United States

In the marine environment, energy supply for distributed sensors is one of the main difficulties facing Internet of Things technology. Up to now, a variety of energy
harvesters have been created to convert wave kinetic energy into electrical energy through electromagnetic induction, piezoelectric effects and other principles. At present, although some
wave energy harvesters can collect wave energy and provide power for some low-power products, the overall output response frequency is greater than 1Hz[1], which is higher than the
most common wave frequency of 0.25Hz-1.0Hz. Some experts with extensive achievements in energy harvesters are committed to the research of low-frequency and broadband, however,
the output voltage of the designed wave energy harvester is too small[2], meantime the overall structure is extremely complex[3]. In addition, scholars have not explored the multidirectional
energy harvesting enough, and the existing studies are mostly based on the spherical friction structure[4], but spherical shapes can lead to lower energy density or material
utilization. In this paper, an electromagnetic wave energy harvester with a special double pendulum structure (as shown in Fig.1) has been proposed, the energy harvester can also capture
vibrational energy in multiple directions, responding to minimum frequencies of less than 0.25Hz and to currents with velocities of approximately 0.4m/s. This energy harvester can charge
a 220μF capacitor to about 32V in 50s with a peak power of 120mW under vibration conditions with a vertical height of 50 cm and a frequency of 1.0Hz, and can charge the capacitor to
about 16V in 50s at a horizontal speed of 0.72m/s (as shown in Fig.2). The results show that the wave energy harvester designed in this paper can respond to multi-directional vibrations,
and the response frequency is lower and wider, which is more favorable for wave energy harvesting.&lt;br&gt;

**References**&lt;br&gt;

[1] H. Liang, G. Hao and O. Z. Olszewski, International Journal of Mechanical Sciences., Vol. 219, 107130 (2022)&lt;br&gt;
[2] M. Li, X. Jing, Energy Conversion and Management., Vol. 244, 114466 (2021)&lt;br&gt;
[3] Z. Li, X. Jiang and P. Yin, Applied Energy., Vol. 302, 117569 (2021)&lt;br&gt;
[4] Q. Gao, Y. Xu and X. Yu, ACS Nano., Vol. 16, p.6781-6788 (2022)&lt;br&gt;

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MMM 2022

Extremely Low Frequency Multi Directional Electromagnetic Wave Energy Harvester Based on Special Double Pendulum Structure

In the marine environment, energy supply for distributed sensors is one of the main difficulties facing Internet of Things technology. Up to now, a variety of energy
harvesters have been created to convert wave kinetic energy into electrical energy through electromagnetic induction, piezoelectric effects and other principles. At present, although some
wave energy harvesters can collect wave energy and provide power for some low-power products, the overall output response frequency is greater than 1Hz[1], which is higher than the
most common wave frequency of 0.25Hz-1.0Hz. Some experts with extensive achievements in energy harvesters are committed to the research of low-frequency and broadband, however,
the output voltage of the designed wave energy harvester is too small[2], meantime the overall structure is extremely complex[3]. In addition, scholars have not explored the multidirectional
energy harvesting enough, and the existing studies are mostly based on the spherical friction structure[4], but spherical shapes can lead to lower energy density or material
utilization. In this paper, an electromagnetic wave energy harvester with a special double pendulum structure (as shown in Fig.1) has been proposed, the energy harvester can also capture
vibrational energy in multiple directions, responding to minimum frequencies of less than 0.25Hz and to currents with velocities of approximately 0.4m/s. This energy harvester can charge
a 220μF capacitor to about 32V in 50s with a peak power of 120mW under vibration conditions with a vertical height of 50 cm and a frequency of 1.0Hz, and can charge the capacitor to
about 16V in 50s at a horizontal speed of 0.72m/s (as shown in Fig.2). The results show that the wave energy harvester designed in this paper can respond to multi-directional vibrations,
and the response frequency is lower and wider, which is more favorable for wave energy harvesting. 

**References** 

[1] H. Liang, G. Hao and O. Z. Olszewski, International Journal of Mechanical Sciences., Vol. 219, 107130 (2022) 
[2] M. Li, X. Jing, Energy Conversion and Management., Vol. 244, 114466 (2021) 
[3] Z. Li, X. Jiang and P. Yin, Applied Energy., Vol. 302, 117569 (2021) 
[4] Q. Gao, Y. Xu and X. Yu, ACS Nano., Vol. 16, p.6781-6788 (2022) 

![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/8f8db1dbb2c896df18d24c8b4090767a.png)

poster

#### Welcome to the 67th Annual Conference on Magnetism and Magnetic Materials, MMM 2022!

The Conference was held from October 31 to November 4 and offers both in-person and on-demand content.

MMM 2022 is sponsored jointly by AIP Publishing and the IEEE Magnetics Society. Members of the international scientific and engineering communities interested in recent developments in fundamental and applied magnetism are invited to attend and contribute to the technical sessions. The technical program will include invited and contributed papers in oral and poster sessions, invited symposia, a tutorial, and several special sessions. This Conference provides an outstanding opportunity for worldwide participants to meet their colleagues and collaborators and discuss developments in all areas of magnetism research.

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Please register for the MMM 2022 conference to join the event.

This Conference provides an outstanding opportunity for worldwide participants to meet their colleagues and collaborators and discuss developments in all areas of magnetism research.

Variable flux memory machines (VFMM) using low coercive force (LCF) permanent magnets (PM) have been extensively investigated [1]-[5]. Normally, the series hybrid
magnet topology equipped with both PM with high coercive force (HCF) and LCF PMs to achieve high torque density and extended constant power speed range simultaneously, and two
kinds of PMs are magnetically connected in series to avoid unintentional demagnetization in LCF magnets. Nevertheless, the role LCF PM acts in the series magnetic circuit and its
potential effect on the air-gap flux density remain unclear. In this paper, the flux barrier effect of LCF PM on series VFMM is revealed and investigated, and an approach to preventing the
air-gap flux density drop is presented.
The conventional series hybrid magnet VFMM and interior permanent magnet (IPM) machine sharing identical usage of HCF PMs are shown in Fig.1. In Fig.1(e), the back-EMF amplitude
of the series VFMM is lower than that of the IPM machine. This is mainly due to the fact that the air-gap flux enhancement by the magnetomotive force of the LCF PM cannot compete
with the weakening effect by the magnetic reluctance of LCF PM. As a result, the flux barrier effect of the LCF PMs is identified, which further leads to a reduction of the torque density.
The topology of VFMM with dual-layer PMs is shown in Fig.1(c). The separation of the PMs weakens the barrier effect on the HCF PM and the bypass flux path reduces the equivalent
reluctance in the magnetic circuit. It can be observed in Fig.1 (d) that the air-gap flux density and flux variable range are improved. That is to say, the magnetic flux barrier effect of LCF
PM is reduced with the proposed dual-layer PM design.
The test results of the open-circuit back-EMF of the dual-layer series hybrid magnet VFMM prototype are shown in Fig.2. The experiments agree well with the FE-predicted results. The
detailed analysis, suppression methods of the flux barrier effect, and the detailed test results, will be given in the full paper. 

**References:** 

[1] V. Ostovic, "Memory motors," IEEE Ind. Appl. Mag., vol. 9, no. 1, pp. 52-61, Jan./Feb. 2003. 
[2] K. Sakai, K. Yuki, Y. Hashiba, N. Takahashi and K. Yasui, "Principle of the variable-magnetic-force memory motor," in Proc. Inter. Conf. Elec. Mach. System. (ICEMS), 2009, pp. 1-6. 
[3] N. Limsuwan, T. Kato, K. Akatsu and R. D. Lorenz, "Design and evaluation of a variable-flux flux-intensifying interior permanent-magnet machine," IEEE Trans. Ind. Appl., vol. 50,
no. 2, pp. 1015-1024, Mar./Apr. 2014. 
[4] H. Hua, Z. Q. Zhu, A. Pride, R. Deodhar and T. Sasaki, "A novel variable flux memory machine with series hybrid magnets," in Proc. 2016 IEEE Energy Conversion Congress and
Exposition (ECCE), 2016, pp. 1-8. 
[5] H. Yang, H. Zheng, H. Lin, Z. Q. Zhu and S. Lyu, "A novel variable flux dual-layer hybrid magnet memory machine with bypass airspace barriers," in Proc. 2019 IEEE International
Electric Machines & Drives Conference (IEMDC), 2019, pp. 2259-2264. 

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Analysis of flux barrier effect of LCF PM in series hybrid magnet variable flux memory machine

This paper presents the effects of magnetostriction of core loss and sound level on the design of power transformers and the results of analysis via the particle swarm
optimization (PSO) method. The core losses and the magnetostrictive forces in the ferromagnetic cores of transformers of various capacities, ranging from 15 MVA to 120 MVA, were
found to be significantly different from each other, as shown in Figure 1. Further, core loss was approximately proportional to capacity and core volume. However, the sound level
performance was not linear because of the squareness ratio (). This study utilized three types of soft core material: 30ZH105, 27ZH100 (Japan), and 27PH100 (Korea). The hysteresis loop
and magnetostriction were measured for various magnetic parameters. It was found that extremely high does not directly affect core loss. Whenwith respect to the sound level is high, the
experimental and design values are almost the same. The PSO method simulation results for transformers with several capacities, with respect to sound level and core loss performance,
were analyzed and compared with experimental values, as shown in Figure 2. 

**References:** 

[1] L. Bernard, , et. al., “Effect of stress on switched reluctance motors: A magnetoelastic finite-element approach based on multiscale constitutive laws,” IEEE Trans. on
Magnetics, vol. 47, no. 9, pp. 2171–2178, 2011. 
[2] Chang-Hung Hsu, et. al., “Reduction of vibration and sound-level for a single-phase power transformer with large capacity,” IEEE Trans. on Magnetics, vol. 51, no. 11, pp. 8403204-1-
4, 2015. 

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The Influence of Electromagnetic Noise of Volume Magnetostriction Anisotropy on Power Transformers

Introduction: Transcranial Magnetic Stimulation (TMS) is a neuromodulation technique currently FDA approved to treat depression, migraine and obsessive-compulsive
disorder (OCD). TMS outcomes are known to vary based on individual neuroanatomy, tractography derived structural connectivity, and functional connectivity which is not well
understood [1,2]. There is a disconnection between what is measured empirically in resting motor threshold (RMT)/treatment outcomes, and computer simulated induced electric fields (EField)
values based on Magnetic Resonance Imaging (MRI) derived head models. In this study, we aim to gain an understanding and explanation of this variability and offer an
improvement by taking region of interest (ROI) specific gray matter (GMV) and white matter volume (WMV) over a previously published relationship between the brain scalp distance
(BSD) and E-Field in the Transcranial Magnetic Stimulation (TMS).
Experimental Details: Twenty-six mild-to-moderate traumatic brain injury (mTBI) patients were recruited as described in our previous publication [3]. Participants underwent MRI scans
followed by guided repetitive TMS using a NextStim NBS4 figure-of-eight double coil. RMTs were taken as a percentage of the maximum stimulator output (%MSO). T1 weighted MRI
images went through SimNIBS pipeline (v3.2.6) to create anatomically accurate head models for each patient. Head models were imported into Meshmixer (v3.5) where BSD and
individual segment volume were taken from the precentral gyrus (knob) as described in [4].
Results: Preliminary analysis indicates a weak but negative correlation between both GMV (R2 = 0.0307, p = 0.392) and WMV (R2 = 0.0388, p = 0.335) versus RMT. And a stronger
positive correlation between BSD (R2 = 0.29, p = 0.0046) and RMT.
Conclusion: Segmented ROI brain volume didn’t improve the correlation between RMT and 3D brain-scalp volume compared to RMT and 1D brain-scalp distance. Further investigations
into E-Field and correlating empirically collected patient outcomes will enable better TMS dosages as a percentage of patient specific RMT for TMS procedures. 

**References:** 

[1] T. Herbsman, L. Forster, C. Molnar, et al., Human Brain Mapping., 30(7), 2044-2055 (2009). Motor threshold in transcranial magnetic stimulation: the impact of white
matter fiber orientation and skull-to-cortex distance. 
[2] N. Mittal, B. Thakkar, C. B. Hodges, C. Lewis, Y. Cho, R. L. Hadimani, & C. L. Peterson, Human Brain Mapping, 1-16 (2022). Effect of neuroanatomy on corticomotor excitability
during and after transcranial magnetic stimulation and intermittent theta burst stimulation. 
[3] L. M. Franke, G. T. Gitchel, R. A. Perera, R. L. Hadimani, K. L. Holloway & W. C. Walker, Brain Injurty, 36:5, p. 683-692, (2022) Randomized trial of rTMS in traumatic brain injury:
improved subjective neurobehavioral symptoms and increases in EEG delta activity. 
[4] T. A. Yousry, U. D. Schmid, H. Alkadhi, D. Schmidt, A. Peraud, A. Buettner, P. Winkler, Brain, Vol. 120, p.141-157 (1997) Localization of the motor hand area to a knob on the
precentral gyrus. A new landmark. 

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Relationship Between Resting Motor Threshold and Neuroanatomy in Mild to Moderate Traumatic Brain Injury Patients during Transcranial Magnetic Stimulation

Lowering the power requirements of transcranial magnetic stimulation (TMS) would allow reducing the size and form factor of the stimulating coils, increasing the focality and penetration depth during the stimulation. Commercial TMS equipment typically uses frequencies from 1 to 5 kHz, while the coil currents vary from 1 to 5 kA. According to the Maxwell-Faraday equation, a large â€“dB/dt is required in the coil to induce an E-field above a stimulation threshold around 100 V/m at the target (Fig 1). Therefore, the development of technologies able to obtain similar E-field strength with lower currents is required. This work shows the design, construction, and tests of a novel high-frequency TM stimulator. For the first time to our knowledge, we have used analog modulations (AM/DSB-SC) over a carrier of 25 kHz to obtain a â€“dB/dt 10 times larger than the commercial stimulators. This permitted the reduction of the TMS currents in the same ratio, with a stimulation tone of 1.5 kHz over the carrier. The modulation shifts the stimulating energy out of the TMS band and audible range, leading to soundless operation compared to the uncomfortable clicking sound in current TMS equipment. Our results demonstrated: a reduction of currents to reach the referential E-field threshold of 100 V/m; a decrease of power dissipation in coils with possibility of unrestricted repetitive TMS (rTMS); a reduction in the coil sizes with increased focality and penetration depth; and hardware requirement reduction. Experimental work with rodents is in progress to demonstrate that, although the modulated signal will not stimulate neurons directly at such high frequency (due to the low-frequency response of the cell membrane), the demodulated version of it, obtained within the brain tissue with the superposition of a non-modulated carrier, can effectively recover the low-frequency envelope, stimulate neurons and induce motor evoked potentials (MEPs) (Fig. 1 and 2).

Development of Novel Transcranial Magnetic Stimulation Technique Using High frequency Modulation for Treatment of Parkinson’s Disease

Transcranial Magnetic Stimulation (TMS) coils are usually specialized for use in either deep brain or focal stimulation. One of the challenges in the development of TMS
therapy is the ability to deliver a focused magnetic field to the desires target in the brain. In the process of delivering a sufficiently strong H field to the target, surrounding areas of the brain
can be stimulated unnecessarily. A new technique is used here whereby deep and focal stimulation can be achieved using temporal interference (TI). TI is a method that allows for control
of steerability, focality, and depth of penetration. TI uses the frequency difference of two independent electric fields [1]. The TI stimulation frequencies in at 10kHz and is filtered by the
brain’s inherent lowpass [2] behavior [3]. The frequency difference between the two induced electric fields results in an envelope which allows improved focality of stimulation. By using a
coil assembly as shown in Figure 1, and using TI, the focality of the peak induced electric can be increased with respect to the surrounding area as shown inf Figure 2.. This focal point can
also be steered along the centerline between the two coils. Our current work involves using Sim4Life software on 50 unique head models derived from magnetic resonance imaging (MRI)
scans. We are investigating the focality of the induced electric field using our coil design with TI signals. The results will be compared with the commonly used figure-of-eight TMS coil
and the novel design Quadruple Butterfly Coil (QBC) [4]. 

**References:** 

[1] M. Zaeimbashi, A. Khalifa, C. Dong, Y. Wei, S. Cash, and N. Sun, “Magnetic Temporal Interference For Noninvasive, High-resolution, and Localized Deep Brain
Stimulation: Concept Validation,” 2020. 
[2] B. Hutcheon and Y. Yarom, “Resonance, oscillation and the intrinsic frequency preferences of neurons,” Trends in Neurosciences, vol. 23, no. 5, pp. 216–222, 2000. 
[3] M. M. Sorkhabi, K. Wendt, and T. Denison, “Temporally Interfering TMS: Focal and Dynamic Stimulation Location,” 2020 42nd Annual International Conference of the IEEE
Engineering in Medicine & Biology Society (EMBC), 2020. 
[4] P. Rastogi, “Novel coil designs for different neurological disorders in transcranial magnetic stimulation,” PhD Thesis, Iowa State University, Ames, IA, USA, 2019. Available:
https://lib.dr.iastate.edu/etd/17547
Brain Mapping, vol. 29, no. 1, pp. 82–96, 2007. 

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Temporal Interference for Increased Focality of Transcranial Magnetic Stimulation

In this in vivo study, we have used Magnetic Pen or MagPen (see Fig. 1(a)) to stimulate the rat sciatic nerve which led to the report of the dosage response curve for
micromagnetic stimulation (μMS). As reported earlier [1], the MagPen prototype consists of sub-mm size microcoil (μcoil) at its tip (see Fig. 1(b)). When driven by alternating current, this
μcoil generates a time-varying magnetic field, which induces an electric field on any conductor (here, the sciatic nerve) according to Faraday’s Law of electromagnetic induction. This
induced electric field activates the nerve. This work reports how the directionality of the magnetic μcoil plays a direct role in activating nerves directly observed in hind limb muscle
twitches. These limb twitches have been quantitatively characterized using electromyography (EMG) recordings. Furthermore, we have studied how on varying the amplitude and
frequency of the micromagnetic stimuli, alters hind limb muscle movements. Thereby, a dosage response curve for μMS was generated. The highlight of this dosage response curve is that,
at higher frequencies, significantly smaller amplitudes of MagPen stimuli can trigger limb twitches. This frequency-dependent nerve activation can be explained directly from Faraday’s
Law as the magnitude of the induced electric field used in neuromodulation is proportional to frequency. In our previous work of in vitro μMS of rat hippocampal slices [1], we explained
the frequency-dependent, low-power activation of μMS through numerical simulations. This work further corroborates the same concept through experiments. Implantable μMS is a novel
neuromodulation technique which is still in its infancy and aims to address the potential drawbacks of electrical implants in terms of MRI compatibility and biofouling. Since the induced
electric fields from these magnetic μcoils are not in galvanic contact with the nerve, μMS offers flexibility in applying waveforms to drive these magnetic implants (see Fig. 1(c)).
Fig 1. (a) Different directionalities of the MagPen prototype. Only Type V can activate the sciatic nerve. (b) Size of the sub-mm size μcoil implant compared to a rice grain. (c) The
waveform that activated the nerve. 

**References:** 

[1] Saha R., Faramarji S et al. (2022) Strength-frequency curve for micromagnetic neurostimulation (μMS) through EPSPs and numerical modeling. J. Neural Eng. 19 016018. 

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In vivo Micromagnetic Stimulation of the Rat Sciatic Nerve

Maintenance of homoeostasis in human body is a very important indicator in all cell activities. Persistent acid-base imbalance leads to diseases such as metabolic and
respiratory acidosis or alkalosis. When exposed to a disease, various immune cells are activated due to the inflammatory response, and particularly T cells play a role in inducing apoptosis
of mutated cells such as tumor cells. When the activity of T cells is very low, infection by external invasion is easy, and on the contrary, excessive activation lead to chronic inflammation
caused by autoimmune diseases. Many clinical studies related to pulsed magnetic field (PMF) demonstrated its efficacy in reducing pain, improving blood circulation, as well as blood's
acid-base balance.[1-2] Therefore, our study has tried to investigate the influence of PMF on the regulation of acid-base homeostasis in EL4 cells, which are T cells formed through
lymphoma generated by inducing 9,10-dimethyl-1,2-benzanthrance to C57BL mice. In addition, we tried to explain the role of PMF on immune cell activity by measuring the level of proinflammatory
cytokines such as TNF-α and INF-γ in culture supernatants. EL4 cells were cultured in a DMEM medium supplemented with 10% FBS and 1% penicillin at a concentration
of 5.5 × 104 cells/ml in an incubator at 37 °C and 5% CO2 condition. Our PMF stimulator has the maximum intensity of 4700G at a transition time of 222 μs with pulse intervals of 1Hz.
The homoeostasis in pH was improved as the intensity of PMF increases.(Fig.1) Cell viability decreased by 32% after PMF stimulus of 4700G. It was observed that the concentration of
TNF-α and INF-γ, a cytokine related to inflammation, also decreased as the strength of PMF increased. These results suggest that PMF stimulus improves the anti-inflammatory effect,
therefore, it is thought to affect the immune system of the human body by balancing the activation and suppression of immune cells. For clinical use, our study might suggest non-invasive
PMF can be developed as a medical devices modulating immune system, although it is necessary to optimize the PMF conditions such as pulse shape, duration, or repetition rate. 

**References:** 

[1] N. M. Shupak, F. S. Prato & A. W. Thomas, Neurosci. Lett. Vol. 363, p.157–162(2004). 
[2] S. Bang & H. Lee, AIP Advances, 11(1), 015242(2021). 

![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/e6f0eb8f8e290ce7d76a58b9278f554b.png)

Effect of pulsed magnetic field in murine T lymphoma EL4 cells

The use of magnetic nanoparticles for cancer cell destruction is widely known due to their applications such as magnetic hyperthermia and magneto mechanical actuation
(MMA). Previously, we presented our results regarding a new type of magnetic particles (MPs), i.e. Fe-Cr-Nb-B MPs, prepared by wet milling of superferromagnetic precursor glassy
ribbons, designed for cancer treatment by MMA [1]. These MPs have an important shape anisotropy and a large saturation magnetization, which generates an improved torque in a rotating
magnetic field, producing important damages on the cellular viability of cancer cells. Inspired by these findings, we tested the possibility of using magnetic nanowires (NWs) that have a
higher shape anisotropy. Furthermore, the Fe-Co alloy that we propose has high saturation magnetization values. We prepared Fe64.5Co35.5 NWs with lengths of 4 microns by electrolytic
deposition in alumina membranes with a pore diameter of 200 nm.
The Fe-Cr-Nb-B MPs and Fe-Co nanowires were tested on human osteosarcoma cells (HOS) using various concentrations of particles and found that both are biocompatible in vitro.
Subsequently, we studied the effect of MMA in a rotating 80 Oe magnetic field and frequency of 2 Hz on the viability of HOS. We used MPs and NW with different concentrations, and
exposure time of 30 minutes, applied 24 hours after the introduction of the MPs and NWs into cell culture media. The results indicated that with a concentration of 1 mg/ml of MPs and 0.1
mg/ml of NWs, respectively, the cell viability decreased to about 6-7%. The concentration of NWs needed to induce cancer cell death is 10 times lower than the one needed for MPs. It is
worth mentioning that although NWs are more efficient when using low quantities, due to their higher magnetization and anisotropy, the magnetic nanoparticles are better internalized and
metabolized by cells. Therefore, MPs can be better targeted in tissues harder to reach than NWs. The latter are also harder to control, being more suitable for superficially-developed cancer
tissues.
Supported by (UEFISCDI) Contract no. PCE20/2021 (PN-III-P4-ID-PCE-2020-2381). 

**References:**
 1. H. Chiriac et al. Sci. Rep., 8.11538 (2018)

Cancer cell destruction by magneto mechanical actuation of nanowires compared with nano/micromagnetic particles

Nanosized magnetic materials form a single domain and, as a result, magnetic nanoparticles (MNPs) usually lose their ferromagnetic properties. However,
superparamagnetic NPs can generate sufficient heat to kill cancer cells under a weak magnetic field. In this study, NiFe2O4 NPs with particle sizes of 3–17 nm were prepared for
application in magnetic hyperthermia treatment (MHT), and their biocompatibility was improved by modification with polyethylene glycol (PEG). PEG is hydrophilic and is often used in
the medical field. Direct current (DC) magnetization measurements showed that all the samples exhibited no hysteresis or superparamagnetic behavior at 300 K. The temperature
dependence of the alternating current (AC) magnetic susceptibilities revealed that the peak temperature of the imaginary part of AC magnetic susceptibilities (χ") varied significantly with
particle size, and the 17 nm sample had a peak at approximately 310 K. It is known that χ" contributes significantly to heat generation owing to magnetic relaxation losses. The temperature
increase of the samples under an AC magnetic field (f = 15 kHz, h = 150 Oe) was measured. The sample with 17 nm particles showed a significant heating effect compared to the other
samples, reaching over 42.5 °C, which is sufficient to suppress cancer cells. Human breast cancer cells (MDA-MB-231) were cultured on a petri dish, and PEG-coated NiFe2O4 NPs were
added. The sample was heated using an AC magnetic field. Approximately 30% of cancer cells were successfully killed, and the magnetic hyperthermia effect was confirmed (Fig.1). To
evaluate the toxicity of PEG-coated magnetic NPs toward cancer cells, cell viability was observed for 24 h after the particles were dispersed in the culture dishes. PEG-coated NiFe2O4 NPs
successfully improved biocompatibility. Thus, NiFe2O4 NPs are expected to be useful agents for MHT. By using a zero-voltage switching (ZVS) circuit and generating an AC magnetic
field from a DC power source, a temperature rise two to eight times higher than that using conventional coils was achieved (Fig.2). 

**References:** 

P. Das, M. Colombo, D. Prosperi, Coll. Surf. B 174, 42 (2019) 

![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/817ebb10ae8b4a8d27386ab0b240148a.png)

Biocompatible Superparamagnetic NiFe2O4 Nanoparticles for Magnetic Hyperthermia Treatment using a ZVS Circuit

This work describes the use of magnetoresistive (MR) sensors coupled with a portable platform for the detection of dengue virus (DENV), a mosquito-borne infection
endemic to low- and middle-income countries, affecting 100-400 million people each year[1]. Nowadays, diagnosis relies on molecular or serological tests. Still, these tests remain discrete
(RNA vs. antibodies), and tend to be complex and/or expensive, requiring expert staff and fully equipped laboratories. As such, this work aims to combine both assays in a single analysis
by simultaneously detecting DENV RNA and anti-DENV antibodies using a portable platform[2,3]. A spin-valve based biochip was designed and functionalized with specific DNA oligo
probes and secondary antibodies (Fig1A)[4]. Extracted RNA and serum samples were provided by INSA-CEVDI and used as targets in molecular and serological assays, respectively. In
both assays, streptavidin coated 250 nm magnetic nanoparticles were used for biolabeling. The measurement output is represented by a voltage drop (dV/V) proportional to the number of
captured target molecules (Fig1B). However, to increase the dynamic range of the assays, the percentage difference of dV/V signals obtained using different immobilization
strategies/probes, was taken as the final output signal. Using the MR-platform, individual tests were carried out for the detection of DENV RNA and anti-dengue human antibodies. The
RNA target was detected down to a few hundreds of pM (Fig2A). For the serological response, a calibration curve with an LOD of 1.38 nM was achieved. Infected patients’ serum was also
tested for anti-DENV antibodies, obtaining a sensitivity of 100% and a specificity of 92%(Fig2B). Finally, simultaneous detection of antibodies and RNA was successfully achieved on the
same chip, showing no differences to the individual assays. To increase the multiplexing capability of the assay, a biochip with 144 sensors and multi-level contact layers was developed
and is under testing using DENV as a model disease. This chip design will allow the simultaneous discrimination of various viruses endemic in the same regions. 

**References:** 

[1] Who.int. 2022. Dengue and severe dengue. [online] Available at: <https://www.who.int/news-room/fact-sheets/detail/dengue-and-severe-dengue> [Accessed 14 June 2022]. 
[2] J. Germano et al., Sensors 9, 4119 (2009). 
[3] V. C. Martins et al., Biosensors and Bioelectronics 24, 2690 (2009). 
[4] D. C. Albuquerque et al., Biosensors and Bioelectronics 210, 114302 (2022). 

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