Body Talk Gets Sweaty

By Lindsey Nield

Being prodded and probed at the doctors might soon become a thing of the past. Scientists have discovered a way to measure your pulse and blood pressure from over 20 cm away from your body.

The advance was made thanks to a chance discovery. Researchers from the University of Jerusalem were investigating the internal structure of the skin using a technique called optical coherent tomography. The images they produced gave a surprising picture of the sweat ducts. These tubes, which conduct sweat from the glands to the skin, are shaped like tiny coils rather than being straight as previously thought.

Helical shapes such as this are used for antennas in wireless communications and these clever investigators didn’t just think “oh look, it’s curly” but wondered whether the sweat ducts might act as an array of antennas themselves.

They decided to test this out by bouncing electromagnetic radiation off the skin of people’s palms. Using frequencies in the range of 75-110 GHz they found that the intensity of the reflected radiation depended strongly on the level of activity of the sweat system. In other words, it was different if measured in someone after they did strenuous exercise, than if they measured it in a subject who just sat relaxing and laughing at the sweaty guy.

They further discovered that if they monitored the signal whilst a subject relaxed after physical activity it strongly correlated to changes in blood pressure and pulse rate measured at the same time. They were able to detect this at the skin surface and then at a distance of 22 cm from the subject.

The research, published in The Physical Review Letters, is still in its initial stages but the researchers envision some impressive applications for their discovery. Apart from the medical benefits of being able to remotely monitor patients, the research could lead to a remote lie detector and have significant implications for the anti-terror and security fields. It sounds as though big brother may soon have a way to tell how we’re feeling. I wonder what George Orwell would make of it...

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