Transactions of China Electrotechnical Society  2024, Vol. 39 Issue (13): 3907-3916    DOI: 10.19595/j.cnki.1000-6753.tces.230649
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High Repetitive Frequency Pulsed Magnetic Field Generator for Cell Activity Studies
Fan Junxian1,2, Zhang Shaozhe1,2, Li Kexin3, Xiang Wenpei3, Han Xiaotao1,2
1. National High Magnetic Field Center Huazhong University of Science and Technology Wuhan 430074 China;
2. State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China;
3. Institute of Reproductive Health Tongji Medical College Huazhong University of Science and Technology Wuhan 430074 China

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Abstract  Cell responses to magnetic fields obey an electromagnetic efficacy window defined by a specific combination of frequency, amplitude and time of exposure. Previous studies suggest that the specific pulsed magnetic field sequences have the potential to modulate the regulation of certain types of cells and tissues. Based on the needs of cell research, it is necessary to develop a programmable pulsed magnetic field generator with a peak magnetic field intensity up to 10 mT, a high stability, a wide range of frequency, a steep pulse edge and a configurable Inter-Stimulus Interval. However, the magnet is a large inductive load, the magnet voltage in the rising edge of the pulse needs to be tens of times higher than that in the flat top stage, which makes it challenge to adjust the magnet current with both high repetitive frequency and high precision.
In this paper, a high repetitive frequency pulsed magnetic field generator to solve the above contradiction was developed. Firstly, the structure of the magnet was designed as a double-layer helical coil, and the unevenness of the cell culture area at the center was 2.4%. The ratio of magnetic field to the current in the magnet was 2 mT/A, and the requirements of the power supply were presented based on the magnet parameters. Secondly, a two-stage joint topology consisting of a synchronous Buck circuit and a bridge circuit was proposed. The working principle of the topology was explained and the calculation formulas for the parameters of the main components were derived. Lastly, in order to achieve the smooth transition of the current from the rapid rise to the stable value, the small-signal analysis of the power supply system was performed to obtain the transfer function of the duty cycle and the output current. Using the results, this paper configured a hybrid controller utilizing the time-optimal dynamic response of the hysteresis controller and the strong steady-state tracking capability of the PI controller. The feasibility of the scheme was verified by simulations.
Based on these, a portable high repetitive frequency pulsed magnetic field generator with a frequency range of 1 Hz~5 kHz, pulse edge less than 50 μs, adjustable precision of 0.1 mT, and peak intensity up to 10 mT was fabricated. A user-friendly Human-Machine Interface was developed to facilitate the effortless recording of experimental data and monitoring of device status. The ratio of magnetic field to the current was measured in the experiments, and the error was less than 0.15% compared to the theoretical values. This paper tested the magnetic field waveforms for different target values, demonstrating the flexibility and the stability of the device. To mitigate the impact of parasitic capacitance on the magnet at high frequencies, the parasitic capacitance value was calculated followed by the design of a continuous current circuit to suppress the oscillation of the magnet voltage. Finally, biological experiments were carried out to observe the effect of the magnetic field on the fertilization ability and embryo development ability of oocytes from aged mice. Exposed to the 1 mT pulsed magnetic field sequence for 10 minutes, the blastocyst developmental rate increased from 15.15% to 52.94%. These results indicate that the pulsed magnetic field significantly enhances the developmental ability of oocytes in elderly mice.
Key wordsRepetitive pulsed magnetic field      cell activity      magnetic field generator      hybrid controller     
Received: 08 May 2023     
PACS: TM46  
  Q28  
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Fan Junxian
Zhang Shaozhe
Li Kexin
Xiang Wenpei
Han Xiaotao
Cite this article:   
Fan Junxian,Zhang Shaozhe,Li Kexin等. High Repetitive Frequency Pulsed Magnetic Field Generator for Cell Activity Studies[J]. Transactions of China Electrotechnical Society, 2024, 39(13): 3907-3916.
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https://dgjsxb.ces-transaction.com/EN/10.19595/j.cnki.1000-6753.tces.230649     OR     https://dgjsxb.ces-transaction.com/EN/Y2024/V39/I13/3907
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