The device has been developed at the California Institute of Technology, and it works better than questionnaires and tests commonly used to measure stress levels.

Although stress is common to all humans (and animals as well), it is more difficult to objectively describe stress than one can imagine.

To a certain degree, this condition is subjective, so questionnaires rarely work and the tests used to determine stress levels are not only slow, but themselves can cause stress as well. A convenient and non-invasive way of detecting and measuring stress levels could significantly prevent it, or enable immediate treatment. That’s exactly what the new sensor is able to do.

At the heart of the wireless device’s operation is a substance that plays a major role in the human body – cortisol, also called the stress hormone. Its presence is easy to detect in sweat, which is what the sensor does.

Astronaut on the grass

A plastic sheet is engraved with laser etching so that it acquires a three-dimensional graphene structure with tiny pores through which the sweat can be analyzed. The amount of cortisol contained in the sweat is then transmitted wirelessly within just a few minutes to a device such as a smartphone. In contrast, a blood test for cortisol can take more than an hour, and the results can be distorted due to the stress associated with the blood sampling.

The results from the sensor are not yet accurate enough as there is no clear relationship between cortisol levels and the presence of stress. The data should be compared to a “baseline” circadian rhythm of the user, which should mark the rise and fall of the cortisol level during the day. Only when the results deviate from that baseline can the presence of stress can be registered.

The non-invasive and remote properties of such a wireless sweat sensor can be used to monitor patients on Earth. NASA seems very interested in the work that Wei Gao, Assistant Professor of Medical Engineering, and his partners are doing at the California Institute of Technology. The benefits of such a sensor for living in space cannot be underestimated, especially when direct testing and medical assistance is virtually impossible in remote locations.