Electromagnetics essentially play leading roles in medical and/or biological research – the interaction of electromagnetic fields with biological systems has been the key to relevant investigations. Within the context, the exposure of human body organs to various types of radiations has been of great concern. For example, one may quote scanning systems that include X-rays, MRI, and lasers, which have been vital in medical diagnostics of various diseases. Considering the importance of electromagnetics in bio-related areas, this Special Issue – Electromagnetics for Biological and Medicinal Applications – of the Journal of Electromagnetic Waves and Applications (JEMWA) focuses on different aspects of electromagnetic exposition to certain mediums that may be utilized for medical applications.
Blood and urine in human body constitute key components to detect certain diseases, for which medical tests and procedures are used to diagnose, and treatments are prescribed under wide variety of conditions. In this stream, the dielectric behavior of blood/urine has been among the subjects with diabetes mellitus. In this Special Issue of JEMWA, Mun et al. presented measurements of the dielectric properties of glycosuria at microwave frequencies at various temperatures of normal convenience using coaxial probe, and tried to match the experimental results with Debye model. Considering different glycosuria groups, it is reported that the dielectric constant strongly depends on the glycosuria level – the method that can be harnessed to ultimately treat diabetic patients.
The use of nano-engineered metallic complex mediums in the monitoring of urine is also discussed in one of the papers in this Special Issue of JEMWA taking into account sculptured thin films (STFs) and columnar thin films (CTFs) treated under the Turbadar–Kretschmann–Raether (TKR) configuration for the coupling of light. The STFs are, in this investigation, comprised of copper nano-helix structures of two different helical turns grown over planar glass surface, whereas the CTFs indicate thin films of copper nano-rods oriented with two different slanting angles. In general, STFs and CTFs both can be used for the sensing purpose. However, a comparison of the results in these two situations exhibits that the STFs yield enhanced sensitivity as compared to what is obtained corresponding to the usage of CTFs into the system.
It is noteworthy that chiral metamaterials can be used for different sensing purposes. Apart from sensing blood hemoglobin, diabetic issues, and urine infections optically, these metamaterials may be used for other biosensing applications as well, such as the monitoring of temperature of marrowbone using microwaves – the technique that is touched upon in this Special Issue, where the design of highly sensitive microwave biosensor based on chiral metamaterials is proposed to determine the temperature of biological tissues of pigs through simulations and experiments. Interestingly, such kinds of microwave biosensors can be realized for real-life applications as well through tuning the structural design as per the frequency range of detection.
Computational electromagnetics has also been of great applications in medical research. This can be further justified through the work presented by Eskandari et al. that is pivoted to the detection of 2D objects through microwave imaging. The work reports simulated results for scattering of microwaves by dielectric and multiple objects immersed in air; the algorithm combines linear sampling method with the sensitivity analysis. Apart from the scattering problems, the use of microwaves to monitor enzyme reactions is discussed by Fanti et al. through simulations. In this work, the electromagnetic behavior of suitably designed resonant cavity is studied under the excitation by microwaves with the aim of using the same to observe enzyme catalyzed homogeneous reactions performed in polar mediums and other biological materials.
High-energy waves do have strong potentials to cause ionization, thereby making the exposure to various types of radiations as of great concern. Health hazards due to prolonged exposure to electromagnetic radiations, e.g. those emitted by cellular phones, base station antennas, and power lines, cannot be ignored. These radiations, in particular, would leave harmful effects on child’s head and brain. The biological effect of high-frequency electromagnetic radiation is predominantly thermal in nature due to the heat absorbed by the human organ. In this viewpoint, preliminary results of the absorbed electromagnetic energy due to heat transfer in biological tissues of adult and child brains are reported in this Special Issue through determining the specific absorption rate (SAR) of the high-energy incident plane waves. For this purpose, the thermal model of brain, based on the extended form of the bioheat transfer equation, is numerically solved using the technique of finite element method. Though the reported results are of the preliminary level, it is expected that the discussions would be greatly helpful in achieving more realistic scenarios with the incorporation of other parameters of brain affecting the radiation field. The discussion essentially lets one to give a thought on reducing the SAR to the extent of having healthy human lifestyle. Indeed, the SAR factor may be controlled by implementing split-ring resonator (SRR) in the antenna system – this is brought forward by Rosaline et al. through the design and analysis of SRR superstrates for patch antenna, the performance of which exhibits substantial reduction of the SAR upon the usage of human head tissues such as skin, fat, bone, dura, CSF, etc.
The exposure to precisely titrated strong electromagnetic radiations is common in the treatments of thyroid and cancer. However, proper design of antennas remains indispensable for obtaining such radiations. For the purpose of cancer treatments, impulse radiating antennas have been proved to be the most suitable in achieving picosecond electromagnetic impulse. This Special Issue of JEMWA incorporates investigation reporting the design of suitable antennas for non-invasive skin cancer treatments.
Since biological tissues interact with electromagnetic fields, these may fall into the category of frequency dispersive dielectric mediums. In this stream, wireless body area networks (WBANs), that operate in the 5−50 MHz frequency band, have been designed for specific environments. It is commonly accepted that the human body can act as wave propagation channel, the dispersive characteristics of which may be used in designing antennas for body-based applications. In light of this, antenna designs are taken up in this Special Issue that can control the effects of frequency dispersion and can be used for ultra wide-band medical technologies. Further, human body communication (HBC) is also a constituent of WBANs. While the human body acts as the (dispersive) transmission channel, achieving reliable transmission of biological signals over the HBC channels remains desirable. Such investigations are presented in one of the papers incorporated in this Special Issue of JEMWA evaluating the bit error rate and the maximum allowable data throughput performances, taking into account different modulation schemes.
In conclusion, the interaction between electromagnetic fields and biological systems has been of great diagnostic and therapeutic values – the theme that has been put forward in this Special Issue of JEMWA by some potential authors through their recent research reports. We are hopeful of finding the papers interesting and useful for further research progress in the relevant fields.
Joint Editors-in-Chief