Tuesday, April 15, 2008

Tiny Antenna

Sweat ducts in human skin act like an array of tiny antennas that pick up radiation at specific frequencies, according to researchers. The finding might one day be used in medical and security technologies to assess a person's mental state from a distance.A team of researchers in Israel has shown that sweat ducts pick up radiation at frequencies of about 100 gigahertz — the so-called extremely high frequency or EHF range, lying between microwaves and terahertz radiation. The antenna behaviour is all down to the ducts' curious shape: they thread through the epidermis as regular helices. Filled with electrically conductive sweat, these channels act rather like coils of wire that absorb radiation across the millimetre and sub-millimetre wavelength band.
Yuri Feldman of the Hebrew University of Jerusalem and his colleagues directed a beam of EHF radiation onto the skin of the palms of subjects who had been jogging for 20 minutes, and measured the radiation that was reflected back. They found a strong band of absorption that was not seen before exercise.
The researchers note in a paper that the findings could serve as the basis for long-distance sensing technology that reads various physiological and emotional parameters, and could lead to the development of a variety of medical and security applications. (read more...)

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