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Bioelectromagnetism

 

1.4 Applications of Electromagnetism in Medicine and Biology

Te advancement in understanding the relationship between electromagnetism and physiology is creat­

ing non-invasive methods for medical treatment. Bioelectromagnetism and electromagnetic felds play

important roles in biomedical engineering. Electromagnetic felds have a strong potential for medical

and therapeutic applications. Tese applications include the use of pulsed magnetic felds, low-frequency

electric and magnetic felds and radiofrequency electromagnetic felds. Shortwave and microwave dia­

thermies have already been used.

As already mentioned, bioelectromagnetism can be divided mainly into two distinct categories. Te

frst is focused on researching the benefcial efects of electromagnetic felds, which have strong poten­

tial in diagnostic and therapeutic applications in medicine. For example, MRI, a non-invasive medical

imaging technique, uses a high-strength magnetic feld, a rapid changing magnetic feld and a radio-

frequency electromagnetic feld. Te second focuses on the research of the interaction between electro­

magnetic felds and living systems, promoting the understanding of the biological and health hazards

efects associated with the exposure to electromagnetic felds.

Ueno and Sekino edited a book on the recent advances of biomagnetics, and particularly, on the

applications of biomagnetic stimulation and bioimaging (Ueno and Sekino, 2016; Ueno, 2020). Te book

reviews principles and applications of biomagnetic stimulation and imaging based mainly on the edi­

tor’s original research which produced signifcant scientifc and technical development in the feld of the

biomagnetics, such as transcranial magnetic stimulation (TMS), biomagnetic measurements and imag­

ing of the human brain by magnetoencephalography (MEG) and by MRI, and the biomagnetic approach

to treat cancers, pain and other neurological and psychiatric diseases such as Alzheimer’s disease and

depression. Since the time when Ueno and Sekino’s book was published, the bioimaging and biosensing

technologies have rapidly developed. Recently, Ueno edited a book which focuses on biomedical imag­

ing and sensing technologies in medicine and technology (Ueno, 2020). Tis book covered scientifc

achievements and imaging technologies using electromagnetics and light. Ueno’s book also reviewed

the recent advances in electromagnetics in medicine and biology (Ueno, 2021). Tis book discussed the

new horizons in bioelectromagnetics, particularly, the potential therapeutic treatment of brain diseases

based on the efects of radiofrequency electromagnetic felds on iron ion release, and uptake into iron

cage proteins, like ferritins.

TMS utilizes a magnetic feld (1–10 kHz) to stimulate nerve cells for the treatment of mental and

neurological diseases (Shigemitsu and Ueno, 2017; Ueno et al., 2019). Magnetic induction tomography

(MIT) and MRI-based electrical properties tomography (MR-EPT) are non-invasive methods for char­

acterizing electromagnetic properties of biological systems at operating frequencies in the range of

10 kHz–30 MHz and from a few MHz to a few hundred MHz. MIT is an imaging technique for mapping

passive electrical properties such as conductivity, permittivity and permeability that could be quicker,

more convenient and less harmless method for tomography in comparison to MRI and to computer

tomography (CT) (Klein et al., 2020). Tis technique applies a magnetic feld to induce eddy currents in

the biological material through an excitation coil, which is mainly used in non-destructive inspection of

in industrial products. MR-EPT is an imaging method that maps the electrical properties of biomateri­

als by the measurement of radiofrequency electromagnetic felds in MRI (Chi et al., 2020). Tis tech­

nique is of interest in clinical diagnosis, in particular, in ultra-high MRI due to the potential evaluation

of patient-specifc absorption rate (SAR).

In the long history of bioelectromagnetism, imaging techniques using non-ionizing radiation, such as

MRI, have been developed and are now used in chemistry, physics, medicine and in engineering felds

like non-destructive testing and security. Te discovery of electromagnetic waves by Maxwell and Hertz

contributed to these achievements. With the progress of electronic and optical technologies, there is

now a lot of research on imaging using electromagnetic waves in the terahertz region, which is close to

light. In the electromagnetic spectrum, a THz wave is typically defned as a radiation with a frequency

between 0.1 and 10 THz (1 THz = 10¹² Hz) and a wavelength between 30 and 3,000 μm. THz waves are