review but rather a summary aiming to highlight these two applications of electrical stimulation and the degree of anatomical/functional recovery associated with these in the field of spinal cord injury research.

The mammalian spinal cord (SC) has a limited self-repair capacity and exogenous treatments are yet to produce substantial functional recovery following SC injury (SCI). The SC contains endogenous neural stem cells (NSCs) with multi-lineage differentiation potential and it may be possible to restore function via interventions that promote NSC differentiation following SCI. Oscillating field stimulation (OFS) has been reported to regulate the Wnt signaling pathway, a known modulator of NSC differentiation. However, the effects of OFS on NSC differentiation following SCI and associated functional recovery have not been previously examined. In the current study, the Basso-Beattie-Bresnahan (BBB) score was used to assess locomotion recovery following SCI in rats and immunofluorescence double-staining was used to examine the regeneration of neurons and oligodendrocytes derived from NSCs. Furthermore, Nissl staining was performed to assess the viability and survival of neurons following SCI, while recovery of the myelin sheath was examined by uranium-lead staining under transmission electron microscopy. OFS delivered via an implanted stimulator enhanced the differentiation of NSCs into neurons and oligodendrocytes and accelerated the regeneration of myelinated axons. Additionally, BBB scores revealed superior locomotion recovery in OFS-treated rats compared with SCI controls. Collectively, these results indicated that OFS may be a feasible strategy to promote SCI recovery by regulating the differentiation of endogenous NSCs.

A description of the dynamical response of uniformly trapped Bose-Einstein condensates (BECs) to oscillating external gravitational fields is developed, with the inclusion of damping. Two different effects that can lead to the creation of phonons in the BEC are identified; direct driving and parametric driving. Additionally, the oscillating gravitational field couples phonon modes, which can lead to the transition of excitations between modes. The special case of the gravitational field of a small, oscillating sphere located closely to the BEC is considered. It is shown that measurement of the effects may be possible for oscillating source masses down to the milligram scale, with a signal to noise ratio of the order of 10. To this end, noise terms and variations of experimental parameters are discussed and generic experimental parameters are given for specific atom species. The results of this article suggest the utility of BECs as sensors for the gravitational field of very small oscillating objects which may help pave the way towards gravity experiments with masses in the quantum regime.

In this paper, we present results of a theoretical study of circulation flow in ferrofluids under the action of an alternating inhomogeneous magnetic field. The results show that the field with the amplitude of about 17 kA m −1 and angular frequency 10 s −1 can induce mesoscopic flow with a velocity amplitude of about 0.5 mm s −1 . This mechanism can be used for intensification of drag delivery in blood vessels. This article is part of the theme issue ‘Patterns in soft and biological matters'.

We present results of theoretical modelling of macroscopic circulating flow induced in a cloud of ferrofluid by an oscillating magnetic field. The cloud is placed in a cylindrical channel filled by a nonmagnetic liquid. The aim of this work is the development of a scientific basis for a progressive method of addressing drug delivery to thrombus clots in blood vessels with the help of the magnetically induced circulation flow. Our results show that the oscillating field can induce, inside and near the cloud, specific circulating flows with the velocity amplitude about several millimetres per second. These flows can significantly increase the rate of transport of the molecular non-magnetic impurity in the channel. This article is part of the theme issue ‘Transport phenomena in complex systems (part 1)’.

Transcranial alternating current stimulation (tACS) applies exogenous oscillatory electric field potentials to entrain neural rhythms and is used to investigate brain-function relationships and its potential to enhance perceptual and cognitive performance. However, due to current spread tACS can cause cutaneous activation of the retina and phosphenes. Several lines of evidence suggest that retinal phosphenes are capable of inducing neural entrainment, making the contributions of central and peripheral stimulation to the effects in the brain difficult to disentangle. In this literature review, the importance of this issue is further illustrated by the fact that photic stimulation can have a direct impact on perceptual and cognitive performance. This leaves open the possibility that peripheral photic stimulation can at least in part explain the central effects that are attributed to tACS. The extent to which phosphene perception contributes to the effects of exogenous oscillatory electric fields in the brain and influence perception and cognitive performance needs to be examined to understand the working mechanisms of tACS in neurophysiology and behaviour. •Transcranial alternating current stimulation evokes phosphenes as a result of current spread to the retina of the eyes.•Retinal phosphenes induce neural entrainment.•Effects of transcranial alternating current stimulation are influenced by retinal phosphenes.•Retinal phosphenes can contribute to perceptual and cognitive performance.

Supercooling has numerous applications in the bio-preservation and food cold chain. This study investigated the effects of oscillating magnetic fields at different intensity levels on the preservation of cherries during supercooling. The magnetic field frequency was 50 Hz, and by applying the magnetic field of 0.1 mT level and mT level intensity, the experiment demonstrated that the magnetic field of mT level could better maintain the degree of supercooling of cherries, and realized 24 h supercooling storage at − 4 ℃. The supercooled samples exhibited food quality comparable to that of the fresh samples, with weight loss in the supercooled samples reduced by 73.2% in comparison to the control group. The mechanism of the effect of different level of magnetic energy density on cherry supercooling is explored from the macroscopic point of view of thermodynamic and the microscopic point of view of hydrogen bonding of water molecules. The oscillating magnetic field makes the Gibbs free energy of water molecules as a whole rise, which leads to a larger energy barrier required for crystallization. In addition, the magnetic field inhibits crystallization by weakening the hydrogen bonding within the water molecule clusters so that the water molecule cluster size does not reach the critical radius. To a certain extent the higher the magnetic energy density, about less prone to freezing under the same supercooling conditions, providing a reference for the future determination of the lowest magnetic energy density for different fruits, and helping to reduce the energy consumption of this technology.

A number of novel freezing systems have been developed that claim to improve the quality of frozen foods by enhancing supercooling in the food prior to ice nucleation and consequently controlling ice crystal formation. One of these is the Cells Alive System (CAS) produced by ABI of Japan, which applies oscillating magnetic fields (OMF) during freezing. This study was carried out to investigate what effect applying OMF (0.04 to 0.53 mT) during freezing had on the freezing characteristics of pork loin samples when compared to freezing under the same conditions without OMF. Overall, the results of this study clearly indicate that freezing under the OMF conditions used in these experiments had no significant effect on the freezing characteristics of pork, in comparison with freezing under the same conditions without OMF.

Purpose Triple-negative breast cancer continues to be one of the leading causes of death in women, making up 7% of all cancer deaths. Tumor-treating electric fields are low-energy, low-frequency oscillating electric fields that induce an anti-proliferative effect on mitotic cells in glioblastoma multiforme, non-small cell lung cancer, and ovarian cancer. Little is known about effects of tumor-treating fields on triple-negative breast cancer and known research for tumor-treating fields only utilizes low (< 3 V/cm) electric field intensities. Methods We have developed an in-house field delivery device capable of high levels of customization to explore a much wider variety of electric field and treatment parameters. Furthermore, we investigated the selectivity of tumor-treating field treatment between triple-negative breast cancer and human breast epithelial cells. Results Tumor-treating fields show greatest efficacy against triple-negative breast cancer cell lines between 1 and 3 V/cm electric field intensities while having little effect on epithelial cells. Conclusion These results provide a clear therapeutic window for tumor-treating field delivery to triple-negative breast cancer.