New saliva tester licks existing stress-measuring methods

February 09, 2013

By SHINYA TAKAGI/ Staff Writer

Researchers have developed a device that measures a person's stress levels by spinning a saliva sample in a mini centrifuge to separate out cortisol, a hormone that rises and falls with stress.

The device is the work of Rohm Co., a Kyoto-based semiconductor maker, which collaborated with a team led by Masaki Yamaguchi, a professor of biomedical engineering at Iwate University's Faculty of Engineering.

A saliva sample is placed on a test chip, which is then inserted into the measuring device. It spins at high speed and separates the cortisol from the rest of the saliva by filtering it through a fine tube less than 100 nanometers in diameter.

A reagent is subsequently added to make the cortisol emit light. A calibrated scale lets an analyst determine stress levels from the intensity of the emitted light.

The entire test takes only 10 minutes, and uses a device 25 centimeters in size and weighing 5 kilograms.

In the past, stress tests have typically measured amylase, a digestive enzyme found in saliva. However, it is difficult to measure amylase levels accurately because they can vary significantly under momentary, transient stress.

On the other hand, cortisol is a more dependable indicator of stress. It exists in blood and saliva, but only in small amounts and does not respond easily to reagents. This means traditional cortisol tests have typically taken four to five hours to complete.

The researchers said they hope to conduct further work on the device to bring it to a high level of accuracy. Their aim is to make it able to determine stress levels with only a single measurement.

They foresee it being ready for commercial production in fiscal 2017.

By SHINYA TAKAGI/ Staff Writer
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The saliva tester can determine stress levels in 10 minutes, faster and potentially more accurately than traditional methods. (Provided by Rohm Co.)

The saliva tester can determine stress levels in 10 minutes, faster and potentially more accurately than traditional methods. (Provided by Rohm Co.)

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  • The saliva tester can determine stress levels in 10 minutes, faster and potentially more accurately than traditional methods. (Provided by Rohm Co.)
  • Masaki Yamaguchi poses with a stress level measurement gauge that he co-developed with Rohm Co., in Morioka, Iwate Prefecture, on Jan. 7. (Shinya Takagi)

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