2021 Fiscal Year Research-status Report
Human sweat ducts as helical antenna: Prospects for practical applications
| Project/Area Number |
21K04174
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| Research Institution | Shizuoka University |
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Principal Investigator |
トリパティ サロジ 静岡大学, 工学部, 准教授 (20648729)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | terahertz / skin / sweat duct / helix |
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| Outline of Annual Research Achievements |
It was reported that the terahertz (THz) wave interacts with human skin at a certain frequency because of the presence of helical structured sweat duct in the epidermis. This frequency depends upon the morphological features of the sweat duct along with the dielectric properties of skin and sweat. Therefore, we studied dielectric properties of human sweat using THz time domain spectroscopy and we found that the real and imaginary part of sweat decreases with the increase in frequency.
Another part of this study is the measurement of the polarization sensitive reflectance of skin. Therefore, we developed polarizers made of a two-dimensional array of metallic helix, which produce both right and left circularly polarized THz wave based upon the winding of the helix used in the polarizer.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Our first objective of this project was to design a polarization sensitive THz time domain spectroscopy system. Therefore, we developed a circular polarizer made of metallic helix array that can produce either left or right circularly polarized THz wave. The frequency band of the circularly polarized wave cannot completely cover the possible frequency of resonance of the sweat duct. Therefore, we are optimizing the size of the metallic helix using electromagnetic wave simulation.
During the experiment, we noted that the dielectric properties of the sweat play an important role in THz wave interaction with skin. Therefore, we developed an attenuated total reflection spectroscopy system and measured the dielectric properties of the sweat in the frequency range of 200 GHz to 2.5 THz.
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| Strategy for Future Research Activity |
A fiber coupled terahertz time domain spectroscopy will be developed to conduct a polarization sensitive terahertz time domain measurement of human skin. Here, a polarizer made of metallic helix array will be used to produce circularly polarized terahertz wave. This experiment enables us to understand how left and right-handed circularly polarized wave interacts with skin and sweat duct. In the next step, some physiological signals such as heart rate and heart rate variability will also be measured using photoplethysmography while measuring the terahertz reflectance from the skin. The correlation between the terahertz reflectance and physiological signals will be investigated and the possibility to remotely sense the biophysical signal will be explored.
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| Causes of Carryover |
I planned to attend and present my research results in an international conference in September 2021, but it was not possible due to the current situation of Covid pandemic. Therefore, the budget allocated for the conference attendance remain unused. This budget will be used in 2022 to attend the national or international conference.
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