Labs Idea #11: Stress, Mood and Emotion Sensing
Wearables measuring stress, emotions and moods are an emerging trend. Autonomous driving and man machine interfaces require knowledge of the human being's emotional state or comfort feeling.
Mostly stress is measured with electrodermal activity (EDA), historically also know as Galvanic Skin Response (GSR), using electrodes to measure skin resistance.This electrical conductivity is tied to changes in moisture levels in the skin when the sweat glands are more active. Sweat glands are linked directly to our nervous system and body processes like our immune system, so EDA can help tap into information about our current physiological and psychological state or comfort feeling.
When our emotions are aroused, our body reacts. The heart beats faster, breathing can become heavier and you start to sweat more. That signals a change in the electrical conductivity of the skin and that's where EDA comes into action.
However, EDA measurements might vary subject to electrode skin contact and are not always conclusive.
A very sensitive relative humidity sensor can detect the perspiration level. Thus, it is possible to detect stress, mood or emotions by measuring directly the sweat evaporated from a human's Skin.
Sensirion's perspiration sensor is explained in the applications section of Sensirion's developers Website: https://developer.sensirion.com/applications/perspiration/
The perspiration was compared to pulse wave velocity (PWV), an indirect measurement method of blood pressure, which is also an indicator of stress.
To suppress activity induced sweat rate effects, the perspiration measurement was conducted during a night's sleep.
Perspiration during night sleep increases with dream induced stress and correlates well with increased pulse wave velocity, which correlates to increased blood pressure due to stress (figure 1).
The measurement results demonstrate that Sensirion's perspiration sensor can detect stress as a function of sweat rate.
- Sensirion's relative humidity sensor can detect the sweat rate of a human being's skin
- Stress, mood or emotions can be derived from perspiration measurement
- Good signal-to-noise during sleep