CC BY
25THz-O-1
Sub-THz radiation of human skin under the influence of mental
stress
K.A. Baksheeva1, R.V. Ozhegov12, G.N. Goltsman12, N.V. Kinev3, V.P. Koshelets3, A. Kochnev4, N. Betzalel4, A. Puzenko4, P. Ben Ishai5 and Y. Feldman4
1 - Moscow Pedagogical State University, Moscow, 119991, Russia 2 - National Research University Higher School of Economics, Moscow, Russia 3 - Kotel'nikov Institute of Radio Engineering and Electronics of RAS, 125009, Moscow, Russia 4 - Department of Applied Physics, The Hebrew University of Jerusalem, Jerusalem, 9190401, Israel 5 - Department of Physics, Ariel University, Ariel, 40700, Israel
Main author email address: goltsman@mspu-phys.ru
In 2007, for the first time, an image of the sweat gland was obtained using optical coherence tomography [1], which showed that the apex of the sweat duct is a spiral. Later, in 2008, based on the geometric dimensions and since the channels are filled with a conductive liquid, it was suggested that the channels for sweat can function as helical antennas of the terahertz range with a low Q factor [2]. The experimental setup is based around a superconducting integrated receiver (SIR), which is being developed at the IRE RAS [3]. The SIR was used to measure the change in the brightness temperature of subject's skin under the influence of mental stress at 507 GHz. The obtained readings were compared with the readings of the traditionally used sensors of mental stress: the sensor of galvanic skin response (GSR) and heart pulse rate (PS).
The results are substantially different from the expected black body radiation signal of the skin surface. Figure 1 shows a histogram of the raw data 57ft (t) for 30 volunteers. The resulting distribution differs from the expected result and requires at least 5 Gaussian distributions to describe. Using a simulation model for the skin, we find that the sweat duct is a critical element. The simulated frequency spectra qualitatively match the measured emission spectra and show that our sub-THz emission is modulated by our level of mental stress. This opens avenues for the remote monitoring of the human state [4, 5].
Temperature [K]
302 304 306 308 310 312 314 316 318 320 322 324
800 600
U) |
°400 200 0
0.0004 0.0006 0.0008 0.0010 0.0012 0.0014 Signal Amplitude [V]
Fig.1. A histogram of raw SIR results for 30 subjects; measured at 507 GHz. The brightness temperature scale (upper axis) assumes an average room temperature of 297 K (24 °C). A minimum of 5 Gaussian distributions (labelled 1- red, 2- blue, 3- purple, 4- dark grey and 5 dark blue) are required to describe the histogram. Student t-testing reveals statistical significance only for the distributions 1,2 and 3. The broad distribution 1 is centered around the core temperature of the human body of 310 K (37 °C). The second and third Gaussians are situated 1 K lower and 2 K higher than body temperature, respectively.
[1] Lademann, J., Otberg, N., Richter, H., Meyer, L., Audring, H., Teichmann, A., Thomas, S., Knüttel, A., Sterry, W., Application of optical non-invasive methods in skin physiology: a comparison of laser scanning microscopy and optical coherent tomography with histological analysis, Skin Res. Technol. 13, 119-132 (2007)
[2] Yu. Feldman, A. Puzenko, P. Ben Ishai, A. Caduff and A. J. Agranat, Human skin as arrays of helical antennas in the millimeter and submillimeter wave range, Phys. Rev. Lett. 100, 128102-4 (2008).
[3] V. P. Koshelets and S. V. Shitov, Integrated superconducting receivers, Supercond. Sci. Technol., vol. 13, pp. R53-R69, 2000.
[4] Baksheeva K., Ozhegov R., Goltsman G., Kinev N., Koshelets V., Kochnev A., Betzalel N., Puzenko A., Ben Ishai P., Feldman Y., Dc humans "shine" in the sub THz?, in: 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz).
IEEE, 2019
