Washington, April 3 : A new proof-of-concept may lay the foundation for lie detection tests wherein investigators will be able to remotely monitor blood pressure, pulse rate, and sweating among people without their knowledge or consent.
Experts at the Hebrew University of Jerusalem say that the shape of sweat ducts, the tiny tubes that connect sweat glands to the outside of the skin, is similar to that of some antennas.
According to them, the wavelength at which human sweat glands interact falls in the sub-terahertz (T-ray) range, which has recently been used in a variety of other applications, from uncovering hidden artwork to finding concealed weapons.
While sweating does not produce T-rays, sweat production changes the wavelength that is bounced back off the sweat duct antenna.
Designing a machine capable enough to measure these wavelengths, surmise the researchers, it may be calculated how much and where a person is sweating.
The researchers have also shown that monitoring the kinds of sweating based on where a person is sweating - such as on the forehead or on the chest and back - may make it possible to measure blood pressure and pulse rate remotely.
Currently, the only way to measure blood pressure is by using an inflatable pressure cuff or a surgically implanted monitor, and the only way to measure sweat is through a cumbersome process that uses electrodes on a small portion of skin.
The researchers say that the new method can do both remotely and constantly.
"This could open up a whole new area of research," Discovery News quoted James Wolff, a doctor at Emerson Hospital in Concord, Massachusetts, who was not associated with the study.
As to how useful such a system can be for conducting lie detection tests, the researchers said that trained professionals could evade polygraphs made on the basis of their physiological responses like faster pulse, higher blood pressure, and increased sweating; however, if a person does not know they are being constantly tested, the new method could be more effective.
Jonathan Marks, a professor of bioethics at Pennsylvania State University, said that lie detection using this method would still have problems with accuracy, as a people anxious over something else at the time of tests could trigger a false positive.
"There are concerns about people's privacy. Is there a justification for screening people en masse for physiological data? Where would you do this?" said Marks.